scholarly journals PROTEIN DEGRADATION, MEIOSIS AND SPORULATION IN PROTEINASE-DEFICIENT MUTANTS OF SACCHAROMYCES CEREVISIAE

Genetics ◽  
1981 ◽  
Vol 97 (1) ◽  
pp. 45-64 ◽  
Author(s):  
George S Zubenko ◽  
Elizabeth W Jones
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Drug Resistance ◽  
Protein Degradation ◽  
Mating Type ◽  
Carboxypeptidase Y ◽  
Wild Type ◽  
Resistance Marker ◽  
Drug Resistance Marker

ABSTRACT During the process of sporulation, a/α diploids degrade about 50% of their vegetative proteins. This degradation is not sporulation specific, for asporogenous diploids of a/a mating type degrade their vegetative proteins in a fashion similar to that of their a/α counterparts. Diploids lacking carboxypeptidase Y activity, prc1/prc1, show about 80% of wild-type levels of protein degradation, but are unimpaired in the production of normal asci. Diploids lacking proteinase B activity, prb1/prb1, show about 50% of wild-type levels of protein degradation. The effect on degradation of the proteinase B deficiency is epistatic to the degradation deficit attributable to the carboxypeptidase Y deficiency. The prb1 homozygotes undergo meiosis and produce spores, but the asci and, possibly, the spores are abnormal. Diploids homozygous for the pleiotropic pep4-3 mutation show only 30% of the wild-type levels of degradation when exposed to a sporulation regimen, and do not undergo meiosis or sporulation. Neither proteinase B nor carboxypeptidase Y is necessary for germination of spores. ——Approximately half of the colonies arising from a/a or α/α diploids exposed to the sporulation regiment that express an initially heterozygous drug-resistance marker (can1) appear to arise from mating-type switches followed by meiosis and sporulation.

scholarly journals CaNdt80 Is Involved in Drug Resistance in Candida albicans by Regulating CDR1

2004 ◽  
Vol 48 (12) ◽  
pp. 4505-4512 ◽  
Author(s):  
Chia-Geun Chen ◽  
Yun-Liang Yang ◽  
Hsin-I Shih ◽  
Chia-Li Su ◽  
Hsiu-Jung Lo
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Drug Resistance ◽  
Candida Albicans ◽  
Type Strain ◽  
Antifungal Agents ◽  
Wild Type Strain ◽  
Efflux Pump ◽  
Antifungal Drugs ◽  
Galactosidase Activity ◽  
Wild Type

ABSTRACT Overexpression of CDR1, an efflux pump, is one of the major mechanisms contributing to drug resistance in Candida albicans. CDR1 p-lacZ was constructed and transformed into a Saccharomyces cerevisiae strain so that the lacZ gene could be used as the reporter to monitor the activity of the CDR1 promoter. Overexpression of CaNDT80, the C. albicans homolog of S. cerevisiae NDT80, increases the β-galactosidase activity of the CDR1 p-lacZ construct in S. cerevisiae. Furthermore, mutations in CaNDT80 abolish the induction of CDR1 expression by antifungal agents in C. albicans. Consistently, the Candt80/Candt80 mutant is also more susceptible to antifungal drugs than the wild-type strain. Thus, the gene for CaNdt80 may be the first gene among the regulatory factors involved in drug resistance in C. albicans whose function has been identified.

scholarly journals RPD3 and UME6 are involved in the activation of PDR5 transcription and pleiotropic drug resistance in ρ0 cells of Saccharomyces cerevisiae

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yoichi Yamada
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Drug Resistance ◽  
Positive Response ◽  
Mrna Levels ◽  
Transporter Gene ◽  
Transcriptional Expression ◽  
Pleiotropic Drug Resistance ◽  
Wild Type ◽  
Binding Partners ◽  
Retrograde Signalling

Abstract Background In Saccharomyces cerevisiae, the retrograde signalling pathway is activated in ρ0/− cells, which lack mitochondrial DNA. Within this pathway, the activation of the transcription factor Pdr3 induces transcription of the ATP-binding cassette (ABC) transporter gene, PDR5, and causes pleiotropic drug resistance (PDR). Although a histone deacetylase, Rpd3, is also required for cycloheximide resistance in ρ0/− cells, it is currently unknown whether Rpd3 and its DNA binding partners, Ume6 and Ash1, are involved in the activation of PDR5 transcription and PDR in ρ0/− cells. This study investigated the roles of RPD3, UME6, and ASH1 in the activation of PDR5 transcription and PDR by retrograde signalling in ρ0 cells. Results ρ0 cells in the rpd3∆ and ume6∆ strains, with the exception of the ash1∆ strain, were sensitive to fluconazole and cycloheximide. The PDR5 mRNA levels in ρ0 cells of the rpd3∆ and ume6∆ strains were significantly reduced compared to the wild-type and ash1∆ strain. Transcriptional expression of PDR5 was reduced in cycloheximide-exposed and unexposed ρ0 cells of the ume6∆ strain; the transcriptional positive response of PDR5 to cycloheximide exposure was also impaired in this strain. Conclusions RPD3 and UME6 are responsible for enhanced PDR5 mRNA levels and PDR by retrograde signalling in ρ0 cells of S. cerevisiae.

scholarly journals A Small Protein (Ags1p) and the Pho80p-Pho85p Kinase Complex Contribute to Aminoglycoside Antibiotic Resistance of the YeastSaccharomyces cerevisiae

1998 ◽  
Vol 180 (7) ◽  
pp. 1887-1894 ◽  
Author(s):  
Stephan Wickert ◽  
Markus Finck ◽  
Britta Herz ◽  
Joachim F. Ernst
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Aminoglycoside Antibiotic ◽  
Carboxypeptidase Y ◽  
Hygromycin B ◽  
Wild Type ◽  
Aminoglycoside Resistance ◽  
Small Protein ◽  
Enhanced Sensitivity ◽  
Chromosome Iii ◽  
Glycosylation Pathway

ABSTRACT We identified the AGS1 and AGS3 genes by their ability to partially complement an ags mutant (RC1707) which is supersensitive to various aminoglycoside antibiotics (J. F. Ernst and R. K. Chan, J. Bacteriol. 163:8–14, 1985).AGS1 is located in proximity to the centromere of chromosome III and encodes a small protein of 88 amino acids. The size of the AGS1 transcript, which in wild-type cells is 1 kb, is reduced to 0.75 kb in mutant RC1707. Disruption of AGS1rendered strains supersensitive to hygromycin B and increased their resistance to vanadate. In addition, ags1Δ strains underglycosylated invertase but had normal carboxypeptidase Y glycosylation, suggesting that Ags1p is required for the elaboration of outer N-glycosyl chains. AGS3 was found to be identical toPHO80 (TUP7), which encodes a cyclin activating the Pho85p protein kinase. Deletion of either PHO80 orPHO85 led to aminoglycoside supersensitivity;pho80Δ ags1Δ strains showed an enhanced-sensitivity phenotype compared to single mutants. pho80 andpho85 mutants were rendered resistant by deletion ofPHO4, indicating that activation of the Pho4p transcription factor is required for increased aminoglycoside sensitivity. Thus, both the Pho80p-Pho85p kinase complex (by Pho4p phosphorylation) and a novel component of the N glycosylation pathway contribute to basal levels of aminoglycoside resistance in Saccharomyces cerevisiae.

Sec59 encodes a membrane protein required for core glycosylation in Saccharomyces cerevisiae

1989 ◽  
Vol 9 (3) ◽  
pp. 1191-1199
Author(s):  
M Bernstein ◽  
F Kepes ◽  
R Schekman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Product ◽  
Carboxypeptidase Y ◽  
Secretory Proteins ◽  
Restrictive Temperature ◽  
Wild Type ◽  
Partial Restoration ◽  
Alpha Factor ◽  
Mutant Cells

When incubated at a restrictive temperature, Saccharomyces cerevisiae sec59 mutant cells accumulate inactive and incompletely glycosylated forms of secretory proteins. Three different secretory polypeptides (invertase, pro-alpha-factor, and pro-carboxypeptidase Y) accumulated within a membrane-bounded organelle, presumably the endoplasmic reticulum, and resisted proteolytic degradation unless the membrane was permeabilized with detergent. Molecular cloning and DNA sequence analysis of the SEC59 gene predicted an extremely hydrophobic protein product of 59 kilodaltons. This prediction was confirmed by reconstitution of the sec59 defect in vitro. The alpha-factor precursor, which was translated in a soluble fraction from wild-type cells, was translocated into, but inefficiently glycosylated within, membranes from sec59 mutant cells. Residual glycosylation activity of membranes of sec59 cells was thermolabile compared with the activity of wild-type membranes. Partial restoration of glycosylation was obtained in reactions that were supplemented with mannose or GDP-mannose, but not those supplemented with other sugar nucleotides. These results were consistent with a role for the Sec59 protein in the transfer of mannose to dolichol-linked oligosaccharide.

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