Eur J Biochem, 1978 Sep 1, 89(2), 353 - 9 RNA-protein neighbourhoods of the ribosome obtained by crosslinking; Baumert HG et al.; It is possible to crosslink protein to nucleic acid with diepoxybutane which reacts mainly with the N-7 of guanine as well as the thiol and aminogroups in protein; the resulting crosslinked complexes are cleavable . When this reagent is applied to ribosomes, even under conditions that minimize the extent of reaction, at least half of the ribosomal proteins can be recovered crosslinked to one or other of the major ribosomal RNA species . In addition, one fourth of the proteins can be recovered crosslinked to the RNA of the heterologous ribosomal subunit . Some of the remaining proteins may also be crosslinkable to the RNA, but additional experiments are required to confirm this. Vopr Med Khim, 1978 Sep-Oct, 24(5), 694 - 9 {Fractionation and purification of DNA methylation enzymes from Escherichia coli CK cells on phosphocellulose P-11}; Aleksandrova SS et al.; Conditions for purification and fractionation of the methylases from E . coli CK cells using phosphocellulose P-11 were studied . A fraction, obtained after ammonium sulphate precipitation, was used as a starting preparation for column chromatography . Elution was carried out with linear gradient of NaCl concentration from O to 0.8 M . The methylase activity was found in effluent fractions, in rinsing solutions and in the gradient zone (G) . The fractions, unadsorbed on P-11, contained methylases of adenine and cytosine . In the experiments with the gradient elution the methylase activity was observed in fractions, corresponding to NaCl concentration of 0.12, 0.18, 0.26, 0.33 and 0.68 M . The specific activity was increased 10-4O-fold in the fraftions during the purification . The G1, G2, and G5 fractions contained only the adenine methylase and did not possess the cytosine-methylating activity . A mixture of enzymes, methylating adenine and cytosine, was found in G3 and G4 fractions . The data obtained suggest that several methylases are present in E . coli CK cells; these enzymes exist apparently as isoenzymes. Proc Natl Acad Sci U S A, 1978 Sep, 75(9), 4276 - 80 Nucleotide sequence of the attenuator region of the histidine operon of Escherichia coli K-12; Di Nocera PP et al.; The attenuator region of the histidine operon of Escherichia coli K-12 has a potential coding capacity for two peptides, one of 16 amino acids and another of 30 amino acids . This region is followed by a perfect palindrome of 14 base pairs separated by five nucleotides . A G+C-rich region precedes and follows a possible transcription termination sequence . These features are compatible with a model in which active translation of a leader mRNA interferes with transcription termination, thus causing derepression of the histidine operon . The sequence of the region coding for the hypothetical 16-amino acid peptide is of particular relevance because it indicates the site and a possible mechanism of action of histidyl-tRNAhis in regulating histidine gene expression . Seven contiguous histidine codons are present within this sequence: : formula: (see text) Proc Natl Acad Sci U S A, 1978 Sep, 75(9), 4247 - 51 Detection of unique tRNA species in tumor tissues by Escherichia coli guanine insertion enzyme; Okada N et al.; The guanine insertion enzyme from Escherichia coli catalyzes exchange of guanine located at the first position of the anticodon of tRNA with radioactive guanine (N . Okada and S . Nishimura, unpublished data) . tRNA isolated from various tumors, including slowly growing Morris hepatoma 7794A, incorporated considerable guanine with E . coli guanine insertion enzyme, whereas tRNA isolated from all normal tissues so far tested, except regenerating rat liver, incorporated scarcely any . In the rat ascites hepatoma AH7974, the guanine was mostly incorporated into minor isoaccepting species of tRNAAsp that contained the guanine residue instead of Q base in the first position of the anticodon . This is a sensitive and easy method for identifying unique tRNA species in tumor tissues. Nucleic Acids Res, 1978 Sep, 5(9), 3389 - 407 A photoaffinity labelling study of the messenger RNA-binding region of Escherichia coli ribosomes; Towbin H et al.; A photoaffinity labelling study of the messenger RNA-binding region of E . coli ribosomes has been made, using oligoadenylic acids as mRNA analogs . The oligonucleotides, of chain length 6 to 8 and thus several nucleotides longer than oligonucleotides previously employed for this purpose, carried a radioactive photolabile aromatic azide reagent bound covalently to the 3'-terminal ribose moiety . The synthesis of the reagent, p-azidobenzoyl-(3H)-glycylhydrazide, is described . The derivatized oligonucleotides were shown to be functional messengers . They stimulated the binding of the cognate aminoacyl-tRNA, lysyl-tRNA: their binding was reciprocally stimulated by lysyl-tRNA; and they competed with underivatized oligoadenylates for ribosomal binding sites . When the 70 S ribosomal binding complex was irradiated, the photolabile reagent reacted covalently with both RNA and proteins of the 30 S subunit and with tRNA, but not with the 50 S subunit . The 16 S RNA appeared to be labelled at more than one site . Of the proteins, S3 and S5 reacted with the reagent with high specificity; and the possibility was not eliminated that S4 may have been labelled to a minor degree . Functional studies in other laboratories have implicated S3 and S5 in the decoding process, but these proteins were not labelled by any of the previously reported mRNA affinity labelling analogs . The results reported here therefore indicate that S3 and S5 not only affect the decoding process, but are located in the mRNA-binding region of the ribosome, presumably to the 3' side of the decoding site. Nucleic Acids Res, 1978 Sep, 5(9), 3337 - 45 Physiochemical studies on interactions between DNA and RNA polymerase . Ultraviolet absorption measurements; Hsieh T et al.; The interaction between Escherichia coli RNA polymerase and a restriction fragment of coliphage T7 DNA containing four promoter sites for the coli enzyme has been studied by difference uv absorption spectroscopy in a low ionic strength buffer containing 10 mm MgCl2 and 50 mM KCl . The binding of the enzyme to the DNA is accompanied by a hyperchromic shift which shows a maximum around 260 nm, and increases with increasing temperature in the temperature range studied (4-40 degrees C) . Measurements were also carried out with whole T7 DNA and a restriction fragment containing no promoter site . A comparison of the results obtained with the various DNAs suggests that the binding of an RNA polymerase to a promoter site in the low ionic strength medium causes the disruption of a short segment of the DNA helix, of the order of ten pairs; the binding of an enzyme molecule to a promotor site appears to have a cooperative effect on the binding of the enzyme molecules to adjacent non-promoter sites with concomitant disruption of DNA base pairs. Nucleic Acids Res, 1978 Sep, 5(9), 3129 - 39 3'End labelling of RNA with 32P suitable for rapid gel sequencing; Winter G et al.; A new general method of labelling the 2',3'-diol end of RNA with 32P has been devised suitable for gel sequencing . Poly(A) polymerase (E . coli) is incubated with the RNA and limiting amounts of alpha-32P-ATP . The mono-addition product is then cleaved with periodate and beta-eliminated with aniline, leaving the RNA terminally labelled with 3' 32P-phosphate . When applied to a model compound, tRNAPhe from E . coli, over 28 residues could be read from the 3' end. J Virol, 1978 Sep, 27(3), 587 - 94 Early events in the replication of Mu prophage DNA; Waggoner BT et al.; To determine whether the early replication of Mu prophage DNA proceeds beyond the termini of the prophage into hose DNA, the amounts of both Mu DNA and the prophage-adjacent host DNA sequences were measured using a DNA-DNA annealing assay after induction of the Mu vegetative cycle . Whereas Mu-specific DNA synthesis began 6 to 8 min after induction, no amplification of the adjacent DNA sequences was observed . These data suggest that early Mu-induced DNA synthesis is constrained within the boundaries of the Mu prophage . Since prophage Mu DNA does not undergo a prophage lambda-like excision from its original site after induction (E . Ljungquist and A . I . Bukhari, Proc . Natl . Acad . Sci . U.S.A . 74:3143--3147, 1977), we propose the existence of a control mechanism which excludes prophage-adjacent sequences from the initial mu prophage replication . The frequencies of the Mu prophage-adjacent DNA sequences, relative to other Escherichia coli genes, were not observed to change after the onset of Mu-specific DNA replication . This suggests that these regions remain associated with the host chromosome and continue to be replicated by the chromosomal replication fork . Therefore, we conclude that both the Mu prophage and adjacent host sequences are maintained in the host chromosome, rather than on an extrachromosomal form containing Mu and host DNA. J Pharmacol Exp Ther, 1978 Sep, 206(3), 555 - 66 Endotoxic shock in the rabbit: the effects of prostaglandin and arachidonic acid administration; Flynn JT; A rabbit model was used to determine the effects of prostaglandins and arachidonic acid on cellular integrity and survival during endotoxic shock . Prostaglandins A2, E1 and F2alpha were infused intravenously at a rate of 1.0 microgram/kg/min for 105 min beginning 15 min after the administration of an LD60 dose of Escherichia coli endotoxin . While each of the prostaglandins tested significantly attenuated the accumulation of lactic acid dehydrogenase in the plasma of shocked animals, none were able to protect against the increase in the plasma activities of glutamic pyruvic transaminase or cathepsin D during the shock state . Prostaglandins A2, E1 and F2alpha did not significantly enhance the survival of the treated animals as compared to vehicle-treated controls . In contrast, arachidonic acid 15 microgram/kg/min i.v.) significantly prevented the accumulation of lactic acid dehydrogenase and glutamic-pyruvic transaminase activities in the plasma of shocked animals, and also significantly increased the number of survivors in this group 48 hours after the endotoxin administration . In summary, while the treatment of endotoxic rabbits with prostaglandins of the A, E and F series was of no survival value, the treatment of these animals with a substrate of the prostaglandin synthetase complex resulted in a dramatic increase in the survival rate . The mechanism of action of arachidonic acid in this regard is not clear. J Gen Physiol, 1978 Sep, 72(3), 283 - 95 Cation transport in Escherichia coli . IX . Regulation of K transport; Rhoads DB et al.; Kinetics of K exchange in the steady state and of net K uptake after osmotic upshock are reported for the four K transport systems of Escherichia coli: Kdp, TrkA, TrkD, and TrkF . Energy requirements for K exchange are reported for the Kdp and TrkA systems . For each system, kinetics of these two modes of K transport differ from those for net K uptake by K-depleted cells (Rhoads, D . B . F.B . Walters, and W . Epstein . 1976 . J . Gen . Physiol . 67:325-341) . The TrkA and TrkD systems are inhibited by high intracellular K, the TrkF system is stimulated by intracellular K, whereas the Kdp system is inhibited by external K when intracellular K is high . All four systems mediate net K uptake in response to osmotic upshock . Exchange by the Kdp and TrkA systems requires ATP but is not dependent on the protonmotive force . Energy requirements for the Kdp system are thus identical whether measured as net K uptake or K exchange, whereas the TrkA system differs in that it is dependent on the protonmotive force only for net K uptake . We suggest that in both the Kpd and TrkA systems formation of a phosphorylated intermediate is necessary for all K transport, although exchange transport may not consume energy . The protonmotive-force dependence of the TrkA system is interpreted as a regulatory influence, limiting this system to exchange except when the protonmotive force is high. J Infect Dis, 1978 Sep, 138(3), 326 - 32 Reovirus-like agent and enterotoxigenic Escherichia coli infections in pediatric diarrhea in the Philippines; Echeverria P et al.; Of 82 children hospitalized with diarrhea in the Philippines during January-June 1976, 14 (17%) had infections due to a reovirus-like agent as determined by detection of viral particles in stools by electron microscopy (12 {15%} of 82) and/or by a rise in titer of antibody to the serologically related Nebraska calf diarrhea virus (eight {20%} of 39) . Escherichia coli producing heat-labile enterotoxin were found in six (7%) of 82 ill children and two (4%) of 49 healthy control children, while E . coli producing heat-stable enterotoxin were isolated from three children with diarrhea and two without gastroenteritis . Thirty-eight percent of enterotoxigenic E . coli isolated from children with diarrhea, but only 6% of isolates from healthy control, were of serotypes similar to those of enterotoxigenic E . coli isolated in previous studies of these pathogens by other investigators in geographically diverse areas (serotypes O6:H16, O8:H9, and O78:H12) (P less than 0.05) . Eight (10%) of the children had infections with multiple enteric pathogens. J Am Vet Med Assoc, 1978 Sep 1, 173(5 Pt 2), 584 - 7 Comparative pathologic findings of Escherichia coli infection in birds; Cheville NF et al.; Of the 3 respiratory tract disease syndromes that occur in birds associated with Escherichia coli infection, acute colisepticemia, characterized by hyperemic and swollen viscera, tended to occur in young birds . Subacute fibrinopurulent serositis involving air sacs and pericardium was more common in older birds . Chronic granulomatous pneumonitis was not seen as flock epornitics but as chronic disease in birds dying in small numbers some time after one of the previously mentioned forms of the disease . Serotypes of 100 E coli isolates from turkey colibacillosis revealed most to be O1, O2, O36, or O78 . Virulence of the isolates, as conducted by IV inoculation of 6-week-old turkeys, showed O78 strains to be highly virulent and O36 strains to vary in virulence. J Am Vet Med Assoc, 1978 Sep 1, 173(5 Pt 2), 560 - 4 Importance of local immunity in enteric infection; Welliver RC et al.; Evidence suggests that protection against intestinal infections is mediated by an immune system that is unique in many ways . The predominant intestinal immunoglobulin differs in structure, function, and site of origin from those immunoglobulins found in the blood-stream . Cell-mediated intestinal immune responses also may arise separately from those of the rest of the body . Further studies are necessary to characterize the local immune response to many human bacterial, viral, and protozoal pathogens, and to clarify the mechanism of "homing" of immunocompetent cells to the large and small intestine, mammary glands, and other external mucosal surfaces. Genetics, 1978 Sep, 90(1), 19 - 35 Metabolism of ribosomal RNA in mutants of Escherichia coli doubly defective in ribonuclease III and the transcription termination factor rho; Apirion D et al.; To determine if proteins RNase III and rho, both of which can determine the 3' ends of RNA molecules, can complement each other, double mutants defective in these two factors were constructed . In all cases (four rho mutations tested) the double mutants were viable at lower temperatures, but were unable to grow at higher temperatures at which both of the parental strains grew . Genetic analyses suggested that the combinations of the rnc rho (RNase III-Rho-) mutations was necessary and probably sufficient to confer temperature sensitivity on carrier strains . Physiological studies showed that synthesis and maturation of rRNA, which is greatly affected by RNase III, as well as other RNAs, was indistinguishable in rnc rho strains as compared to rnc rho+ strains, thus suggesting that RNase III and rho do not complement one another in determining the 3' ends of RNA molecules . In rnc rho strains, however, the newly synthesized rRNA failed to accumulate . Thus, decay of rRNA could be the reason for the temperature sensitivity of the double mutant strains . These experiments suggest that RNase III and rho can both protect rRNA from degradation by cellular ribonucleases . They also point to the possibility that the nucleotide sequences involved in the determination of the 3' ends of RNA molecules by these two factors are not identical. Br J Surg, 1978 Sep, 65(9), 601 - 2 A comparison of noxythiolin and povidone-iodine in experimentally induced peritoneal infection in mice; Browne MK et al.; Noxythiolin (Noxyflex, Geistlich), given intraperitoneally as a 2.5 per cent solution, protected mice from the lethal effects of an intraperitoneal injection of Escherichia coli . Povidone-iodine (Pevidine, Berk), containing 0.075 per cent iodine, gave no protection. Biophys J, 1978 Sep, 23(3), 359 - 73 Conformational prediction and circular dichroism studies on ribosomal protein S4 from Escherichia coli; Allen SH et al.; The conformation of ribosomal protein S4 from Escherichia coli has been studied by circular dichroism (CD) and shown to possess unique conformation free in solution . The near ultraviolet spectrum suggests the existence of unique tertiary structural environment for the aromatic amino acid residues . The far ultraviolet spectrum gives an estimation of its secondary structure which is 32% alpha-helix and 14% beta-structure in reconstitution buffer at 25 degrees C . The conformation of S4 has been predicted from its sequence, and two models are presented here . An attempt is made to correlate these two molecular models with the available physicochemical data concerning the shape, conformation, and possible RNA binding site of protein S4. Am J Physiol, 1978 Sep, 235(3), E311 - 5 Effect of toxigenic Escherichia coli on myoelectric activity of small intestine; Burns TW et al.; When exposed to cholera toxin (CT), distal ileal loops of the rabbit small intestine showed an alteration in myoelectric activity . This alteration was defined as the migrating action potential complex (MAPC) . The purpose of this study was to determine, using myoelectric recording techniques, the effects of live toxigenic Escherichia coli (TEC) on motility . Live TEC, live nontoxigenic E . coli (NTEC), and culture filtrates of these organisms were studied . Live TEC and its filtrate induced MAPC activity similar to that of CT . Live TEC induced a mean of 3.8 MAPCs/h, significantly greater than induced by live NTEC . TEC filtrate induced a mean of 14.2 MAPCs/h, significantly greater than NTEC filtrate . Heating the TEC filtrate to 100 degrees C before use resulted in a significant decrease of MAPC activity . This experiment demonstrated that live TEC and its culture filtrate altered ileal myoelectric activity . The effect may have been mediated by a heat-labile enterotoxin . This study suggests that alterations in small intestinal motility may be important in the pathogenesis of TEC diarrhea. J Bacteriol, 1978 Sep, 135(3), 998 - 1007 Intraperiplasmic growth of Bdellovibrio bacteriovorus 109J: solubilization of Escherichia coli peptidoglycan; Thomashow MF et al.; During penetration of Bdellovibrio bacteriovorus into Escherchia coli, two enzymatic activities, a glycanase and a peptidase, rapidly solubilized some 10 to 15% of the E . coli peptidoglycan . The glycanase activity, which solubilizes peptidoglycan amino sugars, came to a sharp halt with completion of the penetration process . Peptidase activity, which cleaves diaminopimelic acid residues from the peptidoglycan, continued, but at a decreasing rate . By 90 min after bdellovibrio attack, some 30% of the initial E . coli diaminopimelic acid residues were solubilized and present in the culture fluid as free diaminopimelic acid . During bdellovibrio penetration some 25% of the lipopolysaccharide glucosamine was also solubilized by an as yet undefined enzymatic activity that yielded products having molecular weights below 2,000 . The solubilization of E . coli lipopolysaccharide glucosamine also terminated at completion of bdellovibrio penetration . At the end of bdellovibrio growth, a second period of rapid solubilization of bdelloplast peptidoglycan began which resulted in lysis of the bdelloplast and complete solubilization of the peptidoglycan amino sugars and diaminopimelic acid . The final lytic enzyme(s) was synthesized just before the time of lysis. J Bacteriol, 1978 Sep, 135(3), 993 - 7 Enzymes producing 4-thiouridine in Escherichia coli tRNA: approximate chromosomal locations of the genes and enzyme activities in a 4-thiouridine-deficient mutant; Lipsett MN; A previously described mutant of Escherichia coli which lacks 4-thiouridine in its tRNA was here shown to be deficient in factor A, one of the two proteins responsible for this thiolation of uridine . Addition of exogenous factor A restored the thiolating ability of extracts prepared from the mutant . The activities of the two thiolation proteins were governed by genes at two widely separated positions on the chromosome, as determined with F-prime merodiploids . The site governing factor A activity lay roughly in the region of the recently reported position of nuv, a gene controlling the production of 4-thiouridine in tRNA. J Bacteriol, 1978 Sep, 135(3), 935 - 42 Effect of tsl (thermosensitive suppressor of lex) mutation on postreplication repair in Escherichia coli K-12; Ganesan AK et al.; Cells of Escherichia coli K-12 carrying lexA or recA mutations are more sensitive to UV radiation than corresponding wild-type cells and are defective in postreplication repair . Supressor mutations (tsl) have been described previously which increase the UV resistance of lexA uvr+, lexA uvrA, and recAI uvr+ strains, but not the resistance of recA1 uvrA strains . We have studied the effect of the tsl-1 mutation on postreplication repair and find that the enhanced survival conferred by this mutation is correlated with an increased capacity for postreplication repair. J Bacteriol, 1978 Sep, 135(3), 766 - 74 Involvement of the relA gene product and feedback inhibition in the regulation of DUP-N-acetylmuramyl-peptide synthesis in Escherichia coli; Ishiguro EE et al.; The regulation of uridine diphosphate-N-acetylmuramyl-peptide (UDP-MurNAc-peptide) synthesis was studied by labeling Escherichia coli strains auxotrophic for lysine and diaminopimelate with {3H}diaminopimelate for 15 min under various conditions . The amounts of {3H}diaminopimelate incorporated into UDP-MurNAc-tripeptide and -pentapeptide by a stringent (rel+) strain were the same in the presence or absence of lysine . Chloramphenicol-treated rel+ cells showed a 2.8-fold increase in labeled UDP-MurNAc-pentapeptide . An isogenic relaxed (relA) strain deprived of lysine showed a 2.7-fold increase in UDP-MurNAc-pentapeptide . Thus, UDP-MurNAc-pentapeptide synthesis is regulated by the relA gene . D-Cycloserine treatment of rel+ and relA strains caused a depletion of intracellular UDP-MurNAc-pentapeptide . Labeled UDP-MurNAc-tripeptide accumulated in D-cycloserine-treated cells of the rel+ and relA strains, suggesting that UDP-MurNAc-pentapeptide is a feedback inhibitor of UDP-MurNAc-peptide synthesis . In lysine-deprived cells, D-cycloserine treatment caused 41- and 71-fold accumulations of UDP-MurNAc-tripeptide in rel+ and relA strains, respectively . A 124-fold increase in UDP-MurNAc-tripeptide occurred in lysine-deprived rel+ cells treated with both chloramphenicol and D-cycloserine . These results indicate that both the relA gene product and feedback inhibition are involved in regulating UDP-MurNAc-peptide synthesis during amino acid deprivation. J Bacteriol, 1978 Sep, 135(3), 760 - 5 Copy numbers of coexisting plasmids in Escherichia coli K-12; Barth PT et al.; A strain of Escherichia coli K-12 carrying eight compatible and distinguishable plasmids was constructed . The amounts of plasmid DNA (measured as supercoiled molecules) per chromosome in this strain was about equal to the sum of the plasmid DNAs, extracted under controlled conditions, from strains each carrying one of the eight plasmids . Analysis of these DNA preparations showed that each plasmid in the multiplasmid strain was present in the same proportion per chromosome as in the single-plasmid strains . Also the level of phenotypic expression of each plasmid in the multiplasmid strain was the same as in the single-plasmid strains . Each plasmid, therefore, appears to control its own copy number irrespective of the presence of other compatible plasmids. J Bacteriol, 1978 Sep, 135(3), 1165 - 6 Temperature-dependent variation in the extent of methylation of ribosomal proteins L7 and L12 in Escherichia coli; Chang FN; The amount of epsilon-N-monomethyllysine in ribosomal proteins L7 and L12 in Escherichia coli is dependent upon the cell growth temperature . At 37 degrees C or above, very small amounts were detected . Dramatic increase in the content of epsilon-N-monomethyllysine in these proteins was observed when the growth temperature was lowered. J Bacteriol, 1978 Sep, 135(3), 1162 - 4 Control of Escherichia coli growth by CO2; Repaske R et al.; Escherichia coli B dependence on CO2 for growth was demonstrated . At suboptimal CO2 concentrations the rate of growth was controlled by CO2 concentration. J Bacteriol, 1978 Sep, 135(3), 1154 - 5 A single mutation affects L-serine deaminase, L-leucyl-, L-phenylalanyl-tRNA protein transferase, and proline oxidase activity in Escherichia coli K-12; Tam A et al.; A mutation at a single locus, wyb, results in several phenotypic changes in Escherichia coli K-12 . The Wyb- phenotype includes: (i) an increase in L-serine deaminase activity, together with a loss of inducibility by L-leucine; (ii) an absence of L-leucyl-, L-phenylalanyl-tRNA protein transferase activity; (iii) inducibility of proline oxidase by proline; and (iv) a loss of ability to use maltose as a carbon and energy source. J Bacteriol, 1978 Sep, 135(3), 1118 - 29 Identification of three genes controlling production of new outer membrane pore proteins in Escherichia coli K-12; Pugsley AP et al.; Escherichia coli K-12 strains carrying mutations in the ompB gene or double mutations in the tolF and par genes lack the major outer membrane proteins 1a and 1b . These strains are deficient in the transport of small hydrophylic compounds and are multiply colicin resistant . When revertants of these strains were sought, a number of extragenic pseudorevertants were obtained which produced new outer membrane proteins . These new proteins could be divided into three classes by differences in electrophoretic mobility on polyacrylamide gels, by differing specificities for transport of small molecules, and by the identification of three different genetic loci for genes controlling their production . These genetic loci are designated as nmpA (at approximately 82.5 min on the E . coli K-12 genetic map), nmpB (8.6 min), and nmpC (12 min) . The new proteins produced in strains carrying nmpA, nmpB, or nmpC mutations did not cross-react with antiserum against a mixture of proteins 1a and 1b, or with antiserum against phage-directed protein 2 . Production of the new membrane proteins restored sensitivity to some of the colicins. J Bacteriol, 1978 Sep, 135(3), 1080 - 90 Porin activity in the osmotic shock fluid of Escherichia coli; Benz R et al.; Osmotic shock fluid of Escherichia coli exhibited pore-forming activity . This activity could be followed by an in vitro assay based on the conductivity increase for ions due to the presence of pores in black lipid membranes . The histogram (the distribution of conductivity increments in a single pore experiment) obtained with osmotic shock fluid from E . coli was identical to the histogram obtained by detergent-solubilized porin isolated from the outer membrane . The osmotic shock fluid from porin-negative mutants also exhibited pore activity, although the histogram and ion specificity were different from those of porin . Antibodies raised against detergent-solubilized porin were able to form precipitin lines by the Ouchterlony immunodiffusion technique when shock fluids, but not detergent-solubilized porin, were used . These antibodies prevented the formation of pores when shock fluids contained porin but not when shock fluids obtained from porin-negative mutants were used . Macroscopic membrane conductivity of shock fluids due to porin exhibited a concentration dependence, in contrast to detergent-solubilized porin . These results indicate that the hydrodynamic properties of periplasmic or "soluble" porin are different from those of the detergent-solubilized porin of the outer membrane . Periplasmic porin comprises about 0.7% of total protein in the osmotic shock fluid. J Bacteriol, 1978 Sep, 135(3), 1070 - 9 Transconjugant analysis: limitations on the use of sequence-specific endonucleases for plasmid identification; Causey SC et al.; We used the sequence-specific endonucleases EcoRI, SmaI, BamHI, HsuI, and HaeIII as identification tools in following the conjugal transfer of the well-studied R plasmids Sa, R388, RP4, and R6K . Transfers were both intergeneric and intrageneric . Plasmid fingerprints were generated from both single- and combination-enzyme digests . The Sa transconjugants yielded plasmids showing consistent fingerprints for each of the respective endonucleases used, whereas the three other R-plasmid transconjugants showed fingerprint changes. J Bacteriol, 1978 Sep, 135(3), 1053 - 61 Cell-cell interactions in conjugating Escherichia coli: role of F pili and fate of mating aggregates; Achtman M et al.; Bacterial conjugation between Escherichia coli cells was investigated by a combination of physical and genetic techniques, using Hfr, F', or R+ donors and F- recipients . DNA transfer occurred in mating aggregates of up to 50 cells . Multiple interactions between donor and recipient cells occurred, and both F- pilus connections and wall-to-wall contacts were detectable . The detectable F- pilus contacts could be destroyed without either disrupting the mating aggregates or preventing DNA transfer . Hfr X F- mating aggregates did not disaggregate even though recombinant frequencies were inversely proportional to the distance from the origin of DNA transfer . F' or R+ donors formed mating aggregates with F- cells which disaggregated soon after transfer of the autonomous sex factor DNA. J Bacteriol, 1978 Sep, 135(3), 1024 - 31 Reconstitution of an ordered structure from major outer membrane constituents and the lipoprotein-bearing peptidoglycan sacculus of Escherichia coli; Yamada H et al.; An ordered hexagonal lattice structure with a lattice constant of about 7 nm was reconstituted on the entire surface of the lipoprotein-bearing peptidoglycan from outer membrane protein O-8 and lipopolysaccharide . The lattice structure resembled that observed in the cell envelope which had been treated with sodium dodecyl sulfate (Steven et al., J . Cell Biol . 72:292-301, 1977) . The omission of either O-8 or lipopolysaccharide resulted in the failure of formation of the lattice structure . No ordered lattice was formed on the peptidoglycan lacking the bound form of the lipoprotein . In the absence of the lipoprotein-bearing peptidoglycan, O-8 and lipopolysaccharide assembled into vesicles with an ordered hexagonal lattice, the lattice constant of which was also about 7 nm . A preliminary experiment indicated that protein O-9 gave the same result as did O-8 . These results strongly indicate that O-8 and/or O-9 and lipopolysaccharide provide the ordered framework of the outer membrane and that the bound form of the lipoprotein plays a role in the holding of the framework on the peptidoglycan layer. J Bacteriol, 1978 Sep, 135(3), 1015 - 23 Intraperiplasmic growth of Bdellovibrio bacteriovorus 109J: attachment of long-chain fatty acids to escherichia coli peptidoglycan; Thomashow MF et al.; During the initial stages of intraperiplasmic growth of Bdellovibrio bacteriovorus on Escherichia coli, the peptidoglycan of the E . coli becomes acylated with long-chain fatty acids, primarily palmitic acid (60%) and oleic acid (20%) . The attachment of the fatty acids to the peptidoglycan involves a carboxylic-ester bond, i.e., they were removed by treatment with alkaline hydroxylamine . Their linkage to the peptidoglycan does not involve a protein molecule . When the bdelloplast peptidoglycan was digested with lysozyme, the fatty acid-containing split products behaved as lipopeptidoglycan, i.e., they were extracted into the organic phase of 1-butanol:acetic acid:water (4:15) two-phase system; all of the lysozyme split products generated from normal E . coli peptidoglycan were extracted into the water phase . It is suggested that the function of the acylation reaction is to help stabilize the bdelloplast outer membrane against osmotic forces . In addition, a model is presented to explain how a bdellovibrio penetrates, stabilizes, and lyses a substrate cell. J Bacteriol, 1978 Sep, 135(3), 1008 - 14 Intraperiplasmic growth of Bdellovibrio bacteriovorus 109J: N-deacetylation of Escherichia coli peptidoglycan amino sugars; Thomashow MF et al.; During intraperiplasmic growth of Bdellovibrio bacteriovorus on Escherichia coli, the substrate cell peptidoglycan is extensively modified as it is converted to bdelloplast peptidoglycan . The initially lysozyme-sensitive peptidoglycan of E . coli was rapidly converted to a lysozyme-resistant form . The conversion was due to the N-deacetylation of a large portion of the peptidoglycan amino sugars . Chemically acetylating the isolated peptidoglycan restored its sensitivity to lysozyme digestion . However, approximately half of the products of lysozyme digestion exhibited hydrophobic interactions that were shown not to be due to the presence of protein . This suggests that a molecule capable of hydrophobic interactions, other than protein, becomes linked to the bdelloplast peptidoglycan . The data also suggest that much of the Braun lipoprotein is removed from the E . coli peptidoglycan early during bdellovibrio development. Proc Natl Acad Sci U S A, 1978 Sep, 75(9), 4199 - 203 Enzymatic breakage of the cohesive end site of phage lambda DNA: terminase (ter) reaction; Becker A et al.; An in vitro system is described for measuring the endonucleolytic conversion of the phage lambda cohesive end sites in concatemeric DNA to the cohesive chromosomal ends of the mature molecule . This enzymic process, known as the ter reaction, is catalyzed by purified lambda A gene protein . The reaction is markedly stimulated by ATP, Mg2+, spermidine, and one or more uncharacterized factors present in extracts of uninfected Escherichia coli cells . In vitro, the ter reaction proceeds in the absence of proheads under conditions that are similar to those previously found necessary for the formation of a DNA-A gene protein intermediate for the initiation of packaging. Can J Biochem, 1978 Sep, 56(9), 849 - 52 Determination of the rates of synthesis and degradation of adenosine 3',5'-cyclic monophosphate in Escherichia coli CRP- and CRP+ strains; Fraser AD et al.; We have developed a method for estimating the rates of synthesis and degradation of adenosine 3',5'-cyclic monophosphate (cAMP) in Escherichia coli during balanced growth . Applying this method, we have found that an E . coli CRP- mutant 5333 (deficient for cAMP receptor protein) synthesizes cAMP about 25 times faster than does its CRP+ parent 1100 . This accounts for the abnormally high intracellular and extracellular cAMP accumulation in 5333. Proc Natl Acad Sci U S A, 1978 Sep, 75(9), 4180 - 3 Mechanism of the in vitro breakdown of guanosine 5'-diphosphate 3'-diphosphate in Escherichia coli; Heinemeyer EA et al.; Degradation of guanosine tetraphosphate (ppGpp) involves an enzyme associated with the ribosomal fraction from spoT+ strains of Escherichia coli . Double-label experiments with pp{3h}gpp, pp{3H}Gpp, or pp{3H}Gpp as substrate strongly suggest that ppG is the degradation product and that the enzyme releases two phosphates coordinately from the 3' position of ppGpp . In the absence of pppA this reaction proceeds in an uncoupled fashion, yielding ppG and PPi, but in the presence of pppA the decay is considerably enhanced and a pppA-ppi exchange reaction occurs in which the 3'-pyrophosphoryl group of ppGpp displaces the gamma and beta phosphates of pppA . Sodium PPi at 4 m7 inhibits decay of ppGpp regardless of whether or not pppA is present. Proc Natl Acad Sci U S A, 1978 Sep, 75(9), 4102 - 6 Nucleotide sequences related to the transforming gene of avian sarcoma virus are present in DNA of uninfected vertebrates; Spector DH et al.; We have detected nucleotide sequences related to the transforming gene of avian sarcoma vius (ASV) in the DNA of uninfected vertebrates . Purified radioactive DNA (cDNAsarc) complementary to most of all of the gene (src) required for transformation of fibroblasts by ASV was annealed with DNA from a variety of normal species . Under conditions that facilitate pairing of partially matched nucleotide sequences (1.5 M NaCl, 59 degrees), cDNAsarc formed duplexes with chicken, human, calf, mouse, and salmon DNA but not with DNA from sea urchin, Drosophila, or Escherichia coli . The kinetics of duplex formation indicated that cDNAsarc was reacting with nucleotide sequences present in a single copy or at most a few copies per cell . In contrast to the preceding findings, nucleotide sequences complementary to the remainder of the ASV genome were observed only in chicken DNA . Thermal denaturation studies of the duplexes formed with cDNAsarc indicated a high degree of conservation of the nucleotide sequences related to src in vertebrate DNAs; the reductions in melting temperature suggested about 3--4% mismatching of cDNAsarc with chicken DNA and 8--10% mismatching of cDNAsarc with the other vertebrate DNAs. J Virol, 1978 Sep, 27(3), 784 - 90 In vitro synthesis of double-stranded DNA from the Kilham rat virus single-stranded DNA genome; Salzman LA et al.; Double-stranded, full-length linear DNA was synthesized in vitro by using single-stranded linear DNA as a self-priming template from the parvovirus Kilham rat virus and Escherichia coli DNA polymerase "large fragment" as the polymerizing enzyme . To ascertain the order of the synthesis of the cleavage fragments and to assess the accuracy of the in vitro synthesis, restriction endonuclease cleavage sites with known recognition sequences were mapped on the DNA . Comparing the cleavage pattern of the synthesized DNA with that of double-stranded viral DNA isolated from infected cells confirms that the in vitro synthesis produces a faithful copy of the viral single-stranded genome . Electron micrographs of the in vitro product reveal it to be a double-stranded linear molecule. J Am Vet Med Assoc, 1978 Sep 1, 173(5 Pt 2), 577 - 83 Pathogenic relationships of rotavirus, Escherichia coli, and other agents in mixed infections in calves; Moon HW et al.; Infection with agents interpreted as causing or contributing to diarrhea (rotavirus, coronavirus, enterotoxigenic Escherichia coli, and cryptosporidia) were demonstrated in 24 of 32 newborn calves that had naturally occurring diarrheal disease . The calves were from 12 herds in Iowa . Infections as well as enteric lesions and hypoglobulinemia occurred more frequently among diarrheal calves than among nondiarrheal calves from these same herds . In most calves, infections were mixed; ie, both viruses, one or both viruses plus cryptosporidia, or rotavirus plus enterotoxigenic E coli. J Bacteriol, 1978 Sep, 135(3), 1167 - 70 Effects of antipain (a protease inhibitor) on respiration, viability, and excision of pyrimidine dimers in UV-irradiated Escherichia coli cells; Swenson PA et al.; The protease inhibitor antipain increases the effectiveness of UV irradiation on cessation of respiration and cell killing in Escherichia coli B/r cultures without affecting excision of pyrimidine dimers . The actions are similar to those caused by cyclic AMP in irradiated cultures. Z Naturforsch {C}, 1978 Sep-Oct, 33(9-10), 804 - 5 Host factors involved in the growth of microvirid phage alpha 3; Taketo A; Host factors involed in the growth of microvirid phage alpha3 were determined using various replication mutants of Escherichia coli . The viral multiplication was dependent on functional products of dnaE, dnaF(NRDA), DNAG, and dnaZ genes . Host functions directed by dnaA, so-alled dnaH, dnaI, and dnaP genes were dispensable for the viral growth . In contrast with phiZ174 and G4, alpha3 would grow sufficiently In dnaB and dnaC(D) mutants . The viral growth was not significantly affected by host polAts, seg, and groPC mutations. J Environ Pathol Toxicol, 1978 Sep-Oct, 1(1), 113 - 23 Control of intestinal flora in animals and humans: implications for toxicology and health; Thompson GE; The importance of the intestinal flora in disease management is discussed, and apparent relationships noted in experimental and clinical reports are reviewed . It is suggested that investigation of the influence of the intestinal flora upon body organs and systems would productively lay the groundwork for abetter understanding of certain synergistic mechanisms. Invest Urol, 1978 Sep, 16(2), 148 - 53 Chronic pyelonephritis . An electron microscopic study in nonhuman primates; Smith TW Jr et al.; The rhesus monkey (Macaca mulatta) proved to be a successful model for the ultrastructural study of ascending nonobstructive pyelonephritis . The most severe kidney damage occurred where the inflammatory response was greatest, and these areas overlaid a dilated or clubbed calyx . The most prominent ultrastructural changes were in the renal tubular cells that showed swollen mitochondria with ruptured inner membranes, dilated endoplasmic reticulum, and flocculent and irregular basal laminae . No recognizable bacterial structures were seen. Invest Urol, 1978 Sep, 16(2), 128 - 30 Experimental pyelonephritis in the monkey . VI . Infection of infants versus adults; Roberts JA et al.; Pyelonephritis followed ureteral inoculation of bacteria in both infant and adult monkeys . Because of the frequency of reflux in infants this was done by bladder inoculation, although ureteral inoculation was necessary in adults . The longer duration of bacteriuria in infants may be attributable to a relative immunodeficiency. Eur J Biochem, 1978 Sep 1, 89(2), 483 - 90 Involvement of the Escherichia coli phosphoenolpyruvate-dependent phosphotransferase system in regulation of transcription of catabolic genes; Bolshakova TN et al.; Synthesis of catabolite-sensitive enzymes is repressed in mutants defective in the general proteins (enzyme I and HPr) of the Escherichia coli phosphoenolpyruvate-dependent phosphotransferase system (ptsI and ptsH mutations) . To elucidate the mechanism of this phenomenon we constructed isogenic strains carrying pts mutations as well as different lesions of regulation of the lac operon or mutations affecting adenylate cyclase activity (cya mutation) and synthesis of cyclic AMP-receptor protein (crp mutation) Measurements of the differential rate of beta-galactosidase synthesis in these strains showed that the repressive effect of pts mutations was revealed in lac+, lacI, lacOc and cya bacteria, but it was lost in lacP and crp strains . It was concluded that mutational damage to the general components of the phosphoenolpyruvate-dependent phosphotransferase system diminishes activity of the lac promoter . The results obtained led to the conclusion that pts gene products (apparently phospho approximately HPr) are necessary for the initiation of transcription of catabolite-sensitive operons in E . coli. Ann Clin Lab Sci, 1978 Sep-Oct, 8(5), 353 - 65 Surface immunoglobulin in immunoproliferative diseases; Teodorescu M et al.; Malignant B cells may originate from any of the stages of differentiation of B cells, primarily from IgM bearing B cells . The malignant B cells maintain a limited potential for differentiation . In addition to surface immunoglobulins, various markers may be present on the B cell surface; when surface Ig cannot be identified, these markers are used to identify B cells . However, for practical purposes, the detection of surface Ig is most important in the identification of B cells in immunoproliferative diseases, particularly when the malignant cell population displays only one immunoglobulin light chain . The procedures used so far to detect surface Ig have several drawbacks regarding their sensitivity or their specificity . The advantages of new procedures which involve the identification of B cells by their natural binding of B . melitensis or the detection of surface Ig by antibody-coated E . coli are presented . Detection of changes in the percentage of B lymphocytes and in the ratio of kappa- to gamma-bearing B cells in blood smears or in lymphocyte suspensions may be helpful in the early diagnosis of immunoproliferative diseases. J Bacteriol, 1978 Sep, 135(3), 876 - 82 Transport by the lactose permease of Escherichia coli as the basis of lactose killing; Dykhuizen D et al.; Lactose killing is a peculiar phenomenon in which 80 to 98% of the Escherichia coli cells taken from a lactose-limited chemostat die when plated on standard lactose minimal media . This unique form of suicide is caused by the action of the lactose permease . Since uptake of either lactose or galactose by the lactose permease caused death, the action of rapid transport across the membrane must be the cause of the phenomenon . Alternative causes of lactose killing, such as accumulation of toxic metabolic intermediates or action of the beta-galactosidase, have been eliminated . It is proposed that rapid uptake of sugars by the lactose permease disrupts membrane function, perhaps causing collapse of the membrane potential. J Bacteriol, 1978 Sep, 135(3), 775 - 81 In vivo titration of araC protein; Haggerty DM et al.; The requirement for araC protein in the induction of the araBAD operon was investigated . Strains of Escherichia coli carrying an araC(Am) mutation and temperature-sensitive amber suppressors were used to vary the intracellular level of araC protein . The levels of araC protein studied ranged from 0.007 to 1.8 times the normal amount . The results indicate that the normal level of araC protein is just sufficient to provide maximal expression of the araBAD operon. Clin Chem, 1978 Sep, 24(9), 1590 - 4 Double-antibody enzyme immunoassay for nortriptyline; Al-Bassam MN et al.; beta-D-Galactosidase (EC 3.2.1.23) from Escherichia coli was conjugated to desmethylnortriptyline by means of a bifunctional cross-linking reagent, dimethyl adipimidate, and used in a double-antibody immunoassay for nortriptyline . Eighty percent of the enzyme activity was retained after conjugation; 75% of the enzyme was conjugated to desmethylnortriptyline . In the final immunoassay the enzyme activity of the bound fraction was determined with o-nitrophenyl-beta-D-galactopyranoside as substrate . The sensitivity, precision, and simplicity of the enzyme immunoassay compared favorable with that of a published radioimmunoassay method . Results for nortriptyline in plasma samples correlated well with those determined by either radioimmunoassay or gas-chromatography. Clin Chem, 1978 Sep, 24(9), 1452 - 7 Improved enzymatic assay of chloramphenicol; Smith AL et al.; We partly purified R-factor-encoded chloramphenicol acetyltransferase (EC 2.3.1.28) from a highly choloramphenicol-resistant mutant derived from Escherichia coli W677/R5 . The preparation permitted rapid quanitation of chloramphenicol by use of {14C}acetylcoenzyme A, removing the diacetylated product by selective adsorption onto micropore filters . Succinyl and glucuronyl 3-hydroxyl esters of chloramphenicol were not active as substrates for the preparation, nor were they active as inhibitors . The enzyme was free of chloramphenicol reductase activity, and utilizes other biologically active chloramphenicol analogs . Other antibiotics, at concentrations commonly found in human sera, and blood preservatives, at concentrations 10-fold that found in blood-collection tubes, did not interfere with the enzymic quantitation of chloramphenicol . We conclude that this enzyme preparation permits rapid clinical quantitation of chloramphenicol. Mol Biol (Mosk), 1978 Sep-Oct, 12(5), 1163 - 71 {Selective binding of tRNA by RNA dependent DNA-polymerase from Escherichia coli}; Lushnikova TP et al.; Highly purified RNA dependent DNA-polymerase was isolated recently from E . coli by Romashchenko et al . {8} . The present data demonstrate that total E . coli tRNA inhibits poly(dT) synthesis on poly (A): oligo (dT) catalyzed by the enzyme when the enzyme:tRNA ratio is about 1 : 80--100 . The inhibition results from the binding of certain tRNA's by the enzyme . The enzyme tRNA complex was separated from the unbound tRNA's by gel-filtration of Sephadex G-100 . The tRNA's extracted from the complex are able to inhibit completely poly(A):oligo(dT) templated synthesis of poly(dT) under the enzyme:tRNA ratio about 1 : 2--3 . Aminoacylation of tRNA separated from the enzyme complex has shown that E . coli RNA dependent DNA-polymerase selectively binds tRNAThr and to a lesser extent tRNATyr and tRNALys . It is suggested that the enzyme bound tRNA's carry out the functions of natural primers which compete with oligo(dT) for the enzyme responsible for the primer binding. J Med Chem, 1978 Sep, 21(9), 877 - 82 Stereoelectronic factors in the binding of substrate analogues and inhibitors to purine nucleoside phosphorylase isolated from human erythrocytes; Jordan F et al.; Several aspects of the stereoelectronic requirements of substrates of human erythrocytic purine nucleoside phosphorylase (E.C . 2.4.2.1) were elucidated providing the following information: (a) the N1 position cannot have a nonhydrogen substituent; (b) the 5'-OH group must be present for catalytic activity to be exhibited but is not an essential functional group for inhibitory action to be observed; (c) on the C8 position groups larger than -NH2 or -Br cannot be accommodated; (d) the syn-glycosyl conformation (i.e., 8-bromoguanosine) is acceptable but may not be an absolute requirement for phosphorolysis; (e) among nucleic base inhibitors methylation at N3, N7, or N9 vastly decreases the inhibitory properties as does a nitrogen in lieu of C-H in the 8 position . The results clearly indicate that this enzyme differs in its stereoelectronic requirements from the Escherichia coli enzyme. Acta Virol, 1978 Sep, 22(5), 353 - 61 Base pairing mRNA-rRNA . The arrangement of nucleotides in the message for coat protein of phage MS 2; Sedlacek J et al.; The relation of the nucleotide sequences in the message and of the short nucleotide sequence in 3' terminus of 16 S ribosomal RNA was found to differ from statistical expectancy . The observation is interpreted in terms of both the ribosomal interactions and the molecular evolution. J Biol Chem, 1978 Aug 25, 253(16), 5847 - 51 Escherichia coli dnaB protein . Affinity chromatography on immobilized nucleotides; Lanka E et al.; The purification of the Escherichia coli dnaB protein by affinity chromatography on nucleotides bound to agarose is described . The dnaB protein, which contains an associated ribonucleoside triphosphatase activity (Wickner, S., Wright, M., and Hurwitz, J . (1974) Proc . Natl . Acad . Sci . U . S . A . 71, 783-787) binds to immobilized ATP, ADP, and UDP, but not to AMP . The type of linkage of ATP to agarose influences the adsorption, elution, and purification of the enzyme . Optimal purification is achieved using ATP bound to agarose via its oxidized ribose moiety . By this means, the dnaB protein can be obtained at least 95% electrophoretically pure after only three purification steps . The enzyme can be eluted from immobilized nucleoside-5'-di- and -triphosphates by ATP, ADP, and pyrophosphate, but not by AMP or orthophosphate . ADP and pyrophosphate, as well as the substrate ATP in high concentration are at the same time inhibitors of the ribonucleoside triphosphatase . The dnaB complementing and ribonucleoside triphosphatase activities could not be separated from each other by affinity chromatography, supporting the finding of others that they both reside on the same protein complex, namely a dnaB multimer . The results indicate that the dnaB protein binds to immobilized nucleotides by means of its ribonucleoside triphosphatase, and that at least the pyrophosphate moiety is essential for adsorption as well as elution of the enzyme. J Biol Chem, 1978 Aug 25, 253(16), 5579 - 84 Synthesis and degradation of poly(A) in permeable cells of Escherichia coli; Deutscher MP; Poly(A) synthesis and degradation have been examined in Escherichia coli cells made permeable to nucleotides by treatment with toluene . Although newly synthesized poly(A) is normally rapidly degraded in this system, extraction of the soluble portion of the cell effectively eliminates this process without affecting poly(A) synthesis . Poly(A) synthesis in this system displays many properties associated with poly(A) synthesis by purified poly(A) polymerase in vitro including a lag in polymerization, stimulation by increased ionic strength, and a low Mg2+ optimum . As with the purified enzyme, this system uses both ADP and ATP as substrates, requires conversion of ATP to ADP, and is strongly inhibited by dADP, orthophosphate, and pyrophosphate . In contrast to the purified poly(A) polymerase, the permeable cell system displays some properties suggestive of in vivo poly(A) metabolism . Thus, the permeable cells require an endogenous RNA primer for activity, the poly(A) product remains with the cells, and the reaction is greatly stimulated by polyamines . This system should prove extremely useful for studies of poly(A) metabolism in E . coli . A surprising feature of these studies was the finding that mutant strains deficient in polynucleotide phosphorylase were unable to synthesize poly(A) . The possible roles of polynucleotide phosphorylase and poly(A) in E . coli are discussed. J Biol Chem, 1978 Aug 25, 253(16), 5568 - 72 In vivo distribution of phosphothioredoxin and thioredoxin in Escherichia coli; Conley RR et al.; The phosphorylation state of thioredoxin was compared in intact cells and in crude extracts . In crude extracts, the extent of phosphorylation was 0.70 to 0.80 mol of phosphate per mol of thioredoxin, with approximately equal amounts of thioredoxin phosphorylated either on cysteinyl32 (formula: see text) or on cysteinyl35 (formula: see text) . By comparison, the extent of thioredoxin phosphorylation in intact cells was nearly 1.0 with phosphate present almost exclusively on cysteine32 . Nonphosphorylated thioredoxin was present as the reduced thiol form (formula: see text) . These findings imply that (formula: see text) is the relevant in vivo species and that a mechanism is operative in crude extracts for transfer of phosphate from cysteine32 to cysteine35. J Biol Chem, 1978 Aug 25, 253(16), 5594 - 9 Characterization of an endoribonuclease, RNase N, from Escherichia coli; Misra TK et al.; The properties of the enzyme ribonuclease N were investigated . By comparing the distribution in the cell of RNase N with the bonafide intracellular beta-galactosidase, and the periplasmic alkaline phosphatase enzymes, we showed that RNase N is an intracellular enzyme . Since previous studies suggested that it is an endoribonuclease, it was compared to RNase III, the only other known intracellular endoribonuclease in Escherichia coli . Using homopolymers and co-polymers we found that, while RNase III could digest double-stranded RNA only, RNase N digested single-stranded and double-stranded RNA with similar efficiency . Furthermore, all RNAs used, natural as well as synthetic, were substrates for the enzyme . Using 5 S rRNA as a substrate it was confirmed that the enzyme is an endonuclease . The final products of the reaction of this enzyme are 5'-mononucleotides . The molecular weight of the enzyme is about 120,000 and it seems to contain two subunits which are similar in size . These properties thus differentiate this enzyme from all other known ribonucleases in E . coli. Nature, 1978 Aug 24, 274(5673), 775 - 80 Molecular basis of base substitution hotspots in Escherichia coli; Coulondre C et al.; In the lacI gene of Escherichia coli spontaneous base substituion hotspots occur at 5-methylcytosine residues . The hotspots disappear when the respective cytosines are not methylated . We suggest that the hotspots may result from the spontaneous deamination of 5-methylcytosine to thymine, which is not excised by the enzyme DNA-uracil glycosidase. Nature, 1978 Aug 24, 274(5673), 770 - 5 Correlation of nonsense sites in the lacI gene with specific codons in the nucleotide sequence; Miller JH et al.; Nonsense mutations derived from 90 different codons in the lacI gene of Escherichia coli have been correlated with the I gene nucleotide sequence . In over 80 cases the specific codon which generates the nonsense mutation can be identified . The sequence shows that 14-16 sites arise through tandem double base changes. Nature, 1978 Aug 24, 274(5673), 765 - 9 Sequence of the lacI gene; Farabaugh PJ; The structural gene for the lac repressor of Escherichia coli, the lacI gene has been sequenced . This 1,080 base pair region of the E . coli chromosome codes for the lac repressor protein of 360 amino acids . The DNA sequence largely confirms but extends the previously reported protein sequence and allows a structural analysis of genetic phenomena. Nature, 1978 Aug 24, 274(5673), 762 - 5 DNA sequence for a low-level promoter of the lac repressor gene and an 'up' promoter mutation; Calos MP; The promoter for a weakly expressed constitutive gene, the lactose repressor gene (lacI), has been sequenced, along with an 'up' promoter mutation Iq . The 10-fold enhancement in I expression found in Iq is the result of a single base change at position -35 . To facilitate the sequencing, the lacI gene was cloned in a small plasmid. Biochim Biophys Acta, 1978 Aug 23, 520(1), 70 - 81 Age-dependent DNA labeling and deoxyribonucleotide synthesis in wheat seeds; Schimpff G et al.; Utilisation of ribonucleosides as precursors of DNA biosynthesis was studied in germinating wheat embryos because the reductive pathway leading to deoxyribonucleotides is very difficult to demonstrate in extracts of higher plants in vitro . {5-3H}Cytidine and {6-3H}uridine are incorporated into wheat DNA (RNA-free) via ribonucleotide reduction without intermediate scission of the glycosidic bond . This reaction is observed at 20-30 h after the onset of germination only in aged (2-4-year-old) seeds while the embryos isolated from fresh grains show very little cytidine incorporation; in contrast, thymidine incorporation into DNA between 10 and 18 h of germination is not age dependent . Fresh wheat contains a soluble, heat-stable inhibitor fraction, most probably a modified oligonucleotide, which efficiently prevents cytidine incorporation when added to old embryos together with the labeled nucleoside . This material also inhibits purified Escherichia coli ribonucleotide reductase and is thought to be part of the control system for ribonucleotide reduction in wheat; it may gradually decay during storage of the seeds . Dry wheat embryos do not contain deoxyribonucleoside triphosphates . Pool sizes of dATP and dTTP in germinating embryos were found to reach 1 pmol/microgram DNA at 10-15 h of germination (i.e . before ribonucleotide reduction) and were independent of the age of seeds . These data suggest that wheat contains other preformed dexoyribonucleoside derivatives which are phosphorylated at an early time and can initially sustain DNA synthesis . Induction of measurable ribonucleotide reductase activity in fresh winter wheat was for the first time accomplished by 15 days of vernalization of the seeds at +2 degrees C. Biochim Biophys Acta, 1978 Aug 23, 520(1), 233 - 6 Codon-specific interaction of uncharged transfer-RNA with eukaryotic ribosomes; Murchie MJ et al.; Rat liver ribosomes bound {32P}tRNAPhe in both a codon-dependent and codon-independent manner . The codon-dependent binding was studied further by utilising the ability of the unchanged tRNAPhe to inhibit the poly(U)-directed binding of {3H}Phe-tRNA to ribosomes . At least part of the codon-dependent binding of uncharged tRNA appears to be to the ribosomal A-site. Biochemistry, 1978 Aug 22, 17(17), 3551 - 6 Uridine diphosphate galactose 4-epimerase: nucleotide and 8-anilino-1-naphthalenesulfonate binding properties of the substrate binding site; Wong SS et al.; Escherichia coli UDP-galactose 4-epimerase in its native form (epimerase.NAD) binds 8-anilino-1-naphthalenesulfonate (ANS) at one tight binding site per dimer with a dissociation constant of 25.9 +/- 2.1 micrometer at pH 8.5 and 27 degrees C . This appears to be the substrate binding site, as indicated by the fact that ANS is a kinetically competitive reversible inhibitor with a Ki of 27.5 micrometer and by the fact that ANS competes with UMP for binding to the enzyme . Upon binding at this site the fluorescence quantum yield of ANS is enhanced 185-fold, and its emission spectrum is blue shifted from a lambdamax of 515 to 470.nm, which suggests that the binding site is shielded from water and probably hydrophobic . Competitive binding experiments with nucleosides and nucleotides indicate that nucleotide binding at this site involves coupled hydrophobic and electrostatic interactions . The reduced form of the enzyme (epimerase.NADH) has no detectable binding affinity for ANS . The marked difference in the affinities of the native and reduced enzymes for ANS is interpreted to be a manifestation of a conformational difference between these enzyme forms. Biochemistry, 1978 Aug 22, 17(17), 3512 - 6 Threonine inhibition of the aspartokinase--homoserine dehydrogenase I of Escherichia coli . Threonine binding studies; Bearer CF et al.; Both activities of the aspartokinase--homoserine I (AK-HSD) of Escherichia coli are inhibited by threonine . Careful threonine binding studies have now been done which have allowed us to distinguish the various effects of threonine on the enzyme . The ultrafiltration technique of H . Paulus ((1969) Anal . Biochem . 32, 101) for measuring ligand binding was shown to be comparable with equilibrium dialysis techniques . Reduction in error by utilization of this procedure enabled us to obtain evidence for two different sets of threonine sites by direct binding studies . The binding data were mathematically consistent with two independent classes of threonine sites, each of which contained four sites per tetramer and had a Hill coefficient of about 2.3--2.5 . KD for the second set of sites was five- to tenfold greater than the high affinity sites, depending upon conditions . The data now suggest that the sequential model for site--site interactions adequately describes the cooperativity of threonine binding to the high affinity set of sites. Biochim Biophys Acta, 1978 Aug 21, 535(2), 206 - 15 The primary structure of Escherichia coli K12 aspartokinase I-homoserine dehydrogenase I-Isolation and characterisation of the peptides produced by cyanogen bromide; Cossart-Gheerbrant P et al.; The aspartokinase I-homoserine dehydrogenase I from Escherichia coli K12, composed of four identical subunits of molecular weight 86,000, was carboxy-methylated, fragmented by cyanogen bromide treatment and citraconylated . Using gel filtration, ion exchange chromatography and preparative paper electrophoresis and chromatography, 15 of 21 cyanogen bromide peptides were isolated in pure form and characterized by their composition, their N-terminal amino acid, and by their content of known cysteinyl or tryptophanyl tryptic peptides. Mol Gen Genet, 1978 Aug 17, 164(2), 163 - 9 Analysis of the regulatory mechanisms controlling the synthesis of the hexitol transport systems in Escherichia coli K12; Lengeler J et al.; The synthesis of the transport systems (enzymeII-complexes) coded for in the mtl and in the gut (srl) operon was found to be induced by unphosphorylated D-mannitol and D-glucitol respectively . Induction from the outside however is only possible if these polyols are taken up into the cells . Induction of the D-mannitol system is immediate, resistant against catabolite repression, relatively insensitive towards transient repression and starts from a high uninduced level (5--30%) . By contrast, the induction of the D-glucitol system starts at a low basal level (0.5--2.5%), does show a pronounced lag from 25 to 90 min, and is hypersensitive towards catabolite and transient repression . These differences apparently reflect primarely differences in the corresponding operator-promotor genes mtl (P,O) and gut (P,O) as well as differences in the uptake of the first, inducing hexitol molecules . For each operon additional regulatory genes exist, called mtlR and gutR respectively, in which transrecessive, temperature sensitive mutations leading to a constitutive expression of the corresponding operon can be found . The influence of these regulatory mechanisms in diauxie experiments and their importance for the differentiation of the three operons during evolution from apparently one common ancestor operon will be discussed. Biochim Biophys Acta, 1978 Aug 17, 511(3), 305 - 19 Formation of large, ion-permeable membrane channels by the matrix protein (porin) of Escherichia coli; Benz R et al.; One of the major proteins of the outer membrane of Escherichia coli, the matrix protein (porin), has been isolated by detergent solubilisation . When the protein is added in concentrations of the order 10 ng/cm3 to the outer phases of a planar lipid bilayer membrane, the membrane conductance increases by many orders of magnitude . At lower protein concentrations the conductance increases in a stepwise fashion, the single conductance increment being about 2 nS (1 nS = 10(-9) siemens = 10(-9) omega -1) in 1 MKCl . The conductance pathway has an ohmic current vs . voltage character and a poor selectivity for chloride and the alkali ions . These findings are consistent with the assumption that the protein forms large aqueous channels in the membrane . From the average value of the single-channel conductance a channel diameter of about 0.9 nm is estimated . This channel size is consistent with the sugar permeability which has been reported for lipid vesicles reconstituted in the presence of the protein. Biochim Biophys Acta, 1978 Aug 17, 511(3), 487 - 98 Metabolic control of lactose entry in Escherichia coli; Maloney PC et al.; A general method has been developed for determining the rate of entry of lactose into cells of Escherichia coli that contain beta-galactosidase . Lactose entry is measured by either the glucose or galactose released after lactose hydrolysis . Since lactose is hydrolyzed by beta-galactosidase as soon as it enters the cell, this assay measures the activity of the lactose transport system with respect to the translocation step . Using assays of glucose release, lactose entry was studied in strain GN2, which does not phosphorylate glucose . Lactose entry was stimulated 3-fold when cells were also presented with readily metabolizable substrates . Entry of omicron-nitrophenyl-beta-D-galactopyranoside (ONPG) was only slightly elevated (1.5-fold) under the same conditions . The effects of arsenate treatment and anaerobiosis suggest that lactose entry may be limited by the need for reextrusion of protons which enter during H+/sugar cotransport . Entry of omicron-nitrophenyl-beta-D-galactopyranoside is less dependent on the need for proton reextrusion, probably because the stoichiometry of H+/substrate cotransport is greater for lactose than for ONPG. Eur J Biochem, 1978 Aug 15, 89(1), 297 - 304 The mechanism of codon-anticodon interaction in ribosomes . Quantitative study of codon-dependent binding of tRNA to the 30-S ribosomal subunits of Escherichia coli; Kirillov SV et al.; The formation of a ternary complex 30-S-subunit . poly(U) . tRNAPhe is discussed and the conditions for its correct description by Langmuir's isotherm are deduced . The affinity constant of the binary complex 30-S-subunit . poly(U) is measured . The reversibility of binding of tRNAPhe to the complex 30-S-subunit . poly(U) is proved in a direct way . The main reason for the heterogeneity of ternary complexes was found to be due to the ability of high-molecular-weight poly(U) to form complicated aggregates with 30-S subunits . If a fraction of poly(U) of moderate molecular weight (30 000) is used, then the ternary complexes are homogeneous in stability and yield the same affinity constants for deacylated, aminoacylated and peptidyl-tRNAPhe (1 X 10(8) M-1 at 20 mM Mg2+, 200 mM NH+4 and 0 degrees C) . Ribosomal protein S1 increases the binding constant of poly(U) with 30-S subunits but does not change the binding constant of tRNAPhe with the 30-S-subunit . poly(U) complex . All 30-S subunits, even partially stripped of S1 protein, are active in the binding of both poly(U) and tRNAPhe. Eur J Biochem, 1978 Aug 15, 89(1), 221 - 8 Binding of labeled initiation factor IF-1 to ribosomal particles and the relationship to the mode of IF-1 action in ribosome dissociation; van der Hofstad GA et al.; The binding of labeled initiation factor IF-1 to ribosomal particles has been studied in relation to the mode of action of this factor in the dissociation of 70-S ribosomes . It is demonstrated that IF-1 interacts specifically with active 70-S tight couples and free 30-S subunits . The binding of IF-1 to both 70-S and 30-S particles is not influenced by the Mg2+ concentration and the affinity of the factor for both particles is about the same . The interaction of IF-1 with these particles is highest at low Tris-HCl concentrations . Under these conditions IF-1 shows a slight dissociating activity . Using 3H-labeled IF-1 and 14C-labeled IF-3 the formation of a 30-S-subunit.IF-1 . IF-3 complex from 70-S ribosomes is demonstrated . Our studies show that IF-3 enhances the binding of IF-1 to the 30-S subunit . In contrast to IF-1, which binds about equally well to 70-S and 30-S particles in the absence of IF-3, 14C-labeled IF-3 binds predominantly to the 30-S subunit . This finding confirms the view that IF-3 acts as an anti-association factor . On the other hand, IF-1 enhances the supply of 30-S subunits in the presence of IF-3 by acting on the 30-S moiety of the 70-S ribosome. Eur J Biochem, 1978 Aug 15, 89(1), 213 - 20 Initiation factor IF-3 and the binary complex between initiation factor IF-2 and formylmethionyl-tRNA are mutually exclusive on the 30-S ribosomal subunit; van der Hofstad GA et al.; The formation of 30-S initiation complexes depends strongly on initiation factor IF-3; at molar ratios of IF-3 to 30-S ribosomes up to one a stimulation is observed, whereas at ratios higher than one, initiation complex formation declines strongly . The target of the observed inhibition of fMet-tRNA binding at high concentrations of IF-3 is the 30-S initiation complex itself . On the one hand addition of IF-3 to preformed 30-S initiation complexes leads to a release of bound fMet-tRNA which is linear with the amount of factor added, whereas no effect on isolated 70-S initiation complexes is seen . The release of fMet-tRNA from preformed 30-S initiation complexes is accompanied by a release of IF-2 in a one-to-one molar ratio which is in agreement with our previous findings showing that binding of fMet-tRNA takes place via a binary complex: IF-2 . fMet-tRNA (Eur . J . Biochem . 66, 181--192 and 77, 69--75) . On the other hand increasing amounts of both IF-2 and fMet-tRNA relieve the IF-3-induced inhibition of 30-S initiation complex formation . From these findings it is concluded that IF-3 and the IF-2 . fMet-tRNA complex are mutually exclusive on the 30-S ribosome . This implies that under our experimental conditions MS2 RNA binding precedes fMet-tRNA binding if one accepts that the presence of IF-3 on the 30-S subunit is obligatory for messenger binding. Am J Obstet Gynecol, 1978 Aug 15, 131(8), 899 - 902 Effects of endotoxin on the pregnant baboon and fetus; Morishima HO et al.; Effects of E . coli endotoxin upon uterine activity and maternal and fetal condition were studied in four pregnant baboons and their fetuses . Uterine activity increased significantly following administration of endotoxin to the mother . Endotoxin also produced maternal circulatory collapse, severe acidosis, and profound fetal asphyxia resulting in death . Death also occurred in three of the four mothers within 24 hours without amelioration of their conditions. J Biol Chem, 1978 Aug 10, 253(15), 5426 - 30 5-Dehydro-3-deoxy-D-arabino-heptulosonic acid 7-phosphate . An intermediate in the 3-dehydroquinate synthase reaction; Maitra US et al.; 3-Dehydroquinate synthase was purified to homogeneity from Escherichia coli . It was found to be a single polypeptide chain of Mr = approximately 57,000 . Reaction mixtures of pure enzyme and the substrate, 3-deoxy-D-arabino-heptulosonic acid 7-phosphate, were incubated for short times and treated with NaB3H4 . The resulting 3-deoxyheptonic acid 7-phosphate was degraded with sodium periodate, and formic acid representing C-5 of the substrate was isolated . The presence of 3H in the formate corresponding to 15% of the enzyme was interpreted as indicating a 5-dehydro derivative of the substrate as an intermediate of the reaction . Quinic acid, resulting from reduction of 3-dehydroquinate with NaB3H4, was also isolated and degraded with periodate . The formate from C-4 of the quinate was unlabeled, indicating that 3,4-bisdehydroquinate is not an intermediate. J Biol Chem, 1978 Aug 10, 253(15), 5350 - 4 Stereochemistry and mechanism of reactions catalyzed by tryptophanase Escherichia coli; Vederas JC et al.; Several beta replacement and alpha,beta elimination reactions catalyzed by tryptophanase from Escherichia coli are shown to proceed stereospecifically with retention of configuration . These conversions include synthesis of tryptophan from (2S,3R)- and (2s,3s)-{3(-3H)}serine in the presence of indole, deamination of these serines in D2O to pyruvate and ammonia, and cleavage of (2S,3R)-and (2S,3S)-{3(-3H)}tryptophan in D2O to indole, pyruvate, and ammonia . A coupled reaction with lactate dehydrogenase was used to trap the stereospecifically labeled {3-H,2H,3H}pryuvates as lactate, which was oxidized to acetate for chirality analysis of the methyl group . During deamination of tryptophan there is significant intramolecular transfer of the alpha proton of the amino acid to C-3 of indole . To determine the exposed face of the cofactor.substrate complex on the enzyme surface and to analyze its conformational orientation, sodium boro{3H}hydride was used to reduce tryptophanase-bound alaninepyridoxal phosphate Schiff's base . Degradation of the resulting pyridoxylalanine to (2S)-{2(-3H)}alanine and (4'S)-{4'(-3H)}pyridoxamine demonstrates that reduction occurs from the exposed si face at C-4' of the complex and that the ketimine double bond is trans. J Biol Chem, 1978 Aug 10, 253(15), 5490 - 8 Amino acid sequence of beta-galactosidase . VI . Limited tryptic digestion of the citraconylated protein and sequences of tryptic peptides; Fowler AV et al.; Hydrolysis with trypsin of citraconyl-carboxy-methyl-beta-galactosidase was carried out under limiting conditions . No Asp-Arg-X sequences were cleaved and many large peptides were produced . Butanol extraction from dilute acid proved very useful for separating the more hydrophobic fragments . Peptides were purified and sequenced . From this digest and two earlier preparations, all 80 theoretically possible tryptic fragments have been isolated and their structures determined. J Biol Chem, 1978 Aug 10, 253(15), 5521 - 5 Amino acid sequence of beta-galactosidase . XI . Peptide ordering procedures and the complete sequence; Fowler AV et al.; The amino acid sequence of beta-galactosidase has been determined . The monomer contains 1,021 amino acid residues in a single polypeptide chain and has a molecular weight of 116,349 . All 80 tryptic peptides as well as all 24 CNBr peptides have been isolated in pure form . Evidence is presented for the ordering of the CNBr peptides . The sequence determination was aided by analysis of cyanogen bromide peptides obtained from a polypeptide fragment produced by a lacZ termination mutant strain. J Biol Chem, 1978 Aug 10, 253(15), 5515 - 20 Amino acid sequence of beta-galactosidase . X . Sequence of the COOH-terminal segment, CNBr peptides 18 to 24, residues 654 to 1021; Fowler AV et al.; The sequence of the COOH-terminal third (omega) of beta-galactosidase is presented . The size of the 7 cyanogen bromide peptides of this segment is larger on the average, about 52 amino acid residues as compared to an average size of 42 for cyanogen bromide peptides in the whole molecule . Tyrosine, phenylalanine, and valine are low in this segment whereas alanine and lysine are high . This region has a slight excess of basic groups. J Biol Chem, 1978 Aug 10, 253(15), 5510 - 4 Amino acid sequence of beta-galactosidase . IX . Sequence of the central segment, CNBr peptides 10 to 17, residues 378 to 653; Fowler AV et al.; The amino acid sequence in the 8 cyanogen bromide peptides comprising the central segment of beta-galactosidase is presented . This portion of the molecule, about 27% of the protein, contains over 40% of the lysine and tyrosine residues and has a slight excess of basic amino acids. J Biol Chem, 1978 Aug 10, 253(15), 5505 - 9 Amino acid sequence of beta-galactosidase . VIII . Sequence of the NH2-terminal segment, CNBr peptides 1 to 9, residues 1 to 377; Fowler AV et al.; The amino acids in 9 cyanogen bromide peptides have been placed in sequence starting from the NH2 terminus . The peptides account for residues 1 to 377 of the whole protein and include the largest (CNBr7, 119 residues) and the smallest (CNBr1, 2 residues) of the cyanogen bromide peptides . This region contains only 3 of the 20 lysine residues in the polypeptide chain . A high proportion of charged groups are present (28 of 66 arginine, 28 of 60 glutamic acid, and 24 of 65 aspartic acid residues). J Biol Chem, 1978 Aug 10, 253(15), 5499 - 504 Amino acid sequence of beta-galactosidase . VII . Isolation of the 24 cyanogen bromide peptides; Fowler AV; All of the 24 cyanogen bromide peptides of beta-galactosidase have been isolated in pure form . Of these 8 ranged in size from 2 to 5 residues and were purified by paper electrophoresis . The 16 large peptides, from 23 to 119 residues, were chromatographed at pH 5.0 on a carboxymethyl-cellulose column in 0.02 M ammonium acetate buffer containing 8 M urea . A number of peptides were obtained in pure from following Sephadex G-50 or G-75 gel filtration . Others were separated on sulfopropyl-Sephadex or diethyl-(2-hydroxylpropylaminoethyl)-Sephadex . There large peptides were obtained in over 50% yield and several others were obtained in more than 25% yield. J Biol Chem, 1978 Aug 10, 253(15), 5484 - 9 Amino acid sequence of beta-galactosidase . V . Isolation and sequences of chymotryptic peptides; Fowler AV; The amino acid sequence of 72 chymotryptic peptides isolated from 14C-, 3H-labeled carboxymethyl-beta-galactosidase has been determined . A variety of techniques were used in the isolation procedures including separation by solubility, size, and ion exchange and paper chromatography . These peptides contain approximatley 500 amino acids, range in size from 2 to 26 residues, and give overlaps with tryptic peptides of 16 to 55 residues . Peptides from this digest and those reported earlier from tryptic digests account together for the sequence of about 600 of the 1021 residues in the subunit. Biochemistry, 1978 Aug 8, 17(16), 3370 - 6 Tripeptide-specific aminopeptidase from Escherichia coli AJ005; Hermsdorf CL; A tripeptidase, TP, from the ribosome-free fraction of Escherichia coli AJ005, a peptidase-deficient mutant of strain K-12, has been obtained using gel electrophoresis and chromatography on DEAE-Sephadex A-50, hydroxylapatite, and Sephadex G-200 . Characterization studies on tripeptidase TP, freed of other detectable peptidases, indicate that this enzyme is capable of cleaving an amino-terminal leucine, lysine, methionine, or phenylalanine residue from certain tripeptides . Only one band of activity toward several tripeptides (and no activity toward dipeptides) was detected following gel electrophoresis of this preparation . Tripeptidase TP, the only strain AJ005 peptidase known to attack trilysine, was inactive toward all dipeptides, peptide amides, substituted peptides, esters, and tetrapeptides tested as substrates . Trilysine cleavage is optimal at about pH 8.5, as determined in Tris, borate, or phosphate buffers . Tripeptidase TP activity tested under a number of conditions was not inhibited by soybean trypsin inhibitor (3 mg/mL), phenylmethanesulfonyl fluoride (25 micrometer), or iodoacetate (9 mM) . p-Mercuribenzoate (10 micrometer), divalent copper, cobalt, calcium (2.5 mM), zinc (25 micrometer), and mercury (10 micrometer) are inhibitory . Based on Sephadex G-200 chromatography tripeptidase TP has a particle weight of approximately 80 000 daltons . An apparent Km of 5.3 mM was determined for methionylglycylglycine cleavage. Biochemistry, 1978 Aug 8, 17(16), 3363 - 9 A new method for the purification of 30S ribosomal proteins from Escherichia coli using nondenaturing conditions; Littlechild JA et al.; A new method for the purification of Escherichia coli (A19) 30S ribosomal proteins has been developed that avoids the use of denaturing conditions such as urea, acetic acid, and lyophilization . In this way the majority of the proteins from the small ribosomal subunit can be obtained in 5--100 mg quantities and at greater than or equal to 90% purity . This has been achieved by the initial "splitting" of the proteins into two main groups with LiCl followed by fractionating on ion-exchange and gel-filtration columns, in the absence of urea and in the presence of salt . The proteins prepared by this nondenaturing procedure were soluble at high ionic strength and less soluble, being aggregated, at low salt concentrations . This behavior was exactly the opposite of that exhibited by proteins prepared with methods using denaturing conditions . These new methods have enabled additional ribosomal RNA-binding proteins to be found and potential protein-proteins complexes to be isolated . Preliminary evidence that these proteins may retain a more native structure is presented. Biochemistry, 1978 Aug 8, 17(16), 3321 - 5 Photoaffinity inhibition of dipeptide transport in Escherichia coli; Staros JV et al.; A dipeptide containing a nitrene precursor, glycyl-4-azido-2-nitro-L-phenylalanine, has been synthesized . This compound is a photoaffinity inhibitor of dipeptide transport in E . coli . In the dark, the dipeptide is a reversible inhibitor of glycylglycine uptake by live E . coli W cells . The 14C-labeled compound is a substrate for the transport system, with a Km of 7 micrometer and V max of 5 x 10(3) molecules cell-1 s-1 (compare 9 micrometer and 1 x 10(4) molecules cell-1 s-1, respectively, for the transport of glycylglycine under the same conditions) . When intact E . coli cells are photolyzed at approximately 350 nm in the presence of the photolabile dipeptide, their ability to transport either glycylglycine or unphotolyzed glycyl-4-azido-2-nitro-L-phenylalanine is irreversibly inhibited, but their ability to transport arginine is unaffected . The presence of glycylglycine in the medium during photolysis protects the cells against the light-dependent inactivation of dipeptide transport. Biochemistry, 1978 Aug 8, 17(16), 3292 - 7 Control of acetohydroxy acid synthetase in Escherichia coli 9723; Wiginton DA et al.; A method by which three acetohydroxy acid synthetase activities are separated from extracts of Escherichia coli 9723 has been developed . Isoleucine specifically represses synthesis of one of the enzymes, which is not sensitive to valine inhibition, and isoleucine also simultaneously enhances the production of a second activity, which is valine inhibitable . The valine-inhibitable activity is repressed by leucine and valine, a combination of which is more effective than either alone . The third acetohydroxy acid synthetase, which is more active at pH 6 than at 8, is not controlled by the branched-chain amino acids . In a mutant of E . coli 9723 selected for the ability of valine to inhibit growth, the isoleucine-repressible acetohydroxy acid synthetase activity was no longer present, but isoleucine addition still resulted in enhanced production of the valine-inhibitable activity. Mol Gen Genet, 1978 Aug 4, 164(1), 39 - 44 Control of ribosomal RNA synthesis in Escherichia coli . IV . Frequency of transcription of ribosomal RNA genes as a function of growth rate; Muto A; Nucleoids were isolated from Escherichia coli B/r cells in steady-stage growth at different rates . The number of RNA chains growing on each nucleoid was estimated from the amount and size of RNAs synthesized by endogenous RNA polymerase . This figure represents the number of RNA polymerase molecules that are functioning in transcription and thus serves to indicate the frequency of transcription in the cells . With an increase in the growth rate from 0.27 to 1.73 (h-1), (a) the number of total RNA chains per genome increases from about 252 to 838, (b) the number of ribosomal RNA (rRNA) chains per genome increases as a function of the second power of the growth rate from about 19 to 255, and (c) the number of non-rRNA chains per genome increases linearly from about 233 to 538. Mol Gen Genet, 1978 Aug 4, 164(1), 15 - 29 Isolation of a small DNA fragment carrying the gene for a dihydrofolate reductase from a trimethoprim resistance factor; Zolg JW et al.; DNA fragments of the R factor R388 which renders E . coli resistant to trimethoprim by inducing a trimethoprim resistant dihydrofolate reductase (Amyes and Smith, 1974) were inserted into plasmids and screened for the expression of the trimethoprim resistance gene . By means of a two step deletion procedure a 1770 bp EcoRI/BamH1 fragment was isolated which conferred drug resistance and which was found to induce the synthesis of the same dihydrofolate reductase as the parental R factor . Gene dosage experiments indicated that the induction was due to the presence of a dihydrofolate reductase structural gene on the 1770 bp fragment . The gene could be assigned to a segment which was less than 1200 bp long . The 1770 bp fragment and a recombinant plasmid consisting of pSF2124 and part of R388 were mapped with several restriction nucleases . The R factor induced enzyme was partially purified from a strain carrying a multicopy recombinant plasmid into which the 1770 bp fragment was inserted and which induced high levels of dihydrofolate reductase . The enzyme was found to be stable at 100 degrees . Some aspects of the synthesis of dihydrofolate reductase are discussed. Mol Gen Genet, 1978 Aug 4, 164(1), 109 - 12 Mu-1 directed inhibition of DNA breakdown in Escherichia coli, recA cells; Van Vliet F et al.; The spontaneous DNA breakdown exhibited by recA strains, is reduced after heat induction of a thermoinducible Mu-1 prophage . This inhibition is dependent upon RNA synthesis, suggesting that Mu-1 directs synthesis of a recBC nuclease inhibitor, analogous to the product of the lambda gam gene . The genetic evidence presented here shows that Mu-1 enables a lambda red gam phage to grow on a recA host . The in vitro assay for ATP-dependent exonuclease activity reveals a complete inhibition of this activity 30 min after induction of the Mu-1 prophage. Mol Gen Genet, 1978 Aug 4, 164(1), 1 - 8 Organization and expression of the dnaJ and dnaK genes of Escherichia coli K12; Saito H et al.; A temperature-sensitive mutation in the dnaJ gene of Escherichia coli K12 is described which affects replication of the bacterial DNA . The gene is located adjacent to the dnaK gene described previously (Saito and Uchida, 1977) . The physical and functional organization of the dnaJ-dnaK region was studied in detail by analyzing the heteroduplexes and functions of various deletion mutants of lambdadnaJdnaK, a transducing phage carrying both of the dna genes . The sizes of dnaJ and dnaK cistrons were estimated to be at most 1.2 +/- 0.5 and 2.1 +/- 0.4 kilobases, respectively . In vivo expression of the dnaJ function by various deletion phages indicated that the dnaK and dnaJ cistrons were transcribed from a promoter located at the head of the dnaK cistron, dnaJ being downstream to dnaK . Presence of a weak promoter which reads only the dnaJ cistron was also suggested . A simple method for isolating independent deletion mutants of phage lambda was described. Biochim Biophys Acta, 1978 Aug 4, 511(2), 285 - 96 Mechanism of energy coupling for transport of deoxycytidine, uridine, uracil, adenine and hypoxanthine in Escherichia coli; Roy-Burman S et al.; The transport processes for uridine, deoxycytidine, uracil, adenine and hypoxanthine require an energy source and are active under anaerobic or aerobic conditions . Inhibitory effects of cyanide, arsenate, carbonylcyanide m-chlorophenylhydrazone, 2,4-dinitrophenol and N,N'-dicyclohexylcarbodiimide on the transport of uridine and deoxycytidine differ from the corresponding effects on the transport of uracil, adenine and hypoxanthine . The nature of these inhibitory effects supports the conclusion that uridine and deoxycytidine transport is energized either by electron transport or by ATP hydrolysis via (Ca2+ + Mg2+)-ATPase . The transport or uracil, adenine and hypoxanthine is dependent upon ATP or some high energy phosphate derivative of ATP, but is independent of (Ca2+ + Mg+)-ATPase and electron transport . Uptake of the ribose moiety of uridine by a mutant of Escherichia coli B, which lacks the transport system for uracil and intact uridine, is neither stimulated by energy sources nor inhibited by various inhibitors of energy metabolism under either aerobic or anaerobic conditions. Mol Gen Genet, 1978 Aug 4, 164(1), 105 - 8 Degradation of missense mutant beta-galactosidase proteins in Escherichia coli K-12; Bergquist PL et al.; Ten out of 43 missense mutations in the lacZ gene of Escherchia coli gave rise to polypeptide chains that were degraded in vivo . While many of the mutants appeared to be fully or partially CRM-, there appeared to be no obvious correlation between degradation, map position, altered subunit association and the half-life of the mutant proteins. J Biochem (Tokyo), 1978 Aug, 84(2), 259 - 66 Structure and function of 5S ribosomal ribonucleic acid from Torulopsis utilis . IV . Detection of exposed guanine residues by chemical modification with kethoxal; Nishikawa K et al.; The reaction of Torulopsis (Candida) utilis 5S ribosomal RNA with kethoxal (beta-ethoxy-alpha-ketobutyraldehyde) was studied in an attempt to identify the exposed guanine residues . At most 7-8 out of 32 guanine residues in T.utilis 5S RNA were kethoxalated after reaction at 37 degrees C for 4 h in the presence of magnesium ions . Localization of the kethoxalated guanine residues in T.utilis 5S RNA was achieved by sequence analyses of RNase T1 digests of the kethoxalated 5S RNA . These analyses showed that residues G37, G57, G91, and some of the three guanine residues G80, G82, and G85, are the most accessible sites . Residues G30, G41, and G49 also reacted with kethoxal though less strongly . These results are for the most part compatible with our secondary structure model for T.utilis 5S 5S RNA (Nishikawa and Takemura (1974) J . Biochem . 76, 935-947) . However, partial formation of some hydrogen bonds within the loop region of the model seems to be necessary to explain the inaccessibility of residue G101 to kethoxal . The results are also discussed in comparison with those of similar studies on E.coli 5S RNA. Aust J Exp Biol Med Sci, 1978 Aug, 56(4), 441 - 52 Antibodies in the intestinal secretions of rats . Primary and secondary responses to polymeric flagellin; Kenrick KG et al.; The antibody responses in serum and secretions obtained from the mucosal surfaces of the small intestine of rats immunized by a parenteral and intestinal route have been compared . Though no significant differences in the mean serum titres were found, the responses of animals immunized via the latter route to large doses of antigen were far less uniform . Apart from the first few days of the primary response, antibody activity was found in three major immunoglobulin classes (IgG2, IgA and IgM), irrespective of the route of immunization . Significant antibody activity appeared in the intestinal surface secretions only after two injections of antigen . In rats immunized parenterally the activity was found only in the IgG2 component . Whilst activity was found in both IgG2 and IgA fractions of the secretions obtained from intestinally immunized rats, it was predominantly of the IgG2 class . The possible significance of this observation is discussed. Ann Microbiol (Paris), 1978 Aug-Sep, 129B(2), 147 - 54 {Presence of plasmids belonging to group incP and conferring chloramphenicol resistance in "Escherichia coli" strains of avian origin (author's transl)}; Chaslus-Dancla E et al.; Plasmids pCG76, pCG83, pCG110 and pCG111 were transferred from multiresistant Escherichia coli strains of avian intestinal origin to E . coli K12 . They were found to be compatible with reference plasmids of several incompatibility groups, except RP4 . This incompatibility with RP4 is a proof that they belong to group incP . Other plasmids of this group were found in E . coli strains isolated from the feces of hens in two different breeding flocks . The incidence and the importance of this plasmid group in the intestinal bacteria of animals are presently investigated. Jpn J Med Sci Biol, 1978 Aug, 31(4), 357 - 9 Drug resistance of Escherichia coli isolated in Nepal; Tanaka T et al.; We collected Escherichia coli strains from 59 Nepalese porters in 1971 and surveyed for their drug resistance . Drug-resistant E . coli strains were isolated from four porters . (TC . CM . SM . SA . APC.)-resistant strains were isolated from two porters and SA- or APC-resistant strains were isolated from each of the others . The R factors were demonstrated from the multiple-resistant E . coli strains. J Biochem (Tokyo), 1978 Aug, 84(2), 369 - 75 Crystallization of arginine-, formylmethionine-tyrosine-, and glycine-transfer RNAs from Escherichia coli; Morikawa K et al.; Crystals as large as 0.5 X 0.3 X 0.2 mm of purified arginine-transfer RNA from Escherichia coli have been prepared by a vapour diffusion method . X-ray diffraction photographs showed that the crystals gave reflections up to 3.7 A spacing . They have a trigonal space group P31 2 1 (OR P32 2 1) and cell-dimensions a=97.2, b=97.2, c=94.8A . Crystals of a mercury derivative of this transfer RNA have also been obtained, and an X-ray diffusion photography of one of them is presented . Formylmethionine-transfer RNA from E . coli was crystallized in various forms, and the appearance of the polymorphs was found to depend upon the amount of spermine in the solution from which the crystallization took place . Crystals of tyrosine-transfer RNA and glycine-transfer RNA have also been obtained. J Biochem (Tokyo), 1978 Aug, 84(2), 251 - 8 Removal by bovine serum albumin of fatty acids from membrane vesicles and its effect on proline transport activity in Escherichia coli; Goto K et al.; Bovine serum albumin appreciably stimulated the initial rate and the steady-state level of proline uptake in membrane vesicles, while it had no effect on the oxidase activity for ascorbate-phenazine methosulfate, on which the transport activity depends . Bovine serum albumin showed the strongest stimulatory effect on the transport system among the proteins tested . Three other proteins did not show any effect, while beta-lactoglobulin showed a weaker but appreciable effect on the transport activity . The incubation of membrane vesicles with bovine serum albumin resulted in extensive removal of fatty acids, while none of the other membrane components, including proteins and phospholipids, was removed by this treatment . Fatty acids inhibited the proline transport activity, while the inhibited activity was appreciably restored by incubation with the albumin . An experiment with radioactive fatty acids showed that exogenously-added fatty acids bound firmly to the membrane vesicles and were removed by subsequent incubation with the albumin . The incubation of membrane vesicles for several hours resulted in an increase of fatty acids with a concomitant loss of the transport activity . Subsequent incubation with the albumin resulted in the removal of fatty acids and the partial restoration of the transport activity . Based on these results, it is concluded that bovine serum albumin specifically removed fatty acids from membrane vesicles, resulting in activation of the proline transport system. Isr J Med Sci, 1978 Aug, 14(8), 882 - 8 Experimental nephropathy induced in the rabbit by immunization with a lipopolysaccharide from Escherichia coli; Goldstein I et al.; Twenty rabbits were each injected with 100 microgram of lipopolysaccharide from Escherichia coli 055 at weekly intervals for up to 15 months . The antisera showed an immunologic cross-reactivity with rabbit kidney glycoprotein . A macroscopic nephropathy was present in 14 of the 17 rabbits in which the kidneys were examined . All the rabbits showed extensive histologic lesions involving all the structures of the kidney: organized thrombosis of the arteries, extensive areas of infarction, glomerular atrophy, tubular necrosis and proliferation of young connective tissue . A marked infiltration with lymphoid cells and some plasmacytes was present . The immunologic character of this nephropathy and the immunopathogenic mechanism involved in its pathogenesis are discussed. Arch Microbiol, 1978 Aug 1, 118(2), 207 - 18 Pole cap formation in Escherichia coli following induction of the maltose-binding protein; Dietzel I et al.; After induction with maltose, 30--40% of the total protein in the osmotic shock fluid consist of maltose-binding protein while the induction ratio (maltose versus glycerol grown cells) for the amount of binding protein synthesized as well as for maltose transport is in the order of 10 . Induction of maltose transport does not occur during all times of the cell cycle, but only shortly before cell division . Electronmicroscopic analysis of cells grown logarithmically on glycerol or maltose revealed in the latter the formation of large pole caps . These pole caps arise from an enlargement of the periplasmic space . Small cells contain one pole cap, large cells contain two . Pulse label studies with strain BUG-6, a mutant that is temperature sensitive for cell division reveal the following: Growth at the non-permissive temperature prevents maltose-binding protein synthesis and formation of new transport capacity . After shifting to the permissive temperature the cells regain both functions . Simultaneously, the newly formed cells exhibit pole caps . We conclude that the induction of maltose-binding protein is responsible for the formation of pole caps . In addition, beside the presence of inducer, cell cycle events occuring during division are necessary for the synthesis of maltose-binding protein. Appl Environ Microbiol, 1978 Aug, 36(2), 230 - 6 Significance of the inactivation of transport in thermal death of Escherichia coli; Grau FH; Cells of Escherichia coli ML308-225, harvested from the exponential phase, were heated in 50 mM potassium phosphate, and the loss in viability and inability to transport lactose, proline, and alpha-methylglucoside was compared . After cells were heated at 48 degrees C for 15 min, there was a 16% loss in viability and a similarly small reduction in the steady-state accumulation of lactose at 25 degrees C . The initial rates of lactose and proline transport were severely inhibited by heating at either 48 or 50 degrees C, but substantial recovery occurred within 5 to 7 min at 25 degrees C . Heating at 50 degrees C for 15 min caused an 86% loss in viability, but only a 53% decrease in the steady-state accumulation of lactose and only a 24% reduction in the initial rate of alpha-methylglucoside uptake . Twice as much alpha-methylglucoside was accumulated at 50 degrees C as at 25 degrees C . Although alpha-methylglucoside phosphate leaked from the cells at 50 degrees C, the concentration retained within the cells was about 500 times that externally, when only about 14% of the cells were viable . Overall, these results indicate that cells made nonviable by heating at 50 degrees C still have significant membrane integrity. Appl Environ Microbiol, 1978 Aug, 36(2), 217 - 22 Isolation of citrate-positive variants of Escherichia coli from domestic pigeons, pigs, cattle, and horses; Ishiguro N et al.; Twenty-seven isolates of citrate-positive variants of Escherichia coli were obtained from domestic pigeons, pigs, cattle, and horses . With the exception of citrate utilization, all isolates closely resembled typical E . coli in their biochemical reactions . These isolates were multiply resistant to antibiotics in in vitro susceptibility tests . Transfer experiments of multiple-drug resistance to the E . coli K-12 strain showed that all citrate-positive isolates from domestic pigeons, pigs, and cattle, resistant to three or more drugs, carried R plasmids showing temperature-sensitive transfer. Proc Natl Acad Sci U S A, 1978 Aug, 75(8), 3891 - 5 Contranscription of genes for RNA polymerase subunits beta and beta' with genes for ribosomal proteins in Escherichia coli; Yamamoto M et al.; The lambdarifd18 transducing phage carries genes for RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase; EC 2.7.7.6) subunits beta and beta' (rpoB,C) and genes for four ribosomal proteins (rplK for L11, rplA for LI, rplJ for L10, and rplL for L7/L12) . DNA segments of various sizes, which cover the rifd allele of the rpoB gene, were cloned into lambda vector phages . The hybrid phages were then analyzed for their ability to express the rpoB gene and neighboring ribosomal protein genes in ultraviolet-irradiated lambda-lysogenic and nonlysogenic bacterial hosts . The results show that the rpoB gene is cotranscribed with two neighboring ribosomal protein genes and that in the rpoB,C transcription unit is: promoter, rp1J, rp1L, rpoB, and rpoC. Proc Natl Acad Sci U S A, 1978 Aug, 75(8), 3751 - 5 Matrix protein from Escherichia coli outer membranes forms voltage-controlled channels in lipid bilayers; Schindler H et al.; Matrix protein from Escherichia coli was integrated into planar lipid bilayers . The incorporated protein generates aqueous channels across these membranes . Channels are induced irreversibly by voltage, and their number is proportional to the protein content of the membrane and stays constant over hours . They are uniform in size, with a diameter of about 1 nm and a single-channel conductance of 0.14 nS in 0.1 M NaCl . In addition to ionic conductance, the channels allow free diffusion of small, uncharged molecules . Channels assume either an open or a closed state . Membrane potentials shift this two-state equilibrium distribution in favor of closed channels, an observation that explains both negative resistance and inactivation at high potentials . Channels are not randomly distributed in the membrane but interact cooperatively within aggregates . The smallest entity inducible consists of three channels. Proc Natl Acad Sci U S A, 1978 Aug, 75(8), 3742 - 6 High-resolution 13C nuclear magnetic resonance studies of glucose metabolism in Escherichia coli; Ugurbil K et al.; High-resolution 13C nuclear magnetic resonance spectra of suspensions of Escherichia coli cells have been obtained at 90.5 MHz by using the Fourier transform mode . Anaerobic cells incubated with {I-13C}glucose show a time course of glycolysis in which the alpha and beta glucose anomers disappear at different rates, lactate, succinate, acetate, alanine, and valine accumulate as end products of glycolysis, and fructose bisphosphate appears as an intermediate . It is shown that fructose bisphosphate is labeled at C-1 and C-6 during {I-13C}-glucose catabolism . Upon oxygenation, glutamate appears with the 13C ENRICHMENT AT THE C-4, C-3, and C-2 positions, with the C-4 most intense . From the position of the 13C label we conclude that valine is formed by condensation of pyruvate and that carbon enters the tricarboxylic acid cycle mainly through acetyl CoA. Proc Natl Acad Sci U S A, 1978 Aug, 75(8), 3708 - 12 Lysyl-derived aldehydes in outer membrane proteins of Escherichia coli; Diedrich DL et al.; The major outer membrane proteins from Escherichia coli K-12 are modified to contain alpha-aminoadipic acid delta-semialdehyde (allysine) . The allysine was found to be derived from lysine and it was identified by derivatizing it to chloronorleucine by reduction, alpha-aminoadipic acid by oxidation, and to alpha,epsilon-diaminopimelic acid by reacting it with CN- and NH3 . The alpha-aminoadipic acid was identified by mass spectrometry . Two major outer membrane proteins were found to possess allysine, a modified lysine characteristically found to connective tissue. Proc Natl Acad Sci U S A, 1978 Aug, 75(8), 3673 - 7 Low molecular weight RNA species encoded by a multiple drug resistance plasmid; De Wilde M et al.; Multiple drug resistance plasmid NR1 is shown to code for at least 10 low molecular weight RNAs . These species, ranging in size from 60 to 120 nucleotides, have been purified from minicells by two-dimensional gel electrophoresis and characterized by RNase T1 fingerprinting . Hybridization of purified RNAs to restriction endonuclease digests of NR1 DNA indicates that most are derived from the resistance transfer factor region of the plasmid genome . One RNA was found to be coded by the transposable tetracycline resistance element Tn10, and several are associated with DNA fragments that contain origins of replication. Proc Natl Acad Sci U S A, 1978 Aug, 75(8), 3598 - 602 Processing of the 5' end of Escherichia coli 16S ribosomal RNA; Dahlberg AE et al.; We have isolated and partially characterized an endonuclease involved in processing the 5' end of 16S rRNA of Escherichia coli . A mutant strain that is deficient in this enzyme accumulates a new precursor of 16S rRNA, named 16.3S rRNA . This rRNA has the 3' end of mature 16S rRNA but is about 60 nucleotides longer at the 5' end . In vitro, the enzyme preparation cleaves an RNA fragment of about 60 nucleotides from the 5' end of 16.3S rRNA in 30S ribosomal subunits, yielding the mature 5' end of 16S rRNA . In the mutant strain the 16.3S rRNA is associated with a full complement of 21 ribosomal proteins in 30S subunits . These particles, which comprise 50% of the total 30S subunits, are present on polyribosomes. Proc Natl Acad Sci U S A, 1978 Aug, 75(8), 3593 - 7 Complementary sequences 1700 nucleotides apart form a ribonuclease III cleavage site in Escherichia coli ribosomal precursor RNA; Young RA et al.; The nucleotide sequence of Escherichia coli DNA at both ends of the gene for 16S rRNA has been determined for two rRNA operons, rrnD and rrnX . The 400 nucleotides we have examined exhibit only one base change between rrnD and rrnX . Within the 160 nucleotides that precede mature 16S rRNA sequences are cleavage sites for several E . coli endonucleases, including RNase III . A 240-nucleotide segment encompassing the 16S 3' end contains another RNase III site and the point of presumed RNase P scission at the 5' end of tRNA1Ile, the first tRNA appearing in the 16-23S spacer region of rrnD and rrnX . Most importantly, the DNA sequences predict that regions flanking the 16S gene in the rRNA primary transcript extensively base pair to form a double-helical structure whose hairpin loop includes the entire mature 16S molecule; within this structure is a 26-base-pair stem containing the two sequences at which RNase III action generates the 5' and 3' ends of a previously characterized precursor to 16S rRNA . Although our proposed secondary structure for this RNase III site is superficially dissimilar to previously described cleavage sites in the T7 early mRNA precursor, certain common features may constitute signals for RNase III recognition . The suggestion that distant portions of an RNA molecule can form a secondary structure within which specific endonucleolytic cleavages occur may have mechanistic implications for the joining of noncontiguous portions of gene sequences evident in several eukaryotic mRNAs. Proc Natl Acad Sci U S A, 1978 Aug, 75(8), 3569 - 73 Inactivation of phage repressor in a permeable cell system: role of recBC DNase in induction; Oishi M et al.; UV light causes inactivation of phage (phi80) repressor molecules in a plasmolyzed, permeable cell preparation of Escherichia coli . Induction without UV irradiation occurs when the permeable cells are incubated in the presence of four deoxyribonucleoside triphosphates and ATP . The induction triggered by dNTP's requires a functional recBC gene product and is associated with degradation of the DNA replication fork . The role of recBC DNase in the induction of prophage and SOS functions in general is discussed. Nucleic Acids Res, 1978 Aug, 5(8), 2789 - 99 On the role of protein S4 N-terminal residues 1 through 30 in 30S ribosome function; Changchien LM et al.; 30S ribosomal protein S4 contains a single cysteine residue at position 31 . We have selectively cleaved the peptide bond adjacent to this residue using the reagent 2-nitro-5-thiocyanobenzoic acid . The two resultant fragments were purified . The smaller S4-fragment (1-30) was found to be incapable of interacting with 16S RNA directly . This fragment also is not incorporated into a particle reconstituted from 16S RNA and 20 purified proteins with S4 missing . In contrast, the large S4-fragment (31-203) appears to be fully functional in ribosome assembly . Replacement of S4 with this fragment in the reconstitution reaction leads to a complete 30S ribosome containing all 30S proteins . This particle has a full capacity to bind poly U but has lost all activity for poly U directed phe-tRNA binding . We therefore propose that the N-terminus of protein S4 is not critical for ribosome assembly but is essential for tRNA binding. Nucleic Acids Res, 1978 Aug, 5(8), 2721 - 8