摘要:

AbstractIn a previous communication, we have shown that two protein tyrosine phosphatases (PTPases) from fission yeast,pyp1+andpyp2+, act as novel inhibitors of mitosis upstream of thewee1+lmik1+pathway (Ottilieet al., 1992). Here we describe that both genes possess intrinsic PTPase activity as judged byin vitroPTPase assays using32P‐labeled Raytide as a substrate, and that32P‐labeled p107wee1is anin vitrosubstrate for pyp1. To compare the biological activity of pyp1 and pyp2 to that of other known PTPases, we expressed the budding yeastPTP1and human placental phosphatase 1B (PTP1B) genes in either a cdc25–22 or wee1–50 genetic background and established that, in contrast topyp1+andpyp2+,Saccharomyces cerevisiae PTP1and humanPTP1Bcomplement thecdc25mutant, opposing thewee1+lmik1+

ISSN:0749-503X    

DOI:10.1002/yea.320091002

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0749-503X    

DOI:10.1002/yea.320091003

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractTheKTR2gene fromSaccharomyces cerevisiaewas identified by polymerase chain reaction amplification of genomic DNA using primers derived from regions of high homology between the products of three yeast genes,KRE2, YUR1andKTR1. The product encoded by theKTR2gene is a predicted type II membrane protein of 425 amino acid residues with a short cytoplasmic N‐terminus, a membrane‐spanning region and a large lumenal domain containing four potential N‐glycosylation sites. Ktr2p has 58% identity with Yur1p, 39% with Ktr1p and 34% with Kre2p. One member of this gene family,KRE2(also known asMNT1; Häusler and Robbins, 1992), encodes an α‐1,2 mannosyltransferase which adds the third mannose onto O‐linked glycoprotein side‐chains (Häusleret al., 1992). In contrast toKRE2null mutants, which produce shortened (two‐mannose) chains, mutants harboring aKTR2gene disruption synthesize O‐linked chains with the wild‐type patterns of five mannose residues. A null mutation inKTR2leads to partial resistance to killer toxin and hints thatKTR2, which encodes a putative mannosyltransferase, is involved in extracell

ISSN:0749-503X    

DOI:10.1002/yea.320091004

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn the yeastSaccharomyces cerevisiae, there is a general amino acid permease, regulated by nitrogen catabolite repression, and several specific permeases whose nitrogen regulation is not well understood. In this study, we used continuous cultures to analyse the effect of nitrogen limitation and pH on the activity of general and several specific amino acid permeases. General permease activity was maximal in severe nitrogen limitation and diminished 400‐fold in cells grown under nitrogen excess. For the specific permeases, the maximal uptake activity was found between mild limitation and nitrogen excess, while very small activity was detected under strict limitation. These results indicate that the nitrogen regulation of the general and the specific amino acid carriers is coordinated in such a way that no redundancy exists in amino acid transport. The regulation of the specific permeases was similar to that found for a system with anabolic function in nitrogen metabolism.All of these permeases are supposed to work through a proton symport mechanism, and thus rely on pH gradients to carry out their function. We studied the effect of pH on the kinetic constants of the general permease. Our results show that the effect of pH on theKmwas different for acidic, neutral and basic amino acids, while the effect onVmaxwas independent of the electrical charge of the amino acid

ISSN:0749-503X    

DOI:10.1002/yea.320091005

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe yeast plasma membrane H+‐ATPase generates a membrane electrochemical gradient which is required for the secondary uptake of nutrients. Although the ATPase has previously been shown to be post‐translationally regulated in response to the availability of glucose, there has been no evidence to date for transcriptional regulation of the ATPase gene (PMA1). In this work, we have examined the pool of newly synthesized ATPase that accumulates in secretory vesiclesen routeto the cell surface in the temperature‐sensitive secretory mutantsec6‐4, and have observed changes in the level of ATPase polypeptide as a function of the glucose concentration in the growth medium. In parallel, there were rapid and reversible changes in the levels of ATPase mRNA. Finally, when cells were grown on a variety of carbon sources, the amount of ATPase polypeptide was proportional to the specific growth rate, suggesting thatPMA1expression is adjusted according to the metabolic state of the cell. These results complement the findings of Capieauxet al.(Capieaux, E., Vignais, M.‐L., Sentenac, A. and Goffeau, A. (1989).J. Biol. Chem.264, 7437–7446), who show that the transcriptional factor TUF/RAP1 binds to upstream activating sequences in thePMA1gene. Taken together, the results suggest a model in which transcriptional regulation of the ATPase gene by glucose is mediated

ISSN:0749-503X    

DOI:10.1002/yea.320091006

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractTheRLP7gene ofSaccharomyces cerevisiaewas cloned, sequenced and localized to the right arm of chromosome XIV, close to the centromere. It encodes a predicted polypeptide (RLP7p) of 322 amino acids, with a calculated molecular mass of 36 kDa and an isoelectric point of 9·6. Putative open reading frames very similar toRLP7are present in two other yeasts,Kluyveromyces lactisandCandida utilis. The RLP7p gene product has significant sequence similarity to theS. cerevisiaeYL8 polypeptide of the large ribosomal subunit (Mizutaet al., 1992), itself homologous to the L7 subunit of mammalian ribosomes. However, RLP7p and YL8 do not functionally replace each other, since anrlp7‐Δ::HIS3strain is completely inviable. Judging from its predicted mass, isoelectric point and amino acid sequence, RLP7p does not correspond to any ribosomal component biochemically identified so far inS. cerevisiae, and also differs from all known ribosomal proteins by the low codon usage bias of its g

ISSN:0749-503X    

DOI:10.1002/yea.320091007

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn a diploid yeast population which is heterozygous for a given marker,A1A2, mitotic crossover (mit. c.o.) between the centromere and the marker will give rise to homozygous daughter cells,A1A1andA2A2. Since this causes a decrease in the frequency ofA1A2cells, mit. c.o. is an important population genetic process in vegetatively propagated yeast cultures. The effect of mit. c.o. is counteracted by mutations and, in the case of heterosis, by selection. We present a mathematical analysis of these interactions.

ISSN:0749-503X    

DOI:10.1002/yea.320091008

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0749-503X    

DOI:10.1002/yea.320091009

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractAn 11 kb yeast DNA insertion isolated from a genomic library by complementation of a phosphofructokinase‐deficient strain was used as a source for a partial sequence analysis. Four genes were shown to reside on this fragment, namelyPFK2, ISP42, ERG2andRAD14.PFK2was mapped previously to the right arm of chromosome XIII, locating the latter three genes to the same chromosom

ISSN:0749-503X    

DOI:10.1002/yea.320091010

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe nucleotide sequence was determined of a 2·1 kb DNA fragment located at approximately 35 kb to the right of the centromere of chromosome VI fromSaccharomyces cerevisiae. Analysis revealed the presence of a tRNAGLygene, part of a delta element and a remarkable palindromic sequence. The longest open reading frame found encodes a putative protein of 195 amino acids. Although the fragment was isolated by hybridization to a human diacylglycerol kinase cDNA, no evidence was obtained for the presence of a gene encoding diacylglycerol kinase

ISSN:0749-503X    

DOI:10.1002/yea.320091011

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY