Escherichia coli

Mol Gen Genet, 1979 Jun 20, 173(3), 345 - 7
Decreased transfer of pyrimidine dimers from parental to daughter DNA strands in UV-irradiated Escherichia coli deficient in DNA polymerase III; Tomilin NV et al.; The number of pyrimidine dimers (sites sensitive to UV-endonuclease from M . luteus) transferred at 43 degrees to daughter DNA strands during postreplication repair in UV-irradiated E . coli uvr A polCts was found to be decreased as compared to that after repair at 32 degrees . This indicates the involvement of DNA polymerase III in the sister DNA recombination in UV-irradiated E . coli.

Mol Gen Genet, 1979 Jun 20, 173(3), 333 - 8
Studies of colicin induction with an imm- col+ mutant of the plasmid colicin E1; Inselburg J; A mutant of a derivative of the colicin E1 plasmid has been isolated that does not confer immunity to colicin E1 on its host (imm-) although it is still capable of producing colicin (col+) . Cells carrying the col+, imm- plasmid are capable of forming colonies and grow best in liquid culture in the presence of trypsin . The induction of colicin synthesis by ultraviolet light has been analysed using this mutant plasmid . The results suggest that a) the expression of the col+ gene may be delayed for many generations after the inducing stimulus, b) although induced cells are usually killed they can reproduce and c) the capacity to produce colicin can be propagated and segregated into the progeny of an induced cell.

Mol Gen Genet, 1979 Jun 20, 173(3), 323 - 31
Regulation of the L-arabinose operon in strains of Escherichia coli containing ColE1-ara hybrid plasmids; Wallace LJ et al.; Hybrid plasmids were constructed from fragments of F'ara episomes formed by the restriction endonuclease EcoRI and a linear form of the plasmid ColE1 created by cleavage with EcoRI . Hybrid plasmids were constructed containing the entire ara region or the ara region with various parts deleted . E . coli K12 host strains were constructed which contained different deletions of the ara region . The hybrid plasmids were transferred to those strains whose ara deletion complemented that of the plasmid . The initial differential rates of synthesis of L-arabinose isomerase, the product of the araA gene, were determined for the Ara+, plasmid containing strains . These studies demonstrated that strains containing delta(araOIBA)718 produce elevated levels of araC protein, suggesting the araC promoter has been altered by this deletion . Evidence is also presented which suggests that araC protein activates the ara-BAD operon to higher levels when it is present in cis rather than trans . Amplification of the products of the cloned genes is observed when compared to haploid levels in some cases.

Mol Gen Genet, 1979 Jun 20, 173(3), 339 - 43
Expression of the lac operon in RNA polymerase mutants of Escherichia coli K12; Mandecki W et al.; Three temperature-sensitive mutant strains for RNA polymerase beta or beta' subunits (carrying mutations tsx, A2R7 and R120) were used in order to investigate the dependence of the induced lac expression on stimulation by cyclic AMP after the shift to non-permissive temperature . High temperature lowered the rate of beta-galactosidase synthesis . However, the low rate of synthesis could be strongly increased by cyclic AMP (30, 2.4 and 5.7-fold increases for tsX, A2R7 and R120 mutants, respectively) . At the permissive temperature stimulation by cyclic AMP was less than 1.4-fold (minimal medium supplemented with glycerol) . The results suggest that the maximal expression of the lac operon is saturated, that is, a hypothetical increase in RNA polymerase or cAMP-CRP concentration in the cell with not enhance the expression . The concept of saturation explains why it was possible to increase the beta-galactosidase synthesis in conditions of limited promoter binding activity of RNA polymerase through increase in concentration of cyclic AMP-CRP complex in the cell (addition of cyclic AMP) to the values higher than that observed on glycerol.

Biochim Biophys Acta, 1979 Jun 19, 578(2), 365 - 71
Shape of proteins S3 and S17 from the small subunit of Escherichia coli ribosome; Franz A et al.; The shapes of proteins S3 and S17 purified from the 30 S subunit of Escherichia coli A19 were studied by hydrodynamic methods . The proteins have s020,w values of 2.1 +/- 0.1 S and 1.2 +/- 0.1 S and D020,w values of 7.4 +/- 0.5 . 10(-7) cm2/s and 11.4 +/- 0.6 . 10(-7) cm2/s . The respective molecular weights determined by sedimentation equilibrium are 25 800 +/- 500 and 9900 +/- 300 . The intrinsic viscosity values for the two proteins are 5.8 +/- 0.3 ml/g and 4.2 +/- 0.2 ml/g . From these hydrodynamic parameters a slightly elongated shape for S3 and a globular shape for S17 have been concluded.

Biochim Biophys Acta, 1979 Jun 19, 578(2), 337 - 45
Quaternary structure of DNA-dependent RNA polymerase from Escherichia coli . Measurement of distances by fluorescence energy transfer; Stender W et al.; Distances between the subunits in Escherichia coli RNA polymerase (core and holo enzyme) and the rifamycin binding site have been determined using the nonradiative energy transfer technique . The appropriate donor and acceptor labels have been chosen in order to optimize the spectral overlap and maximize the energy transfer . Spacer linked derivatives of rifamycin SV possessing nitrobenzo-oxadiazole groups (energy acceptor) were synthesized for this purpose . The donor label, acetylaminoethylaminonaphthalene sulfonate, was introduced into the intact enzyme, and the subunits were separated . Enzyme molecules selectively labelled on one kind of subunit were produced by mixed reconstitution techniques employing labelled and non labelled subunits . The labelled beta'-subunit could not be prepared in sufficient amounts . Energy transfer distances between the enzyme-bound rifamycin derivative and the subunits were determined to be approximately 5.9 nm for sigma, 7.2 nm for alpha 2 and 6.1 nm for beta.

Biochemistry, 1979 Jun 12, 18(12), 2632 - 6
Biosynthesis of the pyrimidine moiety of thiamin in Escherichia coli: incorporation of stable isotope-labeled glycines; White RH et al.; Methods are described for the cleavage, extraction, and subsequent gas chromatographic-mass spectrometric analysis of the pyrimidine moiety of thiamin as 2-methyl-4-amino-5-{(ethylthio)methyl}pyrimidine . The methods are of a general nature and can be applied to any system . Using these methods to evaluate the incorporation of 13C-, 15N-, and 2H-labeled glycines into the pyrimidine moiety of thiamin by Escherichia coli, we established that the nitrogen and carbon atoms of glycine are incorporated as a unit into the pyrimidine . 13C- and 15N-labeled glycines are incorporated at greater than 60% but deuterium from {2-(2)H2}glycine was incorporated at only 18% . A detailed analysis of the mass fragmentation pattern of the pyrimidine derivative has established that the glycine nitrogen atom supplies the N-1 of the pyrimidine and that the C-1 and C-2 of the glycine supplies the C-4 and C-6 of the pyrimidine, respectively . This evidence is consistent with the substitution of a C2 unit between the C-5 and C-4 of the 4-aminoimidazole ribonucleotide precursor during the biosynthesis of the pyrimidine moiety of thiamin in E . coli.

Biochemistry, 1979 Jun 12, 18(12), 2520 - 5
Shapes of proteins L1, L9, L25, and L30 from the 50S subunit of the Escherichia coli ribosome, determined by hydrodynamic studies; Giri L et al.; Proteins L1, L9, L25, and L30, purified by a nondenaturing method from the 50S ribosomal subunit of Escherichia coli A19, have been characterized . The four proteins were studied under conditions which resemble those used for reconstitution experiments . These proteins have S020,W values of 2.0 S, 1.8 S, 1.8 S, and 1.0 S and D20,W values of 8.4 X 10(-7), 9.0 X 10(-7), 14.0 X 10(-7), and 15.0 X 10(-7) cm2/S . Apparent specific volumes at 20 degrees C are 0.738, 0.733, 0.700, and 0.735 mL/g for the four proteins . The respective molecular weights determined by sedimentation equilibrium are 25 000, 17 300, 12 000, and 6500 . The intrinsic viscosity values for the four proteins are 4.0, 5.5, 3.6, and 3.2 mL/g . From these hydrodynamic parameters L1 and L9 appear to have globular or at most only slightly elongated shapes, whereas L25 and L30 appear to be definitely globular.

Nucleic Acids Res, 1979 Jun 11, 6(7), 2611 - 26
1H NMR studies on the conformational characteristics of 2-thiopyrimidine nucleotides found in transfer RNAs; Yokoyama S et al.; The molecular conformations of naturally occurring 2-thiopyrimidine nucleosides (5-methylaminomethyl-2-thiouridine, 5-methoxycarbonylmethyl-2-thiouridine and 2-thiocytidine) and 5'-mononucleotides (5-methylaminomethyl-2-thiouridine 5'-monophosphate and 2-thiocytidine 5'-monophosphate) in 2H2O solution were elucidated by analyses of the proton NMR spin-coupling constant, nuclear Overhauser effect, and lanthanide-induced shifts and relaxation enhancements . As monomers, these nucleotides are almost exclusively in the 3E-gg-anti form, even in the absence of ordinary stabilizing factors of this form; i . e., base-stacking and base-pairing interactions with other nucleotide units . This inherent conformational rigidity of the 2-thiopyrimidine units probably contributes to stability of the conformation of tRNA.

Nucleic Acids Res, 1979 Jun 11, 6(7), 2583 - 99
Studies on gene control regions X . The effect of specific adenine-thymine transversions on the lac repressor-lac operator interaction; Sista HS et al.; Chemical and enzymatic methods were used to synthesize a transition (AT to GC) and a transversion (AT to TA) at a lac operator site known to interact with lac repressor through the thymine 5 methyl group . These operators also contained a poly(dA) . poly(dT) tail 8 to 12 base pairs in length at one end . Results suggest that the steric constraints of lac repressor relative to the position of the 5 methyl group are quite critical . For example a seven fold reduction in stability was observed for the transversion . Results also suggest that the operator spans at least 21 base pairs.

Nucleic Acids Res, 1979 Jun 11, 6(7), 2569 - 82
Rapid chemical synthesis and circular dichroism properties of some 2'-5'-linked oligoriboadenylates; Markham AF et al.; Specific synthesis of some oligoadenylates including A2'p5'A2'p5'Ap(2'), the 2'-phosphorylated oligoribonucleotide core of the recently discovered protein synthesis inhibitor pppA2'p5'A2'p5'A is described using a novel solid-phase method . The CD spectra of A2'p5'Ap(2'), A2'p5'A2'p5'Ap(2') and A2'p5'A2'p5'A (derived by treatment of the phosphorylated synthetic trimer with E . coli alkaline phosphatase) are presented . Comparison of the latter spectrum with that of A2'p5'A2'p5'A obtained similarly from a biologically derived sample of pppA2'p5'A2'p5'A provides further evidence that this molecule is in fact the first naturally-occurring 2'-5'-linked oligoribonucleotide.

Nucleic Acids Res, 1979 Jun 11, 6(7), 2483 - 97
The use of R-looping for structural gene identification and mRNA purification; Woolford JL Jr et al.; A method is presented for the purification of mRNAs and the identification of structural gene sequences in recombinant DNA molecules . RNA is hybridized to double-stranded linear DNA such that R-loops are formed between most DNAs and their complementary RNA sequences . These R-loops are purified from unhybridized RNAs by gel filtration chromatography in the presence of a high concentration of salt . The complementary RNAs are released from the R-loops by heating, and are assayed by gel electrophoresis or cell free translation to determine their purity and to identify the proteins for which they code . We have demonstrated that recombinant DNAs containing sequences for abundant or moderately abundant mRNAs of Saccharomyces cerevisiae can be identified by this means.

Nucleic Acids Res, 1979 Jun 11, 6(7), 2453 - 70
A ribonuclease-resistant region of 5S RNA and its relation to the RNA binding sites of proteins L18 and L25; Douthwaite S et al.; An RNA fragment, constituting three subfragments of nucleotide sequences 1-11, 69-87 and 89-120, is the most ribonuclease-resistant part of the native 5S RNA of Escherichia coli, at 0 degrees C . A smaller fragment of nucleotide sequence 69-87 and 90-110 is ribonuclease-resistant at 25 degrees . Degradation of the L25-5S RNA complex with ribonuclease A or T2 yielded RNA fragments similar to those of the free 5S RNA at 0 degrees C and 25 degrees C; moreover L25 remained strongly bound to both RNA fragments and also produced some opening of the RNA structure in at least two positions . Protein L18 initially protected most of the 5S RNA against ribonuclease digestion, at 0 degrees C, but was then gradually released prior to the formation of the larger RNA fragment . It cannot be concluded, therefore, as it was earlier (Gray et al., 1973), that this RNA fragment contains the primary binding site of L18.

J Biol Chem, 1979 Jun 10, 254(11), 4698 - 706
Purification and characterization of protease III from Escherichia coli; Cheng YS et al.; An endoproteolytic enzyme of Escherichia coli, designated protease III, has been purified about 9,600-fold to homogeneity with a 6% yield . The purified enzyme consists of a single polypeptide chain of Mr 110,000 and is most active at pH 7.4 . Protease III is very sensitive to metal-chelating agents and reducing agents . The EDTA-inactivated enzyme can be reactivated by Zn2+, Co2+ or Mn2+ . Protease III is devoid of activity toward aminopeptidase, carboxypeptidase, or esterase substrates but rapidly degrades small proteins . When fragments of beta-galactosidase are used as substrates for protease III, the enzyme preferentially degrades proteins with molecular weights of less than 7,000 . Protease III cleaves the oxidized insulin B chain at two sites with an initial rapid cleavage at Tyr-Leu (16-17) and a second slower cut at Phe-Tyr (25-26).

J Biol Chem, 1979 Jun 10, 254(11), 4309 - 12
Characterization of a mutant form of ribosomal protein S1 from Escherichia coli; Subramanian AR et al.; An altered form of ribosomal protein S1 from a mutant of Escherichia coli has been isolated and characterized . The mutant protein (denoted m1-S1) has a molecular weight of 57,000 as shown by sodium dodecyl sulfate-gel electrophoresis and the same NH2-terminal sequence as wild type S1 . Protein m1-S1 binds poly(U) in the same manner as protein S1 and is active in protein synthesis with either synthetic or natural mRNA . Thus, about 75% of the sequence of protein S1 (which includes the NH2-terminal region) contains essentially all the functional domains of this protein involved in protein biosynthesis.

Mol Gen Genet, 1979 Jun 7, 173(2), 217 - 20
Deletions, insertions and rearrangements affecting rpoB gene expression; Collins J; Through cloning and deletion experiments on ColEl hybrids the rpoB gene (Rifr) was located on a physical restriction map; RNA polymerase binding studies showed no binding site within the structural gene . The genetic data and RNA polymerase binding studies lead to the conclusion that rp/L and rpoB are dependent upon a common promoter.

Mol Gen Genet, 1979 Jun 7, 173(2), 197 - 201
Restriction enzyme analysis of the plasmid ColIb DNA; Skorupska A et al.; Plasmid ColIb (61.5 Mdal) was digested with restriction enzymes EcoRI and HindIII . The DNA digestion products were separated by electrophoresis on 1.2% agarose gels . There were identified 22 fragments of ColIb DNA generated by the endonuclease EcoRI and 21 fragments produced by HindIII . Molecular weights of the fragments were estimated . The total molecular weight of the fragments generated by EcoRI was 61.42 Mdal and for HindIII fragments 62.79 Mdal.

Mol Gen Genet, 1979 Jun 7, 173(2), 183 - 7
Post-translational modification of Escherichia coli ribosomal protein S6; Reeh S et al.; Escherichia coli has multiple forms of ribosomal protein S6, differing in number of glutamyl resideus at the C-terminal end . Three forms are revealed when crude cell extracts are fractionated by a two-dimensional gel electrophoresis technique . Pulse-chase experiments show that the shortest and most alkaline form of S6 is the first to appear . In about one doubling time this form reaches equilibrium with the two other forms of S6, implicating the existence of an enzyme, which adds glutamic acid residues to S6 . We show that the relative levels of these three S6 forms are not affected by the growth rate of the culture.

Nature, 1979 Jun 7, 279(5713), 494 - 500
Unusual location and function of the operator in the Escherichia coli galactose operon; DiLauro R et al.; The operator of the gal operon is located about 60 base pairs preceding the startpoints of the transcription of the two gal promoters . This location contrasts with the location of the operator in other phage or bacterial operons where the repressor binds more closely to the respective transcription initiation sites . Models explaining how the repressor-operator interactions may control the two gal promoters are presented.

Nature, 1979 Jun 7, 279(5713), 492 - 4
Modulation of the two promoters of the galactose operon of Escherichia coli; Adhya S et al.; The gal operon of Escherichia coli is controlled by two independent promotors--one is activated and the other inhibited by cyclic AMP and cyclic AMP receptor protein . The two promotors are modulated, however, by the same operator locus and receptor protein.

Mol Gen Genet, 1979 Jun 7, 173(2), 189 - 96
Origin and binding specificity of protein(s) coded for by Mu prophages; Schumann W et al.; Crude extracts of bacteria lysogenic for temperature phage Mu contain proteins that retain specifically Mu DNA on nitrocellulose filters . The amount of binding protein is directly proportional to the number of Mu prophages per E . coli genome . Specificity of the binding reaction could be demonstrated by using heterologous DNAs as substrate and by a competition experiment . By using hybrid plasmids containing different amounts of the immunity end and extending to various degrees into MuDNA, it was found that the binding activity is coded for by the left 1,000 nucleotide-pair HindIII fragment . When using these hybrid plasmids as binding substrate, two different binding sites for the immunity product were detected . Joining of the MucI gene to the left lambda early promoter resulted in increased production of immunity protein at elevated temperature . A possible explanation for the relatively low amounts of immunity protein in all of the different strains studied is discussed.

Biochim Biophys Acta, 1979 Jun 6, 568(2), 467 - 74
Enzyme-enzyme interaction and the biosynthesis of aromatic amino acids in Escherichia coli; Powell JT et al.; The technique of affinity chromatography has been used to demonstrate that enzymes involved in the biosynthesis of tyrosine and phenylalanine in Escherichia coli undergo reversible interactions . Thus it has been shown that the aromatic amino acid aminotransferase (aromatic-amino-acid: 2-oxoglutarate amino-transferase, EC 2.6.1.57) reacts specifically with chorismate mutaseprephenate dehydrogenase (chorismate pyruvate mutase, EC 5.4.99.5 and prephenate: NAD+ oxidoreductase (decarboxylating), EC 1.3.1.12) in the absence of reactants and with chorimate mutase-prephenatedehydratase (prephenate hydro-lyase (decarboxylating), EC 4.2.1.51) in the presence of phyenylpyruvate . Tyrosine causes dissociation of the aminotransferase: mutasedehydrogenase complex while dissociation of the aminotransferase-mutasedehydratase complex occurs on omission of phenylpyruvate . Only the active form of chorismate mutase-prephenate dehydrogenase participates in complex formation.

Biochim Biophys Acta, 1979 Jun 6, 568(2), 428 - 36
The purification of glutamine synthetase from Azotobacter and other procaryotes by blue sepharose chromatography; Lepo JE et al.; We report the facile purification of glutamine synthetase (L-glutamate: ammonia ligase (adenosine 5'-diphosphate-forming), EC 6.3.1.2) in both the adenylylated and unadenylylated form, from Azotobacter vinelandii ATCC 12837 . A general affinity column, which used as an affinity ligand Reactive blue 2 dye (Cibacron blue) covalently linked to Agarose, was employed as an efficient first step of purification . Further purification to electrophoretic homogeneity employed DEAE-cellulose chromatography and an additional Affigel chromatographic step . The method was used successfully to prepare glutamine synthetase from Escherichia coli, Rhodopseudomonas sphaeroides and Anabaena sp . strain CA.

Vet Rec, 1979 Jun 2, 104(22), 496 - 500
Intestinal defence of the neonatal pig: interrelationship of gut and mammary function providing surface immunity against colibacillosis; Chidlow JW et al.; The neonatal requirements for maternal passive immunity and the lactation immunobiology with regard to sow immunisation for neonatal protection are reviewed . A vaccination protocol which combines oral and parenteral antigen administration to produce antibody activity mediated mainly by IgM is described . Its efficacy in affording protection to neonatal piglets was tested against a lethal oral infection with a virulent strain of Escherichia coli "Abbottstown" . Piglets suckled on vaccinated or non-vaccinated sows were exposed to an infective challenge in the gastrointestinal tract and the relative pathology in test and control groups observed over the neonatal period . Death ensued in 76 per cent of piglets suckled on control sows and 26 per cent of piglets suckled on sows vaccinated by two intramuscular injections . Litters suckled on orally vaccinated sows were able to resist a similar infective challenge, there being only one fatality out of 42 piglets.

Cancer Treat Rep, 1979 Jun, 63(6), 1073 - 9
L-cyst(e)ine requirements of malignant cells and progress toward depletion therapy; Uren JR et al.; The L-cyst(e)ine requirements of normal and malignant cells are reviewed and expanded within the context of establishing whether the measurement of gamma-cystathionase levels constitutes a predictive test for tumor sensitivity to L-cyst(e)ine depletion . The ability of both purified L-cysteine desulfhydrase and gamma-cystathionase to inhibit the growth of the L-cystine-dependent L1210 leukemia in culture is presented, as well as approaches to circumvent the limitations of these enzymes for in vivo therapy . The ability of proparagylglycine to inhibit L-cysteine biosynthesis in vivo is reviewed for its possible use in combination therapy . In addition, the ability of poly D,L-alanine modification of Escherichia coli L-asparaginase to increase the plasma half-life in mice tenfold as well as to decrease the immunogenicity of the enzyme is presented.

Tsitologiia, 1979 Jun, 21(6), 722 - 9
{Photoreactivation of cells and phages injuried by ultraviolet radiation in the ecological long-wave band}; Samoilova KA et al.; Photoreactivation (PR) was measured after inactivation by far (254 nm), middle (300-315 nm) and near (315-400 nm) UV radiation of Paramecium caudatum and 8 strains of Escherichia coli differing in PR and dark repair capability . PR volume was high and practically the same after irradiation by far and middle UV, but PR was not observed in near UV-inactivated cells of all the strains . It is proposed that pyrimidine dimers are not significant in near UV lethal lesions in cells, as near UV-irradiated phages (T7 and lambdacI 857) are not photoreactivated in undamaged host bacterial cells.

Zentralbl Bakteriol {Orig A}, 1979 Jun, 244(1), 90 - 104
Colicin receptors and the mechanisms of colicin uptake; Kadner RJ et al.; This review deals in detail with the nature, synthesis, physiologic functions, and the regulation of colicin receptors, which represent components of transportsystems, as well as with the two mechanisms of the colicin uptake within the groups A and B of colicins.

Zentralbl Bakteriol {Orig A}, 1979 Jun, 244(1), 78 - 89
The concept of bacteriocins; Reeves P; After a short description of the discovery of bacteriocins, especially the colicins in this review the following points are discussed: the classification of colicins especially with the aid of resistant mutants of sensitive indicator strains, the bacteriocin-receptors, the bacteriocin-specificity, and the possible ways of transport of colicins across the outer membrane.

Zentralbl Bakteriol {Orig A}, 1979 Jun, 244(1), 105 - 20
Mode of action of colicins Ia, E1 and K; Konisky J et al.; Addition of colicins Ia, E1 or K to sensitive Escherichia coli leads to inhibition of macromolecular synthesis and an uncoupling of electron transport from active transport . Recent results indicate that these colicins affect energy metabolism by interacting directly with the cytoplasmic membrane . This results in a transmembrane flow of ions leading to membrane depolarization . It is proposed that the function of the outer membrane colicin receptor is to mediate access of the colicin molecule to the cytoplasmic membrane.

Rev Can Biol, 1979 Jun, 38(2), 97 - 9
{Localization of a gene responsible for ozone sensitivity in Escherichia coli}; Cotes G et al.; A gene, ozrC, responsible for sensitivity to ozone in Escherichia coli, was localized on the E . coli chromosome between argEH and metA by means of analysis of cotransduction frequencies of the gene ozrC with certain gene markers in the malB region of the chromosome.

Pediatr Res, 1979 Jun, 13(6), 737 - 41
The effect of human colostrum on neutrophil function; Bjorksten B et al.; Strains of Escherichia coli were opsonized in human colostrum via heat stable opsonins and the classic complement pathway, but colostrum lacked capacity to opsonize E . coli via the alternative pathway . There was no bacteriostatic activity against serum sensitive E . coli strains, although specific antibodies against the strains were present . Neutrophils suspended in colostrum had normal chemotaxis and this was not altered by treating the colostrum with HCl.

J Gen Microbiol, 1979 Jun, 112(2), 321 - 8
Location of binding sites on common type 1 fimbriae from Escherichia coli; Sweeney G et al.; Common type 1 fimbriae were isolated from Escherichia coli and their length distribution profile was determined before and after treatment with ultrasound . As fimbriae were shortened, so their haemagglutinating capacity decreased, but their ability to bind to erythrocytes did not decrease to the same extent . Isolated fimbriae did not agglutinate inside-out vesicles prepared from horse erythrocytes or liposomes, suggesting that the binding mechanism was not based on non-specific hydrophobic interactions . The results support a lateral rather than a terminal location for the fimbrial binding site responsible for haemagglutination.

Eur J Biochem, 1979 Jun, 97(1), 23 - 8
Peptide bond formation stimulated by protein synthesis factor EF-P depends on the aminoacyl moiety of the acceptor; Glick BR et al.; Elongation factor EF-P is a soluble protein that stimulates peptide bond synthesis catalyzed by the 50-S ribosomal subunit . This factor was previously identified and characterized based on its ability to promote the synthesis of formylmethionine-puromycin . In the present work, we tested the ability of EF-P to promote peptide bond synthesis between ribosome-bound fMet-tRNA and several analogues of the 3' terminus of aminoacyl-tRNA, i.e . the cytidylyl(3'-5')-{2'(3')-O-L-aminoacyladenosines} . EF-P promoted synthesis to the greatest extent with certain acceptors which were otherwise inefficient in the peptidyl transferase reaction . This activity of EF-P could not be replaced by the other soluble proteins known to be involved in polypeptide synthesis, such as EF-Tu, EF-Ts and EF-G . One role of EF-P in protein synthesis may be to allow peptide bond synthesis to occur more efficiently with some aminoacyl-tRNAs that are poor acceptors for the ribosomal peptidyl transferase.

Can J Genet Cytol, 1979 Jun, 21(2), 213 - 21
Lethal zygosis in recombination-deficient mutants of Escherichia coli; Nestmann ER; Use of nonselective medium for plating cells following mating has revealed that Rec recipient strains of E . coli may be killed as a result of conjugation . Sensitivity of RecA-, RecB-, and RecC- recipients increases with ratio of donor: recipient cells in mating mixtures and with time of mating . A Rec+ recipient shows no lethal zygosis in these experiments performed without aeration . Cell contact does not seem to be responsible for the sensitivity of Rec- strains, since lethality is prevented when cell contact is permitted but DNA transfer is not . Thus, an event(s) occuring subsequent to entry of donor DNA appears to cause lethality in Rec- recipients.

Can J Biochem, 1979 Jun, 57(6), 834 - 42
Elucidation of the quaternary structure of reversibly immobilized alkaline phosphatase derivatives; McCracken S et al.; Escherichia coli alkaline phosphatase has been reversibly immobilized on Sepharose CL-4B through two different methods, both based on a disulfide linkage, under conditions selected to favour the coupling of the enzyme to the solid support through one covalent linkage . The quaternary structure of the reversibly immobilized subunit, produced by dissociation of the matrix-bound dimer, was examined by cross-linking with the bifunctional reagent dimethyl suberimidate . Following release from the solid support, the protein was analysed by sodium dodecyl sulfate gel electrophoresis demonstrating the presence of a sufficient amount of dimeric structures in the immobilized subunit preparation to account for all the enzyme activity observed in this sample . These results suggest that the subunit of alkaline phosphatase may be catalytically inactive . This approach to studying the quaternary structure of immobilized subunit derivatives offers the opportunity to directly determine the homogeneity and structure of matrix-bound 'monomer' preparations and is particularly useful in determining if low levels of catalytic activity observed in some immobilized subunit populations are due to the presence of contaminating oligomeric structures.

Can J Biochem, 1979 Jun, 57(6), 813 - 21
Purification and characterization of membrane-bound fumarate reductase from anaerobically grown Escherichia coli; Dickie P et al.; Fumarate reductase has been purified 100-fold to 95% homogeneity from the cytoplasmic membrane of Escherichia coli, grown anaerobically on a defined medium containing glycerol plus fumarate . Optimal solubilization of total membrane protein and fumarate reductase activity occurred with nonionic detergents having a hydrophobic-lipophilic balance (HLB) number near 13 and we routinely solubilized the enzyme with Triton X-100 (HLB number = 13.5) . Membrane enzyme extracts were fractionated by hydrophobic-exchange chromatography on phenyl Sepharose CL-4B to yield purified enzyme . The enzyme whether membrane bound, in Triton extracts, or purified, had an apparent Km near 0.42 mM . Two peptides with molecular weights of 70 000 and 24 000, predent in 1:1 molar ratios, were identified by sodium dodecyl sulfate polyacrylamide slab-gel electrophoresis to coincide with enzyme activity . A minimal native molecular weight of 100 000 was calculated for fumarate reductase by Stephacryl S-200 gel filtration in the presence of sodium cholate . This would indicate that the enzyme is a dimer . The purified enzyme has low, but measurable, succinate dehydrogenase activity.

Can J Biochem, 1979 Jun, 57(6), 798 - 805
Aspartate transcarbamoylase: loss of homotropic but not heterotropic interactions upon modification of the catalytic subunit with a bifunctional reagent; Chan WW et al.; The role of conformational changes in the allosteric mechanism of aspartate transcarbamoylase from Escherichia coli was studied by reacting the isolated catalytic subunit with the bifunctional reagent tartryl diazide . Two derivatives differing moderately in substrate affinity were obtained depending on whether the reaction was conducted in the presence or absence of the substrate analogue succinate and carbamoyl phosphate . The modification was not accompanied by aggregation or dissociation . The modified catalytic subunits retained the ability to reassociate with unmodified regulatory subunits and produced hybrids similar in size to the native enzyme . These hybrids were appreciably sensitive to the allosteric effectors ATP and CTP but unlike native enzyme showed no cooperativity in substrate binding . The Michaelis constants of these hybrids for aspartate were intermediate between that of the isolated catalytic subunit and that of the relaxed state . Activation by ATP was caused by a reduction in Km to the value characteristic of the relaxed state whereas CTP inhibited by lowering the Vmax . The properties of the hybrids are strikingly similar to the modified enzyme obtained by Kerbiriou and Herve from cells grown in the presence of 2-thiouracil . However, the crucial modifications are found in the regulatory subunits of the enzyme studied by these authors whereas they are located in the catalytic subunits of the hybrids reported here . Our results suggest that interactions between the catalytic and regulatory subunits have considerable effects on the state of the substrate binding sites in the native enzyme.

Can J Biochem, 1979 Jun, 57(6), 749 - 57
Purification and Best Department of Medical Research, University of Toronto, Ont., Canada; Glick BR et al.; Factor EF-P is a nonribosomal (soluble) protein of Escherichia coli that stimulates peptide bond synthesis when certain aminoacyl-tRNA analogues are used . The purification of this protein to apparent homogeneity is described here . EF-P has a molecular weight of about 21 000, a Stokes radius of 27 A (1A = 0.1 nm), and a frictional coefficient of 1.48, suggesting an asymmetric structure . By this and a number of other criteria, EF-P is a new factor that controls peptide bond formation during protein biosynthesis.

Can J Biochem, 1979 Jun, 57(6), 653 - 61
Dicarboxylic acid transport in Escherichia coli K12: involvement of a binding protein in the translocation of dicarboxylic acids across the outer membrane of the cell envelope; Bewick MA et al.; We have previously found that the dicarboxylate transport system in Escherichia coli K12 is an active transport system and that at least one binding protein and two cytoplasmic membrane transport components are involved in the uptake of dicarboxylic acids . Recently, through surface labelling studies, some dicarboxylate binding proteins were found to be exposed on the cell surface . In the present paper, we demonstrate that the dicarboxylate transport component located in the outer membrane can be inactivated by two different kinds of nonpenetrating inhibitors, viz . proteases, and diazosulfanilic acid . These inhibitors seem to act on the dicarboxylate binding protein . By adding this protein to inactivated cells or to transport-negative mutants, we have succeeded in reconstituting the dicarboxylate transport system . These findings suggest that the dicarboxylate binding protein found on the cell surface plays an essential role in the translocation of dicarboxylic acids across the outer membrane.

Am J Vet Res, 1979 Jun, 40(6), 792 - 4
Endotoxin absorption in hay-fed and lactic acidotic sheep; Huber TL et al.; Absorption of endotoxin from the gastrointestinal tract was evaluated in hay-fed and lactic acidotic sheep duodenally infused with 10 mg of Escherichia coli endotoxin, and in lactic acidotic sheep not infused . The effect of abomasal fluid on biological activity of endotoxin was also evaluated . Leukopenia was the criterion used for detecting endotoxemia . Absorption of endotoxin from the gastrointestinal tract was not detected in either hay-fed or lactic acidotic sheep . Endotoxin appeared to maintain its activity after incubation with abomasal fluid, and the presence of endogenous endotoxin in abomasal contents was indicated . The results indicate that endotoxin of alimentary origin may not be involved in the lactic acidosis syndrome in ruminants.

Z Immunitatsforsch Immunobiol, 1979 Jun, 155(5), 387 - 98
Protein I and protein II from the outer membrane of Escherichia coli are mouse B-lymphocyte mitogens; Bessler WG et al.; Protein I from the outer membrane of Escherichia coli is a B-lymphocyte mitogen in mice . Polyclonal activation of mouse splenocytes was demonstrated by 3H-thymidine incorporation into DNA, 3H-uridine incorporation into RNA, and by a hemolytic plaque assay in three inbred mouse strains . B-lymphocytes from LPS responder mice (C57Bl/10, STU/nu/nu) and LPS non-responder mice (C3H/HeJ) both responded well to protein I . The presence of serum was not necessary for mitogenicity; bovine serum albumin exhibited a beneficial effect on serum-depleted cultures . Thymocytes of C3H/HeJ mice were not activated by protein I . Protein II* from E . coli was also tested in our systems and showed a weak B-lymphocyte stimulatory activity . Human peripheral blood lymphocytes were not activated.

Z Gesamte Inn Med, 1979 Jun 1, 34(11), 318 - 9
{Mass screening for bacteriuria in students}; Wachtel D; From 1973 to 1978 in 2.6% out of 244 female students and in none out of 160 male students a significant persisting bacteriuria was proved . By the slight rate of falsely positive findings could be demonstrated that the midstream technique gives evident results when persons able to cooperate are sufficiently instructed.

Infect Immun, 1979 Jun, 24(3), 965 - 6
Evidence for two heat-stable enterotoxins produced by enterotoxigenic Escherichia coli; Kapitany RA et al.; Heat-stable enterotoxins from a bovine and porcine strain of Escherichia coli were isolated and showed significant differences in amino acid composition and heat stability.

Infect Immun, 1979 Jun, 24(3), 895 - 9
B lymphocyte colony formation in renal infection; Miller T et al.; The effect of renal infection on B lymphocyte colony formation has been investigated in the belief that a study of the effect of infection on subpopulations of lymphoid cells might provide direct evidence of the effect of infection on the immmune system . Renal infection was induced in mice, and the specific immune response of the B lymphocyte compartment was quantitated by determining the serum antibody and plaque-forming cell response to infection . Under the conditions of the experiment, the ability of splenic lymphocytes to form B lymphocyte colonies was significantly depressed during the first 7 days of infection, and the results suggest that a study of the responses of lymphoid cells to infection may provide information of diagnostic and prognostic value.

Infect Immun, 1979 Jun, 24(3), 793 - 7
Heat-labile enterotoxin production in isolates from a shipboard outbreak of human diarrheal illness; Wachsmuth K et al.; As reported elsewhere, an enterotoxigenic strain of Escherichia coli serotype O25:K98:NM was epidemiologically incriminated as the etiological agent in a shipboard outbreak of diarrheal illness . This enterotoxigenic E . coli strain and possibly other enteric isolates were found to produce heat-labile toxin and not heat-stable toxin . Since previous genetic analyses of enterotoxigenic E . coli strains producing heat-labile and heat-stable toxins have shown a plasmid location for both toxin determinants and since in this outbreak more than one bacterial strain appeared to produce only heat-labile toxin, the possibility of an extrachromosomal heat-labile toxin determinant was investigated . Results of endonuclease cleavage and hybridization experiments, as well as apparent heat-labile toxin phenotypic instability, strongly suggest a plasmid mediation of toxin production . Additionally, the stability of this heat-labile toxin production was evaluated after several traditional methods of bacterial cell preservation.

Infect Immun, 1979 Jun, 24(3), 606 - 10
Passive immune hemolysis for detection of heat-labile enterotoxin produced by Escherichia coli isolated from different sources; Serafim MB et al.; Fifty-one strains of Escherichia coli isolated from humans, swine, food, and water and identified as enterotoxinogenic by the Y-1 adrenal cell assay, were examined for heat-labile enterotoxin (LT) production by the passive immune hemolysis test . Cholera antitoxin, anti-choleragenoid and anti-LT were used as antisera . Cholera antitoxin was much more potent than anti-choleragenoid and LT antiserum in the detection of LT-positive strains . All strains isolated from pigs and sausage were negative in tests made with LT antiserum . A few strains isolated from humans, food, and water also gave negative results . These data showed that the passive immune hemolysis test is not as efficient as the Y-1 adrenal cell assay in the detection of enterotoxinogenic E . coli strains.

Genetika, 1979 Jun, 15(6), 972 - 88
{Control of plasmid incompatibility: characteristics of the bireplicon hybrid pAS8 and its deletion mutants}; Sakanian VA et al.; The phenomenon of incompatibility has been investigated using deletion mutants of hybrid bireplicon plasmid pAS8 . The hybrid pAS8 displays incompatibility specific for both components of its structure . In contrast to P-specificity of pAS8, functions of ColE1-specificity are not effectively expressed . Expression of ColE1-specificity in pAS8 plasmid and its derivatives is characterized by different directions and this is due to the presence or absence of genes of RP4 replication machinery in the plasmid DNA . Mutant plasmids show different efficiency of P-specificity depending on the extension of deletion in the region of essential genes of the RP4 component . Some of the mutants, in spite of the loss of replication genes, including origin of vegetative replication, are incompatible with the representatives of the Inc P group in both directions of testing . Different character and the level of expression of ColE1- and P-specificity in the pAS8 hybrid and its deletion derivatives are not associated with change in the number of plasmid DNA copies, for all of them are subjects to stringent control of replication . The data suggest the existence of incompatibility functions control mechanism which does not seem to include replication genes . Possible ways of realization of the inc genes functions are discussed.

Eur J Cell Biol, 1979 Jun, 19(2), 120 - 30
Structure of the 50S ribosomal subunit from Escherichia coli . Investigation of the intact subunit and core particles by electron microscopy and analogue image processing; Spiess E; Structures of 50S ribosomal subunits, CsCl and ethidium bromide core particles from these subunits have been investigated by electron microscopy and image processing by FAIRS . This method revealed structural details which are obscured in individual images, and enabled to distinguish six crown forms, different in their side protuberances, and two kidney forms . Crown forms were imaged as symmetrical or asymmetrical forms . The latter type was far more frequent in untreated populations than the first . The depletion of proteins by both agents caused stepwise degradation of the side protuberances in the crown forms thereby transforming asymmetrical to symmetrical forms . It is concluded from these findings that asymmetrical and symmetrical forms in untreated populations represent also structurally different particles . From the higher complexity in terms of component composition and structure it is concluded that the asymmetrical crown forms are more likely to represent the native structure of isolated 50S subunits than the symmetrical forms . Existing models for this subunit are discussed in terms of this finding.

Eur J Biochem, 1979 Jun 1, 96(3), 535 - 43
The influence of ribonucleoside triphosphates, and other factors, on the formation of very-salt-stable RNA-polymerase . su+III-tRNA(tRNATyr)-promoter complexes; Debenham P; The formation of a stable RNA-polymerase . su+III-tRNA-promoter complex was found to require sigma factor and the incorporation of ribonucleoside triphosphates which match the 5' sequence of the su+III tRNA transcript . This complex, stable to at least 2 M KCl, can be retained on a Millipore filter . Its formation closely parallels the extent of transcription obtained from the su+III tRNA promoter in response both to increasing ionic strength and to temperature during incubation of RNA polymerase with the DNA . The RNA-polymerase . DNA complex retained during this assay therefore appears to relate directly to that formed during promoter-directed transcription . The formation of RNA-polymerase . su+III-tRNA-promoter complexes is sensitive to the presence of ppGpp.

Br J Vener Dis, 1979 Jun, 55(3), 214 - 7
Haematuria presenting in outpatients attending a department of genitourinary medicine; Amarasuriya KL; Of all the patients attending a department of genitourinary medicine during a 10-month period, about 2% (1 out of 50) presented with haematuria, or haematuria was discovered on initial examination . In about 25% of cases, the haematuria was due to Escherichia coli infection of the lower genitourinary tract . Gonococcal infection was the next commonest cause; one patient with gonorrhoea presented with frank urethral bleeding . In the remaining patients other causes of haematuria, which included renal cyst . carcinoma of the ureter, bilharziasis, and IgA disease, required more extensive investigations and follow up.

Proc Natl Acad Sci U S A, 1979 Jun, 76(6), 2649 - 53
lac repressor changes conformation upon binding to poly{dA-T)}; Kelsey DE et al.; N-(Iodoacetylaminoethyl)-1-naphthylamine-5-sulfonate reacts with Escherichia coli lac repressor to selectively label cysteine-140 with the fluorescent N-(acetylaminoethyl)-1-naphthylamine-5-sulfonate group . The fluorescence intensity of this label decreases by 20% when labeled repressor associates with poly{d(A-T)} . Fifteen base pairs of poly{d(A-T)} per repressor tetramer are required to complete this decrease . Stopped-flow experiments have shown that the repressor undergoes at least two conformational changes as it binds to poly{d(A-T)}, with half-lives of 5.0 +/- 1.2 msec and 3.5 +/- 1.0 sex . Quite likely, these conformational changes serve to strengthen the interaction of repressor with DNA.

Proc Natl Acad Sci U S A, 1979 Jun, 76(6), 2615 - 9
Initiation of general recombination catalyzed in vitro by the recA protein of Escherichia coli; McEntee K et al.; Homogeneous recA protein catalyzes the hybridization of single-stranded DNA to homologous regions in duplex DNA . The products are D-loops, which are formed with equal efficiency in linear and supercoiled molecules . This assimilation reaction can be separated into two partial reactions . In the first, recA protein binds to duplex DNA and produces a reA protein-DNA complex . The binding shows a sigmoidal dependence on recA protein concentration, requires ATP, GTP or the gamma-thio analog of ATP, and Mg2+, but does not require hydrolysis of the nucleoside triphosphate . In the second reaction, single-stranded regions of the recA protein-ATP-duplex DNA intermediate hybridize with free complementary single strands to produce D-loop structures . This reaction is coupled to ATP hydrolysis and is analogous to the renaturation of single-stranded DNA catalyzed by the recA protein {Weinstrock, G.M., McEntee, K . & Lehman, I.R . (1979) Proc . Natl . Acad . Sci . USA 76, 126-130} . Hydrolysis of ATP appears to be required in these reactions for dissociation of recA protein from the DNA.

J Biochem (Tokyo), 1979 Jun, 85(6), 1527 - 9
Kinetics of selective acylation of sn-glycerol 3-phosphate in the synthesis of phospholipid molecular species; Kito M et al.; The kinetics of the sn-glycerol 3-phosphate acyltransferase {EC 2.3.1.15} reaction support the view that the selective acylation primarily depends on the differences in the affinity of the enzyme for acyl-CoAs.

J Bacteriol, 1979 Jun, 138(3), 944 - 8
Biosynthesis of murein lipoprotein in Escherichia coli: effects of 3,4-dihydroxybutyl-1-phosphonate; Chattopadhyay PK et al.; The effects of 3,4-dihydroxybutyl-1-phosphonate, a four-carbon analog of sn-glycerol 3-phosphate, on the biosynthesis of the glyceryl moiety in murein lipoprotein of Escherichia coli were studied . The compound at a concentration of 55 microM strong inhibits in the incorporation of {2-3H}glycerol radioactivity into lipoprotein by virtue of its inhibition of the synthesis of phosphatidylglycerol . On the other hand, the incorporation of prelabeled {2-3H}glycerol radioactivity into lipoprotein was only partially inhbited by 3,4-dihydroxybutyl-1-phosphonate even at a much higher concentration (1 mM) . These data were consistent with the postulated pathway for the biosynthesis of the lipid moiety in lipoportein: cysteine-lipoprotein + phosphatidylglycerol leads to glycerylcystein-lipoprotein + phosphatidic acid.

J Bacteriol, 1979 Jun, 138(3), 871 - 7
Characterization of Azotobacter vinelandii deoxyribonucleic acid and folded chromosomes; Sadoff HL et al.; The properties of Azotobacter vinelandii deoxyribonucleic acid (DNA) and folded chromosomes were studied and compared to those of Escherichia coli as a standard . Based on melting temperature and buoyant density measurements, the guanosine + cytosine content of purified A . vinelandii DNA was 65%, whereas that of E . coli DNA was 50% . The results of renaturation studies showed that the unique DNA sequence lengths of the two organisms were similar with Cot1/2 values of 7.3 +/- 0.4 mol.s/liter and 7.5 +/- 0.3 mol.s/liter, respectively, for A . vinelandii and E . coli . Folded chromosomes of A . vinelandii sedimented in a centrifugal field at a rate identical to those derived from E . coli, 1,600 to 1,700S . Based on the DNA content per cell and the mass of a single genome, A . vinelandii contains at least 40 chromosomes per cell.

J Bacteriol, 1979 Jun, 138(3), 861 - 70
Chemical heterogeneity of major outer membrane pore proteins of Escherichia coli; Lee DR et al.; Peptide mapping and isoelectric focusing were used to compare the major outer membrane pore proteins from various strains of Escherichia coli K-12, including strains carrying mutations in the nmpA, nmpB, and nmpC genes which result in the production of new membrane proteins . Proteins 1a, 1b, and 2 and the NmpA proteins each gave unique peptide and isoelectric focusing profiles, indicating that these are different polypeptides . The NmpA protein and the NmpB protein appeared to be identical by these criteria . The NmpC protein and protein 2 were nearly identical, although one different peptide was observed in comparing the proteolytic peptide maps of these proteins and there were slight differences in their isoelectric focusing profiles . Antiserum against protein 2 showed partial cross-reactivity with the NmpC protein . These results indicate that the various pore proteins of E . coli K-12 fall into four different classes.

J Bacteriol, 1979 Jun, 138(3), 832 - 8
Genes coding for ribosomal proteins S15, L21, and L27 map near argG in Escherichia coli; Kitakawa M et al.; Mutants with alterations in the structural genes for ribosomal proteins S15, L21, and L27 were used in mapping the genes coding for these proteins . Results from P1kc-mediated transductions indicate that the genes for L21 (rplU) and L27 (rpmA) form a gene cluster and are located between argG and gltB at 68.1 min, whereas the gene for S15 (rpsO) is situated close to, but on the opposite side or, argG . The gene order in this region is concluded to be gltB-(rplU, rpmA)-argG-rpsO-mtr.

J Bacteriol, 1979 Jun, 138(3), 783 - 7
Genetic mapping of a mutation affecting pyridine nucleotide transhydrogenase in Escherichia coli; Hanson RL et al.; A mutation, pnt-1, causing loss of pyridine nucleotide transhydrogenase activity in Escherichia coli, was mapped by assaying for the enzyme in extracts of recombinant strains produced by conjugation, F-duction, and P1 transduction . The site of this mutation was near min 35, counterclockwise from man, and it co-transduced 59% with man . The mutation was associated with loss from the cell membrane fraction of energy-independent and adenosine 5'-triphosphate-dependent transhydrogenase activities, but reduced nicotinamide adenine dinucleotide dehydrogenase activity was not affected . Strains were constructed which lack phosphoglucoisomerase (pgi-2) and which carry either pnt+ or pnt-1 . Although such strains, when grown on glucose, are expected to produce a large excess of reduced nicotinamide adenine dinucleotide phosphate, the growth rate was not affected by the pnt-1 allele.

J Bacteriol, 1979 Jun, 138(3), 770 - 8
Mechanism of export of colicin E1 and colicin E3; Jakes KS et al.; The mechanism of export of colicins E1 and E3 was examined . Neither colicin E1, colicin E3, Nor colicin E3 immunity protein appears to be synthesized as a precursor protein with an amino-terminal extension . Instead, the colicins, as well as the colicin E3 immunity protein, appear to leave the cells where they are made, long after their synthesis, by a nonspecific mechanism which results in increased permeability of the producing cells . Induction of ColE3-containing cells with mitomycin C leads to actual lysis of those cells, as some time after synthesis of the colicin E3 and its immunity protein has been completed . Induction of ColE1-containing cells results in increased permeability of the cells, but not in actual lysis, and most of the colicin E1 produced never leaves the producing cells . Intracellular proteins such as elongation factor G can be found outside of colicinogenic cells after mitomycin C induction, along with the colicin . Until substantial increases in permeability occur, most of the colicin remains cell associated, in the soluble cytosol, rather than in a membrane-associated form.

J Bacteriol, 1979 Jun, 138(3), 715 - 20
Restriction enzyme cleavage sites surrounding the structural gene for the lipoprotein of the Escherichia coli outer membrane; Nakamura K et al.; The purified messenger ribonucleic acid (mRNA) for the lipoprotein of the Escherichia coli outer membrane was hybridized with fragments obtained by digestion of E . coli chromosomal deoxyribonucleic acid (DNA) with eight different restriction enzymes . For each restriction enzyme digestion, one specific fragment separated by agarose gel electrophoresis was found to hybridize with the lipoprotein mRNA . From the analysis of restriction fragments generated by double digestions with various combinations of restriction enzymes, cleavage sites for the restriction enzymes near the locus of the lipoprotein structural gene (lpp) were mapped . No restriction fragments of DNA from the E . coli lpp-2 mutant hybridized with the lipoprotein mRNA, confirming that the mutant has a deletion mutation in the vicinity of the lpp gene.

J Bacteriol, 1979 Jun, 138(3), 705 - 14
Organization of structural and regulatory genes that mediate tetracycline resistance in transposon Tn10; Jorgensen RA et al.; The location of Tn10 genes encoding tetracycline resistance and its regulation was determined by analyzing the properties of recombinant plasmids carrying partial HpaI digestion products of lambda::Tn10 transducing phage deoxyribonucleic acid . Within a 2,700-base pair region are encoded tetracycline resistance, the structural gene (tet) for a tetracycline-inducible polypeptide, and the regulatory elements for the induction of both the resistance phenotype and the polypeptide . Fusion of different sequences to an HpaI site in the tet gene alters the molecular weight and stability of the polypeptide as well as the tetracycline resistance phenotype of strains producing fusion polypeptides . These results indicate the orientation of the tet gene and support the conclusion that the tet polypeptie is required for tetracycline resistance . A HincII cleavage site immediately upstream from the tet gene is protected by ribonucleic acid polymerase, but only the absence of ribonucleotide triphosphates . The possibility that tet transcription is initiated at this site is discussed.

J Bacteriol, 1979 Jun, 138(3), 1033 - 5
Nature of transforming deoxyribonucleic acid in calcium-treated Escherichia coli; Strike P et al.; A study of the reactivation of ultraviolet-irradiated plasmid and phage deoxyribonucleic acid molecules after transformation into Escherichia coli strains indicated that, when double-stranded deoxyribonucleic acid was used as the donor species, it was taken up without conversion to the single-standed form.

Cell, 1979 Jun, 17(2), 389 - 97
In vitro processing of B . mori transfer RNA precursor molecules; Garber RL et al.; Ribonuclease P and 3'-5' nuclease, two enzymatic activities necessary for tRNA synthesis in E . coli, are also found in the silkgland cells of Bombyx mori . B . mori subcellular extracts containing RNAase P activity can cleave the E . coli tRNA precursor molecule endonucleolytically at the same site as the E . coli enzyme, and will also cleave in vitro all E . coli tRNA precursors (pre-tRNAs) which the bacterial enzyme recognizes . B . mori RNAase P will not cleave two E . coli RNAase P substrates that are structurally unrelated to tRNA . Pre-tRNAs from B . mori contain extra 5' and 3' nucleotides as judged by RNA fingerprinting and 5' terminal phosphate analysis . Crude silkgland extracts containing both RNAase P and 3'-5' nuclease can remove the 5' and 3' extra nucleotides from B . mori pre-tRNAs, whereas purified fractions containing RNAase P remove only 5' extra nucleotides . Only large silkworm pre-tRNAs were found to be susceptible to cleavage by B . mori RNAase P . This observation and sequence analysis of intermediates of in vitro processing reactions indicate a two-step process of pre-tRNA maturation in which extra 5' nucleotides are first removed by RNAase P and extra 3' nucleotides are then trimmed off by a 3'-5' nuclease.

J Dent Res, 1979 Jun, 58(6), 1634 - 9
A comparison of the effects of endotoxin upon fibroblast proliferation and macromolecular syntheses; Singer RE et al.; The effects of Escherichia coli endotoxin upon mouse L929 cell proliferation, DNA synthesis, protein synthesis, and proline incorporation were determined . It was found that a level of endotoxin which inhibited cell proliferation prompted a similar inhibition of DNA synthesis and overall cell protein synthesis . In contrast, endotoxin was shown to inhibit incorporation of proline into cell protein to a significantly greater extent.

Fed Proc, 1979 Jun, 38(7), 2134 - 8
Protective effects of supplemental vitamin E against infection; Nockels CF; Vitamin E supplementation (dl-alpha-tocopheryl acetate except where noted) in excess of requirement significantly increased humoral immune response or disease resistance . Mice immunized with sheep red blood cells or tetanus toxoid and fed the supplemental vitamin demonstrated increased plaque-forming cells (PFC) and hemagglutinin (HA) titers . A vitamin E deficiency resulted in decreased PFC and little IgG which was partially corrected by N,N-diphenyl-p-phenylenediamine but not as effectively as by vitamin E . Hens immunized with Brucella abortus and fed different levels of the vitamin produced chicks with increased passive immunity; a biphasic antibody response to the level of the vitamin fed was noted . Vitamin E fed to nonimmunized hens was found to significantly increase the primary immune response of their immunized chicks . Feeding dl-alpha-tocopheryl acetate to guinea pigs immunized with Venezuelan equine encephalomyelitis virus resulted in no increased immunity . Injecting this form of the vitamin resulted in severe tissue reaction . However, injecting dl-alpha-tocopheryl significantly improved hemagglutinin inhibition titers . Chicks and turkeys infected with Escherichia coli and fed supplemental vitamin E had reduced mortality and increased HA titers . Sheep fed vitamin E and challenged with Chlamydia had improved weight gains and no detectable Chlamydia.

Gastroenterology, 1979 Jun, 76(6), 1368 - 73
Prophylactic doxycycline for travelers' diarrhea: results of a prospective double-blind study of Peace Corps volunteers in Morocco; Sack RB et al.; A second randomized double-blind study to determine the efficacy of doxycycline, 100 mg daily, for the prevention of travelers' diarrhea was carried out among 50 Peace Corps Volunteers during their first 10 wk in Morocco . The volunteers took either doxycycline or placebo for 3 wk, and were observed for an additional 7 wk . Eleven of 24 taking the placebo and 2 of 26 taking doxycycline had travelers' diarrhea during the treatment period (P less than 0.01) . One week after cessation of the doxycycline, however, persons in that group developed an increase in frequency of travelers' diarrhea (P less than 0.05) so that by 3 wk after the drug was stopped, there were no differences between groups . Enterotoxigenic E . coli, most of which were sensitive to doxycycline, were the most frequently isolated pathogens during the entire study . This study corroborates the effectiveness of doxycycline prophylaxis for travelers' diarrhea.

Acta Pathol Microbiol Scand {C}, 1979 Jun, 87C(3), 241 - 50
Fractionation of connective-tissue-activating factors from the culture medium of silica-treated macrophages; Aalto M et al.; The medium of cultured, SiO2-treated peritoneal macrophages contained a factor which enhances the incorporation of labelled proline to collagen and other proteins in granulation tissue slices, cells and polysomes . Simultaneously, the activity of alkaline RNase in the whole medium was decreased in comparison with the corresponding control . Polyvinylpyridine-N-oxide, PVNO, protected the macrophages against SiO2 . Latex-particles and E . coli lipopolysaccharide decreased the RNase activity in the macrophage medium, but unlike SiO2 did not cause liberation of the collagen synthesis-stimulating factor . Fractionation of the medium by gel filtration chromatography showed the SiO2-pretreatment to have caused a very significant decrease in the aggregation state of RNase . The fraction from gel filtration chromatography that contained the SiO2-liberated factor stimulating collagen synthesis also contained the disaggregated RNase . There was no RNase-activity in the control sample . A homogenous protein (mol . wt . 14,300) was isolated with repeated gel filtrations from the medium of silica-treated macrophages . It increased the incorporation of 3H proline and 3H thymidine into cultured granuloma cells.

J Bacteriol, 1979 Jun, 138(3), 933 - 43
Aromatic amino acid biosynthesis: regulation of shikimate kinase in Escherichia coli K-12; Ely B et al.; Starvation of cells of Escherichia coli K-12 for the aromatic amino acids results in an increased rate of synthesis of shikimate kinase activity . The two controlling amino acids are tyrosine and tryptophan, and starvation for both results in derepression . The product of the regulator gene tyrR also participates in this control, and shikimate kinase synthesis was depressed in tyrR mutants . Chromatography of cell extracts on diethylaminoethyl-Sephadex allowed partial separation of two shikimate kinase enzymes and demonstrated that only one of these subject to specific repression control involving tyrR . By contrast, chromatography of cell extracts with G-75 or G-200 columns revealed a singl-molecular-weight species of shikimate kinase activity with an apparent molecular weight of 20,000 . The levels of shikimate kinase in a series of partial diploid strains indicated that aroL, the structural gene for the tyrR-controlled shikimate kinase enzyme, is located on the E . coli chromosome between the structural genes proC and purE . By means of localized mutagenesis, an aroL mutant of E . coli was isolated . The mutant was an aromatic prototroph and, by the criterion of column chromatography, appeared to have only a single functional species of shikimate kinase enzyme.

J Bacteriol, 1979 Jun, 138(3), 671 - 7
Effects of 8-substituted analogs of cyclic adenosine 3',5'-monophosphate on in vivo and in vitro syntheses of beta-galactosidase in Escherichia coli; Ito T et al.; Several 8-substituted alkylthio and alkylamino cyclic adenosine 3',5'-monophosphate (cAMP) derivatives were tested for their ability to stimulate beta-galactosidase synthesis in Estherichia coli in vivo and in vitro and to inhibit the cAMP phosphodiesterase activity of E . coli . Stimulation of beta-galactosidease synthesis in vivo by cAMP derivatives decreased with increasing length of the unbranched carbon chain of the substituent . On the other hand, the stimulation in vitro was increased as the carbon chain elongated . The 8-decylthio- and 8-dodecylthio-cAMP compounds stimulated beta-galactosidase synthesis almost eight-fold compared with cAMP, whereas 8-undecyl-, 8-dodectyl-, and 8-tridecylamino-cAMP stimulated beta-galactosidase synthesis about threefold . However, in in vitro experiments with a phosphodiesterase-deficient strain of E . coli, the Crooks strain, the stimulatory effects of the derivatives disappeared, except for 8-dodecylthio cAMP which stimulated beta-galactosidase about 1.4- to 1.6-fold . All derivatives were quite resistant to hydrolysis by phosphodiesterase . Most derivatives competitively inhibited the hydrolysis of cAMP by phosphodiesterase.

Clin Exp Immunol, 1979 Jun, 36(3), 355 - 63
Immunological and purine enzyme studies on hyperuricaemic and normouricaemic patients with Down's syndrome; Watts RW et al.; Hyperuricaemia in Down's syndrome is unreleated to the activity of phosphoribosylamidotransfrease, which catalyses the activity of the first specific step on the purine biosynthetic pathway, and to the activity of hypoxanthine phosphoribosyltransferase and phosphoribosylpyrophosphate synthetase, abnormalities of which are known to be associated with hyperuricaemia . Immunological studies involving serum immunoglobulins, natural E . coli antibodies, test immunization with pneumococcal polysaccharide type III (PnPS), in vitro lymphocyte transformation to mitogens, and pokeweed mitogen (PWM) induced immunoglobulin production showed no difference between hyperuricaemic or normouricaemic Down's patients and institutionalized controls . The Down's patients had higher serum IgA, IgG and IgE, and some also produced more immunoglobulin in PWM-stimulated lymphocyte cultures when compared to normal healthy controls . However, both patients with Down's syndrome and the institutionalized controls had significantly lower responses to PnPs than normal healthy controls . The only deficiency confined to the Down's patients was a signficant depression in delayed hypersensitivity to dinitrochlorobenzene . These findings indicate that the in vivo abnormality of depressed cellular and humoral immunity in Down's patients is not paralleled by in vitro function as measured by PHA lymphocyte transformation and immunoglobulin production by PWM-stimulated lymphocytes . There is also no apparent link between a putative defect in purine metabolism in Down's patients and any immunological abnormalities.

Gene, 1979 Jun, 6(2), 173 - 97
Inceptor and origin of DNA replication in lambdoid coliphages . II . The lambda DNA maximal replication system; Lusky M et al.; In pBR313-lambda dv hydrid plasmids a second system for initiation of DNA replication has been detected in lambdoid replicator DNAs (in the absence of the p0 promoter) . The "maximal" (or "maxi") initiation system depends on the origin of replication (ori) sequence, in conjuction with the "inceptor" (ice) element located in the lambdoid cII genes . Only leftward, but not bidirectional, primer RNA synthesis seems to be initiated at ori in its newly defined boundaries, and it appears to be catalysed by dnaG-coded primase . Only if transcriptionally activated, will ori effectively initiate lambda specific, O and P-dependent "maximal" hybrid-plasmid replication . In addition, it will repress a complete lambda "minimal" initiation system in cis, i.e., if present on the same plasmid molecule . This newly discovered repressive activity of the ori system depends on only three factors: an intact left section of ori, the O product, and transcriptional activation of ori (rightward or leftward) . A repressed minimal initiation system will regain its activity as soon as a segment carrying either part of the O gene or a promoter for transcriptional activation is delected from such a plasmid which was combining both the "mini" and "maxi" systems of lambda replication.

Gene, 1979 Jun, 6(2), 123 - 36
Construction and analysis of recombinant lambda phages containing mitochondrial DNA fragments; Kobayashi M et al.; Rat mtDNA has a molecular length of about 16 kilobase (kb) pairs and is cleaved into seven fragments by restriction endonuclease EcoRI . These fragments were cloned in Escherichia coli K-12 host using lambda gtWES.lambda B' (lambda gtWES.lambda B, for short, in this paper) as a vector . Recombinant DNAs containing one or a few fragments of the mtDNA were transfected to CaCl2-treated E . coli, and the plaques containing specific recombinant phages were selected . DNA amplified in the recombinanat phage lambda gt.mt was shown to contain the same restriction endonuclease cleavage sites as those found in the mtDNA . Present results permitted the DNA sequencing of any portion of the mitochondrial genome.

J Bacteriol, 1979 Jun, 138(3), 923 - 32
Transient growth inhibition of Escherichia coli K-12 by ion chelators: "in vivo" inhibition of ribonucleic acid synthesis; Collins JJ et al.; The ion chelators picolinic acid, quinaldic acid, 1,10-phenanthroline, and 8-hydroxyquinoline, but not ethylenediaminetetraacetate, ethyleneglycol-bis-(beta-aminoethyl ether)-N,N-tetraacetate, or dipicolinic acid, rapidly but transiently arrest growth of Escherichia coli K-12 . Cells adapt and become resistant to growth inhibition by these agents, a process which requires protein synthesis . Mn2+, at low concentrations, decreases the time required for resumption of growth . Proteins synthesized during the lag are quantitatively and qualitatively different from those synthesized during normal growth . Inhibition of growth can explained by an effect on RNA polymerase, a known metalloenzyme.

J Bacteriol, 1979 Jun, 138(3), 726 - 30
Use of chlC-lac fusions to determine regulation of gene chlC in Escherichia coli K-12; Fimmel AL et al.; Gene fusions between the lac structural genes and the chlC locus were isolated, and the regulation of lac gene expression was studied . The fused lac genes were induced by nitrate anaerobically and repressed by the presence of oxygen.

Surgery, 1979 Jun, 85(6), 638 - 43
The effect of septic shock on skeletal muscle action potentials in the primate; Trunkey DD et al.; Techniques developed for the in vivo study of cellular physiology have been applied to septic shock in primates . Measurements of skeletal muscle transmembrane resting and action potentials were correlated with an analysis of fluid and electrolyte changes in the intracellular and extracellular compartments of skeletal muscle . The data obtained indicated a marked depletion of muscle extracellular water and an increase in intracellular sodium chloride and water content during shock . The significant decrease of resting membrane potential was associated with a decrease in amplitude of the action potential and prolongation of both the repolarization and depolarization time . In addition, there was a decrease of muscle intracellular potassium concentration during shock . This study demonstrates that the alterations in cellular membranes in hemorrhagic shock and septic shock are similar.

Infect Immun, 1979 Jun, 24(3), 760 - 9
Isolation and characterization of homogeneous heat-labile enterotoxins with high specific activity from Escherichia coli cultures; Clements JD et al.; The heat-labile enterotoxin (LT) has been isolated in homogeneous form with high specific activity from three sources: cell-free supernatant, NaCl extract, and whole-cell lysates of an enterotoxigenic Escherichia coli strain . In vitro immunological assays were used in lieu of tedious and highly variable bioassays to recognize fractions with activity . This revealed that the major portion of the LT remained adherent to columns containing agarose, from which it could be eluted quantitatively in practically homogeneous form by galactose . Isolated LT has remarkable similarities to the cholera enterotoxin (choleragen) in both subunit structure and amino acid composition, although there are also notable differences in these two enterotoxins, which are related immunologically and by mode of action . Unlike choleragen, in which the A region is totally nicked, E . coli LT, depending on its source, is activated by proteolytic processing . The activity of LT is equivalent to that of choleragen in bioassays on adrenal cells, in rabbit skin, and in rabbit ileal loops, especially when, depending on the source of material, the LT has been activated by treatment with trypsin . The whole-cell lysate is the richest source of LT.

Can J Biochem, 1979 Jun, 57(6), 822 - 33
The reactions of Escherichia coli citrate synthase with the sulfhydryl reagents 5,5'-dithiobis-(2-nitrobenzoic acid) and 4,4'-dithiodipyridine; Talgoy MM et al.; Citrate synthase of Escherichia coli reacts rapidly with 1 equivalent of Ellman's reagent, 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB), per subunit, losing completely its sensitivity to the allosteric inhibitor, NADH . When the enzyme is treated instead with 4,4'-dithiodipyridine (4,4'-PDS), all activity is lost . Certain evidence in this paper is consistent with the belief that the sulfhydryl group modified by DTNB, and that whose modification by 4,4'-PDS inactivates the enzyme, are the same . (i) Both reagents abolish NADH fluorescence enhancement by the enzyme . (ii) Saturating levels of NADH and some other adenylic acid derivatives inhibit the reactions with both reagents . (iii) When the enzyme is modified with one equivalent of DTNB or 4,4'-PDS, subsequent reactivity toward the other reagent is greatly decreased . (iv) Following modifications, the DTNB and 4,4'-PDS derivatives spontaneously lose thionitrobenzoate (TNB) or pyridine-4-thione (PT), respectively, in reactions which are thought to involve displacement of TNB or PT by a second enzyme sulfhydryl group, so that an enzyme disulfide is introduced . The introduction of the disulfide bond, if this is what occurs, does not lead to cross-linking of citrate synthase polypeptide chains, as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis under nonreducing conditions . Certain evidence has also been found, however, that the sites of modification by DTNB and 4,4'-PDS are not the same . (i) DTNB modification desensitizes to NADH but does not inactivate, while 4,4'-PDS inactivates at least 99.9% . (ii) The presumed disulfide from elimination of TNB is also active, while that from PT modification is no more active than the original 4,4'-PDS modified product . (iii) Prior modification of the enzyme with DTNB affords no protection against later inactivation by 4,4'-PDS . The studies therefore indicate a close relationship between the DTNB desensitization and 4,4'-PDS inactivation, but they are unable to identify it exactly . Other properties of the DTNB reaction are also described, and a hypothesis is offered to explain quantitatively the finding that desensitization lags behind modification during the modification of citrate synthase by DTNB.

J Bacteriol, 1979 Jun, 138(3), 969 - 75
Structure of common pili from Escherichia coli; McMichael JC et al.; Several important properties of the common pili from Escherichia coli are discussed . These pili were resistant to the gentle Folin-Ciocalteau reagent methods for protein detection and were not readily solubilized by sodium dodecyl sulfate . They were found to contain a reducing sugar but not peptidoglycan . The pilin had multiple conformations in sodium dodecyl sulfate solution, and the appearance of multiple bands on sodium dodecyl sulfate gels did not necessarily indicate heterogeneity of the preparation . The ilus subunit was found to be a different protein than outer membrane III, which has the same apparent molecular weight . In addition, we conformed the results of Brinton (Trans . N.Y . Acad . Sci 27:1003-1054, 1965): that there is a dramatic change in the properties of pili after they are heated at pH values below 2.

Virchows Arch A Pathol Anat Histol, 1979 May 31, 382(2), 179 - 89
Extensive hepatic cell necrosis produced by the Shwartzman mechanism; Mori W et al.; Acute, severe, and extensive necrosis of the liver was produced in pregnant and non-pregnant female adult rabbits by the Shwartzman mechanism . Shwartzman reagent (E . coli endotoxin) was administered in various combinations by three routes of injection, the portal vein (mesenteric vein), the bile duct, and the ear vein . Morphologic changes of the extrahepatic organs were minimal . The similarity to massive necrosis in human liver and the effect of pregnancy on hepatic necrosis in rabbit and man were discussed . The lesion is presented as a new animal model for acute massive hepatic necrosis and is proposed as a third category of Shwartzman reaction, designated the univisceral type.

Ann N Y Acad Sci, 1979 May 31, 320, 518 - 34
Quantification of total IgM and IgG and specific IgM and IgG to a thymus-independent (LPS) and a thymus-dependent (tetanus toxoid) antigen in the rat by enzyme-linked immunosorbent assay (ELISA); Vos JG et al.; Rat IgM and IgG was determined by mechanized "sandwich" enzyme-linked immunosorbent assay (ELISA) using peroxidase labeled anti-rat-IgM and -IgG . Linear ranges in standard curves of a reference rat serum had a slope similar to the slopes found with sera of 25 rats of various age . IgM and IgG measurements by ELISA in these sera correlated well with results obtained by single radial immuno-diffusion (SRID) . In addition, the precision of the enzyme immunoassay was the same as obtained with the SRID . Compared with SRID, ELISA is less time consuming and the amount of antiserum used in the macro-ELISA is one order of magnitude lower; and again 10 times lower in the mechanized micro-ELISA that is currently being developed . In conclusion, the ELISA is a specific, reliable, sensitive, and economic method for routine measurement of rat serum IgG and IgM e.g . in toxicity studies . In the second part of this study, ELISA and the passive hemagglutination test were compared to determine the primary and secondary antibody response to E . coli lipopolysaccharide (LPS) and tetanus toxoid in rats . In the ELISA, the antigens were bound to the wells of polystyrene microplates . Tetanus toxoid was coated directly, LPS after complexing with methylated bovine serum albumin . After incubation with dilutions of the rat sera, the amount of antibody bound to the solid phase was quantified by means of peroxidase-labeled antiimmunoglobulin . The specificity of the enzyme immunoassay was tested by absorption of the sera with the respective antigens . ELISA proved to be more sensitive than the hemagglution reaction, except when titers were determined during the secondary response to tetanus toxoid . Besides its specificity and sensitivity, ELISA is a convenient method for measuring both IgM and IgG antibodies . Finally, evidence is presented that in the rat, the humoral immune response to LPS is a thymus-independent phenomenon . Thus, by using the antibody response to LPS and tetanus toxoid in function studies of the immune system of the rat, insight can be obtained in the thymus-independent and thymus-dependent humoral immune response.

Biochemistry, 1979 May 29, 18(11), 2139 - 45
Evidence for a conformational change in the Escherichia coli maltose receptor by excited-state fluorescence lifetime data; Zukin RS; The initial signaling event during maltose chemoreception in Escherichia coli is identified with a delocalized liqand-induced conformational change in the maltose binding protein . Substantiation for the conformational change involves a new application of the "distant reporter group technique" {Zukin, R.S., Hartig, P.R., & Koshland, D.E., Jr . (1977a) Proc . Natl . Acad . Sci . U.S.A . 74, 1932-1936} utilizing excited-state fluorescence lifetime measurements . Binding of maltose to its receptor results in changes in the microenvironment of the two tryptophan residues of the receptor protein and of an experimentally attached reporter group, 5-(iodoacetamido) fluorescein . The minimum distance between the two typtophans from efficiency of fluorescence energy transfer theory is 17 A; the minimum distance from the farther tryptophan to the fluorescein is 50 A . Thus, the maltose receptor is shown to undergo molecular rearrangements at distant sites upon ligand binding . The general feature of conformational change as the initial signaling event during chemoreception in the enteric bacteria is discussed.

J Biol Chem, 1979 May 25, 254(10), 4245 - 52
Purification of the o-dianisidine peroxidase from Escherichia coli B . Physicochemical characterization and analysis of its dual catalatic and peroxidatic activities; Claiborne A et al.; Extracts of aerobically grown Escherichia coli B exhibit both catalase and dianisidine peroxidase activities . Polyacrylamide gel electrophoresis demonstrates two distinct catalases which have been designated hydroperoxidases I and II (HP-I and HP-II) in order of increasing anodic mobility . HP-I has been purified to essential homogeneity and found to be composed of four subunits of equal size . Its molecular weight is 337,000, and it contains two molecules of protoheme IX per tetramer . Its amino acid composition is unusual, for so large a protein, in lacking half-cystine . HP-I is a very efficient catalase with an activity optimum at pH 7.5, a Km for H2O2 of 3.9 mM, and a turnover number of 9.8 x 10(5) per min . It is also a broad specificity peroxidase capable of acting upon dianisidine, guaiacol, p-phenylenediamine, and pyrogallol . Dianisidine acted as a powerful reversible inhibitor of the catalatic activity of HP-I and as a suicide substrate when HP-I functioned in its peroxidatic mode.

J Biol Chem, 1979 May 25, 254(10), 4009 - 14
Oxygen-sensitive and -insensitive nitroreduction by Escherichia coli and rat hepatic microsomes; Peterson FJ et al.; Nitrofurazone is shown to undergo an initial 1-electron (oxygen-sensitive) or 2- or more electron (oxygen-insensitive) reduction by partially purified nitroreductases from Escherichia coli . Nitrofurazone (50 micronM) is reduced by the oxygen-sensitive reductase to a nitro anion free radical as indicated by ESR and visible spectroscopy . The visible spectrum of the nitro anion free radical is characterized by an increase in absorption at 406 nm . In the presence of the oxygen-sensitive reductase, nitrofurazone stimulates superoxide formation and oxygen consumption . This enzyme gives a steady state radical concentration which is proportional to the square root of the enzyme concentration, suggesting that the nitrofurazone anion radical is an obligate intermediate in the reduction and that the radical decays by a nonenzymatic second order process . The oxygen-insensitive reductase does not form the nitro anion free radical nor in the presence of nitrofurazone does it stimulate oxygen consumption . Visible spectroscopy shows that nitrofurazone is reduced by the oxygen-sensitive reductase to a species with an absorption maximum at 335 nm, which has been previously identified as the amine . The oxygen-insensitive reductase reduces nitrofurazone to a previously identified cyano derivative with an absorption maximum at 280 nm . Rat hepatic microsomes appear to metabolize nitrofurazone in a manner similar to the oxygen-sensitive E . coli reductase.

J Biol Chem, 1979 May 25, 254(10), 3730 - 7
Nucleoside transport in cells and membrane vesicles from Escherichia coli K12; Munch-Petersen A et al.; Osmotic shock treatment of cells of Escherichia coli K12 caused a reduction in the transport of nucleosides into the cells . The strains used carried mutations in the nucleoside catabolizing enzymes . This indicated that the decrease in transport capacity was not due to loss of these enzymes during the shock treatment . Membrane vesicles, prepared from the same strains, showed a limited transport of cytidine, deoxycytidine, and uridine . Transport of purine nucleosides and of thymidine was very low in vesicles lacking the appropriate nucleoside phosphorylases and no significant stimulation was observed if the nucleoside phosphorylases were present in the membrane vesicles . These results all indicate that components outside the cytoplasmic membrane are important for nucleoside transport . Selection for resistance to fluorodeoxycytidine yielded mutants which were unable to transport any nucleoside, even when the nucleoside phosphorylases were present in high amounts . This finding is consistent with a requirement for a specific transport process prior to the initial enzymatic attack on the incoming nucleoside.

J Biol Chem, 1979 May 25, 254(10), 3873 - 8
The structure of the RNA binding site of ribosomal proteins S8 and S15; Muller R et al.; Proteins S8 and S15 from the 30 S ribosomal subunit of Escherichia coli were bound to 16 S RNA and digested with ribonuclease A . A ribonucleoprotein complex was isolated which contained the two proteins and three noncontiguous RNA subfragments totaling 93 nucleotides, that could be unambiguously located in the 16 S RNA sequence . We present a secondary structural model for the RNA moiety of the binding site complex, in which the two smaller fragments are extensively base-paired, respectively, to the two halves of the large fragment, to form two disconnected duplexes . Each of the two duplexes is interrupted by a small internal loop . This model is supported by (i) minimum energy considerations, (ii) sites of cleavage by ribonuclease A, and (iii) modification by the single strand-specific reagent kethoxal . The effect of protein binding on the topography of the complex is reflected in the kethoxal reactivity of the RNA moiety . In the absence of the proteins, 5 guanines are modified; 4 of these, at positions 663, 732, 733, and 741, are strongly protected from kethoxal when protein S15 is bound.

J Biol Chem, 1979 May 25, 254(10), 3761 - 4
Immunological studies on 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase isoenzymes; McCandliss RJ et al.; An apparently homogeneous preparation of the phenylalanine-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase isoenzyme from Escherichia coli was used as the antigen for antibody production in New Zealand white rabbits . The antibodies were monospecific as judged by immunodiffusion and immunoelectrophoresis . Antigen . antibody complexes maintained full enzyme activity and were inhibited by phenylalanine, indicating that neither the active site nor the feedback-inhibitor binding site is mechanistically connected to amino acid sequences which are antigenic determinants . While phenylalanine-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase could be quantitatively removed from solution by immunoprecipitation with soluble or immobilized antibodies, neither the tyrosine-sensitive nor the tryptophan-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase, the other two isoenzymes catalyzing the first step in the biosynthesis of aromatic compounds, formed any detectable complexes with the antibodies . This indicated less structural similarity than would be expected for isoenzymes . Also, the antibodies did not cross-react with 5-dehydroquinate synthase, the enzyme catalyzing the second step of the common aromatic biosynthetic pathway.

Biochim Biophys Acta, 1979 May 24, 562(3), 534 - 45
Fractionation and structural elucidation of the active components of aurintricarboxylic acid, a potent inhibitor of protein nucleic acid interactions; Gonzalez RG et al.; Commercially available, as well as synthetically prepared, samples of aurintricarboxylic acid (a widely employed potent inhibitor of protein nucleic acid interactions) consist mostly of a heterogeneous collection of polymers, as shown by fractionation schemes utilizing both dialysis and ultrafiltration, and by molecular weight measurements . 13C-NMR studies suggest that the polymeric material is of the phenol-formaldehyde type; inhibitory assays that depend on the formation of a protein-nucleic acid complex revealed that potency varied directly with the molecular weight of the polymer . Fractions of molecular weight 400 were essentially inactive.

Biochim Biophys Acta, 1979 May 24, 562(3), 418 - 28
The effect of differential methylation by Escherichia coli of plasmid DNA and phage T7 and lambda DNA on the cleavage by restriction endonuclease MboI from Moraxella bovis; Dreiseikelmann B et al.; The nucleotide sequence recognized and cleaved by the restriction endonuclease MboI is 5' GATC and is identical to the central tetranucleotide of the restriction sites of BamHI and BglII . Experiments on the restriction of DNA from Escherichia coli dam and dam+ confirm the notion that GATC sequences are adenosyl-methylated by the dam function of E . coli and thereby are made refractory to cleavage by MboI . On the basis of this observation the degree of dam methylation of various DNAs was examined by cleavage with MboI and other restriction endonucleases . In plasmid DNA essentially all of the GATC sequences are methylated by the dam function . The DNA of phage lambda is only partially methylated, extended methylation is observed in the DNA of a substitution mutant of lambda, lambda gal8bio256, and in the lambda derived plasmid, lambdadv93, which is completely methylated . In contrast, phage T7 DNA is not methylated by dam . A suppression of dam methylation of T7 DNA appears to act only in cis dam . A suppression of dam methylation of T7 DNA appears to act only in cis since plasmid DNA replicated in a T7-infected cell is completely methylated . The results are discussed with respect to the participation of the dam methylase in different replication systems.

Biochim Biophys Acta, 1979 May 24, 562(3), 400 - 17
Replication of the linear mitochondrial DNA of Tetrahymena pyriformis; Goldbach RW et al.; 1 . Electron micrographs of the linear mtDNA from Tetrahymena pyriformis strain GL show linear molecules with a duplex 'eye' of variable size in the middle . This indicates that replication of this DNA starts near the middle of the molecule and proceeds bidirectionally to the ends, as previously shown for the mtDNA of strain ST (Arnberg, A.C., Van Bruggen, E.F.J., Clegg, R.A., Upholt, W.B . and Borst, P . (1974) Biochim . Biophys . Acta 361, 266-276) . The mtDNAs of these two strains have little base sequence homology beyond the ribosomal RNA cistron (Goldbach, R.W., Bollen-De Boer, J.E., Van Bruggen, E.F.J . and Borst, P . (1978) Biochim . Biophys . Acta 521, 187-197) . 2 . Electron micrographs of mtDNA from strain ST, spread under non-denaturing conditions, contain only molecules with fully duplex ends . mtDNA spread under conditions of early denaturation contains duplex loops on one end (40% of all molecules) or both ends (37%) . The loops are stable to partial denaturation and vary in size from 0.15 to approximately 1.0 micron, most loops measuring 0.25--0.40 micron . No loops are formed with single-stranded DNA under analogous conditions and we conclude from this result that loop formation is based on the presence of straight, rather than inverted, duplications near the ends . 3 . When full-length 3H-labelled mtDNA from strain ST, 32P-labelled at the 5'-termini with T4 polynucleotide kinase, was sedimented in alkaline sucrose gradients, greater than 70% of the 3H and less than 30% of the 32P cosedimented with full-length molecules; the remaining 32P sedimented heterogeneously and predominantly with the DNA less than 10% the size of intact single strands . Brief incubations of full-length mtDNA with DNA polymerase I from Escherichia coli and labelled dNTPs at 15 degrees C did not lead to preferential labelling of terminal EcoRI fragments of the DNA . From these results we infer that the DNA contains nicks or gaps near the termini and that these are not bordered by free 3'-OH groups . 4 . A model is presented in which straight sequence repetitions at the termini of Tetrahymena pyriformis mtDNA are involved in the later stages of replication . This model can also account for the pronounced terminal heterogeneity previously observed in this DNA.

Biochim Biophys Acta, 1979 May 24, 562(3), 527 - 33
Polynucleotides XLVII . Synthesis and properties of poly(2-methylthio- and 2-ethylthioadenylic acid) . Formation of non-Watson-Crick type complexes; Fukui T et al.; Poly(2-methyl- and 2-ethylthioadenylic acid) were prepared by polymerization of corresponding diphosphates with Escherichia coli polynucleotide phosphorylase . These polynucleotides have relatively large hypochromicity of 30-35% . Acid titration of these polymers showed abrupt transition at pH 5.34-5.4, which may indicate that the introduction of alkylthio group at 2-position of adenine bases reduced their basicity . Thermal melting of these polymers showed no clear transition points at neutral pH, but in acidic media they have Tm values of 57 and 56 degrees C, somewhat lower than that of poly(A) . Upon complex formation with poly(U), these poly(A) analogs showed only one poly(rs2A) . poly(U) type double-strand complexes, similar to that found in the case of poly(m2A) . poly(U).

Mol Gen Genet, 1979 May 23, 173(1), 39 - 50
Expression of Escherichia coli ribosomal protein and RNA polymerase genes cloned on plasmids; Fiil NP et al.; Fragments of lambda drifd 18 DNA with different end-points within the set of structural genes of ribosomal proteins L11 (RPLK), Li (rplA), L10 (rplJ) and L12 (rplL) as well as the beta (rpoB) ANd beta' (rpoC) subunits of RNA polymerase have been cloned on plasmids . These plasmids were transformed in host cells which were mutant for each of the genes, enabling expression of both wild-type (plasmid-borne) and mutant (chromosomal) genes to be differentiated . On the basis of these results we propose the following genetic structure for the region: rplK and rplA are in one operon; rplL, rpoB and rpoC are in a second . Our data suggest the possibility that rplJ is by itself in an operon situated between the other two.

Mol Gen Genet, 1979 May 23, 173(1), 15 - 21
Development of a system useful for studying the formation of unstable alleles of IS2; Peterson PA et al.; IS2-induced deletions of the gal control region were isolated in a plasmid carrying gal OP-308::IS2-7 . This contains a 54 basepair long, unstable mini insertion within IS2, thus allowing constitutive expression of the gal structural genes . Deletion PPI is 11.9 kilobasepairs (kb) long and is Gal+ because it has retained the mini insertion . In PP4 7.2 kb DNA material including markers gal OP, chlD and pgl are deleted . PP4 has lost the mini insertion and is therefore Gal negative . DNA sequencing of the newly formed junction in PP4 reveals that the deletion terminates precisely at nucleotide 1 of IS2 and that no DNA sequence homology is involved in this IS2-mediated deletion formation . PPI segregates Gal- clones due to the loss of the mini insertion . One such segregant PPIS and PP4 both give only constitutive Gal+ revertants, which consist of the previously known mini insertions and also a new class of "supermini" inserts within IS2 of about 10 to 20 basepairs long . Therefore, PPIS and PP4 can be used to study various parameters involved in the formation of mini insertions.

Biochim Biophys Acta, 1979 May 23, 578(1), 188 - 95
Manual solid phase sequence analysis of polypeptides using 4-N-N,-dimethylaminoazobenzene 4'-isothiocyanate; Chang JY; A manual solid-phase method for sequence analysis of polypeptides is described . The immobilized polypeptide was subjected to stepwise degradation by Edman-type reagent, using the 4-N,N-dimethylaminoazobenzene 4'-isothiocyanate phenyllisothiocyanate double coupling method . The N-terminal amino acids were released (after conversion reaction) as 4-N,N-dimethylaminoazobenzene 4'-thiohydantoin (identified by thin layer chromatography) and phenylthiohydantoin derivatives . The method required 2--10 nmol polypeptide.

Biochim Biophys Acta, 1979 May 23, 578(1), 31 - 40
NADP-specific isocitrate dehydrogenase of Escherichia coli . IV . Purification by chromatography on Affi-Gel Blue; Vasquez B et al.; Affinity chromatography on Affi-Gel Blue has been used to purify the NADP-specific isocitrate dehydrogenase (EC 1.1.1.42) from Escherichia coli . The protocol permits rapid purification of the enzyme in milligram quantities with a yield of 50% and is carried out almost entirely at room temperature . The preparation was judged to be homogeneous by non-denaturing electrophoresis at pH 7.5 and denaturing electrophoresis in the presence of sodium dodecyl sulfate . The subunit molecular weight of 53 000, determined by sodium dodecyl sulfate gel electrophoresis, is in reasonable agreement with the value of 46 900 estimated from the amino acid composition data.

J Chromatogr, 1979 May 21, 173(2), 281 - 98
Major and modified nucleosides in tRNA hydrolysates by high-performance liquid chromatography; Davis GE et al.; We describe a high-performance liquid chromatographic analytical method that can be readily placed in operation, and which is particularly well suited to scientists investigating tRNA structure, biosynthesis, and function, and for the determination of major and modified nucleosides of tRNA . The method is characterized by the following features: (1) Sensitivity at the nanogram level; (2) High chromatographic resolution and selectivity; (3) Direct measurement of nucleosides with accuracy and precision; (4) Analysis is non-destructive and the high capacity of this chromatographic system allows easy isolation of pure nucleosides for further characterization; (5) Rapid separation and measurement in ca . 1 h after hydrolysis to nucleosides; and (6) Quantitation without use of radiolabeled compounds; however, labeled compounds are readily isolated and measured.

Biochim Biophys Acta, 1979 May 17, 553(2), 224 - 34
Nature of the regions involved in the insertion of newly synthesized protein into the outer membrane of Escherichia coli; de Leij L et al.; Outer membrane proteins are synthesized by cytoplasmic membrane-bound polysomes, and inserted at insertion sites which cover about 10% of the total outer membrane when cells grow with a generation time of 1 h . A membrane fraction enriched in outer membrane insertion regions was isolated and partly characterized . The rat at which newly inserted proteins are transferred from such insertion regions into the rest of the outer membrane was found to be very fast; the new protein content of insertion regions and that of the remaining outer membrane equilibrate completely within about 20 s at 25 degrees C . Given the rather rigid structure of the outer membrane and the multiple interactions between outer membrane components and the murein layer, lateral diffusion of newly inserted proteins from insertion sites to the remaining outer membrane is not likely to explain this rapid equilibration . Instead, the data support a model in which insertion regions move along the cell surface, leaving behind stationary, newly inserted outer membrane proteins.

Eur J Biochem, 1979 May 15, 96(2), 301 - 9
The synthesis of chloroplast high-molecular-weight ribosomal ribonucleic acid in spinach; Hartley MR et al.; Illuminated suspensions of chloroplasts isolated from young spinach leaves show incorporation of {3H}uridine into several species of RNA . One such RNA species of Mr 2.7 x 10(6) shows sequence homology with both the chloroplast 23-S rRNA (Mr = 1.05 x 10(6)) and 16-S rRNA (Mr = 0.56 x 10(6)), as judged by DNA/RNA competition hybridization . Leaves labelled in vivo with {32P}orthophosphate in the presence of chloramphenicol accumulate labelled RNAs of Mr 1.28 x 10(6), 0.71/0.75 x 10(6) and 0.47 x 10(6) . The 1.28 x 10(6)-Mr RNA shows 80.5% sequence homology with the 1.05 x 10(6)-Mr rRNA and the 0.71/0.75 x 10(6)-Mr RNA mixture shows 76% sequence homology with the 0.56 x 10(6)-Mr rRNA . We conclude that the pathway of rRNA maturation in spinach chloroplasts is similar to that of Escherichia coli.

Eur J Biochem, 1979 May 15, 96(2), 403 - 16
Affinity chromatography of tryptophan synthase from Escherichia coli . Systematic studies with immobilized tryptophanol phosphate; Gschwind HP et al.; Inhibition studies and affinity chromatography indicate that derivatives of tryptophanol phosphate are suitable ligands for the affinity chromatography of tryptophan synthase . A phenyl group on the spacer arm strengthens the interaction of immobilized tryptophanol phosphate with the enzyme . The alpha 2 beta 2 complex specifically requires the presence of 0.3--0.5 M phosphate ions for binding . The alpha subunit binds in dilute Tris buffer, but its binding is also enhanced by the presence of phosphate ions . The beta 2 subunit binds unspecifically but strongly to the affinity material and to a variety of other immobilized hydrophobic ligands . Binding studies with suspensions of affinity material show that the alpha subunit interacts rapidly and reversibly . Indoleglycerol phosphate and indolepropanol phosphate release bound alpha 2 beta 2 complex and alpha subunit in a competitive manner, indicating that the interaction occurs biospecifically, i.e . via the active site of alpha subunit . L-Serine is a non-competitive inhibitor of binding . These results are discussed with regard to the composite-active-site hypothesis {T . E . Creighton (1970) Eur . J . Biochem, 13, 1--10} . Both the alpha subunit and the alpha 2 beta 2 complex of tryptophan synthase from Escherichia coli can be obtained with high yields and in homogenous form by absorption to the affinity material from partially purified preparations . Elution is achieved with linear gradients either of indolepropanol phosphate or of indoleglycerol phosphate or, in the case of the complex, of L-serine . At the low concentrations of the complex found in crude extracts of wild-type E . coli cells, the unexpectedly high affinity of the beta 2 subunit for hydrophobic ligands leads to partial dissociation of the complex.

Biochemistry, 1979 May 15, 18(10), 2103 - 12
Study of the cytoplasmic and outer membranes of Escherichia coli by deuterium magnetic resonance; Davis JH et al.; The cytoplasmic and outer membranes of Escherichia coli were studied between 0 and 40 degrees C by deuterium magnetic resonance quadrupolar echo spectroscopy . The L51 strain of E . coli was used to incorporate perdeuterated palmitic acid into the membrane phospholipids . The cytoplasmic and outer membranes were separated using standard techniques . The spectrum of each membrane preparation was dominated at high temperatures (greater than or equal to 37 degrees C) by the characteristic liquid-crystalline plateau previously observed for perdeuterated palmitate chains in model phospholipid membranes . At low temperatures, the shape and width of the spectrum were characteristic of the gel phase . The relative intensities of the liquid-crystalline and gel features varied systematically with temperature . A quantitative analysis of the acyl chain orientational order was carried out by using the method of moments . The orientational order at each temperature was greater in the outer membrane sample than in that of the cytoplasmic membrane, indicating that the liquid-crystalline-gel transition region in the outer membrane is shifted to higher temperatures than that of the cytoplasmic membrane by about 7 degrees C . It is clear from the results that most of the phospholipid molecules participate in the phase transition.

Biochemistry, 1979 May 15, 18(10), 2028 - 38
Phenylalanyl-tRNA synthetase of Escherichia coli K 10 . Multiple enzyme-aminoacyl-tRNA complexes as a consequence of substrate specificity; Guntner C et al.; The interaction between Phe-tRNA(Phe) or other acyl-tRNA derivatives thereof and phenylalanyl-tRNA synthetase of Escherichia coli K 10 has been investigated by nonequilibrium dialysis, by fluorescence titration in the presence of 2-p-toluidinylnaphthalene-6-sulfonate, by the kinetics of the aminoacylation of tRNA(Phe), and by the kinetics of the catalytic hydrolysis of Phe-tRNA(Phe) . Phe-tRNA(Phe), or derivatives thereof, forms two types of complexes with the synthetase . One type involves the attachment of the phenylalanyl moiety to the phenylalanine-specific site of the enzyme, and the other type, to the tRNA(Phe)-specific binding site . They resemble alternative modes of a destabilized enzyme-product complex and are predicted on the basis of thermodynamic considerations . The two modes of binding of acyl-tRNA compete with each other . The attachment of Phe-tRNA(Phe) to the phenylalanine-specific site dominates . At equilibrium, this complex is present at a fourfold higher concentration than the other type of complex . The HNO2 deaminated Phe-tRNA(Phe) binds exclusively to the site specific for L-phenylalanine . On the contrary, Ile-tRNA(Phe) adds at 94.1% to the tRNA(Phe)-specific site . The association of Phe-tRNA(Phe) with this site leads to enzymatic hydrolysis into L-phenylalanine and tRNA(Phe) . The complex involving the phenylalanine-specific site is hydrolytically unproductive . L-Phenylalanine acts as an activator of the hydrolysis by occupying the amino acid specific site and by shifting the equilibrium between the complexes toward the binding ot Phe-tRNA(Phe) at the tRNA(Phe)-specific site . The association of Phe-tRNA(Phe) at the phenylalanine-specific site does not interfere sterically with the binding of free tRNA(Phe) . The sequential addition of free and aminoacylated tRNA(Phe) exhibits negative cooperativity . Such a mechanism could help to expel the product from the enzyme.

Biochemistry, 1979 May 15, 18(10), 2019 - 27
Conformation of Escherichia coli ribosomal protein L7/L12 in solution: hydrodynamic, spectroscopic, and conformation prediction studies; Luer CA et al.; The conformation of Escherichia coli ribosomal protein L7/L12 in solution has been studied using spectroscopic and hydrodynamic methods . Circular dichroism studies in the near-ultraviolet region reveal two bands at 262 and 268 nm originating from the tertiary conformational environment of the phenylalanyl residues . Additional characterization of the phenylalanine environment includes an intrinsic fluorescence emission spectrum arising from the phenylalanine fluorophores . Computer analysis of the far-ultraviolet circular dichroism spectrum suggests that L7/L12 contains as much as approximately 76% alpha helix . Hydrodynamic properties of L7/L12, measured with the purpose of providing relevant shape information, include the frictional coefficient ratio (1.84 +/- 0.03) and intrinsic viscosity (28 +/- 0.4 mL/g) . The experimentally determined frictional coefficient (6.15 +/- 0.15 X 10(-8) has been compared with theoretical calculations of the same value employing two independent methods and assuming various dimensions for the L7/L12 dimer . Combining the experimental results from this work with those available from the literature, and using conformation predictive methods of Chou & Fasman {P . Y . Chou & G . D . Fasman (1974) Biochemistry 13, 211-222, 222-245} and of Maxfield & Scheraga (F . R . Maxfield & H . A . Scheraga (1976) Biochemistry 15, 5138-5153), several possible molecular models of the L7/L12 dimer have been constructed and critically examined . A model which is consistent with all of the available data is proposed.

Biochemistry, 1979 May 15, 18(10), 1979 - 84
Subunit interaction in tryptophan synthase of Escherichia coli: calorimetric studies on association of alpha and beta 2 subunits; Wiesinger H et al.; Association of the apo-beta 2 and the holo-(beta-PLP)2 subunits of tryptophan synthase from Escherichia coli (L-serine hydro-lyase (adding indole) (EC 4.2.1.20)) with alpha subunits of the same enzyme has been studied by microcalorimetry . The results obtained from thermometric titrations clearly demonstrate that only the native complex alpha2beta 2 is formed, independent of an excess of alpha protein . The reaction of the holo-(beta-PLP)2 with alpha subunits at 25 degrees C is accompanied by a negative enthalpy change, which is almost twice as large as that for complex formation with the apo-beta 2 protein, thus indicating that the interaction enthalpy becomes more favorable in the presence of the coenzyme pyridoxal 5'-phosphate (PLP) . Both reaction enthalpies show very large negative temperature coefficients, -3600 +/- 100 cal K-1 (Mol of beta 2)-1 being the value for the formation of the apoenzyme and -2300 +/- 100 cal K-1 (mol of beta 2)-1 pertaining to formation of the holoenzyme . The studies on the association of alpha and beta2 subunits in the two buffers revealed that at 25 degrees C approximately 0.75 proton are absorbed in the presence and absence of the coenzyme, whereas at 35 degrees C one proton is taken up from the solution when PLP is present, but two if the apo-beta 2 complex reacts . These results are a clear indication of energetic linkage between intersubunit interaction, hydrogen ion equilibria, and the binding of the coenzyme.

Biochemistry, 1979 May 15, 18(10), 2038 - 44
RNA replication: required intermediates and the dissociation of template, product, and Q beta replicase; Dobkin C et al.; Replication complexes containing only one molecule of Q beta replicase and one strand of midivariant RNA (MDV-1 RNA) template were prepared by incubating the replicase with an excess of MDV-1 (-) RNA . In the presence of excess minus strands, these monoenzyme replication complexes were shown to synthesize essentially pure MDV-1 (+) RNA in both the first and second cycles of replication . When an equivalent concentration of mutant MDV-1 (-) RNA was added to this reaction before completion of the first cycle of replication, only wild-type MDV-1 (+) RNA was produced in the first cycle, but both mutant and wild-type MDV-1 (+) RNA were produced in the second cycle of replication . These results demonstrate that a monoenzyme complex is competent to synthesize RNA and, therefore, that a multienzyme replication complex is not a necessary intermediate of replication . The data also imply that after the completion of chain elongation, the product strand is released from the replication complex and that the template and the replicase then dissociate.

Biochemistry, 1979 May 15, 18(10), 2012 - 9
Properties of Escherichia coli 16S ribosomal ribonucleic acid treated with 4,5',8-trimethylpsoralen and light; Karathanasis SK et al.; 16S rRNA reacted with the furocoumarin 4,5',8-trimethylpsoralen (trioxsalen) and 360-nm light showed a number of chemical and physical differences from untreated RNA . After extensive irradiation, five molecules of trioxsalen were bound per molecule of RNA . The trioxsalen-treated RNA had an altered ultraviolet absorption spectrum and a distinctive fluorescence emission spectrum . The modified RNA was significantly more resistant to T1 ribonuclease digestion than was control RNA . Treated RNA, when mixed with purified ribosomal proteins, was not functional in the in vitro reconstitution of 30S subunits and yielded more slowly sedimenting particles which were inactive in protein synthesis assays . By contrast, 16S rRNA within the 30S subunit structure did not exhibit these changes when reacted with the same dose of trioxsalen and light, suggesting that the ribosomal proteins were effective in protecting the RNA from interaction with the drug.

Biochim Biophys Acta, 1979 May 10, 568(1), 234 - 42
Tritium exchange reactions catalyzed by 2-oxo-4-hydroxyglutarate aldolase from Escherichia coli K-12; Grady SR et al.; Tritiated water and tritiated substrates have been used to study exchange reactions catalyzed by Escherichia coli 2-oxo-4-hydroxyglutarate aldolase (4-hydroxy-2-oxoglutarate glyoxylate-lyase, EC 4.1.3.16, 2-oxo-4-hydroxyglutarate in equilibrium pyruvate + glyoxylate) . With pyruvate, the enzyme catalyzes a rapid first-order exchange of all three methyl hydrogens in the absence of added acceptor aldehyde (i.e . glyoxylate) . This reaction is not rate limiting for aldol condensation or cleavage; quite different pH-activity profiles for the exchange reaction versus aldol cleavage and also comparative effects that pH changes have on Km and V values for the two processes favor this conclusion . The exchange reaction with 2-oxobutyrate, a substrate analog, is stereoselective; one methylene hydrogen is removed at a 6-fold faster rate than the other but eventually both are exchanged . No tritium exchange occurs with glyoxylate.

J Biol Chem, 1979 May 10, 254(9), 3382 - 92
Glutamine phosphoribosylpyrophosphate amidotransferase from Escherichia coli . Purification and properties; Messenger LJ et al.; Glutamine 5-phosphoribosylamine:pyrophosphate phosphoribosyltransferase (amidophosphoribosyl-transferase) has been purified to homogeneity from Escherichia coli . The molecular weight of the native enzyme was 194,000 by sedimentation equilibrium centrifugation and 224,000 by gel filtration . A subunit Mr = 57,000 was estimated by gel electrophoresis in sodium dodecyl sulfate . Cross-linking experiments gave species of Mr = 57,000, 117,000, and 177,000 . A trimer or tetramer of identical subunits is indicated for the native enzyme . Highly active E . coli amidophosphoribosyl-transferase lacks significant nonheme iron . Enzyme activity was not enhanced by addition of iron salts and sulfide . Amidophosphoribosyltransferase exhibited both NH3- and glutamine-dependent activities . Glutaminase activity was detected in the absence of other substrates . Both glutamine- and NH3-dependent activities were subject to end product inhibition by purine 5'-ribonucleotides . AMP and GMP, in combination, gave synergistic inhibition . AMP and GMP exhibited positive cooperativity . In addition, GMP promoted cooperativity for saturation by 5-phosphoribosyl-1-pyrophosphate . Glutamine utilization was inhibited by NH3, suggesting that the amide of glutamine is transferred to the NH3 site prior to amination of 5-phosphoribosyl-1-pyrophosphate . The glutamine-dependent activity was selectively inactivated by the glutamine analogs L-2-amino-4-oxo-5-chloropentanoic acid and 6-diazo-5-oxo L-norleucine (DON) and by iodoacetamide . Incorporation of 1 eq of DON/subunit (Mr = 57,000) caused complete inactivation of the glutamine-dependent activity, thus providing evidence for one glutamine site per monomer and for the functional identity of the subunits . Following alkylation with iodoacetamide, carboxymethylcysteine was the only modified amino acid isolated from an acid hydrolysate . The glutamine-dependent activity was sensitive to oxidation . Inactivation by exposure to air was reversed by incubation with high concentrations of dithiothreitol.

J Biol Chem, 1979 May 10, 254(9), 3348 - 53
Tryptic core protein of lactose repressor binds operator DNA; Matthews KS; The core protein produced by mild proteolytic digestion of lactose repressor protein has been purified from native repressor by chromatography on phosphocellulose . The core protein isolated in this manner binds to operator DNA with an apparent dissociation constant of 10(-7) M, and the observed binding is decreased by the presence of inducer . Competition studies with nonspecific DNA indicate that the binding species in the core protein preparations is neither intact lactose repressor nor mixed tetramers containing varying numbers of intact NH2-terminal regions . This conclusion is supported by experiments designed to measure the rate of dissociation of the core protein from the operator DNA . Calculations based on the assumption that the isolated core protein binds similarly to the corresponding region in intact repressor protein indicate that the core region contributes approximately 40 to 50% of the energy of binding to operator DNA . Furthermore, the change in operator affinity upon inducer binding to core accounts for a minimum of 60% of the free energy change in binding to operator observed for the native protein . The demonstration that core protein binds to operator DNA requires a re-evaluation of the various models for repressor binding to DNA . A possible model based on the available information is presented.

J Biol Chem, 1979 May 10, 254(9), 3341 - 7
Activity changes in lac repressor with cysteine oxidation; Manly SP et al.; The effects of prior covalent cysteine modification or nonspecific DNA presence on the reaction of lac repressor protein with N-bromosuccinimide have been investigated . At low excesses, N-bromosuccinimide oxidation causes loss of operator DNA binding activity with simultaneous retention of inducer and nonspecific DNA binding activities . Cysteine and methionine are oxidized under the conditions utilized . Covalent modification of the cysteines of repressor prior to reaction decreased the observed loss of operator DNA binding capacity; the presence of nonspecific DNA partially prevented oxidation of the cysteines by N-bromosuccinimide, and concurrent protection of operator binding ability was observed . Methionine oxidation was observed in the cases where protection of the operator DNA binding capacity of repressor was seen . The region surrounding cysteine 107 was found to be influential in maintaining intact operator DNA binding function in repressor . This observation provides chemical evidence for the contribution of the core region of repressor in determining specificity of the protein in binding the lac operator . The protection from oxidation of cysteine residues in the core region by the presence of nonspecific DNA suggests that this binding influences the core region of the protein.

J Biol Chem, 1979 May 10, 254(9), 3264 - 71
Sequence of the 16 S-23 s spacer region in two ribosomal RNA operons of Escherichia coli; Young RA et al.; The transducing phages lambdadaroE and lambdadilv5, which carry the Escherichia coli ribosomal RNA operons rrnD and rrnX, respectively, have been mapped with the restriction endonucleases BamHI, EcoRI, HindIII, and Sma I . Using hybridization techniques, we have located the ribosomal RNA genes on these phage DNAs . The DNA sequence of the 437-base-pair 16 S-23 S ribosomal RNA intergenic spacer in the two rRNA operons rrnD and rrnX has been determined . The nucleotides examined exhibit only one base pair change between rrnD and rrnX . Both spacer regions contain the genes for tRNA1Ile and tRNA1BAla; the gene sequences are identical with the previously deduced tRNA sequences and are clustered within the first 60% of the spacer DNA . The most striking feature of the 16 S-23 S intergenic region in these two operons is the disparity in G-C content between the tRNA gene sequences (60% G-C) and the remaining spacer DNA (37% G-C) . Spacer sequences are known to be involved in the processing of the ribosomal RNA transcript by RNase III and RNase P . In addition, we report the sequence of the first 108 base pairs of the 23 S rRNA gene.

J Biol Chem, 1979 May 10, 254(9), 3206 - 10
A rapid procedure for isolation of large quantities of Escherichia coli DNA polymerase I utilizing a lambdapolA transducing phage; Kelley WS et al.; DNA polymerase I produced by infection of Escherichia coli K12 with the specialized transducing phage lambdapolA has been purified by a simplified procedure and shown to be identical with the enzyme produced by uninfected E . coli in all aspects which have been examined . The abundance of the enzyme in infected cells and the ease with which it may be purified will simplify the study of the enzyme's physical and chemical characteristics . In addition, the enzyme is now much more readily available for use as an analytical tool in nucleic acid sequence and structure studies.

J Biol Chem, 1979 May 10, 254(9), 3570 - 5
Properties of mutants of Escherichia coli lacking malic dehydrogenase and their revertants; Hansen EJ et al.; Mutants of Escherichia coli lacking malic dehydrogenase activity (mdh) were incapable of growth on acetate", succinate- or malate/mineral medium . Revertants of mdh strains which had regained the ability to grow on C4-dicarboxylic acids could be divided into two distinct classes . One type of revertant had regained the ability to synthesize functional malic dehydrogenase . The other type of revertant still lacked malic dehydrogenase activity but possessed a suppressor mutation which altered the regulation of the synthesis or activity of the C4-dicarboxylic acid transport system, resulting in increased C4-dicarboxylic acid transport activity . This latter class of revertants apparently synthesized oxalacetate from malate via the sequential actions of the NAD-linked malic enzyme, phosphoenolpyruvate synthetase, and phosphoenolpyruvate carboxylase . Evidence has been presented that is consistent with the hypothesis that oxalacetate is the inducer of the C4-dicarboxylic acid transport system . The inability of mutants lacking malic dehydrogenase to grow with a C4-dicarboxylic acid as the carbon source can be attributed to the difficulty such mutants have in synthesizing oxalacetate.

C R Seances Acad Sci D, 1979 May 7, 288(17), 1327 - 30
{Cooperative non-specific binding of the cyclic adenosine 3'--5'-monophosphate receptor protein (CRP) from Escherichia coli to double-stranded thymus and lambda pgal DNA}; Blazy B et al.; Either free or combined with cAMP, CRP binds cooperatively to double-stranded thymus and lambda pgal DNA . The affinity of CRP for both DNAs in these non-specific interactions is increased by cAMP without noticeable change in the degree of cooperativity . Values of the intrinsic association constant, cooperativity parameter, and site size of DNA were determined from ultracentrifugal investigations under near-physiological ionic conditions.

C R Seances Acad Sci D, 1979 May 7, 288(17), 1335 - 8
{In vitro inhibition of tRNA methyltransferases by queen substance, a pheromone of queen honeybees}; Rojas M et al.; The Queen Substance 1, a pheromone of the queen Honeybee Apis mellifica is an in vitro inhibitor of E . coli B tRNA methylations . This activity is not specific of the methylase source, as inhibitions have been observed with preparations from queen honeybee ovaries, Rat liver or a Mouse plasmocytoma 1-adenine methylase . These results, together with preceding ones concerning t, t-farnesyl-acetone 3, are discussed.

Mol Gen Genet, 1979 May 4, 172(2), 229 - 31
Thymidine sensitivity of certain strains of Escherichia coli K12; Ahmad SI et al.; In studies on thymineless death in Escherichia coli K12, it was noted that certain thymine requiring mutants were inhibited by thymidine . The pattern of inhibition varied with the conditions and media employed . Accumulation of deoxyribose-5-phosphate as a possible reason for inhibition is ruled out since the strains are deoB- (formerly drm-) and synthesize deoxyriboaldolase constitutively . We report this inhibition to alert investigators who study thymidine metabolism or use thymidine to label the DNA.

Mol Gen Genet, 1979 May 4, 172(2), 151 - 9
Nucleotide sequence of small ColE1 derivatives: structure of the regions essential for autonomous replication and colicin E1 immunity; Oka A et al.; A small ColE1 derivative, pAO2, which replicates like the original ColE1 and confers immunity to colicin E1 on its host cell has been constructed from a quarter region of ColE1 DNA (Oka, 1978) . The entire nucleotide sequence of pAO2 (1,613 base pairs) was determined based on its fine cleavage map . The sequence of a similar plasmid, pAO3, carrying additional 70 base pairs was also deduced . The sequence in the region covering the replication initiation site on these plasmids was consistent with those reported for ColE1 by Tomizawa et al . (1977) and by Bastia (1977) . DNA sequences indispensable for autonomous replication were examined by constructing plasmids from various restriction fragments of pAO2 DNA . As a result, a region of 436 base pairs was found to contain sufficient information to permit replication . The occurrence of initiation and termination codons and of the ribosome-binding sequence on pAO2 DNA suggests that a polypeptide chain consisting of 113 amino acid residues may be encoded by the region in which the colicin E1 immunity gene has been mapped.

Mol Gen Genet, 1979 May 4, 172(2), 211 - 9
A complementation analysis of mobilization deficient mutants of the plasmid ColE1; Inselburg J et al.; Hydroxylamine was used to induce mutants of the ColE1 derived plasmid pML2 that are inefficiently mobilized (Mob-) during conjugation by an Hfr donor . The ability of those mutants to be complemented by deletion mutants and Tn3 insertion mutants of ColE1 was examined . Three complementation groups were identified and localized on the ColE1 genetic map (Mob1, Mob2, and Mob3) . One hydroxylamine mutant was not complemented by any mobilization deficient mutant but was complemented by mobilizable ColE1 mutants . Two hydroxylamine mutants were not complemented by any ColE1 derivatives . A mutant that had its relaxation nick site deleted had a markedly reduced mobilizability . The relationship between DNA relaxation nick site deleted had a markedly reduced mobilizability . THe relationship between DNA relaxation, replication and mobilization is considered.

Nature, 1979 May 3, 279(5708), 43 - 7
Expression in Escherichia coli of hepatitis B virus DNA sequences cloned in plasmid pBR322; Burrell CJ et al.; Fragments of hepatitis B virus DNA isolated from Dane particles have been inserted into the Escherichia coli plasmid pBR322 and cloned . Cells carrying the hybrid plasmid synthesise antigenic material that reacts specifically with antisera to hepatitis B viral antigens.

Eur J Biochem, 1979 May 2, 96(1), 49 - 57
Procaine, a local anesthetic interacting with the cell membrane, inhibits the processing of precursor forms of periplasmic proteins in Escherichia coli; Lazdunski C et al.; Treatment of Escherichia coli cells with procaine (0.55%, w/v) results in the accumulation of precursor in addition to mature forms of two periplasmic proteins, alkaline phosphatase and glutamine-binding protein . The precursor form of alkaline phosphatase has a higher molecular weight than the mature form by about 2600 . An experimental technique is described to isolate and purify precursor forms of any presumably exported protein . After the membrane solubilization step in the presence of nonionic detergent, a peptidase is stimulated, resulting in partial cleavage of the precursors . The products of this cleavage have been identified as the mature protein and presumably the signal peptide in the case of alkaline phosphatase . The amino acid composition of this peptide, which is comprised of 25 residues, has been determined . Procaine (0.55%, w/v) causes an increase in molecular packing of lipid molecules in the membrane which might result in an alteration of membrane fluidity sufficient for selective inhibition of processing of precursors of exported proteins.

Eur J Biochem, 1979 May 2, 96(1), 87 - 92
Methionyl-tRNA synthetase from Escherichia coli . Inactivation and labeling by periodate-treated initiator tRNA; Fayat G et al.; Both the aminoacylation and isotopic ATP-PPi exchange activities of native and trypsin-modified methionyl-tRNA synthetases from Escherichia coli are specifically inactivated by incubation in the presence of periodate-treated initiator tRNA Met . The inactivation proceeds through the formation of a reversible Schiff's base between the epsilon-amino group of a lysine within the catalytic center of the enzyme and the 2',3'-aldehyde groups created at the 3'-terminal ribose of tRNA . The Schiff's base may be stabilized by reduction with sodium borohydride . Intact tRNA Met f competes with the inactivation by its dialdehyde . It has been verified in the case of the modified enzyme that the protection is afforded according to an equilibrium constant identical to that for tRNA Met f binding at the active site of the enzyme . Finally it is shown that the incorporation of one molecule of the dialdehyde of {14C}tRNA completely destroys the activity of the monomeric trypsin-modified methionyl-tRNA synthetase.

Eur J Biochem, 1979 May 2, 96(1), 167 - 75
Kinetic studies of the interaction between MS2 phage and F pilus of Escherichia coli; Date T; The kinetics of the binding reaction of MS2 phage to free F pili, which were highly purified from Escherichia coli, has been studied using a membrane filter assay . The rate of dissociation (kd) of the MS2-phage--F-pilus complex is very slow and follows first-order kinetics with a half-life of 4.2 h at 30 degrees C in the standard buffer . The dissociation rate is rather insensitive to temperature, but becomes more rapid at high ionic strength or at basic pH . In a 0.25 M ionic strength buffer, the half-life of the complex is about 1.0 min . The rate of association is very fast and follows second-order kinetics with the rate constant for association (ka) being 8 x 10(7) M-1 s-1 at 30 degrees C in the standard buffer . The rate of association is almost insensitive to ionic strength but slightly sensitive to pH or temperature . Monovalent cations can also promote the binding reaction as well as divalent cations but the complex formed with monovalent cation is unstable . A study of the kinetics of dissociation suggests that there are two types of interaction between MS2 phage and F pilus; one is a strong interaction formed with divalent cations and the other is a weak one formed with monovalent cations . The physical nature of the bonds involved in the former and the latter seems to be mainly electrostatic and non-electrostatic respectively . The mechanism of the binding reaction is discussed.

Nord Vet Med, 1979 May, 31(5), 193 - 205
Studies on seminal vesiculitis in the bull . I . Semen examination methods and post mortem findings; Blom E; During the ten-year period 1968--1978, about 1500 bulls were examined yearly for possible inflammatory conditions in the genital organs . Thirty-one cases of vesiculitis with or without accompanying ampullitis, and one case of isolated, one-sided ampullitis were recorded . Twenty-three cases (72%) were found in young bulls aged 18 months or less . Diagnosis was based on clinical examination of the pelvic genital organs or examination of semen, or in most cases on both . In 17 (53%) of the cases the diagnosis was initially established in the laboratory . Of the laboratory methods, the most reliable was the demonstration of pus cells in Giemsa stained semen smears . Twenty-five cases (24 + one case of ampullitis) were examined post mortem . Fifteen showed interstitial vesiculitis, Group I (Galloway, 1964) . The milder 'catarrhal' type (Group II) was found in 9 cases . The 'potential pathogenic' bacteria isolated from the inflamed vesicular glands were: Corynebact . pyogenes, 8 cases (33%), E . coli, 2 cases; Ureaplasma, 2 cases (one in combination with Corynebact . pyogenes) . Four of the bulls were newly imported (stress ?), IN THREE BULLS THERE WAS A HISTORY OF NAVEL INFECTION DURING CALFHOOD, AND IN ONE CASE THE BULL HAD LARGE NUMBERS OF VESICAL CALCULI (ABOUT 300 G) . In ten of the sets of pelvic organs examined (40%) rare congenital defects or anatomical variations were found in or around the colliculus seminalis (Blom, 1979b).

J Pathol, 1979 May, 128(1), 7 - 14
The inflammatory response to endotoxin; Goodman ML et al.; A typical inflammatory response resulted from the intravenous injection of endotoxin (E . coli) into living rabbits . Each rabbit was studied at three levels: the microvasculature and supporting tissue in the ear chamber was observed microscopically (up to X200) before, during, and at regular intervals following the injection of endotoxin; leucocyte and platelet counts were made periodically throughout each experiment; and tissue samples for histological study were obtained from each rabbit prior to death . The animal was anaesthetised before histological samples were secured . Within minutes after the intravenous injection of endotoxin, leucocytes were observed sticking to the endothelial cells lining the venules and the arterioles . Emboli appeared in the microcirculation within 10 min . Swelling of the microvascular endothelial cells was evident at 1 hr; oedema and extravasation of the cellular elements followed . The rectal temperature and leucocyte and platelet counts all fell within 10 min . of endotoxin . Histological examination of tissue from the ear chamber and visceral organs showed inflammatory changes . Congestion of the microvasculature, swelling of the endothelial cells, and margination and migration of neutrophils were common histological features in all organs . The earliest cells affected appeared to be the leukocyte and platelet.

Biophys J, 1979 May, 26(2), 243 - 61
Spatio-temporal structure of migrating chemotactic band of Escherichia coli . I . Traveling band profile; Holz M et al.; We developed a rapid-scanning, light-scattering densitometer by which extensive measurements of band migration speeds and band profiles of chemotactic bands of Escherichia coli in motility buffer both with and without serine have been made . The purpose is to test the applicability of the phenomenological model proposed by Keller and Segel (J . Theor . Biol . 1971 . 30:235) and to determine the motility (mu) and chemotactic (delta) coefficients of the bacteria . We extend the previous analytical solution of the simplified Keller-Segel model by taking into account the substrate diffusion which turns out to be significant in the case of oxygen . We demonstrate that unique sets of values of mu and delta can be obtained for various samples at different stages of migration by comparing the numerical solution of the model equation and the experimental data . The rapid-scanning technique also reveals a hitherto unobserved time-dependent fine structure in the bacterial band . We give a qualitative argument to show that the fine structure is an example of the dissipative structure that arises from a nonlinear coupling between the bacterial density and the oxygen concentration gradient . Implications for a further study of the dissipative structure in testing the Keller-Segel model of chemotaxis are briefly discussed.

Arch Fr Pediatr, 1979 May, 36(5), 508 - 11
{Congenital galactosemia detected by severe Escherichia coli infections}; Janaud JC et al.; Three babies with untreated galactosaemia presented with severe coliform infections in the first month of life . The frequency of coliform infections in untreated patients is emphasised . Galactosaemia should be considered in any baby with a severe coliform infection.

Mutat Res, 1979 May, 60(3), 271 - 8
Mutation induction by thymine deprivation in Escherichia coli B/R . II . Mutation in the repressed and derepressed tryptophan operon; Pons FW et al.; True Trp+ reversions are induced by thymine deprivation in cells with repressed trp operons as efficiently as in derepressed cells . At least part of the mutations are fixed during thymine starvation, i.e . in the absence of net DNA synthesis . The hypothesis is put forward that thymineless mutagenesis is due to repair-replication under limited concentrations of 5'-dTTP, performed by an inducible error-prone "DNA-polymerizing activity" on single-strand gaps.

Mutat Res, 1979 May, 60(3), 239 - 52
The development of a "Microtitre" fluctuation test for the detection of indirect mutagens, and its use in the evaluation of mixed enzyme induction of the liver; Gatehouse DG et al.; The "Microtitre" Fluctuation test recently introduced for the detection of direct mutagens has been adapted for the detection of indirect mutagens through the incorporation of an "S9-mix" metabolic system . It compares favourably with Greens' original method for the detection of a range of chemical mutagens . The technique has been employed in the evaluation of mixed enzyme induction using phenobarbitone and beta-naphthoflavone (benzoflavone), as a safe substitute for Aroclor-1254 . The post-mitchondrial preparations from rats induced with the combined inducers had a similar "metabolic competence" to those derived from Aroclor induced animals . Such a combination would therefore provide a useful alternative to Aroclor-1254 for routine screening . It was found that the level of "S9" present in the metabolic system greatly affected the quantitative mutagenic response . This varied considerably from chemical to chemical and underlined the need for such preliminary investigations in routine screening.

J Gen Microbiol, 1979 May, 112(1), 149 - 59
The pools of ribosomal proteins and ribosomal ribonucleic acids during relaxed control of Escherichia coli A19 (Hfr, rel met rns); Sykes J et al.; The soluble fraction extracted from Escherichia coli A19 (Hfr, rel met rns) during early and late times of phenotypic and genotypic induced relaxed control have been examined for the possible accumulation of ribosomal proteins (r-proteins) and rRNA species during this time of unbalanced macromolecular synthesis . Ribosomal proteins and rRNA species were not found to accumulate within the soluble fraction at any time during this period of relaxed control; even after the typical rRNA accumulation had ceased, r-proteins did not accumulate . It is concluded, from these and related observations, that the r-proteins and rRNA species known to be produced during relaxation must immediately associate to form the unusual ribonucleoprotein particles (e.g . 'relaxed particles' and 'chloramphenicol particles') characteristic of periods of relaxed control . Since r-proteins do not accumulate even when net RNA accumulation halts, it appears that some elements of the normal, basic co-ordination between rRNA and r-protein synthesis/stability persist even during relaxed control.

Horm Metab Res, 1979 May, 11(5), 371 - 4
Plasma renin, renin substrate and angiotensin II changes following experimental endotoxinaemia; Wernze H et al.; The effect of a single dose of endotoxin (B . coli, 1.5 mg/kg intravenously) on plasma renin concentration (PRC), renin substrate (PRSC), and angiotensin II (AT II) was studied in rats over a period of 48 hours . All determinations were performed by specific radioimmunoassay . Six and nine hours following endotoxin administration, renin secretion was decreased, whereas at 48 hours a slight increase in the PRC was found . In contrast, a three-fold elevation of the PRSC occurred during the first 24 hour period, attributable to a stimulation of the hepatic biosynthesis as result of corticosterone oversecretion . According to the observed changes in PRC and PRSC, AT II remains unchanged after six and nine hours, whereas a significant increase was detected after 24 and 48 hours . Based on the actual AT II level, the findings emphasize that in the rat the RAS does participate in the later stages of endotoxin stress only.

Gene, 1979 May, 6(1), 51 - 73
Restriction map, partial cloning and localization of 9S and 12S kinetoplast RNA genes on the maxicircle component of the kinetoplast DNA of Leishmania tarentolae; Masuda H et al.; We have constructed a restriction map of the maxicircle component of the kinetoplast DNA of Leishmania tarentolae for the enzymes EcoRI, Bam HI, HaeIII, HpaII, SalI, BglII and HindIII . The 9 and 12S kinetoplast RNAs were localized on this map . Two fragments of this maxicircle molecule were cloned in the bacterial plasmid, pBR322, including a 4.4 . 10(6) dalton EcoRI/BamHI fragment which contains the 9 and 12S RNA genes.

Gene, 1979 May, 6(1), 23 - 8
Prolonged incubation in calcium chloride improves the competence of Escherichia coli cells; Dagert M et al.; Escherichia coli cells are 4--6 times more transformable and 20--30 times more competent after 24 h incubation in cold calcium chloride than immediately after calcium chloride treatment . With 24-h-old competent cells we obtained routinely 2 . 10(7) transformants per microgram of pBR322 DNA, and transformed over 20% of viable cells.

Can J Microbiol, 1979 May, 25(5), 545 - 59
Effects of some platinum IV complexes on cell division of Escherichia coli; Ferguson CA et al.; A comparison was made of the effects of cis-tetrachlorodiaminoplatinum (IV) (cis-TCDPt), rans-TCDPt), and hexachloroplatinum (HCP) on growth and cell division of Escherichia coli strains D21 and D22 . At or below 40 microgram/mL, cis-TCDPt inhibited cell division but not growth, DNA, or protein synthesis, although areas of increased electron density could be demonstrated in treated cells . In contrast, 40 microgram/mL of trans-TCDPt or HCP inhibited growth . Trans-TCDPt-treated cells developed condensed nucleoids; HCP-treated cells showed no obvious cytological changes to correlate with growth inhibition . Combination of cis-TCDPt with nalidixic acid, both at one-half the lowest filament-forming concentrations, resulted in formation of filaments, suggesting an additive effect . Combination of cis-TCDPt followed by ampicillin on E . coli B/r resulted in single bulges near the center of the filaments . Cis-TCDPt could therefore inhibit an initial step in the septation sequence, possibly at the level of the regulation of the hydrolytic enzymes . Whether cis-TCDPt exerts its effect by interreaction with DNA or with a membrane target is still uncertain.

Helv Chir Acta, 1979 May, 46(1-2), 163 - 5
{Acute and chronic experimental posttraumatic osteomyelitis in guinea pigs}; Passl R et al.; The model of an experimental posttraumatic osteomyelitis is described . Acute and chronic osteomyelitis was produced by inoculation of 10(5) Staph . aureus or E . coli to fractured femora--stabilised or not--with intramedullar nailing . The results are discussed . The model seems to be useful to further studies on posttraumatic osteomyelitis.

Biophys Chem, 1979 May, 9(4), 345 - 53
A rotational diffusion coefficient of the 70S ribosome determined by depolarized laser light scattering; Bruining J et al.; We have obtained a rotational diffusion coefficient of the 70S ribosome isolated from Escherichia-coli (MRE-600), from the depolarized light scattering spectrum measured by photon correlation spectroscopy . The intensity correlation function of depolarized scattered light contains contributions due to multiple scattered and anisotropy scattered light from the ribosomal particle . We discuss extensively the subtraction procedure used to obtain the rotational correlation from the time from the experimental correlation function . We have also obtained the translational diffusion coefficient from the same sample by determining the polarized correlation function . The hydrodynamic radius determined from the rotational diffusion coefficient is only slightly larger than the radius obtained from the translational diffusion coefficient . Therefore the ribosomal particle has a non-spherical shape . This conclusion, however, could be impaired by the effect of free draining of the ribosome.

Mol Biol (Mosk), 1979 May-Jun, 13(3), 690 - 7
{Quantitative studies of interaction of polyuridylic acid with 30S subunits of ribosomes of Escherichia coli}; Kirillov SV et al.; Polyuridilic acid of average molecular weight 18 000 binds to the 30S subunits with stoichiometry 1 : 1 but two kinds of 30S.poly(U) complexes with different stability are formed . The main reason for such heterogeneity was found to be due to the presence or absence of ribosomal protein Sl in 30S subunits . In its presence the association constant of 30S.poly(U) complex is equal 2.7.10(8) M-1, and in the opposite case it is much less 1.5.10(6) M-1 . In the same conditions (20 mM MgCl2, 200 mM HN4Cl, 0 degrees) the association constant of binary complex Sl.poly(U) is equal 5.10(7) M-1.

Mol Biol (Mosk), 1979 May-Jun, 13(3), 531 - 42
{Effect of single-stranded and double-stranded breaks on the melting temperature of phage T2 DNA}; Iurgaitis AP et al.; The effect of single- and double-stranded breaks in DNA phage T2, on the melting temperature of this DNA in the 0,05 M SSC solution, was investigated . The number of cleavages per 1000 nucleotide pairs varied in the range of 0 to 10 . It is shown that single- and double-stranded breaks affect the melting temperature with approximately (within 20%) the same efficiency . The relationship between the melting temperature shift (delta Tm) and the number of cleavages is non-linear . The magnitude of the effect is characterized by delta Tm of 2 +/- 0.4 degrees C for the average inter-cleavage distance of 200 base pairs . It is shown that the observed melting curves are non-equilibrium ones, which is probably due to the fact that the effect of cleavages on the melting temperature is largely results from the complete and practically irreversible separation of strands.

Mol Biol (Mosk), 1979 May-Jun, 13(3), 519 - 30
{Lambdoid phage structural proteins and antigens}; Ivanov VN et al.; The composition of structural proteins of lambdoid phages such as lambda, phi 80 434 divided by molecular weights was determined by means of SDS-disc-electrophoresis in a 15% polyacrylamide gel . The proteins of the same phages were divided by isoelectric points using an isoelectric focusing in a 5,25% polyacrylamide gel with 8 M urea and a gradient pH 7.0--3.5 . The both methods brought out a composition character of the virion proteins and illustrated the high degree of similarity among the structural proteins of phages lambda and 434 and a far less similarity among the proteins lambda and phi 80 . The antigenic composition of the lambdoid phage was determined and the basic antigenes were identified on one-dimensional and two-dimensional immunoelectrophoregrams . The appreciable immunochemical affinity of basic antigenes of the lambda and 434, but a partial affinity of the phages lambda and phi 80 were found . The basic protein of the head pE proved to be immunochemically similar for all three phages.

Mol Biol (Mosk), 1979 May-Jun, 13(3), 509 - 18
{Influence of ionic strength on RNA-polymerase structure}; Savochkina LP et al.; Chromatography of RNA polymerase holoenzyme preincubated under different ionic strength conditions on the DNA agarose column was studied . Ratio of two peaks identified to be core and holoenzyme was analysed . In the range of 0.15 to 0.05 M KCl the relative content of the holoenzyme peak gradually decreased from 100 to 50% . At the same time a peak of free sigma-subunit appeared as detected by the chromatography on DNA agarose gel A-1.5 m . The dissociation of half of the sigma-subunit amount occured within the enzyme dimer-monomer transition range . The results suggest that the dimerization follows the equation: E sigma + E sigma in equilibrium with E2 sigma . Reconstitution of the RNA polymerase holoenzyme from purified core enzyme and sigma-subunit was also studied by the same method . Reconstitution did not occur at a low ionic strength (0--0.1 M KCl), but takes place at ionic strength of 0.2 M or higher . Possible function of the dimerisation of the enzyme in search of promoter site and regulation of RNA synthesis is discussed.

J Med Chem, 1979 May, 22(5), 583 - 6
Potential radiosensitizing agents . Dinitroimidazoles; Agrawal KC et al.; New compounds of the nitroimidazole series have been synthesized as radiosensitizers which selectively sensitize hypoxic cells to the lethal effect of radiation . The reaction of 2,4(5)-dinitroimidazole (2) with chloroethanol or hydrochloric acid yielded 4(5)-nitro-5(4)-chloroimidazole (3), which upon reaction with ethylene oxide yielded the 4-nitro-5-chloroimidazole-1-ethanol (6) . Reaction of 2 with ethylene oxide resulted in a mixture of two compounds, the 2,4-dinitroimidazole-1-ethanol (4) and 2,3-dihydro-5-nitroimidazo{2,1-b}oxazole (5) . The structure of the new heterocyclic compound 5 was confirmed by 1H NMR, mass spectrum, and X-ray crystallography . These agents were tested for their ability to sensitize hypoxic Escherichia coli cells to killing by ionizing radiation . Compound 4 was found to be the most active agent of this series of compounds.

Infect Immun, 1979 May, 24(2), 319 - 25
Resistance to Babesia spp . and Plasmodium sp . in mice pretreated with an extract of Coxiella burnetii; Clark IA; Mice injected intravenously with a commercially available extract of Coxiella burnetii prepared for use as the antigen in the complement fixation diagnostic test for Q fever were subsequently resistant to infection with Babesia microti, Babesia rodhaini, and Plasmodium vinckei petteri . The parasites appeared to die inside circulating erythrocytes . Protection was unaffected by exposing the pretreated mice to 900 rads on the day before they were infected . To explain these findings, it is postulated that pretreatment with Coxiella extract protects by potentiating the interferon-inducing capacity of the challenge dose of protozoa, which perhaps leads to enhanced of natural killer cells . Tumor necrosis factor also warrants investigation.

Am J Surg, 1979 May, 137(5), 657 - 60
Obturator foramen bypass in the management of infected vascular prostheses; Rudich M et al.; Seven patients with infected vascular prostheses in the femoral region were treated by removal of the prosthesis and extraanatomic reconstruction by way of the obturator foramen . Because the operation avoided entry into the infected area, it was considered the best surgical treatment for these patients . Although catastrophic hemorrhage and systemic sepsis were averted, amputation was eventually necessary in five patients, usually because of severe arteriosclerotic disease in distal arteries . Short-term benefit was gained by only two patients . The prevention of infection demands intensive preoperative preparation using prophylactic antibiotics and meticulous operating room technic.

Am J Surg, 1979 May, 137(5), 608 - 10
Changes in the pathogenesis and detection of intrahepatic abscess; Silver S et al.; A comparison of two distinct 11 year time periods at our institution demonstrated a change not only in the cause of intrahepatic abscess but also in the procedures used to diagnose this condition . Significant improvement in the methods of detection of intrahepatic abscess permits earlier diagnosis and therapy and thus a significantly improved prognosis.

Zh Mikrobiol Epidemiol Immunobiol, 1979 May, (5), 72 - 8
{Analysis of merodiploid strains of Sh . flexneri that have lost virulence}; Lycheva TA et al.; Episome F'13 introduced into the genome of a virulent Sh . flexneri strain brought about changes in a number of properties of the recipient strain . The expression of these properties was not connected with the chromosome area allelic to the plasmid genome . These changes seem to be induced by the mobilization of the chromosome genes of E . coli . The loss of virulence in Sh . flexneri strains carrying episome F'13 seemed to be the consequence of two reasons: the overlapping of kcpA gene by its dominant avirulent allele and abnormal synthesis of cell wall lipopolysaccharide due to the transfer of the mobilized genes from the donor strain F'13 . When the preliminary mapping of genes on the chromomome was made with the use of plasmids, it was found necessary to use F-episomes which had no influence on the changes occurring in the phenotypic characteristics of the recipient.

Proc Natl Acad Sci U S A, 1979 May, 76(5), 2390 - 4
Interaction of the cheC and cheZ gene products is required for chemotactic behavior in Escherichia coli; Parkinson JS et al.; Previous work has shown that the cheC gene product of Escherichia coli plays a key role in regulating the direction of flagellar rotation during chemotactic responses . An attempt was made to identify other stimulus transduction elements that interact with the cheC component by examining cheC revertants for functional suppressors . Approximately two-thirds of the revertants studied appeared to be due to back mutation or to second-site mutations near or within the cheC structural gene . The remainder of the revertants carried suppressor mutations that mapped at the cheZ locus . Half of these suppressors impaired chemotaxis in a cheC+ background and were shown by complementation analysis to be defective in cheZ function . These suppressors corrected cheC defects in an allele-specific pattern, suggesting that the cheC and cheZ proteins are in direct contact and are mutually corrective due to protein-protein interaction . Observation of swimming patterns and flagellar rotation in cheC cheZ mutants demonstrated that the interaction of these two gene products influences both the spontaneous frequency of flagellar reversals and the ability of the rotational machinery to respond to chemotactic stimuli . A model of this interaction and its possible role in chemotaxis are discussed.

Proc Natl Acad Sci U S A, 1979 May, 76(5), 2222 - 6
Cloning in Escherichia coli and physical structure of hepatitis B virion DNA; Charnay P et al.; A restriction map of hepatitis B virion DNA was established after cloning of the whole viral genome in Escherichia coli . By use of EcoRI, Xho I, Bgl II, Xba I, BamHI, HincII, and Hae III endonucleases, a total of 28 restriction sites were mapped . The single-stranded region was localized on the restriction map and 5' end of the short strand was mapped at a fixed position.

Proc Natl Acad Sci U S A, 1979 May, 76(5), 2158 - 62
Glutathione-dependent hydrogen donor system for calf thymus ribonucleoside-diphosphate reductase; Luthman M et al.; Purified calf thymus ribonucleoside-diphosphate reductase (2'-deoxyribonucleoside-diphosphate:oxidized-thioredoxin 2'-oxidoreductase, EC 1.17.4.1), showed an absolute requirement for a dithiol as hydrogen donor, whereas the natural monothiol glutathione (GSH) was inactive per se . However, a protein partially purified from thymus coupled the oxidation of GSH to the formation of deoxyribonucleotides by ribonucleotide reductase . In analogy with the ribonucleotide reductase system of Escherichia coli this protein was called glutaredoxin {Holmgren, A . (1976) Proc . Natl . Acad . Sci . USA 73, 2275-2279} . Thymus glutaredoxin had the following properties: (i) its molecular weight determined by gel chromatography was about 12,000; (ii) it was active iwth ribonucleotide reductase in the presence of GSH, NADPH, and glutathione reductase but had no activity with NADPH and thioredoxin reductase; and (iii) it was immunologically different from thioredoxin because it did not bind to antithioredoxin immunoadsorbents . Experiments on the crossreactivity of thymus and E . coli ribonucleotide reductases and the corresponding thioredoxin and glutaredoxin systems showed essentially no specificity for the homologous thioredoxin but a high species specificity for the homologous glutaredoxin.

Proc Natl Acad Sci U S A, 1979 May, 76(5), 2138 - 42
Neuroactive drugs inhibit trypsin and outer membrane protein processing in Escherichia coli K-12; Gayda RC et al.; Previous studies demonstrated that a cloned 2-megadalton (MDal) fragment of Escherichia coli DNA contained the structural gene for major outer membrane protein a (also known as 3b or M2 (40 kDal) . The present study demonstrates that M2 is synthesized from a 42-kDal precursor that also is present in the outer membrane . The conversion of the 42-kDal precursor to M2 is inhibited by a number of different local anesthetics (procaine, piperocaine, lidocaine, cocaine), by the neuroactive drug atropine, and by the classical trypsin inhibitors N alpha-tosyllysine chloromethyl ketone (TLCK) and benzamidine . Our kinetic studies demonstrate that the amidase action of pure trypsin is inhibited competitively by the local anesthetics tested (excluding lidocaine) as well as by atropine and neostigmine . A mechanism of action for local anesthetics as well as atropine in E . coli may to be inhibit trypsinlike proteases, in a competitive manner, in the region of the outer membrane . The mechanism of action of these compounds in regulating nerve conduction in man have certain features in common with the mechanism proposed in E . coli.

J Bacteriol, 1979 May, 138(2), 567 - 74
Biochemical and topographical studies on Escherichia coli cell surface . IV . Giant spheroplast formation from a filamentous cell; Onitsuka MO et al.; Long, nonseptate filamentous cells consisting of 5 to 40 single-cell unit lengths were formed from Escherichia coli surface mutant ONT-3 by treatment with a sublethal concentration of sodium dodecyl sylfate . As distinct from several other elongated cells (e.g., thymine-starved filaments), it was found here that stable giant spheroplasts, 5 to 10 micrometers in diameter, were produced by the action of lysozyme in the presence of bovine serum albumin via the gradual fusion of distinct spheroplasting bulbs.

J Bacteriol, 1979 May, 138(2), 559 - 66
Mutants of the mini-F plasmid pML31 thermosensitive in replication; Eichenlaub R; Hydroxylamine mutagenesis was used for the induction of thermosensitive replication mutants of the mini-F plasmid pML31 . Replication mutants were characterized by studying the segregation kinetics and the incorporation of {3H}-thymidine into plasmid deoxyribonucleic acid at the nonpermissive temperature . Based on these experiments two types of mutants could be distinguished . Mutants of type I are fast segregating with the kinetics expected if plasmid replication was blocked immediately . Double-label experiments showed a rapid shut-off of replication in these mutants at 42 degrees C . Mutants of type II segregate slower, showing only a partial inhibition of plasmid deoxyribonucleic acid synthesis at the nonpermissive temperature . The label incorporated at 42 degrees C was predominantly found in open circular plasmid molecules.

J Bacteriol, 1979 May, 138(2), 530 - 4
Escherichia coli mutant containing a large deletion from relA to argA; Atherly AG; A mutant of Escherichia coli has been isolated that contains a large deletion (about 3 X 10(7) daltons of deoxyribonucleic acid) encompassing argA, fuc, and relA . This mutant strain (AA-787) is also cold sensitive for growth at 18 degrees C . Strain AA-787 was obtained fortuitously as a cold-sensitive pseudorevertant of a strain having a heat-sensitive peptidyl-transfer ribonucleic acid hydrolase . Genetic analysis, using transduction and interrupted mating, showed the cold sensitivity mutation to be located adjacent to relA . Further analysis demonstrated loss of relA, fuc, and argA gene functions but retention of eno and recB, closely linked genes adjacent to relA and argA, respectively . Unusually high cotransduction of flanking markers (cysC and thyA) indicated loss of approximately 1 min of the E . coli genetic map in strain AA-787 . Guanosine 3'-diphosphate 5'-diphosphate (ppGpp) was synthetized in mutant strain AA-787 at basal levels, and ppGpp synthesis was stimulated by carbon-source downshift . No ppGpp synthesis could be obtained using ribosomes isolated from strain AA-787 . These findings, taken together, show that deletion of relA in E . coli does not completely abolish ppGpp synthesis and suggests that another enzyme system must also be responsible for ppGpp synthesis.

J Bacteriol, 1979 May, 138(2), 475 - 85
Ionizing radiation damage to the folded chromosome of Escherichia coli K-12: sedimentation properties of irradiated nucleoids and chromosomal deoxyribonucleic acid; Ulmer KM et al.; The structures of the membrane-free nucleoid of Escherichia coli K-12 and of unfolded chromosomal deoxyribonucleic acid (DNA) were investigated by low-speed sedimentation on neutral sucrose gradients after irradiation with 60Co gamma rays . Irradiation both in vivo and in vitro was used as a molecular probe of the constraints on DNA packaging in the bacterial chromosome . The number of domains of supercoiling was estimated to be approximately 180 per genome equivalent of DNA, based on measurements of relaxation caused by single-strand break formation in folded chromosomes gamma irradiated in vivo and in vitro . Similar estimates based on the target size of ribonucleic acid molecules responsible for maintaining the compact packaging of the nucleoid predicted negligible unfolding due to the formation of ribonucleic acid single-strand breaks at doses of up to 10 krad; this was born out by experimental measurements . Unfolding of the nucleoid in vitro by limit digestion with ribonuclease or by heating at 70 degrees C resulted in DNA complexes with sedimentation coefficients of 1,030 +/- 59S and 625 +/- 15S, respectively . The difference in these rates was apparently due to more complete deproteinization and thus less mass in the heated material . These structures are believed to represent intact, replicating genomes in the form of complex-theta structures containing two to three genome equivalents of DNA . The rate of formation of double-strand breaks was determined from molecular weight measurements of thermally unfolded chromosomal DNA gamma irradiated in vitro . Break formation was linear with doses up to 10 krad and occurred at a rate of 0.27 double-strand break per krad per genome equivalent of DNA (1,080 eV/double-strand break) . The influence of possible nonlinear DNA conformations on these values is discussed.

J Bacteriol, 1979 May, 138(2), 453 - 60
Phospholipid synthesis during the cell division cycle of Escherichia coli; Pierucci O; Stepwise changes in the rate of phosphatidylethanolamine and phospholipid synthesis during the cell division cycle of Escherichia coli B/r were observed . The cell ages at the increases were found to be a function of the growth rate . At each growth rate, the increase occurred around the time new rounds of chromosome replication were inaugurated in the cycle.

J Bacteriol, 1979 May, 138(2), 383 - 96
Expression of ribosomal protein genes cloned in a hybrid plasmid in Escherichia coli: gene dosage effects on synthesis of ribosomal proteins and ribosomal protein messenger ribonucleic acid; Fallon AM et al.; Using ColE1-TnA hybrid plasmid RSF2124 as the cloning vector, we constructed a hybrid plasmid, pNO1001, which carried seven ribosomal protein (r-protein) genes in the spc operon together with their promoter . The plasmid also carried three r-protein genes which precede the spc operon, but did not carry the bacterial promoter for these genes . Expression of r-protein genes carried by pNO1001 was studied by measuring messenger ribonucleic acid and r-protein synthesis in cells carrying the plasmid . It was found that the messenger ribonucleic acid for all the promoter-distal r-protein genes was synthesized in large excess relative to messenger ribonucleic acid from other chromosomal r-protein genes which are not carried by the plasmid . However, only the two promoter-proximal r-proteins, L14 and L24, were markedly overproduced . The absence of large gene dosage effects on the synthesis of other distal proteins appeared to be due, at least in part, to preferential inactivation and/or degradation of the distal message which codes for these proteins; in addition, some preferential inhibition of translation of the distal message might also have been involved . Overproduced L14 and L24 were found to be degraded in recA+ strains at both 30 and 42 degrees C; in recA strains, the degradation took place at 42 degrees C but was very slow or absent at 30 degrees C . The recA strains carrying pNO1001 failed to form colonies at 30 degrees C, presumably because of overaccumulation of r-proteins . The results suggest that degradation of excess r-proteins is an important physiological process.

J Bacteriol, 1979 May, 138(2), 352 - 60
Individual proteins are synthesized continuously throughout the Escherichia coli cell cycle; Lutkenhaus JF et al.; The pattern of synthesis of about 750 individual polypeptides was followed throughout the cell cycle of Escherichia coli B/r . Samples taken at different times in the cell cycle exhibited the same pattern of protein synthesis . No protein could be identified that was synthesized at different rates during different parts of the cell cycle.

J Bacteriol, 1979 May, 138(2), 339 - 44
Isolation and characterization of a temperature-sensitive dnaK mutant of Escherichia coli B; Itikawa H et al.; A temperature-sensitive dnaK mutant (strain MT112) was isolated from Escherichia coli B strain H/r30RT by thymineless death selection at 43 degrees C . By genetic mapping, the mutation {dnaK7(Ts)} was located near the thr gene (approximately 0.2 min on the may) . E . coli K-12 transductants of the mutation to temperature sensitivity were assayed for their susceptibility to transducing phage lambda carrying the dnaK and/or the dnaJ gene . All of the transductants were able to propagate phage lambda carrying the dnaK gene . When macromolecular synthesis of the mutant was assayed at 43 degrees C, it was observed that both deoxyribonucleic acid and ribonucleic acid syntheses were severely inhibited . Thus, it was suggested that the conditionally defective dnaK mutation affects both cellular deoxyribonucleic acid and ribonucleic acid syntheses at the nonpermissive temperature in addition to inability to propagate phage lambda at permissive temperature.

J Bacteriol, 1979 May, 138(2), 333 - 8
Multiple loci affecting photoreactivation in Escherichia coli; Sutherland BM et al.; Sutherland et al . mapped a phr gene in Escherichia coli at 17 min and found that induction of an E . coli strain lysogenic for a lambda phage carrying this gene increased photoreactivating enzyme levels 2,000-fold . Recently, Smith and Youngs and Sancar and Rupert located a phr gene at 15.9 min . We have therefore investigated the properties of photoreactivating enzyme and cellular photoreactivation in cells containing deletions of the gene at 17 min . Cells with this deletion photoreactivated ultraviolet-induced killing at a rate 20% of normal; they also contained approximately 20% of the normal photoreactivating enzyme level . The residual enzyme in these cells was characterized to determine whether the reduced cellular photoreactivation rate and photoreactivating enzyme levels resulted from reduced numbers of normal enzymes or from an altered enzyme . Photoreactivating enzymes from strains carrying a deletion of the region at 17 min had an apparent Km about two- to threefold higher than normal enzyme and showed markedly increased heat lability . The gene at 17 min thus contains information determining the function of the E . coli photoreactivating enzyme rather than the quantity of the enzyme . It is proposed that the gene at 17 min be termed phrA and that located at 15.9 min be termed phrB.

J Bacteriol, 1979 May, 138(2), 324 - 32
Rifampin disrupts conjugal and chromosomal deoxyribonucleic acid metabolism in Escherichia coli K-12 carrying some IncIalpha plasmids; Boulnois GJ et al.; The effects of rifampin and chloramphenicol on the transfer of ColIdrd-1 have been examined to determined whether transfer requires the synthesis of an untranslated species of ribonucleic acid (RNA), as proposed in models for the transfer of another IncIalpha plasmid, R64drd-11 . When RNA synthesis was inhibited throughout mating by rifampin, ColI transfer between dna+ bacteria occurred at the normal rate for about 10 min and then stopped abruptly . Conjugational deoxyribonucleic acid (DNA) synthesis in dnaB mutants indicates that plasmid DNA was made in the rifampin-treated donors to replace the transferred material but the DNA tended to be unstable . In the presence of chloramphenicol, transfer of ColI gradually diminished over a longer period . Rifampin, but not chloramphenicol, was found to have unpredicted effects on chromosomal DNA metabolism in unmated dna+ and dnaB bacteria when they harbor any of three IncIalpha plasmids (ColIdrd-1, R144drd-3, and R64drd-11) . Replication of the bacterial chromosome in such cells stopped abruptly about 15 min after the addition of rifampin, and at 41 degrees C, but not 37 degrees C, this was followed by extensive DNA breakdown . These findings suggest that curtailment of IncIalpha plasmid transfer by the drug results from a general disruption of DNA metabolism rather than from inhibition of a species of RNA essential for transfer.

J Bacteriol, 1979 May, 138(2), 305 - 13
Genetic studies of an Escherichia coli K-12 temperature-sensitive mutant defective in membrane protein synthesis; Sato T et al.; The mutant divE42(Ts) of Escherichia coli K-12, defective in the synthesis of membrane proteins and in the transcription of the lac operon at high temperature, has been further characterized . It was found that a mutation (divE42) located at about min 22 on the E . coli chromosome map is responsible for the Lac- phenotype and temperature-sensitive growth . The mutation could be contransduced with serC, pyrD, or pyrC by phage P1 at a frequency of 4, 16, or 0.5%, respectively, the gene order being serC-pyrD-ompA-sulA-divE-pyrC . Examination of temperature-independent revertants and Pyr+ transductants revealed that all the mutant phenotypes examined (deficiencies in the increase of activities of some membrane enzymes, expression of the lac operon, and synthesis of several other proteins) are due to a single mutation (divE42) which is recessive to the wild-type (divE+) allele . Protein synthesis in the mutant was also analyzed by dodecyl sulfate-polyacrylamide gel electrophoresis . Synthesis of a number of proteins, including membrane proteins, was found to decrease significantly, whereas that of an elongation factor, EF-Tu, increased upon transfer of a log-phase culture to high temperature (42 degrees C) . These effects of temperature shift-up on protein synthesis were evident within 5 min under the conditions used.

Surg Gynecol Obstet, 1979 May, 148(5), 679 - 84
Extracorporeal perfusion without anticoagulation and the response to endotoxin; Beller BK et al.; The results of this study show that an extracorporeal perfusion system without anticoagulation can be established in the dog under certain conditions . The exact mechanisms merit further investigation . It also points to a model to study the effects of endotoxin without heparin interference and as another model for studying the canine blood coagulation system.

Infect Immun, 1979 May, 24(2), 434 - 40
Effect of cyclic adenosine 3',5'-monophosphate antagonists on endotoxin-induced inhibition of human neutrophil chemotaxis; Issekutz AC et al.; We reported previously that Escherichia coli endotoxin inhibited human neutrophil chemotaxis toward C5a . This effect of endotoxin was antagonized by anti-inflammatory steroids . We now report that dibutyryl cyclic adenosine 3',5'-monophosphate, prostaglandin E1, isoproterenol, and cholera toxin also antagonize the suppression of chemotaxis by endotoxin . Each compound inhibited the effect of endotoxin in a dose-dependent fashion . To be effective, each compound except cholera toxin had to be present at the time of endotoxin challenge . Furthermore, propranolol blocked the protective effect of isoproterenol against endotoxin but not the protective effect of dibutyrl cyclic adenosine 3',5'-monophosphate or prostaglandin E1 . Dibutyryl cyclic guanosine 3',5'-monophosphate, adenosine 5'-monophosphate, phenylephrine, prostaglandin F2 alpha, and carbachol did not modify the suppression of chemotaxis by endotoxin . Anti-inflammatory steroids and dibutyryl cyclic adenosine 3',5'-monophosphate are thought to stabilize phospholipids in certain cell membranes . This phospholipid-stabilizing action may contribute, at least in part, to the protective effect against endotoxin-mediated suppression of neutrophil chemotaxis.

Can J Biochem, 1979 May, 57(5), 385 - 95
The interactions of adenylates with allosteric citrate synthase; Talgoy MM et al.; Evidence is presented that a number of derivatives of adenylic acid may bind to the allosteric NADH binding site of Escherichia coli citrate synthase . This evidence includes the facts that all the adenylates inhibit NADH binding in a competitive manner and that those which have been tested protect an enzyme sulfhydryl group from reaction with 5,5'-dithiobis-(2-nitrobenzoic acid) in the same way that NADH does . However, whereas NADH is a potent inhibitor of citrate synthase, most of the adenylates are activators . The best activator, ADP-ribose, increases the affinity of the enzyme for the substrate, acetyl-CoA, and saturates the enzyme in a sigmoid manner . A fluorescence technique, involving the displacement of 8-anilino-1-naphthalenesulfonate from its complex with citrate synthase, is used to obtain saturation curves for several nucleotides under nonassay conditions . It is found that acetyl-coenzyme A, coenzyme A, and ADP-ribose all bind to the enzyme cooperatively, and that the binding of each becomes tighter in the presence of KCl, the activator, and oxaloacetic acid (OAA), the second substrate . Another inhibitor, alpha-ketoglutarate, can complete with OAA in the absence of KCl but not in its presence . The nature of the allosteric site of citrate synthase, and the modes of action of several activators and inhibitors, are discussed in the light of this evidence.

Transfusion, 1979 May-Jun, 19(3), 293 - 8
Concomitant T- and Tk-activation associated with acquired-B antigens; Judd WJ et al.; Three patients with acquired-B antigens are reported whose red blood cells also manifested T- and Tk-activation . The results of tests using purified Arachis hypogaea and Bandeiraea simplicifolia (BS II) lectins, and red blood cells either T, Tk or both T and Tk-activated by bacterial enzymes in vitro, suggest that the acquired-B phenomenon, T-activation and Tk-activation result from the action of different bacterial enzymes.

Proc Natl Acad Sci U S A, 1979 May, 76(5), 2376 - 80
A genetic approach to analysis of transposons; Beck CF; Integration of the tetracycline resistance transposon Tn10 into lacI of a lacI-lacZ gene fusion permits the isolation of deletions that excise DNA from one end of Tn10 and fuse Tn10 genes with lacZ in such a manner that chimeric proteins with beta-galactosidase activity are produced . The synthesis of the chimeric proteins is under the same control as the transposon genes . Thus, regulation of expression of Tn10 genes can be investigated by measuring beta-galactosidase activity . Analysis of Tn10-lacZ fusions revealed different deletion endpoints within Tn10; lacZ has been fused to at least three different Tn10 genes or operons . Two of these genes are under the control of a tetracycline repressor.

J Biochem (Tokyo), 1979 May, 85(5), 1289 - 300
Improved procedure for the conjugation of rabbit IgG and Fab' antibodies with beta-D-galactosidase from Escherichia coli using N,N'-o-phenylenedimaleimide; Hamaguchi Y et al.; The procedures for the conjugation of rabbit IgG and Fab' antibodies with beta-D-galactosidase from Escherichia coli using N,N'-o-phenylenedimaleimide were improved in several respects as compared with the previous methods (Eur . J . Biochem . 62, 285--292, 1976; J . Immunol . 116, 1554--1560, 1976) . Maleimide residues were efficiently introduced into antibodies under an atmosphere of nitrogen; the average number of maleimide residues introduced into IgG and Fab' antibodies were 0.78 (0.65--0.86) and 0.86 (0.80--0.95) per molecule, respectively . The conjugation with the enzyme was performed at 4 degrees C at pH 6.5 for 15 or more hours . The conjugates were almost completely separated from unreacted IgG and Fab' by gel filtration . When the recoveries of IgG, Fab', and beta-D-galactosidase in the conjugates were 23-29, 35-44, and 99%, respectively, the average numbers of IgG and Fab' molecules conjugated with the enzyme were 1.5-1.7 and 2.1-2.8 per molecule, respectively . There was no significant impairment of beta-D-galactosidase activity or the activity of anti-human IgG antibody to bind to human IgG upon conjugation . However, the conjugate preparation was heterogeneous, and one-third of each preparation consisted of aggregated conjugates less useful in sandwich enzymoimmunoassay than the remaining material . The conjugate with Fab' antibody gave lower control values in sandwich enzymoimmunoassay with silicone rubber as a solid phase than that with IgG antibody.

Clin Chem, 1979 May, 25(5), 686 - 91
Substrate-labeled fluorescent immunoassay for phenytoin in human serum; Wong RC et al.; A homogeneous substrate-labeled fluorescent immunoassay has been applied to the measurement of phenytoin concentrations in human serum . We coupled a fluorogenic enzyme substrate, galactosyl-umbelliferone, covalently to a derivative of phenytoin . Under assay conditions, this drug-substrate conjugate was nonfluorescent but became fluorescent upon hydrolysis catalyzed by bacterial beta-galactosidase . When antibody to phenytoin is bound to the drug-substrate conjugate, it is inactive as an enzyme substrate . Addition of phenytoin to competitive-binding reactions relieves the inactivation, and the resulting fluorescence is proportional to the phenytoin concentration . We validated the fluorescent immunoassay by comparing values for phenytoin obtained with this technique to those obtained by gas chromatography and by enzyme immunoassay (EMIT) . All three methods correlated well . The major metabolite of phenytoin, 5-(p-hydroxyphenyl)-5-phenylhydantoin, and other drugs at concentrations expected in serum had no effect on the assay . The fluorescent immunoassay is rapid and simple to perform and requires only 2 microL of serum sample per test.

Biochemistry, 1979 May 1, 18(9), 1820 - 5
Isolation of Euglena gracilis chloroplast 5S ribosomal RNA and mapping the 5S rRNA gene on chloroplast DNA; Gray PW et al.; Ribosomal RNA (5S) from Euglena gracilis chloroplasts was isolated by preparative electrophoresis, labeled in vitro with 125I, and hybridized to restriction nuclease fragments from chloroplast DNA or cloned chloroplast DNA segments . Euglena chloroplast 5S rRNA is encoded in the chloroplast genome . The coding region of 5S rRNA has been positioned within the 5.6 kilobase pair (kbp) repeat which also codes for 16S and 23S rRNA . There are three 5S rRNA genes on the 130-kbp genome . The order of RNAs within a single repeat is 16S-23S-5S . The organization and size of the Euglena chloroplast ribosomal repeat is very similar to the ribosomal RNA operons of Escherichia coli.

Can J Microbiol, 1979 May, 25(5), 560 - 4
Phosphate uptake in chemostat cultures of Escherichia coli K-12 subjected to periodic beta-glycerophosphate pulsing: a system for assaying alkaline phosphatase; Francis JC et al.; Limiting concentrations of beta-glycerophosphate were pulsed into chemostat cultures of Escherichia coli K-12 at intervals equal to the population doubling time . The resultant culture density fluctuations are interpreted in terms of inorganic phosphate uptake which, in this system, is a function of alkaline phosphatase activity . Information concerning in vivo alkaline phosphatase activity at suboptimal (acidic) pH with very low concentrations of substrate (beta-glycerophosphate) is obtained from kinetic analysis of uptake data.

Prikl Biokhim Mikrobiol, 1979 May-Jun, 15(3), 328 - 36
{L-asparatic acid synthesis from ammonium fumarate by free and immobilized Escherichia coli cells}; Iakovleva VI et al.; E . coli 85 cells with a high aspartate-ammonia-lyase activity were immobilized through polyacrylamide gel incorporation . Proper conditions to assay aspartase activity of E . coli cells were developed . Kinetic patterns of aspartate-ammonia-lyase reaction catalyzed by free and immobilized E . coli 85 cells were studied . The synthesis of L-aspartic acid from ammonium fumarate had the following characteristics: specific activity of (4--6) . 10(-5) mmole/mg.sec for free cells and (6--8) . 10(-5) mmole/mg.sec for immobilized cells with their content in polyacrylamide gel of 5--10 mg protein per g wet gelm pH 8.3--10.0.

J Biochem (Tokyo), 1979 May, 85(5), 1355 - 65
Studies on regulatory functions of malic enzymes . VI . Purification and molecular properties of NADP-linked malic enzyme from Escherichia coli W; Iwakura M et al.; NADP-linked malic enzyme {EC 1.1.1.40} was highly purified from Escherichia coli W cells . The purified enzyme was homogeneous as judged by ultracentrifugation and gel electrophoresis . The apparent molecular weights obtained by sedimentation equilibrium analysis, from diffusion and sedimentation constants, and by disc electrophoresis at various gel concentrations were 471,000, 438,000, and 495,000, respectively . The subunit molecular weights obtained by sedimentation equilibrium analysis in the presence of 6 M guanidine hydrochloride and gel electrophoresis in the presence of sodium dodecyl sulfate were 76,000 and 82,000, respectively . The sedimentation coefficient (S(0)20, W) was 13.8S, and the molecular activity was 44,700 min-1 at 30 degrees C . The amino acid composition of the enzyme was determined, and the results were compared with those of NAD-linked malic enzyme from the same organism and those of pigeon liver NADP-linked malic enzyme . The partial specific volume was calculated to be 0.738 ml/g . The Km value for L-malate was 2.3 mM at pH 7.4 . Malonate, tartronate, glutarate, and DL-tartrate competitively inhibited the activity . The saturation profile for L-malate exhibited a marked cooperativity in the presence of both chloride ions and acetyl-CoA . However, acetyl-CoA alone did not show cooperativity or produce inhibition in the absence of chloride ions . Vmax and Km were determined as a function of pH . The optimum pH for the reaction was 7.8 . Inspection of the Dixon plots suggested that three ionizable groups of the enzyme are essential for the enzyme activity . In addition to the oxidative decarboxylase activity, the enzyme preparation exhibited divalent metal ion-dependent oxaloacetate decarboxylase and alpha-keto acid reductase activities . Based on the above results, the molecular properties of the enzymatic reaction are discussed.

J Bacteriol, 1979 May, 138(2), 653 - 6
Deletion mapping of the polA-metB region of the Escherichia coli chromosome; Pahel G et al.; A lambdacI857 prophage inserted into one of the genes of the rha locus was used to select deletions unambiguously ordering the markers polA-glnA-rha-pfkA-tpi-metBJF . Transduction with phage P1 indicates at least 70% linkage between glnA and polA . The order of the pfk and tpi markers is reversed from that previously published . Despite the relatively large distance separating the glnA and rha loci, deletions removing this entire region have no obvious phenotype . The isolation of Tn10 transposons integrated at different sites between rha and glnA greatly facilitated this work.

Biochim Biophys Acta, 1979 Apr 27, 573(1), 207 - 11
Specificity and selectivity of diacylglycerolphosphate synthesis in Escherichia coli; Okuyama H et al.; The glycerolphosphate and 1-acylglycerolphosphate acyltransferase systems Escherichia coli membranes show relatively low specificities for acylcoenzymes A when maximal velocities for the respective acyl-coenzymes A are compared . However, the selectivities for palmitate and oleate in the acylations of the 1- and 2-positions of glycerolphosphate moiety, respectively, are higher at lower concentrations of acceptors in the presence of an equimolar mixture of palmitoyl-CoA and oleoyl-CoA . More 1-palmitoyl-2-oleoyl-glycerolphosphate species and less other species were synthesized at lower concentrations of glycerolphosphate . The fatty acyl moiety at the 1-position of 1-acylglycerolphosphate did not influence significantly the specificity for acyl-coenzymes A of the 1-acylglycerolphosphate acyltransferase system . Thus, the acceptor concentrations being kept low in vivo and in vitro are important for the highly selective incorporations of saturated and unsaturated fatty acids into the 1- and 2-positions of diacylglycerolphosphate, respectively, in the presence of mixtures of saturated and unsaturated acyl-coenzymes A while these acyltransferase systems exhibit relatively low specificies for acyl-coenzymes A when the respective maximal velocities are compared.

Biochim Biophys Acta, 1979 Apr 26, 562(2), 207 - 13
Physical and coding properties of poly(5-methoxyuridylic) acid; Hillen W et al.; The synthesis of poly(mo5U) requires a high concentration (2.7 mg/ml) of polynucleotide phosphorylase as well as a long reaction time (48 h) . The resulting polynucleotide has a chain length of approximately 100 nucleotides . It shows no indication of a stable secondary structure . When poly(mo5U) is mixed with poly(A), a triple-stranded complex poly(A) . 2poly(mo5U) is formed . This complex has a melting temperature of 68.5 +/- 0.5 degrees C at 150 mMNa+ and exhibits a hysteresis loop between melting and reformation of the complex having a delta Tm of 11.5 degrees C . Poly-5-methoxyuridylic acid stimulates the binding of Phe-tRNA to 70-S ribosomes but is inactive in directing poly(Phe) synthesis.

J Biol Chem, 1979 Apr 25, 254(8), 3067 - 73
Novel mechanism of post-transcriptional modification of tRNA . Insertion of bases of Q precursors into tRNA by a specific tRNA transglycosylase reaction; Okada N et al.; The guanine insertion enzyme isolated from Escherichia coli (tRNA transglycosylase) catalyzed the incorporation of bases of Q (queuosine) precursors into E . coli undermodified tRNAAsn and tRNATyr . These bases of Q precursors were inserted in the first position of the anticodon of tRNASn and tRNATyr, replacing guanine originally located in that position . This is a novel type of post-transcriptional modification, inserting a modified base into the polynucleotide chain by cleavage of the N--C glycoside bond without breakage of the phosphodiester bond . One of the bases of Q precursors, 7-(aminomethyl)-7-deazaguanine, was found in the acid-soluble fraction of E . coli cells, supporting the conclusion that formation of Q, 7-(3,4-trans-4,5-cis-dihydroxy-1-cyclopenten-3-ylaminomethyl)-7-deazaguanosine, in tRNA in vivo actually proceeds by the tRNA transglycosylase reaction.

J Biol Chem, 1979 Apr 25, 254(8), 2579 - 81
Guanosine 5'-diphosphate-3'-diphosphate inhibition of adenylosuccinate synthetase; Stayton MM et al.; The mechanism of ppGpp inhibition of adenylosuccinate synthetase (EC 6.3.4.4) was examined . Initial rate kinetic studies demonstrate the ppGpp inhibition is competitive with respect to GTP and noncompetitive with respect to L-aspartate and IMP . This is in contrast to an earlier report (Gallant, J., Irr, J., and Cashel, M . (1971) J . Biol . Chem . 246, 5812-5816), which suggested that ppGpp did not bind at the GTP site . Possible reasons for the discrepancy are discussed . The potency of the ppGpp inhibition is confirmed.

J Biol Chem, 1979 Apr 25, 254(8), 3061 - 6
Isolation and characterization of a guanine insertion enzyme, a specific tRNA transglycosylase, from Escherichia coli; Okada N et al.; A guanine insertion enzyme (tRNA transglycosylase) was purified to a homogeneous state from Escherichia coli B by ammonium sulfate fractionation and DEAE-cellulose, DEAE-Sephadex A-50, phosphocellulose, and Sephadex G-200 column chromatographies . The molecular weight of the enzyme, which appeared to be a single polypeptide, was 4.6 X 10(4) by sodium dodecyl sulfate gel electrophoresis . The enzyme catalyzes exchange of guanine with guanine located in the first position of the anticodon of tRNATyr, tRNAHis, tRNAAsn, and tRNAAsp, but unlike the enzymes isolated from rabbit reticulocytes and Ehrlich ascites tumor cells it does not catalyze the exchange of guanine with queuine (7-(3,4-trans-4,5-cis-dihydroxy-1-cyclopenten-3-ylaminomethyl)-7-deazaguanine) present in these tRNAs . The pH optimum of the reaction was 7.0, and the pH1 value was 4.6 to 4.8 . The reaction required Mg2+ ion . 7-Methylguanine inhibited guanine insertion, but the other purine analogues tested were not inhibitory and could not replace guanine.20

J Biol Chem, 1979 Apr 25, 254(8), 3124 - 8
Some properties of Escherichia coli glutamine synthetase after limited proteolysis by subtilisin; Dautry-Varsat A et al.; Escherichia coli glutamine synthetase is inactivated by subtilisin . Protection against inactivation is afforded by glutamine and ammonium ions . One large fragment (Mr = 35,000) is identified by sodium dodecyl sulfate-gel electrophoresis and carries adenylylation site . Smaller quantities of two other fragments (Mr = 17,000 and 15,000, respectively) are als observed oo observed on the gel . tthe nicked protein remains dodecameric, as evidenced by electrophoresis and centrifugation . It has retained the binding properties toward ADP and Ci-bacron blue and undergoes conformation changes upon binding, as does the intact protein . It is recognized by the antiserum raised against the native enzyme . The nicked protein also remains an excellent substrate of E . coli adenylyltransferase.

Lancet, 1979 Apr 21, 1(8121), 865 - 7
Simple and effective measures for control of enteric cross-infection in a children's hospital; Taylor MR et al.; This report shows how simple measures have reduced the rate of enteric cross-infection from 61 cases a year to close to zero in an old and architecturally unsatisfactory children's hospital.

Mol Gen Genet, 1979 Apr 17, 172(1), 73 - 80
"Nick translation" in Escherichia coli rep strains deficient in DNA polymerase I activities; Hours C et al.; Using phiX1974 replicative form (RF) DNA as an in vivo probe, we have investigated the coordinated action of the 5' leads to 3' exonuclease and polymerase activities of DNA polymerase I in order to understand better its physiological role . We constructed double mutants containing the rep mutation (the replication of phiX174 RF does not occur in rep mutants) together with a mutation affecting DNA polymerase I, either polA12 or polA546ex . Using these mutants, which are believed to be thermosensitive in the polymerase function or the 5' leads to 3' exonuclease function respectively, we studied the kinetics of nick translation at the permissive and non-permissive temperatures in vivo . The substrate was the phiX174 replicative form DNA nicked by the phiX174 gene A protein . E . coli rep polA546ex gave the lowest rate of nick translation, although the ability to perform nick translation, at least as measured by our assay, was still present . E . coli rep polA12 showed a similar low rate at the non-permissive temperature but a rate close to the wild-type level at the permissive temperature . Formation of the parental replicative form molecule in either strain was affected little, even at the restrictive temperature . Our results suggest that DNA polymerase I may not play a major role in ongoing DNA replication.

Mol Gen Genet, 1979 Apr 17, 172(1), 7 - 11
Map position of the replication terminus on the Escherichia coli chromosome; Louarn J et al.; The directions of replication of several prophages integrated with a known orientation in the vicinity of the terminus (tre) of chromosome replication (trp::Mu, min 27; lambda rev integrated within rac, min 31, man::Mu, min 35), have been established by determining the molecular polarity of Okazaki pieces specific to these prophages . The results obtained strongly suggest that the site tre is located between rac and man, an otherwise genetically silent region.

Mol Gen Genet, 1979 Apr 17, 172(1), 53 - 65
Characterisation of Tn1721, a new transposon containing tetracycline resistance genes capable of amplification; Schmitt R et al.; R plasmid pRSD1 contains tetracycline resistance (tet) genes in a 3.55 Mdal-region capable of amplification by forming tandem repeats (Mattes, Burkardt and Schmitt, Molec . gen . Genet., 1979) . The repetitious tet element is itself part of a 7.2 Mdal-transposon, named Tn1721, as demonstrated by the following criteria; (i) Tn1721 has been translocated to phage lambda . The resulting hybrid phage lambda tet contains the 7.2 Mdal-insertion to the right of the attachment site, but not continguous with it indicating translocation of the element by non-homologous recombination . In addition, lambda tet has sustained a 3.4 Mdal-deletion adjacent to the insertion . (ii) Further transposition of Tn1721 to the 21.5 Mdal-plasmid R388 resulted in R388::Tn1721 derivatives, two of which were characterised . They contain Tn1721 inserted into different sites but in the same orientation as shown by restriction and heteroduplex analyses . These translocation of Tn1721 were not accompanied by deletions of DNA . (iii) The insertion plasmid pRSD102(R388::Tn1721) has conserved the capacity of the original plasmid pRSD1 to amplify the 3.55 Mdal-tet region . It has been concluded that Tn1721 constitutes a novel transposon encompassing a tet region capable of selective amplification . The model proposed for Tn1721 contains three short repeats . Two direct repeats, flanking the 3.55 Mdal tet region, provide sequence homology for amplification . The third repeat (located distally to tet) is inverted and provides the basis for transposition of the 7.2 Mdal-element.

Mol Gen Genet, 1979 Apr 17, 172(1), 25 - 30
Evidence for endonucleolytic cleavage at the 5'-proximal segment of the trp messenger RNA in Escherichia coli; Kano Y et al.; The 5'-proximal trp leader RNA segment (about 5S) decays at 2 to 3 times slower rates than the distal trp mRNA sequence . This has been demonstrated by employing the deletion mutants which lack a large portion of the structural genes but retain the promoter-proximal region of the trp operon . Relative stability of the leader RNA is not merely due to the presence of an untranslatable region in the segment; the internal untranslatable segment of trp mRNA downstream from the nonsense alteration site of a double mutant trpAD28.trpE9758 decays as fast as the normal trp mRNA sequence . These results suggest that the trp mRNA is endonucleolytically cleaved to yield the small 5'-proximal leader RNA segment before the distal mRNA decays and that the leader RNA sequence is not subject to usual mode of mRNA decay in the 5' to 3' direction.

Mol Gen Genet, 1979 Apr 17, 172(1), 107 - 11
Mechanism of conjugation . II . Characterization of an Hfr dna ts mutant of Escherichia coli K-12; Blinkowa A et al.; A new conditional thermosensitive Hfr mutant of Escherichia coli K-12 was isolated . The ts mutation is cotransducible with purE and tsx loci on the E . coli chromosome . Upon temperature shift to 42 degrees C the DNA synthesis and transfer of chromosome is stopped immediately and RNA, protein synthesis in about ten minutes.

Biochemistry, 1979 Apr 17, 18(8), 1519 - 25
Cross-linking of the cAMP receptor protein of Escherichia coli by o-phenylenedimaleimide as a probe of conformation; Pampeno C et al.; Reaction of the cAMP (cyclic adenosine 3'--5'-monophosphate) receptor protein (CRP) of Escherichia coli with the bifunctional reagent o-phenylenedimaleimide (oPDM) results in the cross-linking of the two subunits of a CRP protomer . In the presence of cAMP the rate of cross-linking increases . CRP modified with oPDM retains {3H}cAMP binding activity but loses {3H}d(I-C)n binding activity . Proteolysis of cross-linked CRP gives distinct sodium dodecyl sulfate-polyacrylamide gel electrophoretic patterns depending upon whether cAMP was present during the reaction with oPDM . CRP cross-linked in the absence of cAMP retains the same relative resistance to proteolysis as unmodified CRP . The presence of 0.1 mM cAMP during proteolysis results in the production of two fragments, one of approximately 13 000 daltons and a second of approximately 20 000 daltons . CRP cross-linked with oPDM in the presence of cAMP (then dialyzed to remove cAMP) remains sensitive to alpha-chymotrypsin digestion even in the absence of added cAMP producing only the 13 000-dalton fragment . It is suggested that the nature of the oPDM cross-link is a consequence of the conformational state of CRP.

Biochemistry, 1979 Apr 17, 18(8), 1422 - 6
Antigenic architecture of membrane vesicles from Escherichia coli; Owen P et al.; The antigenic architecture of membrane vesicles prepared from Escherichia coli ML 308--225 has been studied using crossed immunoelectrophoresis . Progressive immunoadsorption experiments conducted with control vesicles and with physically disrupted vesicles were used to monitor and quantitate the expression of 14 different immunogens . Eleven immunogens, including NADH dehydrogenase (EC 1.6.33.3), D-lactate dehydrogenase (EC 1.1.1.27), dihydro-orotate dehydrogenase (EC 1.3.3.1), 6-phosphogluconate dehydrogenase (EC 1.1.1.43), polynucleotide phosphorylase (EC 2.3.7.8), and beta-galactosidase (EC 3.2.1.23), exhibit minimal expression (10% or less) unless the vesicles are disrupted . Three unidentified antigens are expressed to a similar extent in untreated and disrupted vesicles . Consideration of these and other results {Owen, P., & Kaback, H . R . (1978) Proc . Natl . Acad . Sci . U.S.A . 75, 3148} in terms of membrane polarity, dislocation of antigens, and possible transmembrane orientation of some immunogens reveals that over 95% of the membrane in the vesicle preparations is in the form of sealed sacculi with the same orientation as the intact cell . Furthermore, antigens are distributed across the membrane in a highly asymmetric manner, indicating that dislocation of components from the inner to the outer surface of the membrane during vesicle preparation does not occur to an extent exceeding 10%.

Mol Gen Genet, 1979 Apr 17, 172(1), 93 - 8
Constitutive expression in Escherichia coli of the Neurospora crassa structural gene encoding the inducible enzyme catabolic dehydroquinase; Hautala JA et al.; In Neurospora crassa the qa-2 gene, which encodes catabolic dehydroquinase, is under positive control exerted by the inducer quinic acid and an activator protein encoded in the closely linked qa-1 gene . In order to determine if this regulatory mechanism is maintained when the qa-2 gene is cloned on a recombinant plasmid and expressed in Escherichia coli, molecular cloning experiments have been performed using DNA isolated from a qa-1+ (inducible), a qa-1C (constitutive) and two qa-1 (non-inducible) strains of N . crassa . The results demonstrate that the level of expression of the qa-2 gene in E . coli is completely independent of the mutational state of the qa-1 gene . Moreover, the level of expression of the cloned qa-2 gene was unaffected by either an intracellularly produced inducer of catabolic dehydroquinase or by the general procaryotic positive effector, the CAP factor . The weight of evidence thus supports the conclusion that transcription of the N . crassa qa-2 gene in E . coli does not require the qa-1 activator protein and thus is not controlled by the same mecahnism which functions in N . crassa.

Biochemistry, 1979 Apr 17, 18(8), 1536 - 9
Phosphorus-31 nuclear magnetic resonance study of D-serine dehydratase: pryridoxal phosphate binding site; Schnackerz KD et al.; The pyridoxal phosphate dependent enzyme D-serine dehydratase has been investigated using 31P nuclear magnetic resonance (NMR) at 72.86 MHz . In the native enzyme, the pyridoxal phosphate 31P chemical shift is pH dependent with pKa = 6.4, indicating exposure of the phosphate group to solvent . Binding of the competitive inhibitor isoserine results in the formation of the isoserine-pyridoxal phosphate complex . This transaldimination complex is fixed to the enzyme via the phosphate group of the cofactor as the dianion, independent of pH . At pH 6.6 the dissociation constant KD for isoserine determined by NMR is 0.43 mM . Reconstitution of the apoenzyme with pyridoxal phosphate monomethyl ester produces an inactive enzyme . NMR and fluorescence measurements show that this enzyme does not form the transaldimination complex, indicating that the fixation of the dianionic phosphate (probably via a salt bridge with an arginine residue) observed in the native enzyme is required for the transaldimination step of the catalytic mechanism.

Biochem J, 1979 Apr 15, 180(1), 213 - 8
Studies on the inhibition of protein synthesis by selenodiglutathione; Vernie LN et al.; Amino acid incorporation in a cell-free system derived from rat liver has previously been found to be inhibited by GSSeSG (selenodiglutathione) . In the present experiments the effect of GSSeSG on protein synthesis in 3T3-f cells, on growth and protein synthesis in Escherichia coli, and on amino acid incorporation in a cell-free system derived from E . coli, was studied . GSSeSG inhibits the incorporation of {3H}leucine into protein by 3T3-f cells . This inhibition cannot be reversed by removing GSSeSG and is correlated with the uptake of GSSeSG . Sodium selenite (Na2SeO3) and oxidized glutathione had no inhibitory effect in this system . {3H}Uridine or {3H}thymidine incorporation into RNA or DNA was not inhibited, indicating that the primary action of GSSeSG was on protein synthesis . GSSeSG did not influence the growth of E . coli in a synthetic medium, although enhanced amino acid incorporation was observed . In the cell-free system derived from E . coli, amino acid incorporation was not changed by GSSeSG, indicating that elongation factor G, in contrast to elongation factor 2 of mammalian cell systems, is not blocked by GSSeSG.

Biochem J, 1979 Apr 15, 180(1), 111 - 8
Properties of membranes from mutant strains of Escherichia coli in which the beta-subunit of the adenosine triphosphatase is abnormal; Senior AE et al.; Five uncoupled mutant strains of Escherichia coli carrying mutations in the uncD gene have been studied . In each of these mutant strains the beta-subunit of the F1 portion of the membrane-bound adenosine triphosphatase is abnormal . In one of the mutant strains (carrying the uncD12 allele) in F1-ATPase aggregate was formed which was purified and found to have low ATPase activity . ATPase activity was absent in the other four strains and the abnormal beta-subunits were tightly bound to the membranes . However, membranes from these strains exhibited various proton permeabilities as indicated by NADH-dependent atebrin-fluorescence quenching and bound different amounts of normal F1-ATPase . The amounts of reconstitution of energy-linked reactions after the addition of normal F1-ATPase also varied depending on the mutant allele . It is apparent that considerable phenotypic variations can occur between strains carrying mutations in the same unc gene.

Biochem J, 1979 Apr 15, 180(1), 103 - 9
The uncA gene codes for the alpha-subunit of the adenosine triphosphatase of Escherichia coli . Electrophoretic analysis of uncA mutant strains; Senior AE et al.; Four mutant strains of Escherichia coli which lack membrane-bound adenosine triphosphatase activity were shown by genetic-complementation tests to carry mutations in the uncA gene . A soluble inactive F1-ATPase aggregate was released from the membranes of three of the uncA mutant strains by low-ionic-strength washing, and purified by procedures developed for the purification of F1-ATPase from normal strains . Analysis of the subunit structure by two-dimensional gel electrophoresis indicated that the F1-ATPase in strains carrying the uncA401 or uncA453 alleles had a subunit structure indistinguishable from normal F1-ATPase . In contrast, the F1-ATPase from the strain carrying the uncA447 allele contained an alpha-subunit of normal molecular weight, but abnormal net charge . Membranes from strains carrying the uncA450 allele did not have F1-ATPase aggregates that could be solubilized by low-ionic-strength washing . However, a partial dipolid strain carrying both the uncA+ and uncA450 alleles formed an active F1-ATPase aggregate which could be solubilized by low-ionic-strength washing of the membranes and which contained two types of alpha-subunit, one of which was normal and the other had abnormal net charge . It is concluded that the uncA gene codes for the alpha-subunit of the adenosine triphosphatase.

J Cancer Res Clin Oncol, 1979 Apr 12, 93(3), 245 - 54
Early mitochondrial damage in the induction of haemorrhagic necrosis in the Crocker sarcoma (S 180) by endotoxin; Jones GR; Disturbances in the functional properties of tumor mitochondria have been studied during the course of induction of haemorrhage brought about by endotoxin in the murine Crocker sarcoma (S 180) . Extensive impairment of function was already present in mitochondria isolated from control tumors, as shown by low respiratory control ratios . The existing mitochondrial damage intensified promptly in response to injection of endotoxin long before the onset of haemorrhage at 4 h . The nature of the additional damage took two forms, depending on the duration of exposure to endotoxin; first, at 30 min, a true uncoupling of oxidative phosphorylation was seen, largely reversible in vitro by pre-treatment of the isolated organelles with bovine serum albumin (BSA) . Second, at 1 h and later, oxygen utilisation in the presence of succinate, ADP and inorganic phosphate (Pi) was depressed . The pre-addition of BSA consistently lowered respiration rates with succinate and Pi in all preparations . The extent of endogenous inhibition of the adenine nucleotide translocase appeared unaltered by endotoxin in vivo.

Biochim Biophys Acta, 1979 Apr 12, 567(2), 325 - 30
Studies on a membrane-bound and solubilized ribonucleotide reductase preparation from Escherichia coli TAU-; Viswanathan G et al.; Ribonucleotide reductase has been shown to be associated with the DNA-membrane complex in Escherichia coli TAU- cells . The membrane-bound enzyme has been released in a soluble form using a combined treatment of 1% sarcosyl (pH 8.0) and 1% sodium deoxycholate (pH 6.5) . Allotropic differences in the modulatory effects of ATP, Mg2+, EDTA and dithiothreitol on the membrane-bound and solubilized enzyme activity are discussed.

Proc R Soc Lond B Biol Sci, 1979 Apr 11, 204(1155), 199 - 210
The cell as an extreme environment; Moulder JW; Living cells and their intracellular parasites show many of the characteristics ascribed to extreme environments and their dominant species . The diversity of species colonizing intracellular habitats is low, and successful inhabitants exhibit special fitness traits that often render them obligately dependent on residence within a host cell . However, the diversity-limiting factor in the extreme environment of the host cell interior is not abiotic, as it is in conventional extreme environments . It is biotic: the living cell itself and its many activities . Host cells bar the entrance to most would-be parasites, they destroy most of those that do manage to get inside, and they deny parasites free access to many components of their soluble metabolite pools . Successful intracellular parasites have evolved fitness traits that give them the capacity to survive in the face of diversity-limiting factors or to modify the intracellular habitat so that those factors no longer operate . Looking on the cell as an extreme habitat emphasizes its simultaneous roles as environment, antagonist, and competitor.

J Biol Chem, 1979 Apr 10, 254(7), 2551 - 60
The effects of substituted pyrimidines in DNAs on cleavage by sequence-specific endonucleases; Berkner KL et al.; The rates of cleavage of DNAs containing substituents at position 5 of thymine or cytosine have been measured for a variety of sequence-specific endonucleases, so as to determine which features in the DNA sequence are being probed . Phage phi e DNA fully substituted with 5-hydroxymethyluracil is cleaved more slowly by enzymes whose recognition sequences contain A-T base pairs than are DNAs containing thymine, but both types of DNA are cleaved at similar rates by enzymes recognizing sequences composed only of G-C base pairs . Phage PBS2 DNA with uracil completely substituted for thymine is cleaved slowly by several enzymes which recognize sequences containing A-T base pairs (endonucleases Hpa I, HindII, and HindIII), while the rates of cleavage by other enzymes (endonucleases EcoRI and BamHI) are not affected . Phage lambda- and P22 DNAs containing 5-bromouracil are cleaved more slowly by several enzymes (endonucleases HindIII, Hpa I, BamHI) than are thymine-containing DNAs . Enzymes that recognize sequence isomers with the composition G:C:2A:2T (endonucleases EcoRI, Hpa I, HindIII) are not equally affected by substitution at position 5 of thymine, suggesting that they differ in their contacts with A-T base pairs . DNA containing glucosylated 5-hydroxymethylcytosine in place of cytosine is resistant to cleavage by all the endonucleases examined.

J Biol Chem, 1979 Apr 10, 254(7), 2561 - 4
Quantitation of the various termini generated by type II restriction endonucleases using the polynucleotide kinase exchange reaction; Berkner KL et al.; Parameters of the polynucleotide kinase-catalyzed exchange reaction between {gamma-32P}ATP and 5'-phosphoryl DNAs have been measured with the termini generated by the following endonucleases: EcoRI (Berkner, K . L., and Folk, W . R . (1977) J . Biol . Chem . 252, 3176-3184), Hpa II, BamHI, and HindIII (external termini); HindII and Hpa I (blunt terminal); Hae II and Hha I (internal termini) . In every case, exchange is reproducible and proportional to the number of termini . However, in most cases, the exchange reaction does not proceed to the theoretical maximum . External termini and single-stranded DNAs are labeled more rapidly and to approximately 5-fold higher levels than blunt or internal termini . Concentrations of 100 to 200 microns ADP and 12 microns ATP are optimal for labeling all types of termini with the exchange reaction.

Nature, 1979 Apr 5, 278(5704), 521 - 4
Transmission of allosteric effects in DNA; Hogan M et al.; Binding of distamycin induces a cooperative transition of calf thymus DNA to a new form with higher affinity for the drug and altered structural properties.

Biochemistry, 1979 Apr 3, 18(7), 1344 - 52
Purification and properties of the sigma subunit of Escherichia coli DNA-dependent RNA polymerase; Lowe PA et al.; An improved purification procedure is described for the sigma subunit of escherichia coli DNA-dependent RNA polymerase {ribonucleoside triphosphate:RNA nucleotidyl-transferase, EC 2.7.7.6} . The method involves chromatography of purified RNA polymerase on single-stranded DNA-agarose, Bio-Rex 70, and finally Ultragel AcA44 . The sigma factor obtained is electrophoretically pure with a yield of about 40% . A number of the chemical--physical properties of sigma are presented . A molecular weight of 82,000 was determined by phosphate buffered sodium dodecyl sulfate--polyacrylamide gel electrophoresis . Ultraviolet absorption spectra were used to determine an E280nm 1% of 8.4 . The amino acid composition and 12-residue N-terminal sequence (Met-Glx-Glx-Asx-Pro-Glx-(Ser or Cys)-Glx-Leu-Lys-Leu-Leu) of sigma have been determined . The isoelectric focusing properties of sigma are presented . Denaturation--renaturation studies indicate that sigma is capable of an unusually rapid and complete recovery of activity after being subjected to denaturing conditions . A stable, 40,000-dalton fragment is generated from sigma by mild trypsin treatment.

Biochemistry, 1979 Apr 3, 18(7), 1275 - 81
Analysis of protein--protein relationships in 30S ribosome assembly intermediates using protection from proteolytic digestion; Changchien LM et al.; Treatment of the intact bacterial ribosome with proteolytic enzymes results in little or no digestion of many of the component proteins {Craven, G . R., & Gupta, V . (1970) Proc . Natl . Acad . Sci . U.S.A . 67, 1329} . In contrast, when the proteins are released from the constraints of ribosome structure they become completely susceptible to proteolytic attack . We have attempted to exploit these observations in an effort to determine the precise steps in ribosome assembly which result in a conversion of the structures of the various proteins from a proteolysis sensitive to a resistant form . Thus, a total of 11 30S ribosome assembly intermediate complexes of proteins and 16S RNA were prepared and digested with trypsin or chymotrypsin . The kinetics of digestion of each protein in the complex were followed by polyacrylamide gel electrophoresis . By a comparison of the digestion pattern of two complexes differing only by the presence of a single protein, it was possible to deduce several specific protective effects of one protein on its neighbor in the complex . On the basis of these studies, we propose nine protein-protein protective effects . The possible relevance of these interrelationships to other well-established proximity relationships is discussed.

Biochemistry, 1979 Apr 3, 18(7), 1245 - 9
Cysteinyl-tRNA synthetase from Escherichia coli does not need an editing mechanism to reject serine and alanine . High binding energy of small groups in specific molecular interactions; Fersht AR et al.; The cysteinyl-tRNA synthetase from Escherichia coli only very slowly activates serine, alanine, and alpha-aminobutyrate, the possible competitors of cysteine . The upper limits on the values of kcat/KM for the amino acid dependent ATP/pyrophosphate exchange reactions, relative to that of cysteine, are less than 10(-8), 2 x 10(-7), and 3 x 10(-6), respectively . It is calculated from these data and the concentrations of the amino acids in vivo that the error rates for the misincorporation of serine and alanine for cysteine are less than 10(-9) and 5 x 10(-8), respectively . There is no need for an error correcting mechanism and no evidence has been found to implicate one: there is no detectable ATP/pyrophosp hatase activity of the enzyme in the presence of tRNACys and alanine; Ala-tRNACys has been synthesized by the reductive desulfurization of Cys-tRNACys and has been found to be relatively resistant to the enzyme-catalyzed deacylation . Part of the high selectivity of the enzyme for the -SH group of cysteine (approximately 5 kcal/mol) appears to be caused by dispersion forces: simple calculations suggest that the dispersion energy between sulfur and a methylene group is about 2.5 times greater than that between two methylene groups . This high "hydrophobicity" of sulfur is consistent with the relative binding energies of substrates of the methionyl-tRNA synthetase . The rest of the high binding energy of the-SH group may come from hydrogen bonding.

Mol Cell Biochem, 1979 Apr 2, 24(3), 175 - 81
Isolation and binding properties of leucyl-tRNA synthetase from Escherichia coli MRE 600; Granda S et al.; A procedure for the large-scale isolation of leucyl-tRNA synthetase from E . cole MRE 600 is described: The enzyme was purified about 320-fold to homogeneity by precipitation with cetyl-trimethyl-ammonium bromide, two consecutive chromatographies on DEAE-cellulose and three on hydroxyapatite with an over-all yield of 4% . The molecular weight of leucyl-tRNA synthetase from E . coli MRE 600 was found to be 99 000 daltons . Bindings studies by ultracentrifugation and equilibrium partition showed that the enzyme binds leucine, leucyl-adenylate and tRNA Leu, each in a 1 : 1 stoichiometry . For ATP only a very weak binding to the enzyme could be observed, which did not allow the evaluation of the complex stoichiometry . The presence of ATP was not required for the binding of leucine or tRNA to leucyl-tRNA synthetase from E . coli MRE 600.

Eur J Biochem, 1979 Apr 2, 95(2), 359 - 66
Protein S1 from Escherichia coli ribosomes: an improved isolation procedure and shape determination by small-angle X-ray scattering; Labischinski H et al.; Ribosomal protein S1 from Escherichia coli was studied in solution by small-angle X-ray scattering and the following parameters were obtained . The radius of gyration R = 8.0 +/- 0.2 nm; largest diameter D = 28 nm; molecular weight = (8--9) x 10(4) . The data also yielded (with the assumption of a rigid particle with almost constant electron density) two radii of gyration of cross-section Rq1 = 2.5 +/- 0.1 nm and Rq2 = 1.05 +/- 0.05 nm and molecular volume = 140 nm3 . The experimental scattering curve of S1 was compared with the theoretical scattering curves for several rigid triaxial homogeneous bodies and the closest fit was given by that of a flat elliptical cylinder with the dimensions of 4.5 nm and 0.88 nm for the two semiaxes and 26.5 nm for height . The results from the present X-ray scattering studies and those from limited proteolytic digestion of protein S1 {J . Mol . Biol . 127, 41--54, (1979)} support the notion that the structure of protein S1 is organized into two distinct subdomains within its elongated overall shape . Protein S1 was purified for this study by an efficient procedure which yielded 12 mg S1/g ribosomes . The isolated protein was fully active in functional tests both before and after X-ray irradiation.

Mutat Res, 1979 Apr, 60(2), 197 - 206
Selectivity of the excision of alkylation products in a xeroderma pigmentosum-derived lymphoblastoid line; Altamirano-Dimas M et al.; Lymphoblastoid cell derived from a complementation group C xeroderma patient were unable to remove 06-methyl guanine residues formed in DNA by treatment of cells with low concentration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) . The xeroderma cells were competent in their ability to excise 3-methyl adenine adducts . MNNG treatment induced excision repair in the xeroderma line and in addition the treatment resulted in the presence of numerous single-strand breaks in the DNA . The single gene, UV-excision-defective mutants of Escherichia coli, uvrA and uvrB, are able to excise MNNG-induced 06-methyl guanine adducts indicating that excision of this compound is not due to operation of UV endonuclease system.

Can J Microbiol, 1979 Apr, 25(4), 436 - 46
Structural and biochemical examination of ghosts derived from a deep rough (heptose-deficient lipopolysaccharide) strain and a smooth strain of Escherichia coli; Irvin RT et al.; Outer membrane derived 'ghosts' can be readily generated from both smooth and deep rough (heptose-deficient LPS) strains of Escherichia coli 08 . MORPHOlogical and biochemical studies confirmed that 'ghosts' of both strains are composed of protein (four major proteins), LPS, and phospholipid (cardiolipin and phosphatidylethanolamine) in the form of a single membrane of roughly the same shape as intact normal cells . The ghost membrane cleaves only slightly in freeze-etch preparations of ghosts derived from the smooth strain as compared to the extensive cleavage plane of ghosts derived from the rough strain . The asymmetrical distribution of ghost proteins was visualized, by critical point drying and shadowing with platinum, as a relatively smooth outer surface with some discernible particles (10-15 nm) and an extremely particulate inner surface (10-15-mm particles . Ghosts derived from the smooth strain retained their structure following chloroform-methanol extraction, while ghosts derived from the rough strain fragmented with chloroform-methanol extraction . Evidence is presented that LPS-protein interactions as well as protein-protein interactions are significant in maintaining the ghost structure.

Ann Microbiol (Paris), 1979 Apr, 130A(3), 295 - 313
{Theoretical analysis of potential variations of "Escherichia coli" K12 cultures in presence of an electron carrier (author's transl)}; Junter GA et al.; Oxygen consumption and reductive hydrogenation of lipoic acid, linked to the exponential growth of Escherichia coli in a "minimal" medium containing a non-limiting amount of glucose, produce reproducible and intelligible variations of the electric potential between a gold electrode and a reference electrode . A simple quasi-stationary mathematical model leads to analytical expressions of the electric potential in function of the experimental conditions and of time . The effects of active or passive transport of lipoic acid are distinguishable . An experimental method results in detecting and following bacterial activity.

J Gen Microbiol, 1979 Apr, 111(2), 387 - 96
Isolation by differential and zonal centrifugation of minicells segregated by Escherichia coli; Barker GR et al.; Minicells segregated from Escherichia coli chi925 carrying a drug-resistance plasmid were separated from nucleated cells by differential centrifugation and purified by rate-zonal centrifugation in sucrose gradients . Minicells purified in this way were capable of donating the plasmid to nucleated cells . They also incorporated thymidine, uridine and methionine into macromolecules . Methods are described for purification of plasmid-containing minicells on a scale large enough to allow isolation of DNA, DNA polymerase and RNA polymerase in sufficient quantities for studies of enzymes involved in replication and transcription of plasmid DNA.

J Gen Microbiol, 1979 Apr, 111(2), 363 - 74
Pleiotropic aspartate taxis and serine taxis mutants of Escherichia coli; Reader RW et al.; Mutants that at one time were thought to be specifically defective in taxis toward aspartate and related amino acids (tar mutants) or specifically defective in taxis toward serine and related amino acids (tar mutants) are now shown to be pleiotropic in their defects . The tar mutants also lack taxis toward maltose and away from Co2+ and Ni2+ . The tsr mutants are altered in their response to a variety of repellents . Double mutants (tar tsr) fail in nearly all chemotactic responses . The tar and tsr mutants provide evidence for two complementary, converging pathways of information flow: certain chemoreceptors feed information into the tar pathway and others into the tsr pathway . The tar and tsr products have been shown to be two different sets of methylated proteins.

Gene, 1979 Apr, 5(4), 305 - 27
The site controlling the specificity of N action is outside the promoter-operator region: a triple hybrid phage lambda N21 imm434nin5; Salstrom JS et al.; A short interval of homology between imm lambda, imm434 and imm21 DNAs was identified near the leftward promoter-operator region . This homology, denoted Hs, was revealed by electron microscopic examination of lambda imm lambda/lambda imm21 and lambda imm434/lambda imm21 heteroduplexes, and permitted us to construct a special lambda hybrid (lambda hyB) which contains the N region of phage 21 and the adjacent imm region from phage 434 . This triple hybrid, labmda N21 imm434nin5, was analysed by genetic, transcriptional and electronic micrographic techniques . Its leftward and rightward promoter-operator regions are of phage 434 specificity and are controlled by the 434 repressor . Surprisingly, the N21 gene of lambda hyB was found to be defective, perhaps to preserve the viability of the hybrid . Its leftward N-recognition system (nutL) is of phage 21 specificity since it responds only to the N21 function in complementation tests, as measured by antitermination of leftward transcription initiated at the pL promotor in the imm434 region . We conclude, therefore, that the pLoL region of 434 contains no information for the specificity of N antitermination . Both lambda imm21 and lambda hyB were found to be missing the tL1 terminator function (see also Salstrom and Szybalski, 1978b) . In these phages, the tL2 terminator was found to be only 60% effective under N21 conditions, and therefore expression of their red-gam genes is sufficient to endow the lambda hyB and lambda N21- imm21nin5 phages with the Fec+ phenotype.

Gene, 1979 Apr, 5(4), 291 - 303
Cloning and expression of the yeast galactokinase gene in an Escherichia coli plasmid; Schell MA et al.; This report describes the construction and isolation of a plasmid, derived from pBR322, which carries a BglII restriction fragment of DNA containing the galactokinase gene from Saccharomyces cerevisiae . This was accomplished by the following procedure: (1) Purified galactokinase mRNA, labelled with 125I, was hybridized to BglII digests of yeast DNA employing Southern's filter transfer technique to identify a restriction fragment containing the galactokinase gene . (2) This fragment was partially purified by agarose gel electrophoresis, ligated into the BamHI site of pBR322 and transformed into Escherichia coli to generate a clone bank containing the galactokinase gene . (3) This bank was screened by in situ colony hybridization with galactokinase mRNA resulting in the identification of a plasmid carrying this gene . This plasmid DNA hybridized with the galactokinase mRNA to the same extent in the presence of absence of a large excess of unlabelled mRNA from cells that were not induced for galactokinase synthesis, while the same amount of unlabelled galactose-induced mRNA reduced the hybridization by 95% . When this plasmid was introduced into an E . coli strain deleted for the galactose operon it caused the synthesis of low levels of yeast galactokinase activity.

Gene, 1979 Apr, 5(4), 275 - 90
Cloning and biological characterization of the immunity region of Escherichia coli phage Mu; Schumann W; The construction of three hybrid plasmids containing different parts of the left or immunity and end of phage Mu DNA is described . The recombinant plasmids pKN05 and pKN54 carry the HindIII.C and PstI.C fragments of Mu DNA, respectively . Neither of these plasmids expresses the killing function . Moreover, they do not allow plating of superinfecting Mu phages . Plasmid pKN62 harbors the fragment located in between the left PstI and EcoRI cleavage sites on Mu DNA, allows plating of superinfecting Mu phages, but does not express the killing function . These data suggest that the gene coding for the killing function is either positively regulated by a product from the EcoRI.C fragment, or the killing function requires a second product not coded for by pKN62 . Mu Vir A- or Mu Vir B- phages are able to grow on bacteria harboring the recombinant plasmid pKN001 which carries the left and EcoRI-C fragment of Mu DNA . This indicates that the superinfecting phages can induce the corresponding gene functions from pKN001 . No such induction could be detected in cells harboring the hybrid plasmids pKN05, pKN54 or pKN62.

Gene, 1979 Apr, 5(4), 255 - 74
A coliphage lambda vector with enhanced biological containment: lambda gtALO.lambda B; Tabor JM et al.; The biological containment of the lambda gt family of cloning vectors has been enhanced by conditionally blocking DNA replication as well as head and tail morphogenesis . The vector, lambda gtALO.lambda B, was constructed by crossing the Oam29, Aama1 and Lam439 mutations into lambda gt.lambda B . The mutation blocking phage DNA replication, Oam29, is suppressed by suII+ or suIII+ . The head gene mutation, Aama1, is suppressed by suIII+ but not by suII+ and the tail gene mutation, Lam439, is suppressed by suII+ but not by suIII+ . This allows the option of increasing the biological containment by producing heads when a large amount of cloned DNA is being prepared from an individual isolate . A model recombinant, lambda gt Aama1 Lam439 Oam29.KmR' (lambda gtALO.KmR') was constructed and the containment of the vector was evaluated by the series of standardized experiments required for EK2 certification.

Rev Bras Pesqui Med Biol, 1979 Apr, 12(1), 67 - 73
Modification of a mathematical model for survival curves in photobiology; Pelico JV et al.; A modification of the Haynes' mathematical model (1966) can be suggested as a result of bacterial UV-survival experiments carried out . A new equation is proposed: lnS = Fi(x), + Fr(x), wherein x is the radiation dose, Fi(x) = -- kox describes how radiation damage is produced on the cell and Fr(x) = (krec + kc)x + Re(x) describes how repair systems act . ko is the relative inactivation efficiency of radiation on each cell . krec is the recombination recovery system efficiency . kc gives the additional repair increasing per cell when excision and recombination systems act simultaneously . Re(x) = a(1-e-bs) describes solely the excision repair process . The asymptote of non-exponential curves intercepts the survival fraction axis on the ordinate so (extrapolated point) . In the modified model a=lnSo instead of a=So (Haynes' model).

J Clin Microbiol, 1979 Apr, 9(4), 493 - 7
Use of colony pools for diagnosis of enterotoxigenic Escherichia coli diarrhea; Merson MH et al.; Diagnosis of enterotoxigenic Escherichia coli diarrhea was made in 109 adult males with an acute dehydrating cholera-like syndrome in Dacca, Bangladesh, by testing 10 colonies isolated from admission stool specimens for production of heat-labile and heat-stable toxins . Toxin testing of one colony yielded a diagnosis in 92% of the cases, testing of two colonies yielded a diagnosis in 95% of the cases, testing of a pool of 5 colonies yielded a diagnosis in 95% of the cases, and testing of a pool of 10 colonies yielded a diagnosis in 96% of the cases . From stool cultures obtained on subsequent days, toxin testing of individual colonies and pools revealed diminished efficacy of pooling with decreasing numbers of enterotoxin-positive isolates in the pool . To detect the presence of enterotoxigenic E . coli in stools, toxin testing of 5 individual isolates and a pool of 10 colonies was found to be almost as effective as the testing of 10 individual isolates.

J Biochem (Tokyo), 1979 Apr, 85(4), 915 - 21
Comparison of denaturation by guanidine hydrochloride of the wild type tryptophan synthase alpha-subunit of Escherichia coli and two mutant protein (Glu 49 replaced by Met or Gln); Yutani K et al.; In order to elucidate the roles of individual amino acid residues in the conformational stability of proteins, the denaturation by guanidine hydrochloride of the wild-type trytophan synthase alpha-subunit of Escherichia coli and two mutant proteins, trpA33 (Glu 49 leads to Met) and trpA11 (Glu 49 leads to Gln), has been compared by means of CD measurements at pH 7.0 and various temperatures . CD spectra of the two mutant proteins were similar to that of the wild-type protein . The trpA33 and the trpA11 proteins were more and less resistant, respectively, to guanidine hydrochloride than the wild-type protein at 9.7 to 49.6 degrees C . The free energy change of unfolding in water delta delta Gnd H2O, was evaluated assuming a three state denaturation, since the denaturation curves of three proteins suggested the presence of one stable intermediate . The values of delta Gnd H2O for the trpA33, the wild-type, and the trpA11 proteins at 25.8 degrees C and pH 7.0 were 13.4,8.8, and 6.3 kcal/mol, respectively . The delta Gnd H2O of the trpA11 protein was almost independent of temperature, though that of the trpA33 protein was remarkably dependent on temperature . The conformation stabilities of the three proteins were correlated with the hydrophobicities of the substituted amino acid residues.

Infect Immun, 1979 Apr, 24(1), 289 - 90
Production of heat-stable enterotoxin by the O128 serogroup of Escherichia coli; Reis MH et al.; Nine out of 11 Escherichia coli strains belonging to enteropathogenic O128 serogroup were shown to produce heat-stable enterotoxin . This property may be related to the pathogenicity of this serogroup of bacteria.

Infect Immun, 1979 Apr, 24(1), 127 - 31
Endotoxin lethality and tolerance in mice: analysis with the B-lymphocyte-defective CBA/N strain; Zaldivar NM et al.; Immune-defective and immunologically normal F1 mice derived from the CBA/N strain were used to study the influence of anti-endotoxin antibody on the lethal effects of endotoxin . Immune-defective F1 male mice were unable to make specific responses to purified preparations of E . coli O111:B4 endotoxin, whereas their immunologically normal F1 female littermates made excellent responses . The ability to form antibody to lipopolysaccharide (LPS) in these F1 mice did not influence either their natural resistance to endotoxin challenge or the effects of pretreatment with sublethal amounts of endotoxin on subsequent challenge with higher normally lethal doses . Furthermore, transfer of sera with high titers of anti-LPS antibody to mice prior to challenge with LPS failed to protect . Thus, anti-LPS antibody does not appear to play a critical role in protection of immune-defective (CBA/N X DBA/2) F1 male mice to the lethal effects of endotoxin or to the protective effects of a single sublethal dose of endotoxin on subsequent endotoxin challenge.

Tsitologiia, 1979 Apr, 21(4), 452 - 8
{Intercellular information transfer in the process of immunogenesis . VI . The induction of antiphage antibody synthesis in the cells of rat transplantable lymphosarcoma under the influence of splenic RNA from rats and mice immunized with phage T2}; Pogodina ON et al.; It has been proved that nuclear and cytoplasmic RNAs, isolated from spleens of T2 phage immunized rats and mice, can induce T2 phage antibodies in cells of the transplantable rat lymphosarcoma . With the nuclear RNA from rat spleens, the effect is persisting in a number of subsequent cell generations . The data presented are principally in accord with results of the authors' previous studies in which lymphosarcoma cells were treated with RNA extracted from spleens of rat immunized with sheep red cells . These results well compare with the authors' earlier advanced hypothesis suggesting a possible involvement of RNA in deblockation of genes responsible for the synthesis of the antibodies in question.

Tsitologiia, 1979 Apr, 21(4), 447 - 51
{Temperature-dependent structural rearrangements in the cytoplasmic membranes of Escherichia coli cells}; Kirillov VA et al.; By the freeze-etching method, in has been shown that E . coli plasma membranes undergo a structural transition in the range of temperatures within 0 and 20 degrees C which could be observed as redistribution of intramembrane particles with free-zone formation . The onset of temperature interval of this transition (20 degrees) well correlate with the break in the Arrhenius curves characterizing the cell membrane permeability for free nucleotides and for respiration intensity.

Proc Natl Acad Sci U S A, 1979 Apr, 76(4), 1741 - 5
Further studies on the mode of action of the heme-controlled translational inhibitor; de Haro C et al.; We have isolated {de Haro, C . & Ochoa, S . (1978) Proc . Natl . Acad . Sci . USA 75, 2713-2716} a protein factor (eIF-2 stimulating protein, ESP) that is essential for formation of ternary and 40S initiation complexes by the eukaryotic polypeptide chain initiation factor 2 (eIF-2) at the low concentrations of eIF-2 present in reticulocyte lysates . The fact that stimulation of complex formation by ESP is virtually abolished when the small (38,000 daltons) subunit of eIF-2 is phosphorylated by ATP in the presence of eIF-2 kinase (heme-controlled inhibitor, HCI) is consistent with the notion that HCI inhibits translation in lysates by blocking the interaction of eIF-2 with ESP . Our present work, with highly purified eIF-2 and ESP, has additionally established that, unlike phosphorylation of the small subunit, phosphorylation of the middle (52,000 daltons) subunit of eIF-2, which does not lead to translational inhibition in lysates, does not affect eIF-2-ESP interaction . This provides further support for our model of translational inhibition by HCI.

Proc Natl Acad Sci U S A, 1979 Apr, 76(4), 1697 - 701
Nucleotide sequence of the ribosomal protein gene cluster adjacent to the gene for RNA polymerase subunit beta in Escherichia coli; Post LE et al.; The 3072-nucleotide-long sequence of a segment from the 88-min region of the Escherichia coli chromosome has been determined . The sequence covers the genes for ribosomal proteins L11 (rplK), LI (rplA), L10 (rplJ), and L7/L12 ((rplL), and the 5' end of the gene for the beta subunit of RNA polymerase (rpoB), along with the presumed regulatory regions for these genes . The probable locations of the promoter for the first two genes (the L11 operon) and the promoter for the latter three genes (the proximal part of the beta operon) have been identified . We have also found that the four ribosomal protein genes preferentially use codons that are recognized efficiently by the most abundant tRNA species . These and other features of the sequence results are discussed in relation to available information obtained from both in vitro and in vivo experiments on the expression of these ribosomal and RNA polymerase subunit genes.

Proc Natl Acad Sci U S A, 1979 Apr, 76(4), 1623 - 7
Hyperdegradation of proteins in Escherichia coli rho mutants; Simon LD et al.; An Escherichia coli mutant, HDF026, defective for growth of phage T4, has been characterized biochemically and genetically . The mutant displays an elevated level of degradation of abnormal proteins, such as puromycyl polypeptides or canavanine-containing polypeptides . Genetically, HDF026 appears to be an allele of rho, which also encodes the transcription termination factor and RNA-dependent ATPase, Rho . The mutation contransduces by phage PI with ilv, weakly suppresses polar mutations in gal, and permits some growth of lambda N- phage . Temperature sensitive lambda mutants in gene O exhibit a reduced efficiency of plating at intermediate temperature on HDF026 mutants; presumably the lambda Ots protein is rapidly degraded in these strains . The ability of wild-type lambda to grow on HDF026 is also reduced, apparently the result of the lambda N product deficiency . gal escape synthesis, which reflects the level of lambda N activity, is decreased 50-66% in the HDF026 mutant . lambda r32, which requires more N function than wild-type phage, does not grow at all in HDF026 . A lon mutation, which decreases protein degradation, partially reverses some of these phenotypes, suggesting that they are related to the protein hyperlability of HDF026.

Can J Biochem, 1979 Apr, 57(4), 336 - 45
Partial characterization of the mode of inhibition of Escherichia coli RNA polymerase by the mixed disulfide, CoASSG; Bees WC et al.; The coenzyme A-glutathione mixed disulfide (CoASSG), when complexed with iron, is capable of inhibiting the RNA polymerase of Escherichia coli . A modified procedure involving a short time of exposure to high salt allowed the reliable preparation of CoASSG-Fe which was active in inhibiting RNA polymerase . The CoASSG-Fe complex acted as a noncompetitive inhibitor for the incorporation of all four nucleoside triphosphates but had a greater effect on GMP and CMP incorporation than AMP and UMP incorporation . Neither temperature nor ionic-strength changes affected CoASSG-Fe inhibition, and the use of rifampicin showed that CoASSG-Fe did not inhibit either the initiation or elongation processes of the polymerase . CoASSG-Fe was a more effective inhibitor at low DNA-template concentrations and it was more effective in inhibiting the incorporation of CMP and GMP on simple dG-dC containing templates and the asymmetric polymer poly d(T-C) . poly d(G-A) . The inhibition of transcription of poly d(I-C) was less effective than the inhibition of transcription of poly d(G-C) . Equilibrium dialysis in microdialysis cells showed that CoASSG-Fe could associate with DNA in the absence of RNA polymerase.

Acta Pathol Microbiol Scand {B}, 1979 Apr, 87B(2), 85 - 91
Influence of O and K antigens on the surface properties of Escherichia coli in relation to phagocytosis; Stendahl O et al.; Strains of Escherichia coli with different O and K antigens were investigated with respect to physicochemical surface characteristics and liability to phagocytosis . Using two-phase partitioning analysis for the surface characterization, three main groups of strains emerged: Group I (O1:K1, O2:K1, O3:K2ab) showing both smooth hydrophilic O antigens and negatively-charged K antigen which rendered the strains maximally resistant to phagocytosis . Group II (O55:K59, O111:K58) showed no acidic K antigen but only smooth hydrophilic O antigen properties . However, these strains were as resistant to phagocytosis as the strains in group I . A third group (O14:K7, O24:K +) contained strains with rough, hydrophobic O antigen and negatively-charged K antigen . When the K antigen was removed by heat treatment these strains became more sensitive to phagocytosis . Certain other strains (O28:K-, O56:K + and O118:K-) did not fit into the three groups . These experiments show that the physicochemical surface effects and biological significance of the K antigen must be evaluated in relation to the properties conveyed by the corresponding O antigens.

J Bacteriol, 1979 Apr, 138(1), 70 - 9
Clustering of genes involved in replication, copy number control, incompatibility, and stable maintenance of the resistance plasmid R1drd-19; Molin S et al.; Plasmid R1drd-19 is present in a small number of copies per cell of Escherichia coli . The plasmid was reduced in size by in vivo as well as in vitro (cloning) techniques, resulting in a series of plasmid derivatives of different molecular weight . All plasmids isolated contain a small region (about 2 x 10(6) daltons of deoxyribonucleic acid) of the resistance transfer factor part of the plasmid located close to one of the IS1 sequences that separates the resistance transfer factor part from the resistance determinant . All these derivatives were present at the same copy number, retained the incompatibility properties of plasmid R1drd-19, and were stably maintained during cell division . Genes mutated to yield copy mutations also were found to be located in the same region.

J Bacteriol, 1979 Apr, 138(1), 273 - 4
Distribution of cell lengths in cultures of a lexA mutant of Escherichia coli K-12; Howe WE et al.; Distributions of cell lengths in lexA+ and lexA mutant cultures during normal growth and under thymidine starvation conditions are presented . During normal growth lexA mutant cells were slightly shorter, on the average, than were lexA+ cells . lexA mutant cells were also shorter in comparison with lexA+ cells after a period of thymidine starvation . These results are consistent with the hypothesis that the lexA gene is involved in the coordination of cell division with DNA repair.

J Bacteriol, 1979 Apr, 138(1), 270 - 2
Increased amplification of pBR322 plasmid deoxyribonucleic acid in Escherichia coli K-12 strains RR1 and chi1776 grown in the presence of high concentrations of nucleoside; Norgard MV et al.; When pBR322 plasmid-harboring Escherichia coli strains RR1 or chi1776 were grown in the presence of 1 mg of uridine or cytidine per ml and later treated with chloramphenicol, as much as three times more plasmid deoxyribonucleic acid was recovered than would normally be obtained by routine plasmid amplification procedures.

J Bacteriol, 1979 Apr, 138(1), 264 - 7
Mapping hisS, the structural gene for histidyl-transfer ribonucleic acid synthetase, in Escherichia coli; Parker J et al.; The structural gene for histidyl-tRNA synthetase was localized to 53.8 min on the Escherichia coli genome . The gene order in this region was determined to be dapE-purC-upp-purG-(guaA, guaB)-hisS-glyA.

J Bacteriol, 1979 Apr, 138(1), 254 - 6
Cross-linking analysis of the two forms of protein I, a major outer membrane protein of Escherichia coli; Palva ET et al.; The two forms of protein I were cross-linked to molecules of the same species, even when both were present simultaneously . This suggests that they form separate multimers in the outer membrane.

J Bacteriol, 1979 Apr, 138(1), 24 - 32
Genetic and biochemical studies of transport systems for branched-chain amino acids in Escherichia coli; Yamato I et al.; Mutants of Escherichia coli K-12 requiring high concentrations of branched-chain amino acids for growth were isolated . One of the mutants was shown to be defective in transport activity for branched-chain amino acids . The locus of the mutation (hrbA) was mapped at 8.9 min on the E . coli genetic map by conjugational and transductional crosses . The gene order of this region is proC-hrbA-tsx . The hrbA system was responsible for the uptake activity of cytoplasmic membrane vesicles . It was not repressed by leucine . The substrate specificities and kinetics of the uptake activities were studied using cytoplasmic membrane vesicles and intact cells of the mutants grown in the presence or absence of leucine . Results showed that there are three transport systems for branched-chain amino acids, LIV-1, -2, and -3 . The LIV-2 and -3 transport systems are low-affinity systems, the activities of which are detectable in cytoplasmic membrane vesicles . The systems are inhibited by norleucine but not by threonine . The LIV-2 system is also repressed by leucine . The LIV-1 transport system is a high-affinity system that is sensitive to osmotic shock . When the leucine-isoleucine-valine-threonine-binding protein is derepressed, the high-affinity system can be inhibited by threonine.

J Bacteriol, 1979 Apr, 138(1), 201 - 6
Characterization of arithmetic deoxyribonucleic acid synthesis at restrictive temperature in a dnaE mutant of Escherichia coli K-12; Wechsler JA et al.; The dna-293 mutation is shown to be a dnaE allele . The linear deoxyribonucleic acid synthesis previously observed in this mutant has been further characterized . The production of small deoxyribonucleic acid intermediates and their subsequent joining were identical in the mutant and its dnaE+ parent at 42.5 degrees C . Though the mutant cells continued to divide at the nonpermissive temperature, the rate of division was reduced . The data are consistent with a lack of production of replicationally active deoxyribonucleic acid polymerase III at the restrictive temperature.

J Bacteriol, 1979 Apr, 138(1), 17 - 23
Length growth of two Escherichia coli B/r substrains; Meyer M et al.; Length growth of synchronized Escherichia coli B/r substrain A (ATCC 12407) and B/r substrain F26 (Thy his) was followed with an electron microscope . Cells were grown with doubling times (tau) of 60 min (B/rA) and of 82 and 165 min (B/rF26) . Different length growth patterns were found for the two substrains . In B/rF, the length growth rate increased about midway in the cell cycle . For tau = 165 min, the rate increase was preceded by a short period of slow growth . For B/r A (r = 60 min), this period seemed to occur at the beginning of the cell cycle . The possibility is raised that the different length growth patterns are related to different deoxyribonucleic acid replication patterns of the respective strains.

J Bacteriol, 1979 Apr, 138(1), 133 - 8
Alteration of the fatty acid composition of Escherichia coli by growth in the presence of normal alcohols; Sullivan KH et al.; The addition of normal alcohols in the series n-butanol to n-octanol to cultures of Escherichia coli ML308 grown on defined or lipid-free medium (at 17, 27, and 37 degrees C) caused an alteration in the fatty acid composition of this organism: the ratio of saturated to unsaturated fatty acids increased . Changes in the relative quantities of individual fatty acid species elicited by increasing concentrations of these alcohols were as follows: (i) myristic acid remained constant: (ii) palmitic acid increased; and (iii) the combined amount of palmitoleic plus cis-methylene hexadecanoic acids changed in a way which was reflected inversely by changes in the amount of cis-vaccenic acid . Comparable changes were not observed when cells were grown in the presence of n-nonanol and n-decanol in the concentration range tested . The changes observed upon addition of normal alcohols (n-butanol to n-octanol) paralleled, in part, the alterations in fatty acid composition observed when growth temperature was increased.

J Bacteriol, 1979 Apr, 138(1), 118 - 21
Properties and biosynthesis of cyclopropane fatty acids in Escherichia coli; Cronan JE Jr et al.; The lipid phase transition of Escherichia coli phospholipids containing cyclopropane fatty acids was compared with the otherwise homologous phospholipids lacking cyclopropane fatty acids . The phase transitions (determined by scanning calorimetry) of the two preparations were essentially identical . Infection of E . coli with phage T3 inhibited cyclopropane fatty acid formation over 98%, whereas infection with mutants which lack the phage coded S-adenosylmethionine cleavage enzyme had no effect on cyclopropane fatty acid synthesis . These data indicate that S-adenosylmethionine is the methylene in cyclopropane fatty acid synthesis.

J Bacteriol, 1979 Apr, 138(1), 105 - 8
Repair of ultraviolet light-damaged deoxyribonucleic acid in sbc-A strains of Escherichia coli K-12; Shlaes DM et al.; An Escherichia coli strain carrying both rec+ and sbcA has been constructed . Repair of ultraviolet light-induced deoxyribonucleic acid damage was examined by measuring survival and thymine-dimer excision in the rec+ sbcA strain as well as rec+ sbcA+ and recB recC sbcA strains . The sbcA mutation restores normal survival in both recB recC uvrB and recB recC uvr+ strains . Excision of thymine-containing dimers does not occur in uvrB mutants, regardless of the rec or sbcA genotype . Survival, after ultraviolet-light damage, of a rec+ sbcA strain is quantitatively similar to rec+ sbcA+ and recB recC sbcA strains.

J Bacteriol, 1979 Apr, 138(1), 1 - 6
Thermoresistant revertants of an Escherichia coli strain carrying tif-1 and ruv mutations: non-suppressibility of ruv by sfi; Otsuji N et al.; Spontaneous thermoresistant revertants were isolated from Tif1 Ruv- and Tif1 Ruv+ strains of Escherichia coli K-12 . They were divided into five groups; backmutants to tif+ and recA structural gene mutants accounted for at least two of these groups . Mutations with an unconditional RecA- phenyotype were detected at a higher frequency in the Tif1 Ruv- strains (65%) than in the Tif1 Ruv+ strains (25%) . A third group consisted of revertants exhibiting a RecA- phenotype at low temperature . Revertants with normal recombination ability and UV resistance, but with a thermosensitive defect in propagating lambda bio11 phage, were also isolated (group 4) . The alleles responsible for this property were cotransducible with the srl gene, suggesting that they are located at the recA locus . Other revertants, which might carry lex, LEXB, or zab mutations, were UV sensitive and were able to propagate lambda bio11 phage (group 5) . The sfi mutation, which suppresses filamentation in the Tif1 and UV-sensitive Lon- strains, does not restore UV resistance of the Ruv- mutant.

Am J Pathol, 1979 Apr, 95(1), 225 - 38
Kinetics of prostaglandin production in various inflammatory lesions, measured in draining lymph; Johnston MG et al.; Efferent lymph was collected over long periods via catheters surgically placed in popliteal and prefemoral lymph nodes of sheep . Prostaglandin (PG) E and F equivalents were measured with a radioimmunoassay . After stimulation with heat-killed Escherichia coli, PG levels rose dramatically in the efferent lymph but were undetectable in the contralateral control lymphatics or in the systemic circulation . When E coli were infused directly into a lymph node, the PG levels in the effluent lymph were inhibited with indomethacin . Carrageenan, delayed hypersensitivity, and lymphocyte transfer reactions were also studied . In the classic acute inflammations (caused by E coli and carrageenan) the PG levels rose early in the response (first 4 to 6 hours) compared with delayed production in the immune reactions . With PPD, PG levels peaked between 10 and 20 hours after injections, while PG rose 127 hours after allogeneic lymphocytes were injected . These results are discussed in relation to the role of PG in inflammation, and the use of the sheep lymphatic model in PG research is emphasized.

Radiology, 1979 Apr, 131(1), 27 - 9
Alteration of perirenal fat secondary to diffuse retroperitoneal infiltration; Fritzsche P et al.; Inflammatory effusions and diffuse neoplasia in the fatty retroperitoneal space, which can alter the perirenal fat, can be recognized radiographically because of density differences . The opacity of fluid and tumor accentuates the remaining fat which conforms to the renal contour . This perirenal fatty border appears as a lucent strip when the perirenal fat is not violated and as abnormal perirenal streakiness when the perirenal fat is infiltrated by fluid or tumor . Six cases are described.

Radiology, 1979 Apr, 131(1), 171 - 5
Computed tomographic evaluation of abdominal and pelvic abscesses; Callen PW; The CT characteristics of abdominal and pelvic abscesses in 29 patients were analyzed . The pathological development of an abscess as it relates to the CT appearance is discussed . Findings such as low-density areas within a soft-tissue mass or a definable wall or rim, while seen in abscesses, can be seen in other pathological entities as well, such as hematomas, noninfected inflammatory masses, and cystic or necrotic tumors . The most specific CT sign of an abscess was extraluminal gas, seen in 38% of patients.

Neurology, 1979 Apr, 29(4), 502 - 6
Humoral immunity before and after thymectomy in myasthenia gravis; Scadding GK et al.; Humoral immunity was studied in 10 patients with myasthenia gravis before thymectomy, in 15 different patients over 10 years after thymectomy, and in normal controls . Antibody titers to acetylcholine receptor were significantly (p less than 0.01) lower in the post-thymectomy group . However, other antibody titers to common viruses, and to Escherichia coli, and isohemagglutinins showed no significant change . Levels of IgM and IgE (with atopic subjects excluded) decreased following thymectomy (p less than 0.05) . Autoantibodies persisted, apart from those directed against the acetylcholine receptor . The absence of any significant changes in humoral immunity after thymectomy for myasthenia gravis suggests that there is no generalized loss of helper T-cell function.

Proc Natl Acad Sci U S A, 1979 Apr, 76(4), 1716 - 20
In vitro regulation of DNA-dependent synthesis of Escherichia coli ribosomal protein L12; Goldberg G et al.; The DNA of the transducing phage lambdarifd18 contains, among others, the genes for the ribosomal proteins L11, L1, L10, and L12 and the beta and beta' subunits of RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) . In a coupled in vitro protein-synthesis system, lambdarifd18 DNA directs the synthesis of about four to five molecules of L12 per molecule of L10 . This is consistent with the finding that there are four copies of L12 per ribosome . The ratio of L12/L10 was also examined from an EcoRI fragment of lambdarifd18 that contains the L10 gene and about 50% of the L12 gene . A significantly lower ratio of truncated L12/L10 was observed compared to the intact phage . The binding of RNA polymerase to various lambdarifd18 DNA restriction fragments was used to locate possible promoter sites . These binding experiments suggest that the beta and beta' subunits of RNA polymerase are cotranscribed with at least ribosomal protein L12 and, also, that there may be an additional promoter site for the L12 gene within the structural gene for L10.

Proc Natl Acad Sci U S A, 1979 Apr, 76(4), 1706 - 10
Regulation of the threonine operon: tandem threonine and isoleucine codons in the control region and translational control of transcription termination; Gardner JF; The DNA sequence of 178 base pairs preceding the first structural gene of the threonine operon of Escherichia coli has been determined . A region of perfect 2-fold rotational symmetry, involving 28 base pairs, precedes the first structural gene . The structural similarity of this sequence to known RNA polymerase termination sites suggests that this region is the termination site of the threonine operon leader RNA . Moreover a mutation (thr 79-20), which confers a depressed, constitutive phenotype, was sequenced and found to be a G.C insertion in the putative terminator . A potential coding region for a 21-amino acid leader peptide ends approximately 18 base pairs before the terminator . This peptide contains eight threonine and four isoleucine codons . Eleven of these codons are in tandem . A model for threonine operon regulation, involving alternative secondary RNA structures and translation of leader RNA, is discussed.

J Virol, 1979 Apr, 30(1), 108 - 15
RNase III cleaves vesicular stomatitis virus genome-length RNAs but fails to cleave viral mRNA's; Wertz GW et al.; The procaryotic RNA processing enzyme RNase III (endoribonuclease III {EC 3.1.4.24}) was used to probe vesicular stomatitis virus (VSV) RNAs for specific sites that could be recognized and cleaved . The effect of the enzyme on the RNAs was monitored by measuring their subsequent migration in denaturing agarose-urea gels . VSV virion RNA (negative strand; Mr, 4 X 10(6)) was cleaved by the enzyme to yield a set of discrete fragments which ranged on size from 3.5 X 10(6) to 0.2 X 10(6) daltons . The cleavage was a function of enzyme concentration, salt concentration, and time . A maximum of 20 to 22 fragments was generated under conditions of low enzyme concentration or short times of incubation . VSV genome-length intracellular RNA of both + and - polarity was also cleaved by RNase III . In contrast to the findings with virion-length RNA, however, the migration rates of VSV mRNA's purified by chromatography on polyuridylic acid-Sepharose were unaffected by treatment with RNase III . These results show that specific sites in the virion RNA and its full-length complement can be recognized by RNase III . Sites of this type are not present in the polyadenylic acid-containing mRNA, however.

J Clin Microbiol, 1979 Apr, 9(4), 525 - 9
Diarrhea and rotavirus infection associated with differing regimens for postnatal care of newborn babies; Bishop RF et al.; Surveillance of 2,041 babies born during 4 winter months in one obstetric hospital in Melbourne, Australia, showed that 215 developed acute diarrhea during the first 2 weeks of life . Babies requiring special care from birth had a high incidence of sporadic diarrhea (36%) . The incidence of diarrhea among healthy full-term babies was low if they were "rooming-in" with their mothers (2 to 3%) but high if they were housed in communal nurseries (29%) . The most important factor influencing incidence of diarrhea was proximity to other newborn babies and frequency of handling by related adults . Breast feeding did not always protect babies from diarrhea . Excretion of rotaviruses was temporally retlated to diarrhea in 61 to 76% of healthy full-term babies and in 44% of babies requiring special care . Other eneteric pathogens, including enerotoxigenic Escherichia coli, were occasionally isolated . Calculation of the ratios of symptomatic to asymptomatic infection suggests that babies requiring special care are much more likely to develop symptomatic illness after rotavious infection than are full-term babies.

Zentralbl Bakteriol {Orig A}, 1979 Apr, 243(2-3), 245 - 57
Detection of enterotoxigenicity and attachment factors in Escherichia coli strains of human, porcine and bovine origin; a comparative study; Guinee PA et al.; Porcine and bovine strains of E . coli suspected to be enterotoxigenic, were tested for heat-labile enterotoxin (LT) production by means of a test measuring the stimulation of the synthesis of 3151 cyclic adenosin monophosphate (cAMP test) and rounding mouse adrenal tumor Y1 cells (Y1 test), and for heat-stable enterotoxin (ST) production by means of the baby mouse test (BM test) . The test results were compared with those of the ligated gut test (LG test) using pig and calf intestine . One hundred and eleven strains of human origin were tested in the cAMP test, the Y1 test and the BM test . All strains were tested for the presence of the attachment factors K88, K99, P987 and CF10407 . Seventy-four of 117 bovine strains produced only ST and all 74 ST-producing strains possessed K99 antigen . None of the 43 nonenterotoxigenic strains possessed K99 . The presence of K99 antigen is therefore a reliable indicator of enterotoxigenicity in bovine strains . Porcine strains produced LT, ST or LT + ST . The K88 antigen was found in 52 out of 101 enterotoxigenic strains, K99 and P987 in 7 and 6 strains respectively and the latter 13 strains produced only ST . P987 was only detected after subculturing in liquid medium to enhance pilus formation . Eleven out of 111 strains of human origin stimulated cAMP synthesis but failed to round Y1 cells, whereas 4 known LT producers were positive in both tests . Attachment factors were found only in 2 of the latter 4 strains.

Proc Natl Acad Sci U S A, 1979 Apr, 76(4), 1702 - 5
An Escherichia coli mutant defective in single-strand binding protein is defective in DNA replication; Meyer RR et al.; An Escherichia coli mutant, temperature-sensitive for DNA synthesis in vivo and in vitro, is defective in single-strand binding protein (SSB; DNA-binding protein) . Conversion of phage G4 single strands to the duplex form is defective in crude enzyme fractions of the mutant and is complemented by pure wild-type SSB . Radioimmunoassays of mutant extracts show normal levels of material crossreacting with anti-SSB antibody . SSB purified to homogeneity from the mutant is active, with lower specific activity, in the reconstituted G4 replication assay at 30 degrees C, but virtually inactive at 42 degrees C . Surprisingly, the mutant protein, like the wild-type protein, survives heating at 100 degrees C . Thus, mutant SSB is structurally heat-resistant but is functionally thermosensitive in vitro and in vivo . Both the in vivo and in vitro defects are tightly linked in transductions by phage P1 . The mutation in the binding protein, designated ssb-1, is located between 90 and 91 min on the E . coli genetic map.

Nucleic Acids Res, 1979 Apr, 6(4), 1535 - 46
A possible mechanism responsible for the correction of transcription errors; Volloch VZ et al.; Nucleoside triphosphate phosphohydrolase (NTPase) activity was found in a preparation of E . Coli RNA polymerase . This enzymatic activity is capable of hydrolysing all four ribonucleoside triphosphates to the nucleoside diphosphates . However, during in vitro RNA synthesis directed by poly(dC) or poly(dT), only the non-complementary nucleoside triphosphate of the same heterocyclic class was hydrolysed . No incorporation of the non-complementary precursor into RNA could be detected in these experiments . When another RNA polymerase preparation, devoid of NTPase activity, was employed, there was no hydrolysis of any nucleoside triphosphate and significant incorporation of non-complemtary precursor into RNA was observed . These observations lead us to the conclusion that NTPase, acting in conjunction with RNA polymerase, has the function of correcting errors in transcription.

J Bacteriol, 1979 Apr, 138(1), 275 - 9
Catabolite and transient repression in Escherichia coli do not require enzyme I of the phosphotransferase system; Yang JK et al.; Transient and catabolite repression with changes in intracellular concentrations of cyclic adenosine 3',5-monophosphate is produced by glycerol and by glucose-6-phosphate in a strain with a partial deletion of the structural gene for enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system.

Biokhimiia, 1979 Apr, 44(4), 715 - 9
{Interrelationship between metabolic and genetic regulation of alkaline phosphatase and poly- and pyrophosphatases}; Maraeva OB et al.; The effects of orthophosphate and mutations in the regulatory genes of alkaline phosphatase on the activities of pyrophosphatase and polyphosphatase of E . coli were studied . It was shown that orthophosphate represses the synthesis of alkaline phosphatase as well as that of polyphosphatase without having any effect on pyrophosphatase . The genes phoR and phoS are involved in the formation of a repressory complex both for alkaline phosphatase and polyphosphatase . The gene phoT is probably involved in a partial repression of pyrophosphatase synthesis.

Proc Natl Acad Sci U S A, 1979 Apr, 76(4), 1638 - 42
Purified Escherichia coli recA protein catalyzes homologous pairing of superhelical DNA and single-stranded fragments; Shibata T et al.; Purified Escherichia coli recA protein catalyzed ATP-dependent pairing of superhelical DNA and homologous single-stranded fragments . The product of the reaction: (i) was retained by nitrocellulose filters in 1.5 M NaCl/0.15 M Na citrate at pH 7, (ii) was dissociated at pH 12.3 but was not dissociated by heating at 55 degrees C for 4 min or by treatment with 0.2% sodium dodecyl sulfate and proteinase K, (iii) contained covalently closed circular double-stranded DNA (form I DNA), (iv) contained single-stranded fragments associated with replicative form (RF) DNA, and (v) contained a significant fraction of D-loops as judged by electron microscopy . Linear and nicked circular double-stranded DNA did not substitute well for superhelical DNA; intact circular single-stranded DNA did not substitute well for single-stranded fragments . Homologous combinations of single-stranded fragments and superhelical DNA from phages phiX174 and fd reacted, whereas heterologous combinations did not . The reaction required high concentrations of protein and MgCl2 . The ATPase activity of purified recA protein was more than 98% dependent on the addition of single-stranded DNA . In 1 mM MgCl2, the ability of superhelical DNA to support the ATPase activity was two-thirds as good as that of single-stranded DNA.

J Bacteriol, 1979 Apr, 138(1), 87 - 91
Solubilization of adenosine triphosphatase from membranes of Escherichia coli: effect of p-aminobenzamidine; Downie JA et al.; The five subunits of the membrane-bound adenosine triphosphatase (F1) from Escherichia coli were identified on electrophoretograms of membranes which had been washed with a low-ionic-strength buffer containing the protease inhibitor p-aminobenzamidine . All of the subunits of the membrane-bound F1 appeared to have the same molecular weights and isoelectric points as those of the soluble F1, as judged by two-dimensional electrophoresis . p-Aminobenzamidine inhibited the solubilization of F1 rebound to F1-depleted membranes, and was found to inhibit the membrane-bound adenosine triphosphatase activity to a much greater extent than the solubilized activity . It is therefore unlikely that p-aminobenzamidine inhibits the solubilization of F1 by inhibiting a protease, as suggested previously by Cox et al . (G.B . Cox, J.A . Downie, D.R.H . Fayle, F . Gibson, and J . Radik, J . Bacteriol . 133:287--292, 1978).

Clin Exp Immunol, 1979 Apr, 36(1), 183 - 8
Human immunoglobulin D in colostrum, saliva and amniotic fluid; Sewell HF et al.; An antiserum raised to a partially purified preparation of secretory IgA isolated from human colostrum was shown to contain antibodies directed against human IgD . The inferred presence of IgD in the human colostrum was confirmed and also its association with antibody activity, as demonstrated by the presence of anti-E . coli antibodies . IgD was also shown to be present in whole saliva, parotid saliva and amniotic fluid, but could not be detected in jejunal juice.

Nucleic Acids Res, 1979 Apr, 6(4), 1669 - 82
Cooperative interactions among protein and RNA components of the 50S ribosomal subunit of Escherichia coli; Spierer P et al.; Copperative interactions among constituents of the 50S ribosomal subunit of Escherichia coli have been analyzed in order to elucidate its assembly and structural organization . Proteins L5 and L18 were shown to be necessary and sufficient to effect the association of the 5S and 23S RNAs into a quaternary complex that contains equimolar amounts of all four components . Measurement of diffusion constants by laser light scattering revealed that integration of the 5S RNA induced the 23S RNA to adopt a somewhat more open conformation . An investigation of relationships among proteins associated with the central and 3' portions of the 23S RNA demonstrated that attachment of L5, L10 + L11, and L28 depends upon the RNA-binding proteins L16, L2, and L1 + L3 + L6, respectively, and that L2 interacts with the central segment of the 23S RNA . These data, as well as the results of others, have been used to construct a scheme that depicts both direct and indirect associations of the 5S RNA, the 23S RNA, and over two-thirds of the subunit proteins . The 5' third of the 23S RNA apparently organizes the proteins required to nucleate essential reactions, whereas a region within 500 to 1500 bases of its 3' terminus is associated primarily with proteins involved in the major functional activities of the 50S ribosomal particle.

Zh Mikrobiol Epidemiol Immunobiol, 1979 Apr, (4), 43 - 6
{New data on the tachyphylactic properties of sodium nucleinate}; Zemskov VM et al.; Sodium nucleinate, when injected into mice in combination with killed E . coli or prodigiozan, caused a decrease in side effects produced by the vaccine or polysaccharide . The combined injection of sodium nucleinate and prodigiozan in doses, ineffective if introduced separately, was accompanied by the potentiation of their tachyphylactic action . The use of sodium nucleinate in combination with polyvinylprrolidone (hemodez) prolonged the tachyphylactic action of sodium nucleinate and increased its effectiveness . The proposed principle is supposed to be suitable for decreasing the reactogenicity of bacterial vaccines and polysaccharides.

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