摘要:

AbstractReplication origins inSaccharomyces cerevisiaehave been identified through the clonning of autonomous replication sequence (ARS) elements that allow the extrachromosonal maintenance of plasmid molecules. ARS activity requires a close matcht to an 11 bp consensus sequence and A+T‐rich flanking DNA. ARS elements with a wide range of capacities for promoting plasmid maintenance have been described. We determined the ARS activity of plasmid with inserts consisting of repetitions of a 64 bp 100% A+T sequence that has sequence similarities to known ARS elements. An insert with approximately four repeats did not yield transformants, but inserts with either eight or eleven repeats did. The cooperative of ARS activity did not require a contiguous arrangement since a plasmid containing two inserts of four repeats each, separated by about 1 kb, was functional. Our results show that a charge from non‐function to function can be accomplished by the cumulative action of individually inactive sequences. We conclude that the probability of replication initiation is too low with only four repeats to allow plasmid maintenance, but the overall probability is increased by further sequence iteration to provide origin activity. We suggest that chromosomes may contain streches with dispersed, weak origin elements, each undetected by the conventional ARS assay, that in sum provide origin funct

ISSN:0749-503X    

DOI:10.1002/yea.320060302

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractSeveral authors have shown that the halotolerant yeastDebaryomyces hansenii, when growing exponentially in glucose medium in the presence of sodium chloride, maintains osmotic balance by establishing sodium and glycerol gradients of opposite signs across the plasma membrane. Evidence is presented here that the two gradients are linked through a sodium‐glycerol symport that uses the sodium gradient as a driving force for maintaining the glycerol gradient. The symporter also accepts potassium ions as co‐substrate. The kinetic parameters at 25°C, pH 5·0 were the following:Vmax, decreasing from over 500 to less than 40 μmol g−1per h over a concentration range of 0–3Mextracellular sodium chloride;Km(glycerol) 0·40–0·6 mMover the same range;Km(sodium ions) 16·0 ± 3·21μM;Km, (potassium ions) 10·4 ± 3·6μM. Furthermore, it was observed that glycerol uptake was accompanied by proton uptake when extracellular sodium chloride was present and that the protonophore carbonylcyanide‐M‐chlorophenylhydrazone induced collapse of the glycerol gradient, supporting earlier proposals by others that the sodium gradient is maintained by an active sodium

ISSN:0749-503X    

DOI:10.1002/yea.320060303

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractWe have studied the alcohol dehydrogenase (ADH) system in the yeastKluyvefromyces lactis. Southern hybridization to theSaccharomyces cerevisiae ADH2gene indicates four probable structuralADHgenes inK. lactis. Two of these genes have been isolated from a genomic bank by hybridization toADH2. The nucleotide sequence of one of these genes shows 80% and 50% sequence identity to theADHgenes ofS. cerevisiaeandSchizosaccharomyces pomberespectively. OneK. lactis ADHgene is preferentially expressed in glucose‐grown cells and, in analogy toS. cerevisiae, was named K1ADH1. The other gene, homologous to K1ADH1in sequence, shows an amino‐terminal extension which displays all of the characteristics of a mitochondrial targeting presequence. We named this gene K1ADH3. The two genes have been localized on different chromosomes by Southern hybridization to an orthogonal‐field‐alternation gel electrophoresis‐resolvedK. lactisgenome. ADH activities resolved by gel electrophoresis revealed several ADH isozymes which are differently expressed inK. lactiscells depending on the carb

ISSN:0749-503X    

DOI:10.1002/yea.320060304

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractFragile mutants ofSaccharomyces cerevisiaeare defective in the structure of the cell wall and plasma membrane. The mutant cells lyse in hypotonic solutions but grow exponentially when osmotic stabilizer is induced in the medium. These mutants display a general increase in the permeability of the plasma membrane. We show here that fragile yeast cells of the same mating type can fuse without protoplast formation. The frequency of cell × cell fusion is lower than that observed for protoplast × protoplast fusion and can be significantly increased if the cells of one partner are converted to protoplasts. Microscopic observations and genetic analysis demonstrate that the hybrids obtained are fusion products. The fusion between fragile cells is explained in terms of the existence of local defects on their surface where the cell wall is thinner (or even missing), thus allowing a direct contact of cells by means of their plasma membrane

ISSN:0749-503X    

DOI:10.1002/yea.320060305

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe extent of nuclear DNA complementarity was determined for members of the genusZygosaccharomyces. From these comparisons, nine species have been identified:Z. baillii, Z. bisporus, Z. cidri, Z. fermentati, Z. florentinus, Z. mellis, Z. microellipsoides, Z. mrakii, andZ. riuxii. Candida mogii, the proposed anamorph ofZ. rouxii, showed low relatedness to all nine species. The recently describedSaccharomyces astigiensisandS. albasitensiswere conspecific withZ. fermentati, andS. placentaeshowed high relatedness withZ. rouxii. Growth tests were defined that allow recognition of allZygosaccharomycesspecies.

ISSN:0749-503X    

DOI:10.1002/yea.320060306

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe expression of acid phosphatase (Apase) fromPHO5andMFα‐PHO5hybrid genes is regulated by inorganic phosphate and mating type locus respectively, as well as thePHO4andMATα1gene products respectively. WhenPHO5andMFα‐PHO5hybrid genes were cloned in theBamHI site of the pBR322 sequence of the yeast shuttle vectors (YRp7 or YEp9T), in one orientation they were regulated normally but in the other orientation their expression was not regulated but expressed constitutively. The pBR322 sequences present upstream of the inserted genes are responsible for the constitutive expression. By replacing thePHO5upstream activating sequences (UAS) element with pBR322 fragments, we have identified three pBR322 sequences, rom nucleotides 376 to 650, 2068 to 2116 and 2136 to 2247, which were able to promote expression of APase. A comparison of these three pBR322 fragments revealed 5′ ATCGCGCGAG 3′ and 5′ CGGTGATGNCGG 3′ to be the common sequences likely to act as USAs inSaccharomyces cerevisiae. By using synthetic oligonucleotides, it was found that both sequences are required for maximum expression of

ISSN:0749-503X    

DOI:10.1002/yea.320060307

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThecdc28‐srm mutation inSaccheromyces cerevisiaedecreases spontaneous and induced mitochondrial rhomutability and the mitotic stability of native chromosomes and recombinant circular minichromosomes. The effects ofcdc28‐srm on the genetic stability of cells support the hypothesis that links cell cycle regulation in yeast to changes in chromatin organization dependent on the start geneCDC28(Hayles and Nurse, 19

ISSN:0749-503X    

DOI:10.1002/yea.320060308

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractWe have cloned theMASgene, encoding the microbody matrix enzyme malate synthase (EC 4.1.3.2.) from the methylotrophic yeastHensenula polymorphia. The gene was isolated by screening of a genomic library with a mixed‐sequence probe, based on the partial amino acid sequence of the purified enzyme. The nucleotide sequence of a 2·4‐kilobase stretch of DNA covering theMASgene was determined. The gene contains an open reading frame 555 amino acids, amounting to a calculated molecular mass of 63 254 for the encoded protein. Comparison of the amino acid sequence with the malate synthase sequences ofEscherichia coli, Brassica napusL. andCucumis sativusL. Clearly establishes the homology of all four proteins. Compared to the soluble enzyme fromE. coli, the malate synthases fromH. polymorphaand both plant species, which are located in the microbodies, have a short carboxy‐terminal extension. In the plant malate synthases, the extension is probably involved in routing to the microbodies, since it contains the potential peroxisomal targeting signal, Ser‐Arg/Lys‐Leu, at the carboxy terminus. TheH. polymorphaenzyme terminates with similar amino acids, but their sequence, Ser‐Leu‐Lys, does not conform to any of the known peroxisomal tar

ISSN:0749-503X    

DOI:10.1002/yea.320060309

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe rate of formation of carbon dioxide in cytoplasmic yeast extracts in an open system with continuous infusion of glucose was measured by membrane inlet mass spectrometry during glycolytic oscillations. The rate of CO2production rose in the first third of each cycle to a maximum of about 100 μmol per ml yeast extract per hour and subsequently diminished to a final level of about 50 μmol per h. Measurements of the NADH light absorption under the same conditions revealed oscillations of relaxations type. The phase of high CO2production could be related to the phase of the high NADH level, giving evidence that the flux in glycolysis is increased during the phase of high NADH concentration. Only half of the amount of injected glucose was metabolized to CO2during the sustained oscillation, although free glucose did not accumulat

ISSN:0749-503X    

DOI:10.1002/yea.320060310

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractGamma‐aminobutyrate (GABA) accumulation in growing cultures ofSaccharomyces cerevisiaewas shown to occur by means of an active transport system that is inhibited by proton ionophores, azide, fluoride and arsenate ions. Transport occurred maximally at pH 5·0 and exhibited apparentKmvalues of 12 μMand 0·1 mM. Accumulated GABA did not efflux upon treatment with proton ionophores and exchanged with extracellular material only very slowly. However, release was complete upon treatment with nystatin. These observations raise the possibility that a major portion of intracellular GABA is sequestered in the vacuole. The response of GABA uptake to growth on various nitrogen sources suggested that uptake may be subject to several types of regula

ISSN:0749-503X    

DOI:10.1002/yea.320060311

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY