摘要:

AbstractThe gene for ornithine decarboxylase inSaccharomyces cerevisiae, SPE1, has been assigned to chromosome XI by the technique of transverse alternating pulsed field electrophoresis and DNA–DNA hybridization. Genetic mapping by tetrad analysis shows that theSPE1gene is located on the left arm of chromosome XI, 6 cM from theLAP1gene and 43 cM from theTRP3gene. Thespe10mutation previously isolated in this laboratory is mapped to the N‐terminal region of theSPE1gene, and therefore should be designated as aspe1all

ISSN:0749-503X    

DOI:10.1002/yea.320060602

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractSUP2(SUP35)is an omnipotent suppressor gene, coding for an EF‐1α‐like protein factor, intimately involved in the control of translational accuracy in yeastSaccharomyces cerevisiae.In the present study aSUP2gene analogue from yeastPichia pinuswas isolated by complementation of the temperature‐sensitivesup2mutation ofS. cerevisiae.The nucleotide sequence of theSUP2gene ofP. pinuscodes for a protein of 82·4 kDa, exceeding the Sup2 protein ofS. cerevisiaeby 6 kDa. Like theSUP2gene product ofS. cerevisiae, the Sup2 protein ofP. pinusrepresents a fusion of a unique N‐terminal part of a region homologous to EF‐1α. The comparison of amino acid sequences of the Sup2 proteins reveals high conservations (76%) of the C‐terminal region and low conservation (36%) of the N‐terminal part where, in addition, the homologous correspondence is ambiguous.Proteins related to the Sup2 ofS. cerevisiaewhere found inP. pinusand some other yeast species by the immunoblotting technique.The relation between the evolutionary conservation of different regions of the Sup2 protein and their functional significa

ISSN:0749-503X    

DOI:10.1002/yea.320060603

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractIn order to determine the effect of nucleotide composition of the 5′‐untranslated (leader) region on the translational efficiency of mRNA in yeast, we replaced a large part of the leader region of the phosphoglycerate kinase (PGK) gene by various deoxyoligonucleotides of defined sequence. All mutations left the context of the transcription initiations site and AUG start codon intact. The mutant genes were introduced into yeast cells on a multicopy vector and the ratio of the steady‐state levels ofPGKmRNA and protein were determined.We found the translational efficiency to be unaffected by the presence of either an 18 nucleotides (nt) long poly A or poly C tract or by sequences consisting of mixtures of A and C residues in any proportion. In contrast, a polyU tract, as well as mixtures of U and C residues, reduced translational efficiency by a factor of two to three, presumably by long‐rang base ‐pairing between the leader and sequences elsewhere in the coding or 3′‐non‐coding regions of the messenger. In agreement with this hypothesis, a five‐fold reduction in translational efficiency was found for an mRNA carrying a polyC tract in the leader as well as a polyG tract in the trailer, neither of which had any effect on translational efficiency by itself. Therefore, we conclude that the leader and trailer regions (including the polyA tail) ofPGKmRNA are sufficiently close to base‐pair when containing complementary sequences. The resulting secondary structure evidently constitutes a barrier for incoming 40S subunits on their way to the AUG start codon.The presence of an 18 nt long polyG tract in the leader completely abolished translation of thePGKmRNA in accordance with earlier observations. However, we found the leaders containing up to 40% G residues interspersed with either A or U, still allow highly efficient translation. This value is about four times as high as the average G content of leader sequence in naturally occurring yeast mRNAS.Finally, neither deletion of about 40% of the trailer sequence ofPGKmRNA, not replacement of this sequence by homopolymer tracts had any effect on trans

ISSN:0749-503X    

DOI:10.1002/yea.320060604

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractWe have developed a new assay to determine relative cell wall porosity in yeasts, which is based on polycation‐induced leakage of UV‐absorbing compounds. Polycations with a small hydrodynamic radius as measured by gel filtration (poly‐L‐lysine) caused cell leakage independent of cell wall porosity whereas polycations with a large hydrodynamic radius (DEAE‐dextrans) caused only limited cell leakage due to limited passage through the cell wall. This allowed the ratio between DEAE‐dextran‐ and poly‐L‐lysine‐induced cell leakage to be used as a measure of cell wall porosity inSaccharomyces cerevisiae, Kluyveromyces lactisandSchizosaccharomyces pombe. Using this assay, we found that the composition of the growth medium affected cell wall porosity inS. cerevisiae. In addition, we could show that cell wall porosity is limited by the number of disulphide bridges in the wall and is dependent on cell turgor. It is argued that earlier methods to estimate cell wall porosity inS. cerevisiaeresulted in lar

ISSN:0749-503X    

DOI:10.1002/yea.320060605

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe cell porosity of batch‐grownSaccharomyces cerevisiaewas maximal in the early exponential phase and fell off rapidly to lower levels in later growth phases.Treatment of stationary‐phase cells with alpha‐mannosidase restored wall porosity to the level of cells in early exponential phase. When cells in the early exponential phase were treated with alpha‐mannosidase, or tunicamycin, an inhibitor of N‐glycosylation, even higher porosities were obtained. Mutants with truncated mannan side‐chains in their wall proteins also had very porous walls. The importance of the mannan side‐chains for wall porosity was also seen during sexual induction. Treatment with alpha pheromone, which leads to the formation of wall proteins with shorter mannan side‐chains, enhanced wall porosity.Disulphide bridges also affect cell wall porosity. They were predominantly found in the glucanase‐soluble wall proteins. Because the main part of the mannan side‐chains is also found in this family of wall proteins, our results demonstrate that the glucanase‐soluble mannoproteins limit cell w

ISSN:0749-503X    

DOI:10.1002/yea.320060606

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractWe have studied growth of two peroxisome‐deficient mutant strains ofHansenula polymorphaon glucose in the presence of different organic nitrogen sources (methylamine, ethylamine andD‐alanine), the metabolism of which is mediated by peroxisome‐borne oxidases in wild‐type (WT) cells. Both strains grew well on each of these substrates with growth rates comparable to WT cells. Growth on both methylamine and ethylamine was associated with enhanced levels of catalase and amine oxidase in the cells; inD‐alanine‐grown cellsD‐amino acid oxidase activity and increased. In WT cells ofH‐polymorphathe activities of these enzymes were confined to the peroxisomal matrix; however, in both peroxisome‐deficient strains their activities were localized in the cytosol. Electron microscopy indicated that, dependent on the stage of growth, the enzymes may form large protein aggregates.The molecular masses of both amine oxidase andD‐amino acid oxidase in the mutant strains were identical to their respective counterparts in WT cells, indicating that both proteins were correctly assembled and ac

ISSN:0749-503X    

DOI:10.1002/yea.320060607

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractWe studied the physiological responses ofHansenula polymorphaduring adaptation of cells to oleic acid‐containing media. Growth experiments indicated that the organism was unable to use oleic acid as the sole source of carbon and energy. However, upon incubation of glucose‐grown cells in mineral media containing oleic acid, activities of various enzymes of the β‐oxidation pathway were induced. These enzymes were localized in microbodies together with alcohol oxidase. Furthermore, a drastic increase in phospholipid content of the cells was observed; this was due to a rapid proliferation of membranes. These consisted of a variable number of membranous layers which were continuous with the peroxisomal membrane. Upon continued incubation, the membrane proliferations extended and large compartments were formed. This process was dependent on the presence of peroxisomes in the cells since it was not observed in peroxisome‐deficient mutant strains ofH. polymorpha. The newly formed membranous compartments differed from peroxisomes since they did not contain peroxisomal matrix proteins; these were confined to the single enlarged organelle which was incorporated in the membranous structure and characterized by a large alcohol oxidase crystalloid. The membranous compartments are considered to be whole entities since they could not be separated from the peroxisomes by common cell fraction methods; also they were degraded entirely after a shift of cells to glucose‐excess condition.Freeze fracturing reveled that the substructure of the membranes greatly resembled that of normal peroxisomal membranes. Since a distinct enhancement of different peroxisomal membrane proteins was observed during the initial hours after the shift, we assume that exposure ofH. polymorphato acid lead to a drastic overproduction of peroxisomal

ISSN:0749-503X    

DOI:10.1002/yea.320060608

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractWe report here the DNA sequence of a segment of chromosome III extending over 8·2 kb. The sequence was determined using the random clone strategy followed by oligonucleotide‐directed sequencing. The segments contains five long open reading frames,YCR521, 522, 523, 524and526, with only short distances between them.YCR523(333 codons) endodes a ribokinase, a new function for yeast.YCR526originates inside theMATcassette, which is in continuity with the present segment, and extends over 358 codons outside ofMAT.YCR524(923 codons) codes for a putative membrane protein.YCR521, 522and524, have each been disrupted by insertion of aURA3cassette and are non‐essential genes. An activeARSelement is located withinYCR523or its vici

ISSN:0749-503X    

DOI:10.1002/yea.320060609

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

ISSN:0749-503X    

DOI:10.1002/yea.320060610

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

ISSN:0749-503X    

DOI:10.1002/yea.320060601

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY