Biochem J, 1978 Oct 1, 175(1), 221 - 5 Modification of yeast ribosomal proteins . Methylation; Kruiswijk T et al.; Two-dimensional polyacrylamide-gel electrophoretic analysis of yeast ribosomal proteins uniformly labelled in vivo with {methyl-3H}methionine and {1-14C}methionine revealed that four ribosomal proteins are methylated, i.e . proteins S31, S32, L15 and L41 . Lysine and arginine appear to be the predominant acceptors of the methyl groups . The degree of methylation ranges from 0.09 to 0.20 methyl group per modified ribosomal protein species. Biochem J, 1978 Oct 1, 175(1), 213 - 9 Modification of yeast ribosomal proteins . Phosphorylation; Kruiswijk T et al.; Two-dimensional polyacrylamide-gel electrophoretic analysis of yeast ribosomal proteins labelled in vivo with 32PO43- revealed that the proteins S2 and S10 of the 40S ribosomal subunit, and the proteins L9, L30, L44 and L45 of the 60S ribosomal subunit, are phosphorylated in vivo . Most of the phosphate groups appeared to be linked to serine residues . Teh number of phosphate groups per molecule of phosphorylated protein species ranged from 0.01 to 0.79 . Since most of the phosphorylated ribosomal proteins appear to associate with the pre-ribosomal particles at a very late stage of ribosome assembly, phosphorylation is more likely to play a role in the functioning of the ribosome than in its assembly. Nucleic Acids Res, 1978 Oct, 5(10), 3913 - 27 Pulsed FT-NMR double resonance studies of yeast tRNAPhe: specific nuclear Overhauser effects and reinterpretation of low temperature relaxation data; Johnston PD et al.; Cross-relaxation effects are demonstrated between the imino protons and other protons in yeast tRNAPhe and H2O . A detailed examination has been made of the observed relaxation rate of the proton resonance at 11.8 ppm from DSS as a function of the D2O content in the solvent . This result, as well as the size and number of observed nuclear Overhauser effects, suggests that dipolar magnetization transfer between solvent H2O, amino, imino, and other tRNA protons may dominate the relaxation processes of the imino protons at low temperature . At higher temperatures the observed relaxation rate is dominated by chemical exchange . The selective nuclear Overhauser effects are shown to be an important aid in resonance assignments . By these means we were able to identify tow protons from the wobble base pair GU4 at 11.8 ppm and 10.4 ppm. Nucleic Acids Res, 1978 Oct, 5(10), 3565 - 77 Thermodynamics of a stable yeast 5.8S rRNA hairpin helix; Lightfoot D; The 5 . 8S ribosomal RNA of bakers yeast contains one particularly stable hairpin helix which is isolated by partial T1 ribonuclease digestion . Thermal hyperchromism analysis of the hairpin fragment showed that it dissociates cooperatively with 18% hyperchromism, with a Tm of 83 degree C at 2.7 mM sodium ion concentration, and with a hyperchromic difference spectrum indicative of over 90% G + C content . The probable secondary structure for the fragment was used to predict a helix free energy, delta G = -16.2 kcal/mole, which was the same as that determined from the melting equilibrium . The predicted enthalpy however, was 77% of the value, delta H = -114 kcal/mole, determined from the van't Hoff relationship . The effect on these data of a G.U base pair within the 9 base pair helix is discussed. J Bacteriol, 1978 Oct, 136(1), 63 - 8 Relationship between phosphate content and immunochemical properties of subfractions of bakers' yeast mannan; Okubo Y et al.; The mannan of bakers' yeast (Saccharomyces cerevisiae) was fractionated on a column of diethylaminoethyl-Sephadex into five subfractions . Phosphate content of these mannan subfractions was proportional to the concentration of NaCl solutions used in the chromatographic separation . Quantitative precipitin reactions showed that the serological reactivities of the subfractions were proportional to the content of phosphate . The result of acetolysis study showed that the amounts of mannotetraose and phosphate-containing oligosaccharide fractions increased proportionally to the acidity, whereas the amount of mannose decreased inversely . The results from quantitative precipitin reaction tests and acetolysis study demonstrated that both phosphate contents and multiplicity of branching moieties of mannan subfractions increased proportionally, i.e., micro-heterogeneity concerning the acidity comprised in the parent bulk mannan is not attributable merely to the coexistence of molecular species containing different amounts of phosphate but also to the presence of more of the branching moieties. Proc Natl Acad Sci U S A, 1978 Oct, 75(10), 4848 - 52 Glucose-induced conformational change in yeast hexokinase; Bennett WS Jr et al.; The A isozyme of yeast hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1) crystallized as a complex with glucose has a conformation that is dramatically different from the conformation of the B isozyme crystallized in the absence of glucose . Comparison of the high-resolution structures shows that one lobe of the molecule is rotated by 12 degrees relative to the other lobe, resulting in movements of as much as 8 A in the polypeptide backbone and closing the cleft between the lobes into which glucose is bound . The conformational change is produced by the binding of glucose (R.C . McDonald, T.A . Steitz, and D.M . Engelman, unpublished data) and is essential for catalysis {Anderson, C.M., Stenkamp, R.E., McDonald, R.C . & Steitz, T.A . (1978) J . Mol . Biol . 123, 207-219} and thus provides an example of induced fit . The surface area of the hexokinase A-glucose complex exposed to solvent is smaller than that of native hexokinase B . By using the change in exposed surface area to estimate the hydrophobic contribution to the free energy changes upon glucose binding, we find that the hydrophobic effect alone favors the active conformation of hexokinase in the presence and absence of sugar . The observed stability of the inactive conformation of the enzyme in the absence of substrates may result from a deficiency of complementary interactions within the cavity that forms when the two lobes close together. Biokhimiia, 1978 Oct, 43(10), 1743 - 8 {Identification of the functional groups of yeast thiamine pyrophosphokinase}; Voskoboev AI et al.; The content of free sulfhydril groups in yeast thiamine pyrophosphokinase (EC 2.7.6.2) was studied . Their blocking was found not to affect considerably the enzyme activity . N-bromsuccinimide developes the inhibitory effect only if taken in excessive concentrations, which indicates that tryptophane has no key position for the enzyme-substrate complex formation . On account of high speed of photoinactivation with Rose bengale and methilene blue, sigmoid dependence of activity loss on pH under irradiation, characteristic narrowing of the modified enzyme absorption spectrum, it is suggested that imidazole residue of the histidine is one of the functional groups of thiamine pyrophosphokinase. Biochim Biophys Acta, 1978 Sep 28, 530(3), 487 - 502 Formation of 3-hexaprenyl-4-hydroxybenzoate by matrix-free mitochondrial membrane-rich preparations of yeast; Casey J et al.; It has been shown that a 10 000 x g matrix-free mitochondrial membrane-rich preparation from commercial bakers' yeast is able to synthesize 3-all-transhexaprenyl-4-hydroxybenzoate from 4-hydroxybenzoate and isopentenyl pyrophosphate . The synthesis is Mg2+ dependent and is stimulated markedly by the primer for polyprenylpyrophosphate synthesis of 3-hexaprenyl-4-hydroxybenzoate from 4-hydroxybenzoate, isopentenyl pyrophosphate and 3,3-dimethylallyl pyrophosphate the priming function of 3,3-dimethylallyl pyrophosphate can be performed by either geranyl pyrophosphate (most efficient) or farnesyl pyrophosphate . At high Mg2+ concentrations, however, geranyl pyrophosphate and farnesyl pyrophosphate act mainly as sources of preformed side chains and 3-diprenyl- and 3-tripenyl-4-hydroxybenzoate, respectively, are produced . In the presence of a source of preformed polyprenyl pyrophosphates the membrane preparations catalysed the polyprenylation of methyl-4-hydroxybenzoate, 4-hydroxybenzaldehyde, 4-hydroxybenzylalcohol and 4-hydroxycinnamate . No evidence was obtained for the involvement of either 4-hydroxybenzoyl CoA or 4-hydroxybenzoyl-S-protein in the formation of 3-polyprenyl-4-hydroxybenzoates. J Biol Chem, 1978 Sep 25, 253(18), 6303 - 6 The use of orthacryl two-dimensional polyacrylamide gel electrophoresis to identify and compare the subunit polypeptides of bovine heart and yeast cytochrome c oxidases; Poyton RO et al.; A two-dimensional electrophoretic method which takes advantage of the "migration anomalies" experienced by some polypeptides on gels of different porosities has been successfully used to resolve the seven subunit polypeptides of yeast cytochrome c oxidase and the nine polypeptides associated with bovine cytochrome c oxidase . The two-dimensional maps provided by this method reveal clear differences between these two cytochrome c oxidases. Mol Gen Genet, 1978 Sep 20, 165(1), 113 - 4 Inhibition of yeast sporulation by ethidium bromide; Newlon MC et al.; Ethidium bromide blocks ascus formation in the yeast Saccharomyces cerevisiae . This may mean that the presence of the mitochondrial genome is required for sporulation in this organism. Biochemistry, 1978 Sep 19, 17(19), 4033 - 40 Nuclear magnetic resonance studies of inorganic phosphate binding to yeast inorganic pyrophosphatase; Hamm DJ et al.; Yeast inorganic pyrophosphatase is a dimer of identical subunits . Previous work (Rapoport, T.A., et al . (1973) Eur . J . Biochem . 33, 341) indicated the presence of two different Mn2+ binding sites per subunit . In the present work, the binding of inorganic phosphate to the Mn2+-inorganic pyrophosphatase complex has been studied by 1H and 31P nuclear magnetic resonance . Two distinct phosphate sites have been found, having dissociation constants of 0.24 mM and 18 mM . The Mn2+-31P distance from tightly bound Mn2+ to phosphate bound in the low affinity site (6.2 A) is consistent with outer sphere binding . Binding to both phosphate sites can be simultaneously inhibited by the pyrophosphate analogue, hydroxymethanebisphosphonate, providing evidence for the physical proximity of these two sites . The weaker Mn2+ site is apparently far from both phosphate sites . From the magnitudes of the dissociation constants found for both phosphate and analogue binding and the recent work of P.D . Boyer and his co-workers (private communication) on enzyme-catalyzed phosphate-water exchange, it appears unlikely that the hydrolysis of enzyme-bound pyrophosphate is the rate-determining step in the overall enzymatic catalysis of pyrophosphate hydrolysis, at least when Mn2+ is the required divalent metal ion cofactor. Biochemistry, 1978 Sep 5, 17(18), 3825 - 33 Yeast inner histones and the evolutionary conservation of histone-histone interactions; Mardian JK et al.; The inner histones of the yeast, Saccharomyces cerevisiae, have been isolated and identified by their amino acid compositions . H4 appears to be close to its calf and pea counterparts . H2a, H2b, and H3 have diverged . The isolation of the histones was accomplished by consecutive slab-gel fractionation, and a number of novel features of the method are described . These appear to be generally useful for preparing many types of protein . The binding pattern of the yeast inner histones is identical to the binding pattern for calf and for pea histones . Data on interspecies complexing indicate that the surfaces across which the histones interact are very highly conserved. Zh Mikrobiol Epidemiol Immunobiol, 1978 Sep, (9), 127 - 30 {Incidence among children of Candida yeast-like fungi}; Rybakova NA; The incidence of Candida fungi in healthy children and those suffering from noninfectious diseases was studied . In dealthy children--from the time of birth to 7 years--it constituted 39%, and in sick children treated with antibiotics--53% . Dependence of the frequency of Candida fungi state on age was revealed; there was also a correlation between the amount of the fungi and the presence of lesions on the oral mucosa . Candida fungi were also revealed in the washings from the environmental objects, on the pharyngeal mucosa and hands of the personnel, and in the samples of food for children. Infect Immun, 1978 Sep, 21(3), 705 - 13 Delayed hypersensitivity responses of experimental animals to histoplasmin from the yeast and mycelial phases of Histoplasma capsulatum; Scalarone GM et al.; Controlled yeast lysate (CYL) and controlled mycelial lysate (CML) histoplasmins were produced from Histoplasma capsulatum grown in a nutritionally lean, chemically defined medium . The lysates were assayed for skin-test activity in guinea pigs sensitized by infection with the homologous organism . In some studies, nonliving vaccine preparations were employed also . Inter-lot biological variation was minimal, and 20 lots of the CYL reagent elicited strong dermal reactions with high specificity . Further, CYL reagents were nonreactive in guinea pigs infected with Coccidioides immitis, whereas the commercial Food and Drug Administration preparations cross-reacted to some degree . The CML histoplasmins were generally less reactive than the CYL preparations and exhibited somewhat more inter-lot variation in sensitivity and specificity . No correlation between potency and protein:polysaccharide ratios were observed with either reagent . An intradermal test with the CYL reagent did not induce significant changes in the complement-fixing titer of sensitized guinea pigs . Such changes in sensitized animals were elicited by a skin test with commercial histoplasmin. Proc Natl Acad Sci U S A, 1978 Sep, 75(9), 4224 - 8 Electron microscopic heteroduplex analysis of "killer" double-stranded RNA species from yeast; Fried HM et al.; Wild-type and mutant double-stranded RNA (dsRNA) species from the yeast Saccharomyces cerevisiae were studied by electron microscopic heteroduplex mapping to determine the sequence relationships among the different RNA molecules . Three mutant dsRNAs, 1.5, 1.4, and 0.73 kilobase, were found to be derived by the same internal deletion of the wild-type (I83 kilobases) molecule . This deletion includes a wild-type (1.83 kilobases) molecule . This deletion includes a segment of about 200 base pairs that was estimated to be nearly 100% A+U . In addition, the sequences of the two larger mutant RNA species are tandem, direct duplications . One of the duplicated molecules appears to have a second internal deletion that occurred after the duplication . The mutant dsRNAs are functionally similar to the defective interfering virus particles of animal viruses--all of the mutant species prevent the propagation of the wild-type dsRNA when both are present in the same cell . The four dsRNAs share the same sequences at their termini, a finding that may suggest that these sequences are important for the replication of the dsRNAs. J Bacteriol, 1978 Sep, 135(3), 1146 - 8 Differences in crystal violet uptake and cation-induced death among yeast sterol mutants; Bard M et al.; Yeast sterol mutants exposed to crystal violet demonstrated greater dye uptake than the wild type . In addition, exposure for 10 min to hypertonic cation solutions showed a greater decrease in cell viability for mutants than for wild type. Biokhimiia, 1978 Sep, 43(9), 1665 - 9 {Reverse electron transfer from the cytochrome c level in cyanide-resistant mitochondria of the yeast, Candida lipolytica}; Golovchenko NP et al.; The ability of cyanide-resistant mitochondria of yeast Candida lipolytica to perform reverse electron transfer from cytochrome c to alternative oxidase was studied . It was shown that the energy for such a transfer can be provided by high energy intermediates or membrane potential but not by ATP . Reverse electron transfer from cytochrome c is impossible due to energy of NADH and alpha-glycerophosphate oxidation via alternative pathway in the presence of cyanide . These results prove once again that electron transfer via alternative pathway is not connected with the energy accumulation. Eur J Biochem, 1978 Sep 1, 89(2), 425 - 32 Reaction of tRNAPhe from yeast with 1-fluoro-2,4-dinitrobenzene . Attachment sites of the potential antigenic-determining 2,4-dinitrophenyl residues; Watanabe K et al.; The reaction of 1-fluoro-2,4-dinitrobenzene with tRNAPhe from yeast, for the introduction of antigenic-determining 2,4-dinitrophenyl residues into tRNA, took place only at adenosine residues in tRNAPhe . After reaction at pH 8.0 and 50 degrees C two kinds of products were detected: one was ribose-modified adenosine which was derived from the 3' terminus of tRNA, and the other was base-modified adenosine . The sites and extent of the modification of each particular adenosine residue of tRNAPhe were determined as follows: 5 (6% modified), 31 (2%), 35 (36%), 67 (5%), and 76 (51%) . Thus mainly the terminal adenosine and one adenosine in the anticodon loop bear the 2,4-dinitrophenyl residue. Biochim Biophys Acta, 1978 Aug 23, 520(1), 88 - 102 Study of a haploid yeast strain with an unusually high rDNA content . III . Unequal meiotic segregation of the gamma-DNA fraction; Oyen TB et al.; DNA from different strains of Saccharomyces cerevisiae has been fractionated in preparative Ag+/Cs2-SO4 density gradients . The results show that there are real differences in amount of the nuclear satellite component, the gamma-DNA, from one strain to the other . The gamma-DNA forms a homogeneous dense band that contains all the rDNA, and the amount of gamma-DNA estimated from the gradients can be correlated to amount of rDNA derived from rRNA-DNA hybridizations . By various crossings and sporulations we have obtained diploid and haploid strains with gamma-DNA contents ranging from 7 to 20% of the nuclear DNA . During meiosis, the amount of gamma-DNA appears to segregate in a pattern that indicates unequal crossing over as a possible mechanism for differences in gamma-DNA contents. Biochim Biophys Acta, 1978 Aug 23, 520(1), 164 - 74 Yeast phenylalanyl-tRNA synthetase . Properties of the histidyl residues; Raffin JP et al.; Reactivity of the histidyl groups of yeast phenylalanyl-tRNA synthetase was studied in the absence or presence of substrates . In the absence of substrates about 10 histidine residues were found to react with similar kinetic constants . Phenylalanine at 10(-3) M was found to protect two histidyl residues; increasing the amino acid concentration to 5 . 10(-3) M resulted in the protection of two more histidyl groups . tRNAPhe did not afford any protection to histidine residues, but acylated phenylalanyl-tRNA (Phe-tRNAPhe) protected two of the four histidyl groups already protected by phenylalanine . These results suggest the existence of two different sets of accepting sites for phenylalanine: one specific for the free amino acid, the other one specific for the amino acid linked to the tRNA, but being accessible to free phenylalanine, with a somewhat lower binding constant, ATP was found to mask around four histidyl residues against diethylpyrocarbonate modification . By photoirradiation of enzyme-phenylalanine complex in the presence of rose bengale, a significant amount of amino acid was bound to the alpha subunit (Mr = 73 000) of phenylalanyl-tRNA synthetase, confirming that the amino acid binding site is located on this subunit, as previously suggested by modification of thiol groups . Upon irradiation of an enzyme-tRNA complex, almost no covalent binding of tRNA occurred during enzyme inactivation, suggesting that the histidyl residues involved in the enzymic activity are not required for tRNA binding. Biochemistry, 1978 Aug 22, 17(17), 3459 - 68 Aminoacyl-tRNA synthetases from yeast: generality of chemical proofreading in the prevention of misaminoacylation of tRNA; Igloi GL et al.; The specificity of valyl-, phenylalanyl-, and tyrosyl-tRNA synthetases from yeast has been examined by a series of stringent tests designed to eliminate the possibility of artefactual interference . Valyl-tRNA synthetase, as well as activating a number of amino acid analogues, will accept alanine, cysteine, isoleucine, and serine in addition to threonine as substrates for both ATP-PPi exchange and transfer to some tRNAVal species . The transfer is not observed if atempts are made to isolate the appropriate aminoacyl-tRNAVal-C-C-A but its role in the overall aminoacylation can be suspected from both the formation of a stable aminoacyl-tRNAVal-C-C-A(3'NH2) compound and from the stoichiometry of ATP hydrolysis during the aminoacylation of the native tRNA . Similar tests with phenylalanyl-tRNA synthetase indicate that this enzyme will also activate and transfer other naturally occurring amino acids, namely, leucine, methionine, and tyrosine . The tyrosine enzyme, which lacks the hydrolytic capacity of the other two enzymes (von der Haar, F., & Cramer, F (1976) Biochemistry 15, 4131--4138) is probably absolutely specific for tyrosine . It is concluded that chemical proofreading, in terms of an enzymatic hydrolysis of a misacylated tRNA, plays an important part in maintaining the specificity in the overall reaction and that this activity may be more widespread than has so far been suspected. J Biol Chem, 1978 Aug 10, 253(15), 5255 - 8 Phosphorylation of NAD-dependent glutamate dehydrogenase from yeast; Hemmings BA; The NAD-dependent glutamate dehydrogenase from Candida utilis was isolated from 32P-labeled cells following enzyme inactivation promoted by glutamate starvation and found to exist in a phosphorylated form . Analysis of purified, fully active NAD-dependent glutamate dehydrogenase (a form) and inactive NAD-dependent glutamate dehydrogenase (b form) for alkalilabile phosphate revealed that the a form contained 0.09 +/- 0.06 mol of phosphate/mol of enzyme subunit and b form 1.25 +/- 0.06 mol of phosphate/mol of enzyme subunit . Phosphorylation caused a 10-fold reduction in enzyme specific activity . Dephosphorylation (release of 32P) and enzyme reactivation occurred on incubation with cell-free yeast extracts, indicating the presence of a phosphoprotein phosphatase in such preparations. Biochim Biophys Acta, 1978 Aug 7, 525(2), 297 - 306 Selective denaturation of several yeast enzymes by free fatty acids; Tortora P et al.; The denaturation of eight purified yeast enzymes, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, 3-phosphoglycerate kinase, alcohol dehydrogenase, beta-fructosidase, hexokinase and glucose-6-phosphate isomerase, promoted under controlled conditions by the free fatty acids myristic and oleic, is selective . Glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP+ 1 oxidoreductase, EC 1.1.1.49) is extremely sensitive to destabilization and was studied in greater detail . Results show that chain length and degree of unsaturation of fatty acids are important to their destabilizing effect, and that ligands of the enzyme can afford protection . The denaturation process results in more than one altered form . These results can be viewed in the perspective of the possibility that amphipathic substances, and in particular free fatty acids, may play a role for enzyme degradation in vivo, by initiating steps of selective denaturation. Nature, 1978 Aug 3, 274(5670), 438 - 45 Structure and processing of yeast precursor tRNAs containing intervening sequences; O'Farrell PZ et al.; We have isolated a precursor of yeast tRNATyr and shown that it contains an intervening sequence identical to that found in the gene for tRNATyr . The conformation of pre-tRNATyr is similar to that of mature tRNATyr except for the anticodon loop . The loop is sensitive to endonucleolytic cleavage by S1 nuclease near to the ends of the intervening sequence . This pre-tRNA is functionally inactive as it cannot be aminoacylated and the anticodon is not accessible for hydrogen bonding . A crude nuclear extract from yeast contains an excision-ligase activity which will process pre-tRNATyr into mature tRNATyr. Hoppe Seylers Z Physiol Chem, 1978 Aug, 359(8), 999 - 1003 A new inhibitor protein from rat uterus against yeast proteinase B; Afting EG et al.; An inhibitor of yeast proteinase B has been enriched from uterine smooth muscle (myometrium) of the rat . This inhibitor behaves like a glycoprotein and has a molecular weight of 90 000 . It activity can be clearly distinguished from the proteinase inhibitory activity of serum . Proteinase B inhibitory activity has also been demonstrated in liver, lung, heart, skeletal muscle, spleen and brain and these activities, too, are clearly distinguishable from the serum inhibitory activity . The activity in rat uterus decreases during the postpartal period. Mutat Res, 1978 Aug, 51(2), 181 - 8 Determination of radiation equivalence of ethyl methanesulphonate (EMS) for induction of gene conversion in diploid yeast; Murthy MS et al.; A unit Rad-Equivalent Chemical (REC) has been suggested for purposes of quantitating the mutagenic hazards of chemicals . The usefulness of this approach is demonstrated by the establishment of a constant relationship between the forward mutation frequency and haploid genome size in various organisms for both radiation and chemical EMS . However, it is necessary to determine the radiation equivalence of chemicals in as many organisms and for as many end-points as possible . For end-points we are limited to forward mutations . Another relevant genetic end-point of interest in this regard is gene conversion which can also monitor any kind of DNA damage in a suitable diploid system . Hence, we have determined the REC value for EMS in diploid yeast with gene conversion as the end-point . This agrees well with the REC values estimated in a number of organisms with forward mutation as the end-point . This finding further underlines the generality of the REC concept. J Bacteriol, 1978 Aug, 135(2), 436 - 44 Replication of bromodeoxyuridylate-substituted mitochondrial DNA in yeast; Leff J et al.; The DNA of several strains of Saccharomyces cerevisiae was labeled by growing the culture in medium supplemented with thymidylate and bromodeoxyuridylate . It was thus possible to follow the course of mitochondrial DNA replication in density shift experiments by determining the buoyant density distribution of unreplicated and replicated DNAs in analytical CsCl gradients . DNA replication was followed for three generations after transfer of cultures from light medium to heavy medium and heavy medium to light medium . Under both conditions, the density shifts observed for mitochondrial DNA were those expected for semiconservative, nondispersive replication . This was further confirmed by analysis of the buoyant density of alkali-denatured hybrid mitochondrial DNA . With this method, no significant recombination between replicated and unreplicated DNA was detected after three generations of growth. Mutat Res, 1978 Aug, 54(1), 27 - 32 Photolytic binding of the monoazido analog of ethidium to yeast mitochondrial DNA: competition by ethidium; Morita T et al.; The {14C}-labeled monoazido analog of ethidium, 3-amino-8-azido-5-ethyl-6-phenylphenanthridinium chloride, when mixed with yeast cells and photolyzed, produced covalent adducts with both nuclear and mitochondrial DNA via the light-generated nitrene . The binding efficiency was about 12 times higher in mitochondrial than nuclear DNA . Moreover, the parent ethidium bromide at a 5-fold excess was an effective competitor for the binding of the monoazide analog with mitochondrial DNA, but not with nuclear DNA. Genetics, 1978 Aug, 89(4), 653 - 65 Deletions of the iso-1-cytochrome c and adjacent genes of yeast: discovery of the OSM1 gene controlling osmotic sensitivity; Singh A et al.; Some of the deletions in the yeast Saccharomyces cerevisiae that encompass the CYC1 gene, which determines iso-1-cytochrome c, extend into the OSM1 gene, causing inhibition of growth on hypertonic media, and into the RAD7 gene, causing sensitivity to UV light . Two deletions (cyc1--363 and cyc1--367) encompass only the CYC1 gene, two deletions (cyc1--366 and cyc1--368) encompass the CYC1 and OSM1 genes, three deletions (cyc1--1, cyc1--364 and cyc1--365) encompass the CYC1, OSM1 and RAD7 genes, while none of the deletions extend into the closely linked SUP4 gene. Biotechnol Bioeng, 1978 Aug, 20(8), 1235 - 47 Toxic effects of fatty acids on yeast cells: possible mechanisms of action; Hunkova Z et al.; As shown in a previous paper, threshold concentrations of lower and intermediate fatty acids inhibit the uptake of inorganic phosphate, growth, and cell division in yeast cells . This demonstrates that, apart from these effects, the acids cause an increase in the respiration quotient (RQ), inhibition of CO2 fixation, production of ethanol at the expense of anabolic processes, and inhibition of active amino acid transport in the yeast Candida utilis . On the other hand, the threshold concentrations have no effect on intracellular pH . The inhibition of the inorganic phosphate uptake cannot be the sole primary mode of action of fatty acids since the omission of inorganic phosphate in the incubation medium brings about an inhibition of anabolic processes that is lower than that brought about by fatty acids since the omission of inorganic phosphate in the incubation medium brings about an inhibition of anabolic processes that is lower than that brought by fatty acids at concentrations still premitting some phosphate uptake . Although 2,4-dinitrophenol and caproic acid at low concentrations cause an analogous decrease in biomass yield, their combination does not bring about any marked increase in the effect . Considering the physicochemical properties of fatty acids and their preferential action on energy-requiring processes, one of the key sites of action can be assumed to be the mitochondrial membrane . Fatty acids might inhibit the transport of anions, especially phosphate, across the membrane, and disturb the membrane potential by affecting the transport protons . The physiocochemical properties of fatty acids may also give rise to their binding to other intracellular membranes and to a subsequent interference with the function of the corresponding organelles. Chromosoma, 1978 Jul 31, 67(3), 263 - 74 Folded chromosomes in non-cycling yeast cells: evidence for a characteristic g0 form; Pinon R; Folded chromosomes from stationary phase or ammonia-starved yeast (Saccharomyces cerevisiae) cells can be isolated as compact structures, distinct and separable by sedimentation from the folded chromosomes of pre-replicative (G1) and post-replicative (G2) nuclei . Such cells are in a dormant or non-cycling (G0) stage . The folded genome from such cells is referred to as the g0 form and has a sedimentation velocity of about 1700S . Sedimentation analysis of mixed G0 and G1 and G2 lysates indicates that the g0 structure is not an artifactual breakdown product of the g1 or g2 structures . A comparison of the proteins from g0 versus g1 and g2 structures by gel electrophoresis has revealed differences in about 10--11 non-histone and perhaps 2 histone proteins . Entry into the G0 stage, and emergence into G1 after G0 arrest, are accompanied by an ordered transition from g2 to g1 to g0, and from g0 to g1 to g2 forms, respectively . Hence, entry into G0 and re-emergence from G0 can be considered as differentiative processes, not normally part of the cell cycle, and accompanied by specific changes in the tertiary organization of the genome. Mycopathologia, 1978 Jul 28, 63(2), 105 - 11 {Study of the Sporothrix schenkii (yeast forms) extract . Electrophoretic and immunoelectrophoretic analyses: characterization of enzymatic activities}; Walbaum S et al.; An extract from living yeast forms of S . schenckii was prepared . The yeasts originated from a shake culture in B.H.I . broth (Difco) incubated for 3 days at 35 degrees C in darkness; they were harvested, washed and disrupted with glass beads in a model MSK Braun mechanical cell homogenizer; a freezing-thawing was added to improve the extract . After electrophoretic separation in agarose gel, the extract's components were characterized by their enzymic activity; with this technique, 30 bands were revealed . These enzymic activities were also investigated on the antigenic fractions of the extract revealed by a rabbit hyperimmunserum: 16 among 22 immunoprecipitates are identified by their catalytic properties . Study of the earliest precipitating antibodies (appearing-order and enzymic caracterization) in rabbits just immunized completes this work . How to ameliorate the quality of the extract by culture and extraction conditions is also specified. J Biol Chem, 1978 Jul 10, 253(13), 4574 - 83 Squalene synthetase . Solubilization from yeast microsomes of a phospholipid-requiring enzyme; Agnew WS et al.; Squalene synthetase was solubilized from yeast microsomal membranes with deoxycholate . Solubilized enzyme was associated with one or more proteins with s20, w = 3.3 S, Stokes' radius = 40 A, and computed molecular weight = 54,500 . In the presence of detergent the enzyme was catalytically inactive and unstable to heat . When detergent was removed with cholestyramine resin, both phases of squalene synthesis (farnesyl pyrophosphate leads to presqualene pyrophosphate leads to squalene) were recovered, and the enzyme was reaggregated to form sedimentable particles with a density of approximately 1.16 g/ml . Both activities were lost to variable extent upon chromatography over Sephadex G-200 in the presence of 0.2% deoxycholate, but could be recovered if phosphatidylcholine or phosphatidylethanolamine (but not phosphatidylserine or phosphatidylinositol) were added to fractions before removal of detergent . There was an apparently absolute requirement for phospholipid by the enzyme . The proteins catalyzing the two phases of squalene synthesis could not be resolved from one another and behaved in an identical fashion throughout a variety of manipulations. J Biol Chem, 1978 Jul 10, 253(13), 4505 - 7 The release and reassociation of 5.8 S rRNA with yeast ribosomes; Nazar RN; Yeast 5.8 S rRNA is released from purified 26 S rRNA when it is dissolved in water or low salt buffer (50 mM KCl, 10mM Tris-HCl, pH 7.5); it is not released from 60 S ribosomal subunits under similar conditions . The 5.8 S RNA component together with 5 S rRNA can be released from subunits or whole ribosomes by brief heat treatment or in 50% formamide; the Tm for the heat dissociation of 5.8 S RNA is 47 degrees C . This Tm is only slightly lower when 5 S rRNA is released first with EDTA treatment prior to heat treatment . No ribosomal proteins are released by the brief heat treatment . A significant portion of the 5.8 S RNA reassociates with the 60 S subunit when suspended in a higher salt buffer (e.g.0.4 m KCl, 25 mM Tris-HCl, pH 7.5, 6 mM magnesium acetate, 5 mM beta-mercaptoethanol) . The Tm of this reassociated complex is also 47 degrees C . The results indicate that in yeast ribosomes the 5.8 S-26 S rRNA interaction is stabilized by ribosomal proteins but that the association is sufficiently loose to permit a reversible dissociation of the 5.8 S rRNA molecule. Mol Gen Genet, 1978 Jul 6, 163(1), 87 - 90 Recessive nonsense-suppression in yeast: involvement of 60S ribosomal subunit; Smirnov VN et al.; The ribosomal protein patterns of recessive suppressor strain and parent strain of Saccharomyces cerevisiae were analyzed by two-dimensional polyacrylamide gel electrophoresis . About 30 proteinspots were found for ribosomal proteins of small subunit for both mutant and parent strain . These patterns do not differ from each other neither in intensity of staining, nor in mobility of spots . 41 protein spots were found in electrophoregrams of 60S ribosomal proteins both from parent strain and recessive suppressor strain . The electrophoretic picture of the 60S proteins from the parent and mutant strains is similar except the intensity of staining of the L30 spot . This protein is present in 60S subunit of suppressor strain and completely absent or only weakly stained on electrophoregrams of ribosomal proteins of parent strain . The possible relationships between the content of L30 protein and the mechanism of recessive suppression in yeast are discussed. Mol Gen Genet, 1978 Jul 6, 163(1), 29 - 34 Affinity labelling of yeast ribosomal peptidyl transferase; Perez-Gosalbez M et al.; Using p-nitrophenylcarbamyl-phenylalanyl-tRNA (PNPC-Phe-tRNA) and N-Iodoacetylphenylalanyl-tRNA as affinity labels we have attempted to identify the components of the aminoacyl-tRNA binding sites located in the vicinity of the peptidyl transferase centre of the yeast ribosome . Both Phe-tRNA derivatives bind to the ribosomal A-site in the presence of 20 mM Mg++ ion concentration and can be translocated to the ribosomal P-site in the presence of elongation factor . After the labels have been allowed to react covalently with ribosomes they were found associated with the large ribosomal subunit . Proteins L36, L43, L42, L29, L2, L17/18, L19/20 and proteins L26, L38, L22/23, L7/9, L4/6, L36, L11, L43, L39 were labelled in samples treated with PNPC-Phe-tRNA and N-iodoacetyl-Phe-tRNA respectively . In contrast, when only the components of the ribosomal P-site were analysed by reacting the treated particles with puromycin fewer spots were labelled, corresponding to proteins L36 and L19/20 using PNPC-Phe-tRNA and proteins L4/6, L36, and L43 using N-Iodoacetyl-Phe-tRNA. Mol Gen Genet, 1978 Jul 4, 162(3), 319 - 22 Yeast mutant, rna 1, affects the entry into polysomes of ribosomal RNA as well as messenger RNA; Petersen NS et al.; The entry of newly labeled ribosomal subunits and mRNA into polysomes was examined in the yeast mutant rna1 . The entry of both types of RNA into polysomes is inhibited rapidly at the restrictive temperature . Analysis of the labeling of the ATP pool and the kinetics of synthesis and processing of mRNA at the restrictive temperature leads to the conclusion that the primary defect in the mutant affects transport of both ribosomes and messenger across the nuclear membrane. Mol Gen Genet, 1978 Jul 4, 162(3), 259 - 68 Yeast ribosomal proteins . I . Characterization of cytoplasmic ribosomal proteins by two-dimensional gel electrophoresis; Otaka E et al.; The cytoplasmic 80s ribosomal proteins from the cells of yeast Sachharomyces cerevisiae were analysed by SDS two-dimensional polyacrylamide gel electrophoresis . Seventyfour proteins were identified and consecutively numbered from 1 to 74 . Upon oxidation of the 80s proteins with performic acid, ten proteins (no . 15, 20, 35, 40, 44, 46, 49, 51, 54 and 55) were dislocated on the gel without change of the total number of protein spots . Five proteins (no . 8, 14, 16, 36 and 74) were phosphorylated in vivo as seen in 32P-labelling experiments . The large and small subunits separated in low magnesium medium were analyzed by the above gel electrophoresis . At least forty-five and twenty-eight proteins were assumed to be in the large and small subunits, respectively . All proteins found in the 80s ribosomes, except for no . 3, were detected in either subunit without appearance of new spots . The acidic protein no . 3 seems to be lost during subunit dissociation. Eur J Biochem, 1978 Jul 3, 87(3), 489 - 95 Evidence for catabolite degradation in the glucose-dependent inactivation of yeast cytoplasmic malate dehydrogenase; Neeff J et al.; The cytoplasmic malate dehydrogenase of Saccharomyces cerevisiae was radioactively labeled during its synthesis on a glucose-free derepression medium . After purification a sensitive radio-immunoassay for this enzyme could be developed . The assay showed that after the physiological, glucose-dependent 'catabolite inactivation' of cytoplasmic malate dehydrogenase an inactive enzyme protein is immunologically not detectable . Together with the irreversibility of this reaction in vivo this finding strongly suggest a proteolytic mechanism of enzyme inactivation . For this process the term 'catabolite degradation' is used. Prikl Biokhim Mikrobiol, 1978 Jul-Aug, 14(4), 523 - 6 {Induced methanol dehydrogenase in the yeast Hansenula polymorphia DL-1}; Dudina LP et al.; The yeast Hansenula polymorpha DL-I showed NAD-specific dehydrogenase activity involved in the methanol primary oxidation . This enzyme was found to be induced during periodic and continuous H . polymorpha cultivation, using methanol as the sole source of carbon and energy . The enzyme was absent during yeast cultivation on the glucose and ethanol containing medium. Mikrobiologiia, 1978 Jul-Aug, 47(4), 765 - 7 {Nature of wine yeast glutamate dehydrogenase inhibition by adenylic nucleoside phosphates}; Kardash NK et al.; The mode of inhibition of NADP-dependent glutamate dehydrogenase by adenylic nucleoside phosphates (ATP, ADP, AMP) was studied with Saccharomyces vini . AMP was found to be a competitive inhibitor for glutamate dehydrogenase whereas the action of ADP and ATP was of a mixed character. Biokhimiia, 1978 Jul, 43(7), 1260 - 5 {Effect of detergents on the main respiratory chain and cyanide-resistant pathway of electron tranfer of Candida lipolytica yeast mitochondria}; Medentsev AG et al.; Effects of detergents--triton X-100 and deoxycholate--on the main respiratory chain and cyanide-resistant electron transfer pathway in the mitochondria of Candida lipolytica yeast were studied . Triton X-100 and deoxycholate were shown to completely inhibit the activity of alternative oxidase at concentrations of 0.7 and 1.2 mM, respectively . At these concentrations the detergents did not inhibit the activity of the main respiratory chain . The inhibiting effect of triton X-100 was exerted both in the presence of Mg2+ and without them, whereas the inhibiting action of deoxycholate was observed in the presence of Mg2+ . The addition of asolektine in the presence of Mg2+ prevented the inhibiting effect of detergents . These data lead us to the conclusion that inhibition of electron transfer through the alternative pathway is caused by separation of alternative oxidase from the main respiratory chain with the disturbance of structural integrity of inner mitochondrial membrane under the action of detergents . Inhibition of electron transfer in the alternative pathway does not decrease the rate of oxygen consumption by mitochondria . Therefore, the main respiratory chain in the presence of detergents can provide for transfer of all reducing equivalents which were earlier transferred both by the respiratory chain itself and by alternative oxidase. Int J Radiat Biol Relat Stud Phys Chem Med, 1978 Jul, 34(1), 17 - 26 On the nature of damage involved in liquid-holding recovery in diploid yeast after gamma- and alpha-irradiation; Rao BS et al.; Cells surviving after liquid-holding recovery following gamma- and alpha-irradiations are found to be slightly more sensitive to a second series of radiation doses . Further, the shoulder on the gamma survival curve of the pre-irradiated and liquid-held cells disappears . The shoulder and sensitivity are restored only when these cells are grown in broth before the second series of doses . In addition to this, liquid-holding recovery reduces progressively if the cells after irradiation are incubated in broth for different periods of time before holding . These observations suggest that: (1) the so-called potentially lethal damage may consitute that part of the sub-lethal damage which interact with one another to form lethal damage; (2) during liquid-holding, the interaction among sub-lethal damage transforming them to the status of lethal damage is inhibited; (3) the 'recovered' cells are saturated with sub-lethal damage, the repair of which will be completed only when the cells are placed in a nutrient medium . The inhibitory process is not a passive one, but requires energy metabolism. Proc Natl Acad Sci U S A, 1978 Jul, 75(7), 3133 - 7 Evaluation of the partitioning of bound inorganic phosphate during medium and intermediate phosphate in equilibrium water oxygen exchange reactions of yeast inorganic pyrophosphatase; Hackney DD et al.; During the rapid exchange of oxygens of Pi with water catalyzed by yeast inorganic pyrophosphatase, Pi at the catalytic site may either dissociate or undergo reversible loss of an oxygen to water . The effective partitioning of bound Pi during exchange starting with medium Pi containing 18O in all four oxygens has been evaluated by mass spectral analysis of the change in the distribution of Pi species containing zero to four 18O oxygens per Pi . This analysis indicates that the rate of Pi release from the enzyme is only 1.4 times faster than the rate of reformation of the anhydrous intermediate . A similar partitioning of bound Pi is observed during PPi hydrolysis, indicating that hydrolysis and medium exchange have common intermediates . The approach should be applicable to study of related phosphate oxygen exchanges. Mutat Res, 1978 Jul, 51(1), 11 - 9 Biochemical analysis of damage induced in yeast by formaldehyde . II . Induction of cross-links between DNA and protein; Magana-Schwencke N et al.; Exposure of Saccharomyces cerevisiae cells to formaldehyde-induced cross-links between DNA and proteins . This damage was demonstrated by three different techniques . Ultraviolet irradiation also produced cross-links between DNA and proteins in yeast. Cell, 1978 Jul, 14(3), 673 - 80 Identification and isolation of the yeast cytochrome c gene; Montgomery DL et al.; The iso-1-cytochrome c gene of yeast has been identified and cloned using a synthetic oligodeoxynucleotide as a hybridization probe . The oligomer d{pT-T-A-G-C-A-G-A-A--C-C-G-G} is complementary to a region near the N terminal coding region of the yeast cyc 1 gene . Of several yeast Eco RI fragments which hybridize to this probe, one is changed in size by a G leads to T mutation which eliminates an Eco RI site within the cyc 1 gene . Both the wild-type and the RI- mutant forms were cloned in lambda gt vectors . Maxam-Gilbert sequencing for 91 nucleotides into the coding region for iso-1-cytochrome c yielded a DNA sequence in perfect correspondence with the known protein sequence. J Bacteriol, 1978 Jul, 135(1), 39 - 44 Kinetics of glucose repression of yeast cytochrome c; Zitomer RS et al.; The kinetics of glucose repression of cytochrome c synthesis was measured by a radioimmune assay . When 5 or 10% glucose was added to a derepressed culture, the rate of cytochrome c synthesis was reduced to the repressed level with a half-life of 2 min . The addition of 1 or 0.5% glucose repressed the rate of cytochrome c synthesis to the same level as high glucose concentrations but with a longer half-life of 3 min . Glucose repression had no effect on the stability or function of the cytochrome c protein . Cellular levels of active cytochrome c mRNA during glucose repression were measured by translation of total cellular polyadenylic acid-containing RNA and immunoprecipitation cytochrome c from the translation products . The results of these measurements indicate that glucose represses the rate of cytochrome c synthesis through a reduction in the level of translatable cytochrome c mRNA. Biochemistry, 1978 Jun 27, 17(13), 2654 - 8 Role of arginyl residues in yeast hexokinase PII; Borders CL Jr et al.; Yeast hexokinase PII is rapidly inactivated (assayed at pH 8.0) by either butanedione in borate buffer or phenylglyoxal, reagents which are highly selective for the modification of arginyl residues . MgATP alone offers no protection against inactivation, consistent with low affinity of hexokinase for this nucleotide in the absence of sugar . Glucose provides slight protection against inactivation, while the combined presence of glucose and MgATP gives significant protection, suggesting that modified arginyl residues may lie at the active site, possibly serving to bind the anionic polyphosphate of the nucleotide in the ternary enzyme:sugar:nucleotide complex . Extrapolation to complete inactivation suggests that inactivation by butanedione correlates with the modification of 4.2 arginyl residues per subunit, and complete protection against inactivation by the combined presence of glucose and MgATP correlates with the protection of 2 to 3 arginyl residues per subunit . When the modified enzyme is assayed at pH 6.5, significant activity remains . However, modification by butanedione in borate buffer abolishes the burst-type slow transient process, observed when the enzyme is assayed at pH 6.5, to such an extent that after extensive modification the kinetic assays are characterized by a lag-type slow transient process . But even after extensive modification, hexokinase PII still demonstrates negative cooperativity with MgATP and is still strongly activated by citrate when assayed at pH 6.5. Biochemistry, 1978 Jun 27, 17(13), 2530 - 6 Initiation of enzymatic DNA synthesis by yeast RNA polymerase I; Plevani P et al.; In vitro DNA synthesis by yeast DNA polymerase I can be initiated by partially purified yeast RNA polymerases in the presence or absence of rNTPs . Homogeneous yeast RNA polymerase I initiates DNA synthesis by yeast DNA polymerase I on single-stranded DNA templates only in the presence of all four rNTPs . A protein capable of initiating enzymatic DNA synthesis on single-stranded DNA in the absence of rNTPs has also been separated from partially purified yeast RNA polymerase I fractions . Analysis of the RNA polymerase I initiated replication products of phage fd DNA on alkaline sucrose gradients showed noncovalent linkage between the newly synthesized DNA and the template . Isopycnic analyses of the ribonucleotide initiated fd DNA replication products demonstrated covalent linkage between the initiator RNA and newly synthesized DNA . Results from 32P-transfer experiments confirmed the covalent linkage between RNA and DNA chains and showed the presence of all four ribo- and deoxyribonucleotides at the RNA--DNA junctions . The ribonucleotide found most frequently at the RNA--DNA junction is uridylate and the purine deoxynucleotides occur more frequently than pyrimidine deoxynucleotides. Biochemistry, 1978 Jun 27, 17(13), 2510 - 6 Phosphate transport in yeast mitochondria: purification and characterization of a mitoribosomal synthesis dependent proteolipid showing a high affinity for phosphate; Guerin M et al.; It is possible to obtain from yeast mitochondria a proteolipid able to bind phosphate, by two different procedures . One of them, generally used for lipid extraction, leads to the preparation of a more active crude proteolipid . This crude proteolipid has been purified by various chromatographic procedures and the active fraction, in phosphate binding, is always associated with cardiolipin . Its molecular weight seems to be close to 10000 . The phosphate binding shows ligand saturation behavior and is inhibited by arsenate and N-ethylmaleimide; succinate is noninhibitory . This protein seems to be dependent on the mitoribosomal synthesis since it is not present in mitochrondria of mutant "petite colonie" and its amount largely decreases in mitochondria from yeast grown in the presence of chloramphenicol . It is possible to extract a proteolipid from the oligomycin sensitive ATPase, showing the same activity and properties . The hypothesis that this proteolipid acts as a part of the Pi carrier and constitutes the oligomycin-sensitive ATPase complex is discussed. J Biol Chem, 1978 Jun 25, 253(12), 4419 - 25 Solubilization and partial purification of yeast chitin synthetase . Confirmation of the zymogenic nature of the enzyme; Duran A et al.; Chitin synthetase was solubilized with digitonin from a particulate yeast fraction . The solubilized enzyme, which did not sediment at 200,000 X g and emerged after the void volume in a Sepharose 6B column, was active only after treatment with a protease . This confirms that chitin synthetase exists in the plasma membrane as a zymogen and that initiation of the chitin septum occurs by localized activation of the enzyme . By differential extraction with sodium cholate and digitonin, followed by chromatography on Sepharose 6B, a 20-fold purification of the enzyme was achieved with respect to the crude particles . The purified enzyme showed a requirement for a phospholipid; phosphatidylserine and lysophosphatidylserine were the best activators . Unsaturated fatty acids strongly inhibited synthetase activity, whereas their saturated counterparts were inert . The solubilized enzyme catalyzed the formation of insoluble chitin in the absence of added primer . The synthetic polysaccharide was examined by electron microscopy and found to consist of lozenge-shaped particles about 60 nm long and 10 nm wide. J Biol Chem, 1978 Jun 25, 253(12), 4396 - 401 Identification of cytochrome c oxidase subunits in nuclear yeast mutants lacking the functional enzyme; Cabral F et al.; Yeast mutants specifically lacking cytochrome c oxidase activity were screened for cytochrome c oxidase subunits by one- and two-dimensional electrophoresis, electrophoresis in exponential gradient gels, and immunoprecipitation with antisera against one or more of the cytoplasmically made subunits of the enzyme . Two cytochrome c oxidase-less nuclear mutants previously described from this laboratory each lack one or more mitochondrially synthesized cytochrome c oxidase subunits while possessing all four cytoplasmically synthesized subunits of that enzyme . The subunits remaining in these mutants were not assembled with each other; the cytoplasmically made subunits IV and VI could be released from the mitochondria by sonic oscillation, in contrast to the situation in wild type cells . No electrophoretically detectable alterations were found in any of the cytochrome c oxidase subunits present in the mutants . Nuclear mutations may thus cause both a loss as well as a defective assembly of mitochondrially made cytochrome c oxidase subunits. Mol Gen Genet, 1978 Jun 14, 162(2), 221 - 8 8-hydroxyquinoline inhibition of DNA synthesis and intragenic recombination during yeast meiosis; Mills D; Complete inhibition of sporulation was observed in two strains of Saccharomyces cerevisiae to which 8-hydroxyquinoline was added at a final concentration of 5 microgram/ml during the initial 4 to 6 h of sporulation . The cells were most sensitive to the inhibitor during 4 to 6 interval beginning at approximately 2 h (T2) . Its addition during that interval resulted in 70 to 80% lethality in strain 4579 and about 40% in API at T24 . When present from T0 onward, 5 microgram/ml of 8-hydroxyquinoline severely inhibited premeiotic DNA replication and reduced the frequency of intragenic recombination at the ade 2 and leu 2 loci by 70 and 100%, respectively, relative to control cultures which did not have the inhibitor present . During the period when the cells were most sensitive, the incorporation of 14C-leucine into protein and 14C-adenine into RNA was not inhibited nor was the polysome content affected . At 150 microgram/ml of inhibitor, incorporation of labeled precursors into RNA and protein were inhibited and the percentage of active ribosomes was reduced by 35% within 45 min, but neither transcription or translation appeared to be completely inhibited at this concentration of the inhibitor. Mol Gen Genet, 1978 Jun 14, 162(2), 183 - 90 The modification of induced genetic change in yeast by an amino acid analogue; Davies PJ et al.; Treatment of diploid yeast cultures with the amino acid analogue, para-fluorophenylalanine (PFPA), at concentrations which caused inhibition of growth, resulted in up to 5 fold increases in the frequency of mitotic gene conversion at two different heteroallelic loci . With haploid yeast cultures, growth in PFPA increased the rate of forward mutation to canavanine resistance by at least 2 fold . Growth of diploids in PFPA prior to exposure to the deaminating agent nitrous acid, the cross-linking agent mitomycin C, the alkylating chemical ethylmethanesulphonate (EMS) and UV light resulted in significant changes in the potency of these diverse mutagens to induce intragenic recombination . For all four mutagens, increased frequencies of gene convertants/viable cell were observed in those cultures which had been exposed to the amino acid analogue prior to mutagen treatment . In haploid WT yeast cells, amino acid analogue incorporation resulted in an enhanced frequency of UV induced forward mutation to canavanine resistance whilst in a DNA repair deficient rad 6 mutant this interaction between UV and PFPA was abolished . The results have been interpreted on the basis of incorporation of the analogue into enzymes involved with DNA replication with a consequent loss of fidelity of such enzymes and increased errors in base incorporation. Biochim Biophys Acta, 1978 Jun 9, 524(2), 418 - 27 Comparison of a nitrate reductase-inactivating enzyme from the maize root with a protease form yeast which inactivates tryptophan synthase; Wallace W; A maize root fraction which inactivates nitrate reductase has been shown to have protease activity which can be measured by the hydrolysis of azocasein . This inactivating enzyme was also found to inactivate yeast tryptophan synthase . Yeast proteases A and B, which inactivate this latter enzyme, also gave a specific inactivation of the maize nitrate reductase . The maize root inactivating enzyme, like yeast protease B, degraded casein, and was inhibited by phenylmethylsulphonyl fluoride . A partially-purified yeast inhibitor prevented catalysis by the yeast proteases and maize root inactivating enzyme, but purified yeast inhibitors were without effect on the latter protein . The level of nitrate reductase-inactivating activity, and associated azocasein-degrading activity, increased with age of the maize root . Evidence was obtained for a heat stable inhibitor which maintained them in an inactive state, especially in the young root tip cells. Science, 1978 Jun 9, 200(4346), 1171 - 3 A mutant of yeast defective in cellular morphogenesis; Sloat BF et al.; In the budding yeast Saccharomyces cerevisiae, each bud appears within a ring of chitin formed in the cell wall of the mother cell . Temperature-sensitive mutants defective in gene cdc24 synthesize chitin at restrictive temperatures, but do not organize it into the discrete rings found in normal cells, nor do they form buds . The chitin ring or an annular precursor structure may play an essential role in reinforcing the region of the cell wall involved in budding. Biochem Genet, 1978 Jun, 16(5-6), 415 - 32 Functional mutants of yeast alcohol dehydrogenase affecting kinetics, cellular redox balance, and electrophoretic mobility; Wills C et al.; Repeated selection of petite (respiratorily incompetent) Saccharomyces cerevisiae on medium containing allyl alcohol, both on plates and in the turbidostat, results in mutants with a remarkably similar response . Most of the mutations affect the constitutive alcohol dehydrogenase, resulting in enzymes with a cathodal shift in electrophoretic mobility, and none shows a significant anodal shift . The genetics, kinetics, and physiological effect of three of the mutants have been investigated in detail, and while all confer resistance to allyl alcohol through a shift in the NAD/NADH ratio, they do so in slightly different ways . The potential of this system for exploring the range of short-term adaptations open to this organism is discussed. Nucleic Acids Res, 1978 Jun, 5(6), 2055 - 71 Analysis of the steady-state mechanism of the aminoacylation of tRNAPhe by phenylalanyl-tRNA synthetase from yeast; Thiebe R; The steady-state mechanism of the aminoacylation of tRNAPhe by the corresponding synthetase from yeast has been investigated in detail by kinetic experiments . It was found that there are two alternative mechanisms: one favoured at low tRNA concentrations and the other at high tRNA concentrations . ATP and Phe are bound randomly to the enzyme . AMP is released immediately after the binding of ATP and Phe . Between the release of AMP and pyrophosphate (PPi) there is at least one additional step . Based on the experimental results a model of the steady-state mechanism is proposed . This model includes the sequence of addition of substrates to the enzyme and the release of products from the enzyme as well as the composition of the intermediate complexes with the enzyme . This model is in accordance with previous results based on different techniques . The results are explained by a "flip-flop" mechanism for all the substrates and products involved in the reaction. Nucleic Acids Res, 1978 Jun, 5(6), 1907 - 17 Transcription of DNA-histone complexes by yeast RNA polymerase B; Karagyozov LK et al.; Transcription of denatured DNA complexed with histones (total, H1 or H2A/H2B/H3/H4) by yeast RNA polymerase B is investigated . Binding of histones to DNA restricts its template activity by decreasing the formation of active, heparin-resistant, RNA polymerase initiation complexes . The elongation of pre-initiated RNA on denatured DNA, complexed with histones, is possible, although resulting in somewhat shorter RNA chains . It is suggested that RNA polymerase B can elongate on a DNA strand covered with histones. J Virol, 1978 Jun, 26(3), 762 - 72 Relatedness of the double-stranded RNAs present in yeast virus-like particles; Bruenn J et al.; The relatedness of several double-stranded RNAs (dsRNA's) present in the virus-like particles of yeast was examined by T1 fingerprint analysis . The dsRNA's examined were L, the dsRNA encoding the capsid polypeptide of yeast virus-like particles; M, which appears to code for a toxic polypeptide and for resistance to the effects of the toxin; and two S dsRNA's present in particles analogous to the defective interfering particles of animal viruses . S3, a dsRNA of 0.46 X 10(6) daltons, was derived entirely from M, a dsRNA of 1.2 X 10(6) daltons . S1, a dsRNA of 0.92 X 10(6) daltons, was a duplication of S3 . This conclusion has also been reached independently by heteroduplex mapping techniques (H . M . Fried and G . R . Fink, personal communication) . S1 and S3, at least in one yeast strain, were unstable in sequence, apparently due to the accumulation of sequence variants of the same molecular weight . L was a species of 3 X 10(6) daltons, unrelated in sequence to M, S1, or S3 . S1, S3, and M had a 3' T1 dodecanucleotide in common. Eur J Biochem, 1978 Jun 1, 87(1), 55 - 68 Metabolism of 2-deoxy-2-fluoro-D-{3H}glucose and 2-deoxy-2-fluoro-D-{3H}mannose in yeast and chick-embryo cells; Schmidt MF et al.; 2-Deoxy-2-fluoro-D-{3H}glucose and 2-deoxy-2-fluoro-D-{3H}mannose have been prepared by tritiation of the corresponding unlabeled 2-fluoro sugars . The tritiated 2-fluoro sugars are phosphorylated and activated by UTP and by GTP to yield UDP-2-deoxy-2-fluoro-D-{3H}glucose, UDP-2-deoxy-2-fluoro-D-{3H}mannose, GDP-2-deoxy-2-fluoro-D-{3H}glucose and GDP-2-deoxy-2-fluoro-D-{3H}mannose in both cell types . The nucleotide derivatives could also be labeled in the nucleotide moiety by feeding the cells with {14C}uridine or {14C}guanosine in the presence of unlabeled 2-fluoro sugar . No evidence was obtained for metabolic steps in which the six-carbon chain of 2-fluoro sugars was not preserved . No epimerisation of the label to 2-deoxy-2-fluoro-D-{3H}galactose could be observed by radioactive gas-liquid chromatography of the enzymatic cleavage products of the different 2-fluoro sugar metabolites isolated from either cell type . Yeast and chick embryo cells both incorporate 2-deoxy-2-fluoro-D-{3H}glucose and 2-deoxy-2-fluoro-D-{3H}mannose specifically into glycoproteins, although this incorporation is very low when compared to the incorporation of 2-deoxy-D-{3H}glucose. Cell, 1978 Jun, 14(2), 221 - 36 Transcription and processing of intervening sequences in yeast tRNA genes; Knapp G et al.; Genes for yeast tRNATyr and tRNAPhe have been sequenced (Goodman, Olson and Hall, 1977; Valenzuela et al., 1978) which contain additional nucleotides (intervening sequences) within the middle of the gene that are not present in the mature tRNA . We have isolated precursors to rRNATyr and tRNAPhe from a yeast temperature-sensitive mutant (at the rna1 locus) which accumulates only certain precursor tRNAs at the nonpermissive temperature . The tRNATyr and tRNAPhe precursors were analyzed by oligonucleotide mapping; they each contain the intervening sequence and fully matured 5' and 3' termini . Furthermore, these precursors were used as substrates to search for an enzymatic activity which can remove the intervening sequences and religate the ends . We have shown that wild-type yeast contains such an activity, and that this activity specifically removes the intervening sequences to produce mature-sized RNAs. J Bacteriol, 1978 Jun, 134(3), 844 - 53 Glycogenolytic enzymes in sporulating yeast; Colonna WJ et al.; During meiosis in Saccharomyces cerevisiae, the polysaccharide glycogen is first synthesized and then degraded during the period of spore maturation . We have detected, in sporulating yeast strains, an enzyme activity which is responsible for the glycogen catabolism . The activity was absent in vegetative cells, appeared coincidently with the beginning of glycogenolysis and the appearance of mature ascospores, and increased progressively until spourlation was complete . The specific activity of glycogenolytic enzymes in the intact ascus was about threefold higher than in isolated spores . The glycogenolysis was not due to combinations of phosphorylase plus phosphatase or amylase plus maltase . Nonsporulating cells exhibited litle or no glycogen catabolism and contained only traces of glycogenolytic enzyme, suggesting that the activity is sporulation specific . The partially purified enzyme preparation degraded amylose and glycogen, releasing glucose as the only low-molecular-weight product . Maltotriose was rapidly hydrolyzed; maltose was less susceptible . Alpha-methyl-D-glucoside, isomaltose, and linear alpha-1,6-linked dextran were not attacked . However, the enzyme hydrolyzed alpha-1,6-glucosyl-Schardinger dextrin and increased the beta-amylolysis of beta-amylase-limit dextrin . Thus, the preparation contains alpha-1,4- and alpha-1,6-glucosidase activities . Sephadex G-150 chromatography partially resolved the enzyme into two activities, one of which may be a glucamylase and the other a debranching enzyme. Biochem J, 1978 Jun 1, 171(3), 613 - 27 Inhibition by ethanol, acetaldehyde and trifluoroethanol of reactions catalysed by yeast and horse liver alcohol dehydrogenases; Dickenson CJ et al.; 1 . Produced inhibition by ethanol of the acetaldehyde-NADH reaction, catalysed by the alcohol dehydrogenases from yeast and horse liver, was studied at 25 degrees C and pH 6-9 . 2 . The results with yeast alcohol dehydrogenase are generally consistent with the preferred-pathway mechanism proposed previously {Dickenson & Dickinson (1975) Biochem . J . 147, 303-311} . The observed hyperbolic inhibition by ethanol of the maximum rate of acetaldehyde reduction confirms the existence of the alternative pathway involving an enzyme-ethanol complex . 3 . The maximum rate of acetaldehyde reduction with horse liver alcohol dehydrogenase is also subject to hyperbolic inhibition by ethanol . 4 . The measured inhibition constants for ethanol provide some of the information required in the determination of the dissociation constant for ethanol from the active ternary complex . 5 . Product inhibition by acetaldehyde of the ethanol-NAD+ reaction with yeast alcohol dehydrogenase was examined briefly . The results are consistent with the proposed mechanism . However, the nature of the inhibition of the maximum rate cannot be determined within the accessible range of experimental conditions . 6 . Inhibition of yeast alcohol dehydrogenase by trifluoroethanol was studied at 25 degrees C and pH 6-10 . The inhibition was competitive with respect to ethanol in the ethanol-NAD+ reaction . Estimates were made of the dissociation constant for trifluoroethanol from the enzyme-NAD+-trifluoroethanol complex in the range pH6-10. FEBS Lett, 1978 Jun 1, 90(1), 97 - 102 Threonyl-tRNA synthetase from yeast: aminoacylation of tRNA on its non-accepting 3'-terminal hydroxyl group and its behaviour in enzyme-catalyzed deacylation; Igloi GL et al.; Methods have been developed by which tRNA Thr may be aminoacylated at the normally non-accepting 3'-terminal ribose OH . Two of the methods utilize the mischarging ability of the synthetases under special conditions of low salt concentration and presence of organic solvents . The third method demonstrates for the first time that for some synthetases the 2',3' specificity may be manipulated by use of similar special conditions . In the case of threonyl-tRNA synthetase, Thr-tRNAThr-C-C-A(3'd) has been synthesised by this method . The behaviour of threonyl esters of tRNAThr-C-C-A, tRNAThr-C-C-A(2'd) and tRNA Thr-C-C-A-(3'd) in the free enzyme-catalyzed deacylation has been studied and the results indicate that the cis diol functional group is necessary for this hydrolysis . The position on the terminal ribose from which the amino acid is removed in this reaction remains to be identified. Mol Gen Genet, 1978 May 31, 161(3), 323 - 31 Yeast chromatin: search for histone H1; Sommer; Yeast chromatin, isolated by a rapid procedure contains in addition to histones H2A, H2B, H3 and H4 a fifth major basic protein . This fifth polypeptide is not an intrinsic component of the nucleosome structure . It has properties of both histone and nonhistone proteins and might represent an early form of histone H1 and of high mobility group nonhistone proteins of higher eukaryotes . Electron microscopic visualization of isolated yeast nucleosomes substaniates further the similarity of the chromatin structudre of this unicellular eukaryote to that of higher eukaryotes. Biochim Biophys Acta, 1978 May 23, 518(3), 539 - 42 Strong magnesium binding sites in yeast phenylalanine transfer RNA; Narayanan P et al.; To ascertain the sites that are available for strong binding between magnesium ions and phosphate groups in yeast phenylalanine transfer RNA, all distances below 5.5 A separating the phosphoryl oxygens (Op) of the 76 nucleotide residues have been computed from the latest atomic coordinates for the monoclinic form of the tRNA crystallized in the presence of magnesium chloride . The 5.5 A distance is chosen as the upper limit expected for Op....Op distances involved in strong magnesium-phosphate binding, on the basis of studies on a model magnesium phosphodiester hydrate, taking into account the quoted standard deviation in the tRNA atomic coordinates . It is concluded that there are four possible sites for strong magnesium binding in the tRNA molecule, in addition to the three sites previously reported . One of the hypothetical sites: m2G10-OL, U47-OR, could be involved in the first stage of melting of the tRNA molecule, and may be relevant to tertiary structure stabilization, since it links the dihydrouridine arm with the extra (V) loop. Biochim Biophys Acta, 1978 May 23, 518(3), 464 - 81 Biological effects and repair of damage photoinduced by a derivative of psoralen substituted at the 3,4 reaction site: photoreactivity of this compound and lethal effect in yeast; Averbeck D et al.; A newly synthesized linear psoralen derivative, 3-carbethoxypsoralen is shown to bind to yeast nucleic acids after 365 nm light treatment . As compared to 8-methoxypsoralen, a well-known bifunctional furocoumarin, 3-carbethoxypsoralen exhibits a high photoaffinity for DNA in vivo . Both compounds bind and photoreact more efficiently in vivo than in vitro . In contrast to 8-methoxypsoralen, 3-carbethoxypsoralen does not form cross-links in yeast DNA as demonstrated by heat denaturation-reassociation studies at least in the range of doses used . Thus 3-carbethoxypsoralen reacts as a monofunctional compound . Wild-type cells of Saccharomyces cerevisiae are 6 times more resistant to 3-carbethoxypsoralen than to 8-methoxypsoralen plus 365 nm light treatment in terms of lethal effect . In comparison to angelicin, another monofunctional (but angular) furocoumarin, 3-carbethoxypsoralen is more photoreactive . When the photoaffinity for DNA of 8-methoxypsoralen and 3-carbethoxypsoralen are considered in relation to photoinduced cell killing, it is clear that monoadducts are very efficiently repaired in wild-type cells . In contrast to the additivity obtained with 8-methoxypsoralen, a synergistic interaction of the two different repair pathways blocked by the rad2 and the rad9 mutation is observed after 3-carbethoxypsoralen plus 365 nm light . Dark holding experiments show that the excision repair function which is present in wild-type and rad9-4 cells is important for dark recovery. Mol Gen Genet, 1978 May 3, 161(2), 205 - 14 Mutants of yeast with depressed DNA synthesis; Johnston LH et al.; Seven temperature-sensitive mutants have been isolated in Saccharomyces cerevisiae which show a reproducible defect in DNA synthesis at the restrictive temperature . One of these is allelic with rna11 (Hartwell et al., 1970) but the remaining mutants define six complementation groups and probably represent six different genes . The gene symbol dds (for depressed DNA synthesis) is proposed . At the restrictive temperature, rna11-2, dds2-1 and dds6-1 show a rapid and almost total cessation of DNA and RNA synthesis, whilst protein synthesis continues for several hours . The remaining dds mutants show a reduced rate of DNA synthesis from the time of temperature shift (dd1, dds3, dds4) or a cessation of DNA synthesis at a later time (dds5) . In some cases, RNA synthesis is affected concomitantly with, or soon after, the depression in DNA synthesis . Possible reasons for the phenotypes of these mutants, and for the relative absence of yeast mutants which are unambiguously and specifically affected in DNA synthesis, are discussed . In addition, we report the isolation of seven new alleles of known cdc genes and ten new mutants with a cell cycle phenotype that complement those already known. Vopr Pitan, 1978 May-Jun, (3), 48 - 53 {Biological value of a yeast isolate}; Petrovskii KS et al.; Subject to determination was the biological value of protein separated from food yeast by using chemical, enzymatic (chargeability with proteolytic enzymes) and biological (growing male rattlings-weanglings with the initial mass of 45 +/- 1.0 g) methods . The protein content (with no account of nucleinic acids) in rations balanced as to all the ingredients and energy amounted to 10 per cent . The experiments lasted for 28 days . In spite of good assailability of the isolate with pepsin and trypsin and a quite satisfactorily balanced of its amino acids the anabolic effect of the compound was found to be rather low, viz . PER--1.8; BV--49.1%; NPU--40.3% and in the control (caseine)--2,1; 79.0; 60.2 per cent, respectively . This is attributed to the deficiency in compound of sulphur-containing amino acids and to a relative excess of lysine . The biological value of the isolate amounted to 71 per cent of that of caseine . The method of separating protein from the yeast biomass does not have any noticeable adverse effect on its biological value. Nucleic Acids Res, 1978 May, 5(5), 1551 - 60 A novel conformational change of the anticodon region of tRNAPhe (yeast); Urbanke C et al.; The temperature dependence of the fluorescence of the Y-base of tRNAPhe (yeast) was investigated kinetically by the temperature jump method . In the range between -15 degrees C and +30 degrees C A NOVEL CONFORMATIONAL TRANSITION OF THE TRNA could be characterized . This conformational change was found in the absence of any artificial label; it is a characteristic property of tRNAPhe in its native structure . This transition accounts for 30% of the total fluorescence change . Its activation enthalpy is 16 kcal/mole (67 kJ/mole), and the transition enthalpy is between -2 kcal/mole and +2 kcal/mole (+/-8 kJ/mole) . A model is represented in which this transition can be explained by a a change in the stacking pattern of the anticodon loop . The experimental findings are discussed with respect to several hypotheses about the molecular mechanism of protein biosynthesis which postulate conformational rearrangements of the anticodon loop. Biotechnol Bioeng, 1978 May, 20(5), 755 - 66 Effect of thiol reagents on extractability of protein from yeast; Shetty KJ et al.; The effect of soluble thiol reagents on the extractability of protein from yeast cells was studied . The incubation of yeast cells with dithiothreitol, 2-mercaptoethanol, or monothioglycerol markedly stimulated the release of soluble carbohydrates into the medium . There was a concomitant improvement (over twofold) in the extractability of protein from the yeast cells . The thiol reagents activated the proteolytic enzymes of the yeast cells . Unless inactivated, these enzymes hydrolyze the extracted protein. Nature, 1978 Apr 27, 272(5656), 795 - 8 Induced intragenic recombination in yeast can occur during the G1 mitotic phase; Fabre F; The conditional cell division cycle yeast mutants cdc have been used to demonstrate that intragenic recombination induced by ultraviolet or gamma rays occurs in diploids arrested in G1, a short time after irradiation and before the initiation of the S phase . This implies that pairing of homologous chromosomes does not require duplicated chromatids. J Biol Chem, 1978 Apr 25, 253(8), 2501 - 3 Inactivation of uridine nucleosidase in yeast . Purification and properties of an inactivating protein; Magni G et al.; It has been previously demonstrated in our laboratory that uridine nucleosidase (EC 3.2.2.3) is subjected in yeast to inactivation . An inactivating fraction has been isolated and purified to homogeneity with a procedure which includes gel filtration, adsorption chromatography, and electrofocusing techniques . The molecular weight of the enzyme, estimated either by sodium dodecyl sulfate disc gel electrophoresis or by gel filtration is approximately 44,000 . No quaternary structure was evidenced . The inactivating activity possesses proteolytic activity against casein and hemoglobin with pH optima of 2.5 and 3.2, respectively . The optimal pH for uridine nucleosidase inactivation is around 4.7 . The inactivating activity as well as the proteolytic activity of the preparation can be inhibited by IA but not by IB2 and IC, yeast macromolecular inhibitors for proteinase A (EC 3.4.23.8), B (EC 3.4.22.9), and C (EC 3.4.12.8), respectively . The apparent isoelectric point is pH 4.03 . The carbohydrate content is 8.5% . A comparison of the properties of the inactivating protein with those of known yeast proteinases leads to the conclusion that it is identical with the enzyme previously designated as proteinase A, which for the first time has been obtained homogeneous and characterized . It has been shown that proteinase A could play a physiological role in the uridine nucleosidase inactivation process when it is associated, as a complex, with proteinase B. Biochemistry, 1978 Apr 18, 17(8), 1541 - 7 Fluorescence-quenching study of glucose binding by yeast hexokinase isoenzymes; Feldman I et al.; A study of the effect of varying ionic strength on the glucose-induced quenching of tryptophan fluorescence of hexokinase isoenzymes A(P-I) and B(P-II) was carried out at pH 8.3 and pH 5.5 . At p/ 8.3 both isoenzymes gave apparently linear Scatchard-type data plots even with protein concentrations and ionic strengths for which both dimeric and monomeric forms of hexokinase coexist in signiciant amounts . Taking inco account a 1% accuracy in the experimental measurements, we concluded that the intrinsic dissociation constants K(M) and K(D), for the binding of glucose to the monomeric and dimeric forms of HkB, are within a factor of two of each other, i.e . K(D)/K(M) less than or equal to 2 . The values of K(M), estimated from the apparent K, were so greatly influenced by ionic strength that it is clear that it is meaningless to compare K(M) and K(D) values measured at different ionic strengths as has been done in the literature . Curvature in the pH 5.5 . fluorescence-quenching plots for relatively low ionic strengths demonstrates cooperativity for glucose-binding to the dimer, positive for HkA but negative for HkB . In contrast, the binding is relatively non-cooperative at high ionic strength at this pH . These results were attributed to the well known effect of salt-neutralization of side chain electrical charges on the flexibility and compactness of proteins. Eur J Biochem, 1978 Apr 17, 85(2), 503 - 16 The steady-state kinetics of yeast phosphoglycerate kinase . Anomalous kinetic plots and the effects of salts on activity; Scopes RK; 1 . A re-investigation of the kinetics of yeast phosphoglycerate kinase in the direction of 1,3-bisphosphoglycerate formation has been carried out, covering a 1000-fold range in substrate concentrations . A variety of improved spectrophotometric and fluorimetric assay procedures have been used . 2 . Kinetic plots proved to be non-linear for each variable substrate . A variety of checks have been carried out to show that this is not due to artifacts in the assay procedures or heterogeneity of the enzyme preparation . 3 . The effects of a variety of salts on the activity of the enzyme have been examined . Most salts, especially those with multivalent anions, can cause activation of the enzyme, but inhibit at high concentration . 4 . The salt effect is shown to be principally due to anions rather than cations, and not to ionic strength changes . Sulphate, as one of the most effective anions has been used in most comparisons . 5 . Salt activation is steepest when the substrate concentrations are low; maximum activation has been about 5-fold with 0.2 mM MgATP and 0.2 mM 3-phosphoglycerate . Inhibition at the higher salt concentrations is strongest at the same substrate concentrations as when activation is steepest, indicating a link between the two effects . 6 . The presence of 20 mM or more Na2SO4 converted non-linear kinetic plots to linear ones . A study of the kinetics in the presence of 40 mM Na2SO4 was interpreted in terms of a random sequential binding mechanism, with sulphate acting as a competitive inhibitor . 7 . Possible explanations for these anomalous results are discussed in terms of several mechanisms which have been shown to apply in other systems. Eur J Biochem, 1978 Apr 17, 85(2), 345 - 50 Anion binding to yeast phosphoglycerate kinase; Wrobel JA et al.; The single thiol of yeast phosphoglycerate kinase was labelled with the chromophoric sulfhydryl reagent, 2-chloromercuri-4-nitrophenol . Sequential additions of individual anions to this modified enzyme brought about a decrease in absorbance at 410 nm that reflected the degree of saturation of the enzyme with anion . The binding curves were analyzed to determine the dissociation constants of a number of anions with charges varying from--1 to--4.1 . A linear relationship was found between the charge of the anion and the negative logarithm of the dissociation constant for the labelled enzyme-anion complex . The highly charged anions, such as ATP, bound more tightly than did anions with less charge, such as Cl- . The average number of binding sites for those anions for which accurate results could be obtained was 1.06 mol per 47000 g of enzyme . Several lines of evidence suggested that titration of the active center was not being monitored . Anions bound to phosphoglycerate kinase decreased the rate of reaction between the enzyme thiol and 5,5'-dithiobis(2-nitrobenzoic acid) . The relationship between the degree of saturation of the anion binding site and the reaction rate constant was used to calculate the dissociation constant between anion and enzyme . Dissociation constants determined in this manner were in good agreement with those determined by titration of the enzyme-mercurial complex. Biochim Biophys Acta, 1978 Apr 12, 523(2), 368 - 76 Yeast 3-phosphoglycerate kinase . Essential arginyl residues at the 3-phosphoglycerate binding site; Philips M et al.; Yeast 3-phosphoglycerate kinase (ATP:3-phospho-D-glycerate 1-phospho-transferase, EC 2.7.2.3) is inactivated by phenylglyoxal . Loss of activity correlates with the modification of two arginyl residues, both of which are protected by all of the substrates . The modification is not accompanied by any significant conformational change as determined by optical rotatory dispersion . Ultraviolet difference spectrophotometry indicates that the inactivated enzyme retains its capacity for binding the nucleotide substrates whereas the spectral perturbation characteristic of 3-phosphoglycerate binding is abolished in the modified enzyme . The data suggest that at least one of the two essential arginyl residues is located at or near the 3-phosphoglycerate binding site . A likely role of this residue could be its interaction with the negatively charged phosphate or carboxylate groups of 3-phosphoglycerate. Can J Microbiol, 1978 Apr, 24(4), 433 - 5 Torulopsis pampelonensis sp . nov . A new species of yeast isolated from beech forest soil; Ramirez C et al.; A new yeast species, Torulopsis pampelonensis is described . Six strains were recovered from a gleyic Andosol under a beech forest and two other strains from the surface of fallen leaves of Fagus silvatica L . Although it showed some morphological and physiological similarities with Torulopsis tannotolerans Jacob and Torulopsis navarrensis Ramirez and Moriyon, it differed from all Torulopsis species presently known. J Biochem (Tokyo), 1978 Apr, 83(4), 1109 - 16 Accumulation of zymosterol in yeast grown in the presence of ethionine; Ariga N et al.; In order to identify the methyl acceptor for the methylation of sterol side-chains in ergosterol biosynthesis, Saccharomyces cerevisiae (wild type) was grown in the presence and absence of ethionine which was expected to be an inhibitor of the methylation . Gas-liquid chromatographic analyses of the sterols in the cells grown in the absence of ethionine showed that ergosterol was the most abundant sterol . On the other hand, a sterol, named sterol Z, accounted for more than 50% of the total sterols in the cells grown in the presence of ethionine . As a result of experiments to raise the yield of sterol Z, the best concentration of DL-ethionine for the production was found to be 1.0 mM . The use of the methionine-less mutant was less effective for the production of sterol Z . Sterol Z was isolated by repeated TLC and was identified as zymosterol from its melting point, GLC and mass spectrometry . The role of zymosterol and other sterols as the methyl-acceptor sterol in ergosterol biosynthesis is also discussed. J Bacteriol, 1978 Apr, 134(1), 295 - 305 Characterization of two types of yeast ribosomal DNA genes; Petes TD et al.; The intragenic organization of ribosomal DNA from a diploid strain of Saccharomyces cerevisiae was analyzed by using recombinant DNA molecules constructed in vitro . Restriction analysis of the yeast ribosomal DNA with the EcoRI restriction enzyme indicated that eight restriction fragments were present in the ribosomal DNA of this strain: X' (1.87 X 10(6) daltons), A (1.77 X 10(6) daltons), B (1.48 X 10(6) daltons), C (1.22 X 10(6) daltons), D (0.39 X 10(6) daltons), E (0.36 X 10(6) daltons), F (0.22 X 10(6) daltons), and G (0.17 X 10(6) daltons) . These fragments were distributed between two different types of ribosomal DNA genes, which had the restriction maps: (formula: see text) in which the underlined region shows the repeating unit . The diploid yeast strain contained approximately equal amounts of each of these two types of genes . The analysis of the recombinant DNA molecules also indicated that the yeast ribosomal genes are homogeneous and extensively clustered. J Bacteriol, 1978 Apr, 134(1), 261 - 9 New cytoplasmic genetic element that controls 20S RNA synthesis during sporulation in yeast; Garvik B et al.; Under conditions that induce meiosis and sporulation in Saccharomyces cerevisiae, most strains accumulate a 20S RNA, amounting to as much as 15% of the newly synthesized RNA . The ability of cells to accumulate this new RNA species depends on a dominant genetic element that is cytoplasmically inherited, but is distinct from the other cytoplasmic elements that have been previously identified . The ability to synthesize 20S RNA does not depend on mitochondrial DNA, 2-micron DNA, the translational suppressor psi, the genetic element carrying URE3, or double-stranded killer RNA . However, all 20S- strains examined were also nonkillers, although many nonkiller strains were 20S+ . This work also shows that 20S RNA accumulating is not essential for sporulation even though it is induced only by conditions that initiate sporulation . Furthermore, strains that are unable to complete meiosis are still capable of producing 20S RNA when placed under the nitrogen starvation conditions that promote sporulation. Eur J Biochem, 1978 Apr, 85(1), 85 - 8 The aminoacyladenylate mechanism in the aminoacylation reaction of yeast phenylalanyl-tRNA synthetase; Fasiolo F et al.; It is shown from a combination of rapid quenching and steady-state kinetics that the phenylalanyl-tRNA synthetase from yeast catalyses the formation of phenylalanyl-tRNA by the amino-acyladenylate pathway at pH 7.8 and 25 degrees C . The rate-determining step at saturating reagent concentrations is not the dissociation of the charged tRNA from the enzyme. Genetics, 1978 Apr, 88(4 Pt 1), 689 - 707 A chromosomal translocation causing overproduction of iso-2-cytochrome c in yeast; Sherman F et al.; The CYC7-1 mutation in the yeast Saccharomyces cerevisiae causes the production of approximately 30 times the normal amount of iso-2-cytochrome c . Genetic analysis established that the CYC7-1 mutation is a reciprocal translocation involving the left arm of chromosome V and the right arm of chromosome XVI . The chromosome V arm was broken adjacent to the gene CYC7, which determines the primary structure of iso-2-cytochrome c, and this fragment containing the CYC7 gene was joined to the segment of chromosome XVI . It appears as though the elevation of iso-2-cytochrome c is caused by an abnormal controlling region adjacent to the structural region of the CYC7 gene. Radiat Environ Biophys, 1978 Mar 30, 15(1), 85 - 95 Synthesis of inducible enzymes in irradiated yeast: UV effects on regulation and activity per cell; Gocke E et al.; The synthesis of two inducible enzymes in UV irradiated cells was determined during an 8 h postirradiation incubatin . In contrast to the reduction of synthesis shortly after irradiation the effect after a longer period of incubation depends on the radiation sensitivity of the strain . Since exposure inhibits division leading to different cell number in controls and irradiated samples the data are also analysed on a per cell basis . ta considerable increase of the activity per cell was observed . A maximum is reached at the end of the division delay. Eur J Biochem, 1978 Mar, 84(1), 61 - 8 Inhibition of yeast phosphatidic-acid synthesis by free fatty acids; Morikawa M et al.; Particulate preparations obtained from cells of yeast Saccharomyces sake have been shown to possess glycerolphosphate acyltransferase and 1-acylglycerolphosphate acyltransferase activities . Glycerolphosphate acyltransferase exhibits a high specificity for saturated and monoenoic fatty acyl-CoA thioesters . When palmitoyl-CoA is employed as sole acyl group donor, the major lipid product is lysophosphatidic acid . 1-Acylglycerolphosphate acyltransferase of this yeast species has a rather strict specificity for monoenoic fatty acyl-CoA thioesters as acyl donor . These two acyltransferases are strongly inhibited in vitro by low concentrations of free fatty acids . 1-Acylglycerolphosphate acyltransferase is much more susceptible to fatty acid inhibition than glycerolphosphate acyltransferase . The inhibition is dependent not only on the concentration of fatty acid, but also on the length of exposure to fatty acid . Both saturated and unsaturated fatty acids inhibit the acyltransferase activities . The inhibitory effects of fatty acids cannot be ascribed to a nonspecific surfactant action of fatty acids . The present results support the view that free fatty acid serves as a regulator of glycerolipid synthesis. Nucleic Acids Res, 1978 Mar, 5(3), 961 - 73 Yeast seryl tRNA synthetase: two sets of substrate sites involved in aminoacylation; Pachmann U et al.; Seryl tRNA synthetase from Saccharomyces Carlsbergensis C836 contains two sets of sites for tRNASer, L-serine, and Mg2+-ATP, both of which are involved in aminoacylation . This is based on the following experimental results: (a) at low serine concentrations, second order kinetics in tRNASer are observed; (b) biphasic kinetics result when the amino acid is the varied substrate indicating anticooperative binding of two serine molecules to the synthetase; (c) when two molecules of serine are bound the rate of aminoacylation increases strongly and becomes first order in tRNASer; (d) the involvement of more than one site for Mg2+ and ATP is deduced from systematic variations of the concentrations of Mg2+ and ATP . Implications of the anticooperative binding of the substrates for possible reaction mechanisms are discussed . The results indicate that under normal conditions, the activity of seryl tRNA synthetase is regulated mainly by tRNASer while at high serine concentrations regulation by the amino acid itself prevails. Nucleic Acids Res, 1978 Mar, 5(3), 975 - 85 Yeast seryl tRNA synthetase: interactions between the ATP binding site and the sites for tRNASer and L-serine; Pachmann U et al.; T1 ribonuclease digestion of yeast tRNASer in the presence of seryl tRNA synthetase was used for monitoring the relationship between the substrate binding sites on the synthetase . It was found that (a) ATP displaces the tRNA from the synthetase with an effector affinity constant corresponding to the Km for ATP of 10 micron; (b) AMP and a number of nucleoside triphosphates, while influencing the rate of aminoacylation, do not displace the tRNA from the enzyme; (c) ADP and PPi inhibit the aminoacylation and the binding of tRNASer; (d) adenylyl diphosphonate is bound to the synthetase and lowers the protection of the tRNA against the nuclease attack in a similar way as does ATP; (e) interactions between the sites of L-serine and tRNASer could only be shown when both sites for serine were saturated and, in addition, the ATP analog or ADP was present . It is concluded that in seryl tRNA synthetase binding sites for ATP interact with the ones for tRNA as well as with the ones for serine . These findings contribute to the understanding of the mechanism of aminoacylation. J Environ Pathol Toxicol, 1978 Mar-Apr, 1(4), 411 - 8 Genetic activity of trichloroethylene in yeast; Bronzetti G et al.; Trichloroethylene (TCE) was tested for its ability to induce both point mutation and mitotic gene conversion in diploid strain of yeast . Saccharomyces cerevisiae (strain D7) was tested for both activities in culture with and without a mammalian microsomal activation system and in the intrasanguineous host-mediated assay in mice . Strain D4 (gene conversion) was tested only in the host-mediated assay . In suspension tests with D7, TCE was toxic but not genetically active without microsomal activation . When a mouse liver 10,000 xg supernatant was included in the suspension tests, dose related increases in both mutation and gene conversion were seen at survival levels of greater than 50 percent . In the host-mediated assay, TCE induced both point mutation and gene conversion in D7 and gene conversion in D4 when recovered from the liver and kidneys after both acute and subacute dosing . Yeasts recovered from the lungs showed little, if any, increase in either point mutation or gene conversion. Mikrobiologiia, 1978 Mar-Apr, 47(2), 300 - 5 {Cryofractographic study of the structure of yeast cells found in an anabiotic state}; Biriuzova VI et al.; Cryofractographic studies of normally growing yeast cells have shown that the length, number and arrangement of slit-like invaginations, as well as the number, frequency of arrangement and dimensions of pores on the nucleolemma, differ among various yeast species . The data on the structure of various organoids published earlier have been confirmed . The volume of all cellular organoids, with an exception of mitochondria, decreases upon dehydration . The invaginations of the plasmalemma coalesce to form a common network . This is important in the course of changes in the volume and density of the cytoplasm of cells in the anabiotic state, maintaining the structural connection of the plasmalemma with the cellular contents, which is necessary for the survival of an organism under extreme conditions. Biokhimiia, 1978 Mar, 43(3), 568 - 74 {Comparative study of the effect of ionic and non-ionic surface-active compounds on plasmic membrane of yeast protoplasts}; Tukmachev VA et al.; Lytic effect of some cationic surface-active compounds (SAC) on yeast protoplast plasmic membrane is studied . Comparative analysis of the lytic effect of anionic, cationic and non-ionic SAC is carried out, a correlation between key physico-chemical characteristics of the agents (critical concentration of micellization, hydrophyle-lipophyle balance) and their lytic activity is investigated . A proposition is made on the presence in all biphylic compounds of a hydrophyly gradient, which is due to the effect of hydrophylic group on lipophylic properties of hydrophobic part of the molecule, and possible role of this factor in thelytic effect of biphylic compounds on biological membranes is discussed. Can J Microbiol, 1978 Mar, 24(3), 312 - 20 Free proline content and sensitivity to desiccation and heat during yeast sporulation and spore germination; Ho KH et al.; Ascospores of a strain of Saccharomyces cerevisiae Hansen were less sensitive to desiccation and heat than vegetative cells . Desiccation resistance was acquired earlier during sporulation and lost later during spore germination than heat resistance . As spores matured, resistance to both stresses increased . With the exception of the first few hours in sporulation medium, when proline appeared to be utilized, the intracellular free proline content increased during sporulation and decreased during spore germination . Not all the proline lost could be detected in the germination medium, indicating that some was metabolically utilized by the germinating spores . Since exogenous proline supplied to vegetative or sporulating cells before desiccation increased their survival, it is suggested that the high level of free proline in mature spores may protect against desiccation stress. J Biochem (Tokyo), 1978 Mar, 83(3), 681 - 91 Ergosterol biosynthesis in yeast . Pathways in the late stages and their variation under various conditions; Osumi T et al.; {Methyl-14C}methionine was supplied to yeast cells under aerobic and anaerobic conditions for the investigation of the pathway for ergosterol biosynthesis after the methylation of the side-chain . Under aerobic conditions, the incorporation of radioactivity into ergosterol was high . With a limited oxygen supply, in contrast, the radioactivity was first accumulated in ergosta-7,24(28)-dien-3beta-ol and ergosta-8,24(28)-dien-3beta-ol, and then transferred to ergost-7-en-3beta-ol, ergost-8-en-3beta-ol and ergosta-7,22-dien-3beta-ol with time . Under strictly anaerobic conditions, a double bond was introduced neither to delta5 nor to delta22 . The results of the tracer experiments suggested the operation of several pathways in the late stages of ergosterol biosynthesis . It was also suggested that the main pathways varied depending on the conditions such as oxygen supply and other factors . The above conclusion was supported by the results of the analyses of the sterol compositions of the cells grown under various conditions. J Biochem (Tokyo), 1978 Mar, 83(3), 21 - 5 Studies on the oligomeric structure of yeast aldehyde dehydrogenase by cross-linking with bifunctional reagents; Tamaki N et al.; The molecular w:ight of yeast aldehyde dehydrogenase determined by sucrose density gradient centrifugation was 207,000 +/- 13,000 . The enzyme activity was proportional to the enzyme concentration in the range of 2 X 10(-11) M to 1 X 10(-7) M . Cross-linking patterns obtained with yeast aldehyde dehydrogenase after treatment with a series of diimidoesters of increasing chain lengths with different reaction times resulted in the appearance of tetramers as the largest cross-linked product of the enzyme subunits . The molecular weights of its monomer, dimer, trimer, and tetramer were, 57,000, 114,000, 171,000, and 228,000, respectively, as estimated from their mobilities on SDS-electrophoresis . In tetramers monomers are probably assembled in a heterologous square arrangement. Proc Natl Acad Sci U S A, 1978 Mar, 75(3), 1437 - 41 Chromosome mapping of the CYC7 gene determining yeast iso-2-cytochrome c: structural and regulatory regions; Sherman F et al.; The primary structures of iso-1-cytochrome c and iso-2-cytochrome c in the yeast Saccharomyces cerevisiae are determined by the genes CYC1 and CYC7, respectively . The CYC1 locus was previously shown to be on the right arm of chromosome X, and the CYC7 locus is shown in this investigation to be on the left arm of chromosome V closely linked to the min1 and mak10 markers . The CYC7 locus appears to be composed of a structural region and a regulatory region . Mutations in the structural region can cause a deficiency or alteration of iso-2-cytochrome c, whereas mutations in the regulatory region can cause increases in the amount of iso-2-cytochrome c . Single-site gene conversion, occurring at a relatively high frequency of approximately 4%, caused intragenic recombination of a mutational site in the structural region and a mutational site in the regulatory region, enabling us to suggest the order of the sites in relationship to other markers on the chromosome. Biochim Biophys Acta, 1978 Mar 1, 539(2), 253 - 60 Cyclic AMP-induced enhancement of calcium accumulation by the sarcoplasmic reticulum with no modification of the sensitivity of the myofilaments to calcium in skinned fibres from a yeast skeletal muscle; Fabiato A et al.; In the presence of low concentrations of total EGTA (5 . 10(-4) M) and free Mg2+ (3.16 . 10(-5) M) and in the presence of caffeine (8 . 10(-3) M), cyclic AMP (5 . 10(-6) M) produces a relaxation of the tension developed by skinned fibres from cat caudo-femoralis . The relaxation can be attributed to an enhancement of the Ca2+ accumulation by the sarcoplasmic reticulum, since cyclic AMP does not modify the sensitivity of the myofilaments of Ca2+ . These results are similar to those previously reported for the effect of cyclic AMP on skinned cardiac cells in the presence of a higher free Mg2+ concentration and in the absence of caffeine . This similarity suggests that the mode of action of cyclic AMP on the sarcoplasmic reticulum is not fundamentally different in cardiac and fast skeletal muscles. Eur J Biochem, 1978 Mar, 84(1), 167 - 72 Yeast DNA polymerases: antigenic relationship, use of RNA primer and associated exonuclease activity; Wintersberger E; Highly purified preparation of DNA polymerases A and B from yeast were compared with respect to antigenic relationship, ability to use ribonucleotide primers and associated nuclease activity . The following results were obtained . 1 . Antiserum directed against DNA polymerase A inhibits this enzyme but does not interfere with activity of DNA polymerase B or of mitochondrial DNA polymerase, nor does it precipitate the latter two enzymes . 2 . DNA polymerase A is capable of using oligo(ribouridylic acid) as a primer for the polymerization of dTMP . This reaction is not catalyzed by polymerase B to any significant extent . 3 . Whereas DNA polymerase A is devoid of nuclease activity, DNA polymerase B catalyses an exonucleolytic release of mononucleotide units from the 3' end of polynucleotides . The results of several experiments suggest that this nuclease activity is associated with the DNA polymerase B molecule. Mol Cell Biochem, 1978 Feb 24, 19(1), 23 - 9 Specific localization and quantification of biotin transport components in yeast by use of a biotin-conjugated, impermeant, electron-dense label; Bayer EA et al.; Two approaches are described for the localization and quantification of biotin transport components in yeast cells . One approach is based on tracing the fate of a radioactive affinity label for the biotin transport system, {14C}biotinyl-p-nitrophenyl ester (pBNP), through various stages of subcellular fractionations . A complementary method involves the use of a biotin-derivatized, impermeant, electron-dense, affinity-cytochemical label (ferritin-biotin conjugates) for subsequent visualization by electron microscopy . Values of approximately 8,000 and 4,000 sites/cell, respectively, were achieved by the two methods . Complicating factors, future perspectives and the relevance of the two methods to the isolation of transport components are discussed. Nature, 1978 Feb 23, 271(5647), 726 - 30 Novel cell cycle control of RNA synthesis in yeast; Fraser RS et al.; During the fission yeast cell cycle, the rate of polyadenylated messenger RNA synthesis doubles when the cell reaches a critical size . This size-related control maintains average mRNA content in balance with total cell mass during exponential growth, even in cells growing at different absolute growth rates per cell. Biochim Biophys Acta, 1978 Feb 16, 517(2), 378 - 89 The course of the assembly of ribosomal subunits in yeast; Kruiswijk T et al.; The course of the assembly of the various ribosomal proteins of yeast into ribosomal particles has been studied by following the incorporation of radioactive individual protein species in cytoplasmic ribosomal particles after pulse-labelling of yeast protoplasts with tritiated amino acids . The pool of ribosomal proteins is small relative to the rate of ribosomal protein synthesis, and, therefore, does not affect essentially the appearance of labelled ribosomal proteins on the ribosomal particles . From the labelling kinetics of individual protein species it can be concluded that a number of ribosomal proteins of the 60 S subunit (L6, L7, L8, L9, L11, L15, L16, L23, L24, L30, L32, L36, L40, L41, L42, L44 and L45) associate with the ribonucleoprotein particles at a relatively late stage of the ribosomal maturation process . The same was found to be true for a number of proteins of the 40 S ribosomal subunit (S10, S27, S31, S32, S33 and S34) . Several members (L7, L9, L24 and L30) of the late associating group of 60-S subunit proteins were found to be absent from a nuclear 66 S precursor ribosomal fraction . These results indicate that incorporation of these proteins into the ribosomal particles takes place in the cytoplasm at a late stage of the ribosomal maturation process. Mol Gen Genet, 1978 Feb 16, 159(2), 223 - 5 Ribosomal proteins of yeast strains carrying mutations which affect the efficiency of nonsense suppression; Waldron C et al.; We have examined the ribosomal proteins of strains of Saccharomyces cerevisiae which differ in the efficiency with which ochre nonsense mutations are suppressed . The strains in which ochre suppression is poor were {psi}- or carried antisuppressor mutations; those in which suppression was highly efficient were {psi}+ or carried allosuppressor mutations . The ribosomal proteins of these strains, as judged by two-dimensional polyacrylamide gel electrophoresis, were indistinguishable from those of wild-type. Biochim Biophys Acta, 1978 Feb 16, 517(2), 457 - 63 Electrophoretic behaviour of yeast mitochondrial translation products; Groot GS et al.; We have studied the mobility of yeast mitochondrial transla