scholarly journals A heat shock-resistant mutant of Saccharomyces cerevisiae shows constitutive synthesis of two heat shock proteins and altered growth.

1984 ◽  
Vol 99 (4) ◽  
pp. 1441-1450 ◽  
Author(s):  
H Iida ◽  
I Yahara
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Heat Shock ◽  
Type Strain ◽  
Wild Type Strain ◽  
Growth Control ◽  
Protein S ◽  
Resistant Mutant ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Sulfur Starvation

A heat shock-resistant mutant of the budding yeast Saccharomyces cerevisiae was isolated at the mutation frequency of 10(-7) from a culture treated with ethyl methane sulfonate. Cells of the mutant are approximately 1,000-fold more resistant to lethal heat shock than those of the parental strain. Tetrad analysis indicates that phenotypes revealed by this mutant segregated together in the ratio 2+:2- from heterozygotes constructed with the wild-type strain of the opposite mating type, and are, therefore, attributed to a single nuclear mutation. The mutated gene in the mutant was herein designated hsr1 (heat shock response). The hsr1 allele is recessive to the HSR1+ allele of the wild-type strain. Exponentially growing cells of hsr1 mutant were found to constitutively synthesize six proteins that are not synthesized or are synthesized at reduced rates in HSR1+ cells unless appropriately induced. These proteins include one hsp/G0-protein (hsp48A), one hsp (hsp48B), and two G0-proteins (p73, p56). Heterozygous diploid (hsr1/HSR1+) cells do not synthesize the proteins constitutively induced in hsr1 cells, which suggests that the product of the HSR1 gene might negatively regulate the synthesis of these proteins. The hsr1 mutation also led to altered growth of the mutant cells. The mutation elongated the duration of G1 period in the cell cycle and affected both growth arrest by sulfur starvation and growth recovery from it. We discuss the problem of which protein(s) among those constitutively expressed in growing cells of the hsr1 mutant is responsible for heat shock resistance and alterations in the growth control.

scholarly journals Disruption of the RAD52 gene alters the spectrum of spontaneous SUP4-o mutations in Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 122 (3) ◽  
pp. 535-542 ◽  
Author(s):  
B A Kunz ◽  
M G Peters ◽  
S E Kohalmi ◽  
J D Armstrong ◽  
M Glattke ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Base Pair ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mutator Phenotype ◽  
In The Wild ◽  
Single Base Pair ◽  
Almost All

Abstract Defects in the RAD52 gene of the yeast Saccharomyces cerevisiae confer a mutator phenotype. To characterize this effect in detail, a collection of 238 spontaneous SUP4-o mutations arising in a strain having a disrupted RAD52 gene was analyzed by DNA sequencing. The resulting mutational spectrum was compared to that derived from an examination of 222 spontaneous mutations selected in a nearisogenic wild-type (RAD52) strain. This comparison revealed that the mutator phenotype was associated with an increase in the frequency of base-pair substitutions. All possible types of substitution were detected but there was a reduction in the relative fraction of A.T----G.C transitions and an increase in the proportion of G.C----C.G transversions. These changes were sufficient to cause a twofold greater preference for substitutions at G.C sites in the rad52 strain despite a decrease in the fraction of G.C----T.A transversions. There were also considerable differences between the distributions of substitutions within the SUP4-o gene. Base-pair changes occurred at fewer sites in the rad52 strain but the mutated sites included several that were not detected in the RAD52 background. Only two of the four sites that were mutated most frequently in the rad52 strain were also prominent in the wild-type strain and mutation frequencies at almost all sites common to both strains were greater for the rad52 derivative. Although single base-pair deletions occurred in the two strains with similar frequencies, several classes of mutation that were recovered in the wild-type background including multiple base-pair deletions, insertions of the yeast transposable element Ty, and more complex changes, were not detected in the rad52 strain.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Nuclear Export of Heat Shock and Non-Heat-Shock mRNA Occurs via Similar Pathways

2000 ◽  
Vol 20 (11) ◽  
pp. 3996-4005 ◽  
Author(s):  
Irina E. Vainberg ◽  
Ken Dower ◽  
Michael Rosbash
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Heat Shock ◽  
Late Stage ◽  
Nuclear Export ◽  
Type Strain ◽  
Wild Type Strain ◽  
Mrna Export ◽  
Differential Regulation ◽  
Wild Type

ABSTRACT Several studies of the yeast Saccharomyces cerevisiaesupport differential regulation of heat shock mRNA (hs mRNA) and non-hs mRNA nuclear export during stress. These include the finding that hs mRNA export at 42°C is inhibited in the absence of the nucleoporinlike protein Rip1p (also called Nup42p) (C. A. Saavedra, C. M. Hammell, C. V. Heath, and C. N. Cole, Genes Dev. 11:2845–2856, 1997; F. Stutz, J. Kantor, D. Zhang, T. McCarthy, M. Neville, and M. Rosbash, Genes Dev. 11:2857–2868, 1997). However, the results reported in this paper provide little evidence for selective non-hs mRNA retention or selective hs mRNA export under heat shock conditions. First, we do not detect a block to non-hs mRNA export at 42°C in a wild-type strain. Second, hs mRNA export appears to be mediated by the Ran system and several other factors previously reported to be important for general mRNA export. Third, the export of non-hs mRNA as well as hs mRNA is inhibited in the absence of Rip1p at 42°C. As a corollary, we find no evidence for cis-acting hs mRNA sequences that promote transport during heat shock. Taken together, our data suggest that a shift to 42°C in the absence of Rip1p impacts a late stage of transport affecting most if not all mRNA.

scholarly journals Role of glutathione in heat-shock-induced cell death of Saccharomyces cerevisiae

2000 ◽  
Vol 352 (1) ◽  
pp. 71-78 ◽  
Author(s):  
Kei-ichi SUGIYAMA ◽  
Atsuki KAWAMURA ◽  
Shingo IZAWA ◽  
Yoshiharu INOUE
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Heat Shock ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Glutathione Synthesis ◽  
Heat Shock Stress ◽  
Shock Stress

Previously we reported that expression of GSH1 (γ-glutamylcysteine synthetase) and GSH2 (glutathione synthetase) of the yeast Saccharomyces cerevisiae was increased by heat-shock stress in a Yap1p-dependent fashion and consequently intracellular glutathione content was increased [Sugiyama, Izawa and Inoue (2000) J. Biol. Chem. 275, 15535–15540]. In the present study, we discuss the physiological role of glutathione in the heat-shock stress response in this yeast. Both gsh1 and gsh2 mutants could acquire thermotolerance by mild heat-shock stress and induction of Hsp104p in both mutants was normal; however, mutant cells died faster by heat shock than their parental wild-type strain. After pretreatment at a sublethal temperature, the number of respiration-deficient mutants increased in a gsh1 mutant strain in the early stages of exposure to a lethal temperature, although this increase was partially suppressed by the addition of glutathione. These results lead us to suspect that an increase of glutathione synthesis during heat-shock stress is to protect mitochondrial DNA from oxidative damage. To investigate the correlation between mitochondrial DNA damage and glutathione, mitochondrial Mn-superoxide dismutase (the SOD2 gene product) was disrupted. As a result, the rate of generation of respiration-deficient mutants of a sod2∆ strain was higher than that of the isogenic wild-type strain and treatment of the sod2∆ mutant with buthionine sulphoximine, an inhibitor of glutathione synthesis, inhibited cell growth. These results suggest that glutathione synthesis is induced by heat shock to protect the mitochondrial DNA from oxidative damage that may lead to cell death.

scholarly journals Effects of Mutations of RAD50, RAD51, RAD52, and Related Genes on Illegitimate Recombination in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 383-391 ◽  
Author(s):  
Yasumasa Tsukamoto ◽  
Jun-ichi Kato ◽  
Hideo Ikeda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quantitative Analysis ◽  
Structural Analysis ◽  
Recombination Rate ◽  
Type Strain ◽  
Negative Selection ◽  
Wild Type Strain ◽  
Illegitimate Recombination ◽  
Wild Type ◽  
In The Wild

Abstract To examine the mechanism of illegitimate recombination in Saccharomyces cerevisiae, we have developed a plasmid system for quantitative analysis of deletion formation. A can1 cyh2 cell carrying two negative selection markers, the CAN1 and CYH2 genes, on a YCp plasmid is sensitive to canavanine and cycloheximide, but the cell becomes resistant to both drugs when the plasmid has a deletion over the CAN1 and CYH2 genes. Structural analysis of the recombinant plasmids obtained from the resistant cells showed that the plasmids had deletions at various sites of the CAN1-CYH2 region and there were only short regions of homology (1-5 bp) at the recombination junctions. The results indicated that the deletion detected in this system were formed by illegitimate recombination. Study on the effect of several rad mutations showed that the recombination rate was reduced by 30-, 10-, 10-, and 10-fold in the rad52, rad50, mre11, and xrs2 mutants, respectively, while in the rud51, 54, 55, and 57 mutants, the rate was comparable to that in the wild-type strain. The rad52 mutation did not affect length of homology at junction sites of illegitimate recombination.

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 Topoisomerase I involvement in illegitimate recombination in Saccharomyces cerevisiae.

1996 ◽  
Vol 16 (4) ◽  
pp. 1805-1812 ◽  
Author(s):  
J Zhu ◽  
R H Schiestl
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Aberrations ◽  
Topoisomerase I ◽  
Wild Type Strain ◽  
Hot Spot ◽  
Illegitimate Recombination ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae

Chromosome aberrations may cause cancer and many heritable diseases. Topoisomerase I has been suspected of causing chromosome aberrations by mediating illegitimate recombination. The effects of deletion and of overexpression of the topoisomerase I gene on illegitimate recombination in the yeast Saccharomyces cerevisiae have been studied. Yeast transformations were carried out with DNA fragments that did not have any homology to the genomic DNA. The frequency of illegitimate integration was 6- to 12-fold increased in a strain overexpressing topoisomerase I compared with that in isogenic control strains. Hot spot sequences [(G/C)(A/T)T] for illegitimate integration target sites accounted for the majority of the additional events after overexpression of topoisomerase I. These hot spot sequences correspond to sequences previously identified in vitro as topoisomerase I preferred cleavage sequences in other organisms. Furthermore, such hot spot sequences were found in 44% of the integration events present in the TOP1 wild-type strain and at a significantly lower frequency in the top1delta strain. Our results provide in vivo evidence that a general eukaryotic topoisomerase I enzyme nicks DNA and ligates nonhomologous ends, leading to illegitimate recombination.

scholarly journals Sml1 Inhibits the DNA Repair Activity of Rev1 in Saccharomyces cerevisiae during Oxidative Stress

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Rui Yao ◽  
Pei Zhou ◽  
Chengjin Wu ◽  
Liming Liu ◽  
Jing Wu
Keyword(s):  
Oxidative Stress ◽  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Survival Rate ◽  
Type Strain ◽  
Mutation Frequency ◽  
Wild Type Strain ◽  
Yeast Cells ◽  
Wild Type ◽  
Content Type

ABSTRACT In Saccharomyces cerevisiae, Y family DNA polymerase Rev1 is involved in the repair of DNA damage by translesion DNA synthesis (TLS). In the current study, to elucidate the role of Rev1 in oxidative stress-induced DNA damage in S. cerevisiae, REV1 was deleted and overexpressed; transcriptome analysis of these mutants along with the wild-type strain was performed to screen potential genes that could be associated with REV1 during response to DNA damage. When the yeast cells were treated with 2 mM H2O2, the deletion of REV1 resulted in a 1.5- and 2.8-fold decrease in the survival rate and mutation frequency, respectively, whereas overexpression of REV1 increased the survival rate and mutation frequency by 1.1- and 2.9-fold, respectively, compared to the survival rate and mutation frequency of the wild-type strain. Transcriptome and phenotypic analyses identified that Sml1 aggravated oxidative stress in the yeast cells by inhibiting the activity of Rev1. This inhibition was due to the physical interaction between the BRCA1 C terminus (BRCT) domain of Rev1 and amino acid residues 36 to 70 of Sml1; the cell survival rate and mutation frequency increased by 1.8- and 3.1-fold, respectively, when this interaction was blocked. We also found that Sml1 inhibited Rev1 phosphorylation under oxidative stress and that deletion of SML1 increased the phosphorylation of Rev1 by 46%, whereas overexpression of SML1 reduced phosphorylation of Rev1. Overall, these findings demonstrate that Sml1 could be a novel regulator that mediates Rev1 dephosphorylation to inhibit its activity during oxidative stress. IMPORTANCE Rev1 was critical for cell growth in S. cerevisiae, and the deletion of REV1 caused a severe growth defect in cells exposed to oxidative stress (2 mM H2O2). Furthermore, we found that Sml1 physically interacted with Rev1 and inhibited Rev1 phosphorylation, thereby inhibiting Rev1 DNA antioxidant activity. These findings indicate that Sml1 could be a novel regulator for Rev1 in response to DNA damage by oxidative stress.

Sulphide Resistance in the Cyanobacterium Microcystis aeruginosa: a Comparative Study of Morphology and Photosynthetic Performance Between the Sulphide-Resistant Mutant and the Wild-Type Strain

2015 ◽  
Vol 71 (4) ◽  
pp. 860-872 ◽  
Author(s):  
Elena Bañares-España ◽  
María del Mar Fernández-Arjona ◽  
María Jesús García-Sánchez ◽  
Miguel Hernández-López ◽  
Andreas Reul ◽  
...  
Keyword(s):  
Comparative Study ◽  
Microcystis Aeruginosa ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistant Mutant ◽  
Photosynthetic Performance ◽  
Wild Type
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