摘要:

AbstractThe genetics of flocculation in the yeastSaccharomyces cerevisiaeare poorly understood despite the importance of this property for strains used in industry. To be able to study the regulation of flocculation in yeast, one of the genes involved,FLO1, has been partially cloned. The identity of the gene was confirmed by the non‐flocculent phenotype of cells in which the C‐terminal part of the gene had been replaced by theURA3gene. Southern blots and genetic crosses showed that theURA3gene had integrated at the expected position on chromosome I. A region of approximately 2 kb in the middle of theFLO1gene was consistently deleted during propagation inEscherichia coliand could not be isolated. Plasmids containing the incomplete gene, however, were still able to cause weak flocculation in a nonflocculent strain. The 3′ end of theFLO1gene was localized at approximately 24 kb from the right end of chromosome I, 20 kb centromere‐proximal toPHO11. Most of the newly isolated chromosome I sequences also hybridized to chromosome VIII DNA, thus extending the homology between the right end of chromosome I and chromosome VIII to approximatel

ISSN:0749-503X    

DOI:10.1002/yea.320090102

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractEight independentchl(chromosomeloss) mutants were isolated using yeast haploid strain disomic for chromosome III. In these mutants, chromosome III is lost during mitosis 50‐fold more frequently than in the wild‐type strains.chlmutants are also incapable of stable maintenance of circular and linear artificial chromosomes. Seven of the eight mutations are recessive, and one is semidominant. Complementation tests placed these mutants into six complementation groups (chl11throughchl16). Based on tetrad analysis,chl12, chl14andchl15correspond to mutations in single nuclear genes. Tetrad analysis of the other mutants was not possible due to poor spore viability. Complementation analysis was also carried out between collection ofchlmutants andctfmutants (chromosometransmissionfidelity) (Spenceret al., 1990). Thechl3, chl4, chl8, chl12andchl15mutants were unable to complementctf3, ctf17, ctf12, ctf18andctf4, respectively. ThreeCHLgenes were mapped by tetrad analysis. TheCHL3gene is placed on the right arm of chromosome XII, between theILV5(33·3 cM) andURA4(21·8 cM) loci. TheCHL10gene is located on the left arm of chromosome VI, 12·5 cM from the centromere. TheCHL15gene is tightly linked to theKAR3marker of the right arm of chromosome XVI (8·8 cM). The mapping data indicate that these three genes differ from other genes known to affect chromosome stability in mitosis. Therefore, the total number of theCHLgenes identified (including those described by us earlier) is 13 (CHL1–CHL10, CHL12, CHL14

ISSN:0749-503X    

DOI:10.1002/yea.320090103

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractTheSCH9yeast gene, that was previously identified as a suppressor ofcdc25andras1−ras2‐tstemperature‐sensitive mutants, encodes a putative protein kinase that positively regulates the progression of yeast cells through the G1 phase of the cell cycle. We have determined the structure of theSCH9transcription unit, using primer extension and S1 mapping techniques. The corresponding mRNA included an unusually long 5′ region of more than 600 nucleotides preceding the major open reading frame (ORF). While the latter corresponded to a protein of 824 amino acids, an upstream open reading frame (uORF) within the 5′ leader could potentially encode a 54 amino acid peptide. To investigate the role of the AUGs within the uORF, we engineered chimaeric plasmid vectors in whichSCH9sequences including the promoter, the mRNA leader and the first 514 nucleotides of the major ORF were fused in‐frame with β‐galactosidase‐coding sequences. Upon introduction into yeast cells, the fusion protein was efficiently expressed. However, mutational disruption of the uORF using oligonucleotide‐directed mutagenesis did not affect the level of expression of the fusion protein. This indicates that regulatory mechanisms inSaccharomyces cerevisiaeprevent upstream AUGs within theSCH9mRNA leader sequence from influencing translation from downstream

ISSN:0749-503X    

DOI:10.1002/yea.320090104

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractRapidly growing cells ofSaccharomyces cerevisiaeare sensitive to heat shock, while non‐growing stationary phase cells are highly resistant. We find that slowly growing cells have an intermediate degree of heat shock resistance that can be nearly as great as that of stationary phase cells. This resistance is correlated both with slow growth and with carbon catabolite derepression. Slowly growing cells also showed resistance to Zymolyase digestion of their cell walls. The stress resistance is a property of all the cells in the culture, and cell cycle position makes little difference to the degree of stress resistance. At least some of the properties normally associated with stationary phase cells do not require residence in stationary phase or any other particular compartment of the cell cycle. Stress resistance may be due to a diverse set of physiological adaptations available to cells regardless of their position in the cell cycle. That is, although stress resistance and stationary phase are often correlated, neither is the cause of the othe

ISSN:0749-503X    

DOI:10.1002/yea.320090105

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSKI8is a yeast antiviral gene, essential for controlling the propagation of M double‐stranded RNA (dsRNA) and thus for preventing virus‐induced cytopathology. Our DNA sequence ofSKI8shows that it encodes a 397 amino acid protein containing two copies of a 31 amino acid repeat pattern first identified in mammalian β‐transducin and Cdc4p of yeast. There are also four copies of this repeat in yeast Mak11p, necessary for M dsRNA propagation, and three copies in the putative product of theDictyostelium AAC3gene. Analysis of 36 cases of the repeat unit shows they have a consensus predicted structure: N–helix–sheet–turn–sheet–tu

ISSN:0749-503X    

DOI:10.1002/yea.320090106

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractBy employing pulsed‐field gel electrophoresis we have determined the size of the rDNA cluster in wild‐type yeast strains representing genera ofCandida,Kluyveromyces,Pachysolen,SchizosaccharomycesandTorulaspora. Although the genome size of the examined species is similar (12·3–13·9 Mb), at least a four‐fold variation has been observed between the lowest amount of rDNA repeats inP. tannophilus(28) and the highest inC. glabrataandS. poombe(>115).In two species the rDNA cluster is represented by two loci, residing either in one (S. pombe) or two chromosomes (C.

ISSN:0749-503X    

DOI:10.1002/yea.320090107

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractTo study the conservation of peroxisomal targeting signals, we have determined the intracellular localization of human peroxisomal catalase when expressed in yeast. Using immunofluorescence, differential centrifugation and immunoelectron microscopy, we show that the protein is targeted to the peroxisomes of the heterologous cell and assembled in its active tetrameric form. These data show the conservation of the catalase targeting signal and import specificity between human and yeast peroxisomes.

ISSN:0749-503X    

DOI:10.1002/yea.320090108

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe use of β‐glucuronidase (β‐GUS) as a reporter and sensitive detection system forYarrowia lipolyticawas studied. TheEscherichia coli gusAgene was expressed under control of the homologousLEU2promoter in a transcriptional fusion. AnNcoI restriction site was introduced at the translational start‐ATG, conserving the most favorable context for initiation of translation. The chimericLEU2′‐gusAgene was integrated into theLEU2locus by homologous recombination. The β‐GUS assay was very sensitive and highly reproducible, using the cytosolic fraction or a total cell extract as the source of enzyme. In a leucine‐free medium, β‐GUS activity was at a high, constant level, independent of growth phase. In transformants grown on complete medium, β‐GUS activity was reduced about three‐fold, but doubled during logarithmic growth. No intrinsic β‐GUS activity was detectable in untransformedY. lipolyticaand no effect of β‐GUS expression on growth was obseved. β‐GUS‐producingY. lipolyticacells could be directly detected on media plates containing X‐gluc (5‐br

ISSN:0749-503X    

DOI:10.1002/yea.320090109

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn the budding yeastSaccharomyces cerevisiaethe cell wall, mainly composed of mannoproteins and glucans, constitutes a barrier to protein excretion in the growth medium. In this paper we have studied the effects of different environmental parameters on excretion ofEscherichia coliβ‐galactosidase obtained by exploiting the glucoamylase II signal sequence. Excretion of the unglycosylated β‐galactosidase was detectable only in cells grown in rich medium, was affected by temperature (36°C>30°C>>24°C) and slightly stimulated by reducing agents. On the contrary, glycosylated proteins, such as α‐galactosidase and glucoamylase II, were excreted to a good extent under all tested conditions of medium composition, growth temperature and pH. These data indicate that optimization of environmental parameters may help the excretion of heterologous proteins, offering advantages for protein p

ISSN:0749-503X    

DOI:10.1002/yea.320090110

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractFlocculent strains of brewing yeast grow and ferment as single cells and flocculate in the stationary phase of growth. The switch from single‐celled yeast growth to multi‐celled aggregation, flocculation onset, is of critical importance to the brewing industry. Yeast flocculation involves adhesion of surface‐lectins on flocculent cells to carbohydrate receptors on neighbouring cell‐walls. The presence of carbohydrate receptors, outer‐chain mannan side‐branches, was monitored throughout growth of flocculent and non‐flocculent strains ofSaccharomyces cerevisiae, with particular attention to the growth phases where flocculation is normally developed. Receptors were probed by coflocculation with flocculent strains and by aggregation with concanavalin A, a lectin shown to use the same receptors as flocculation.While considerable variation was found in coflocculation and concanavalin A aggregation between strains, little or no change in receptor availability was found throughout the growth of all yeast strains. Yeast cells could easily be coflocculated at any growth stage. It was concluded that receptor availability is not involved in the process of flocc

ISSN:0749-503X    

DOI:10.1002/yea.320090111

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY