ISSN:0749-503X    

DOI:10.1002/yea.320050602

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

ISSN:0749-503X    

DOI:10.1002/yea.320050603

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

ISSN:0749-503X    

DOI:10.1002/yea.320050604

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractSaccharomyces cerevisiaeproduces two chitin synthases (Chs1 and Chs2) encoded by separate genes. Although these enzymes catalyze the same reaction, Chs2 is essential for septum formation whereas Chs1 has a repair function. To determine if these physiological differences are reflected in the enzyme structures, theCHS2gene was sequenced and compared to that ofCHS1. The predicted amino acid sequence of Chs2 shares substantial similarity with that of Chs1 in the carboxyl two‐thirds of the protein. The amino one‐third segments differ in predicted isoelectric point by almost 5 pH units. It is suggested that the similar regions are related to common catalytic function. The unrelated regions may be involved in regulation or localization of the respective enzymes.CHS1andCHS2are unlinked but may have arisen from the duplication of an ancestral g

ISSN:0749-503X    

DOI:10.1002/yea.320050605

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractA mutant ofSchwanniomyces castelliiwith reduced glucose phosphorylation and with practically no phosphorylation of fructose was investigated. Carbon catabolite represion of α‐glucosidase and amylases was reduced. Repression of β‐galactosidase was normal. We have compared in continuous culture this mutant strain with wild type and another previously described mutant. The relationship between the specific rate of glucose consumption (Qs) and residual glucose concentration (s) in an inverse mode, suggests that there may be two types of transport of glucose. Mutation at the phosphorylation level causes apparent modification of the kinetic parameters of glucose uptake rate. The consequence of mutation at the phosphorylation level on biomass production was disc

ISSN:0749-503X    

DOI:10.1002/yea.320050606

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractWhen cells of the fission yeast,Schizosaccharomyces pombe, are incubated in medium devoid of a nitrogen source, they accelerate into cell division and differentially synthesize two polypeptides at 46 and 27 kD (named p46 and p27) after a delay of about an hour. The synthesis of p46 and p27 is transient. These proteins have no obvious cell cycle connection since they are also evident in nitrogen‐starved (but not accelerated) cells of the temperature‐sensitive mutant ofS. pombe,wee1·50h−. We infer from this that p46 and p27 are synthesized as a direct result of nutritional stress. The possibility that p46 and p27 represent examples of general environmental stress proteins was investigated by comparing nitrogen starvation with the heat‐shock response inS. pombe.Heat‐shock analysis of cells revealed the existence of two proteins of similar Mr to p46 and p27. In addition, nitrogen‐starved cells acquired thermotolerance in a manner similar to heat‐shocking cells. We suggest that nitrogen starvation in fission yeast induces a subset of the total array of heat

ISSN:0749-503X    

DOI:10.1002/yea.320050607

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractExpression of flocculation in yeast requires the presence of multi‐charged cations. Calcium ions fulfil this role over a broad pH range. At near neutral pH, magnesium and a variety of transition elements can induce flocculation. Calcium‐induced flocculation was competitively inhibited by excess sodium ions whereas magnesium‐induced flocculation was not competitively inhibited. Potassium and lithium ions caused similar inhibition but to a lesser extent.45Ca effux from yeast cells was greatly increased by the external presence of buffer and cations. Inhibition of flocculation by chelating agents, EDTA or EGTA, was overcome by excess calcium ions. Flocculation could not be induced, under these conditions, by excess magnesium or transition‐element salts.It was concluded that yeast flocculation has a direct specific requirement for calcium ions. Other ions cause flocculation indirectly by effecting calcium ion leakage from cells, which is then able to initiate flocculation. Low calcium concentrations were susceptible to competitive inhibition by sodium ions present in most acidic buffers. In addition, citrate ions inhibited flocculation, probably by sequestration of leaked calcium. Flocculation by salts, other than calcium, was thus restricted to a neutral or high p

ISSN:0749-503X    

DOI:10.1002/yea.320050608

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractStrains ofSaccharomyces cerevisiaeexpressing P28‐I, an antigen inducing protection against schistosomiasis, have been constructed. Transformants containing a very high copy number of a P28‐I expression vector were selected by genetic complementation involving deficientLEU2orURA3alleles carried by plasmids. Using theura3fur1auto‐selection system, constitutive and stable expression of P28‐I could be obtained in cultures grown in rich medium.The accumulation of the foreign protein exceeds 25% of total yeast proteins when estimated by Coomassie Brilliant Blue staining of SDS‐PAGE. Moreover, P28‐I which was located intracellularly was soluble and biologic

ISSN:0749-503X    

DOI:10.1002/yea.320050609

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

摘要:

AbstractA new complementation group of temperature‐sensitive mutants of the yeastSaccharomyces cerevisiae(ts26‐1andts26‐2) has been isolated and characterized. This mutation maps at 40·7 cM fromarg8and 48·9 cM fromarg1on the left arm of chromosome XV of yeast, providing that it is a newly identified gene. The dumbbell‐shape terminal morphology of the mutant cells at the restrictive temperatures is a characteristic of mutants defective in DNA replication. To study the defect of macromolecule synthesis in the mutant cells, DNA, RNA, and protein synthesis were measured at both permissive and restrictive temperatures. The data suggest that the primary defect of this mutation is at the initiation step of DNA synthesis.The gene has been cloned from anS. cerevisiaegenomic library by rescue of the conditional lethality of the mutants. It is present as a single copy in the haploid genome. DNA–RNA hybridization of the gene has identified 1 kb RNA, which is under cell‐division‐cycle control. DNA sequence analysis of the gene has identified an open reading frame capable of encoding a protein of molecular weight 25 055 (2

ISSN:0749-503X    

DOI:10.1002/yea.320050610

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY

ISSN:0749-503X    

DOI:10.1002/yea.320050601

出版商:John Wiley&Sons, Ltd.    

年代:1989

数据来源: WILEY