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  • 1
    Electronic Resource
    Electronic Resource
    Glutathione is an essential metabolite required for resistance to oxidative stress in the yeastSaccharomyces cerevisiae (1996)
    Springer
    Current genetics 29 (1996), S. 511-515 
    Details
    ISSN: 1432-0983
    Keywords: Oxidative stress ; Glutathione ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glutathione (GSH) is an abundant cellular thiol which has been implicated in numerous cellular processes and in protection against stress caused by xenobiotics, carcinogens and radiation. Our experiments address the requirement for GSH in yeast, and its role in protection against oxidative stress. Mutants which are unable to synthesis GSH due to a gene disruption inGSH 1, encoding the enzyme for the first step in the biosynthesis of GSH, require exogenous GSH for growth under non-stress conditions. Growth can also be restored with reducing agents containing a sulphydryl group, including dithiothreitol, β-mercaptoethanol and cysteine, indicating that GSH is essential only as a reductant during normal cellular processes. In addition, theGSH 1-disruption strain is sensitive to oxidative stress caused by H2O2 and tert-butyl hydroperoxide. The requirement for GSH in protection against oxidative stress is analogous to that in higher eukaryotes, but unlike the situation in bacteria where it is dispensable for growth during both normal and oxidative stress conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426954
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  • 2
    Electronic Resource
    Electronic Resource
    Involvement of the Saccharomyces cerevisiae UTH1 gene in the oxidative-stress response (1998)
    Springer
    Current genetics 34 (1998), S. 259-268 
    Details
    ISSN: 1432-0983
    Keywords: Key wordsSaccharomyces cerevisiae ; Oxidative stress ; Ageing ; Gene regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The UTH1 gene was identified by screening a Saccharomyces cerevisiae promoter-probe gene bank for oxidative stress-responsive genes. Transcription of UTH1 was decreased by the superoxide anion and increased by hydrogen peroxide. Deletion of UTH1 did not affect the growth of grande cells, however in a ρ 0 background it caused retarded growth. The uth1 mutant showed increased resistance to peroxides and, in contrast, was sensitive to superoxide or the thiol oxidant diamide. Furthermore, the mutant exhibited increased survival under starvation conditions, with elevated levels of dormant cells in starved cell cultures. A multicopy plasmid containing the first half of the ORF could confer increased resistance to superoxide and increased sensitivity to peroxides/diamide/starvation on wild-type cells. The same plasmid in the uth1 background caused a highly increased mortality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002940050395
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  • 3
    Electronic Resource
    Electronic Resource
    Stationary-phase induction of GLR1 expression is mediated by the yAP-1 transcriptional regulatory protein in the yeast Saccharomyces cerevisiae (1996)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 22 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Glutathione (GSH) is an abundant low-molecular-mass thiol which has been implicated in numerous cellular processes including protection against cytotoxic agents such as xenobiotics, carcinogens and free radicals. Utilization of GSH results in its conversion to the oxidized form (GSSG), and it is recycled to GSH by the action of glutathione reductase (GLR) using the reducing power of NADPH. We show that GLR activity is increased by three- to fourfold during stationary-phase growth compared to exponential phase growth, and that a yeast strain deleted for GLR1, encoding glutathione reductase, shows an elevated sensitivity to H2O2 challenge during stationary phase. These data indicate an increased requirement for GSH as the cell arrests growth and enters stationary phase. The stationary-phase increase in GLR activity is entirely dependent upon the action of the yAP-1 transcriptional regulatory protein, previously implicated in regulating GLR activity in response to oxidative stress. Thus, both oxidant- and growth phase-mediated control of GLR1 expression are regulated by the same transcriptional control mechanism. In addition, strains lacking GLR or yAP-1 do not accumulate GSSG during stationary-phase growth, indicating that the cell possesses alternative means of preventing an accumulation of GSSG during stationary phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.d01-1727.x
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  • 4
    Electronic Resource
    Electronic Resource
    Role of the glutathione/glutaredoxin and thioredoxin systems in yeast growth and response to stress conditions (2001)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 39 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Sulphydryl groups (-SH) play a remarkably broad range of roles in the cell, and the redox status of cysteine residues can affect both the structure and the function of numerous enzymes, receptors and transcription factors. The intracellular milieu is usually a reducing environment as a result of high concentrations of the low-molecular-weight thiol glutathione (GSH). However, reactive oxygen species (ROS), which are the products of normal aerobic metabolism, as well as naturally occurring free radical-generating compounds, can alter this redox balance. A number of cellular factors have been implicated in the regulation of redox homeostasis, including the glutathione/glutaredoxin and thioredoxin systems. Glutaredoxins and thioredoxins are ubiquitous small heat-stable oxidoreductases that have proposed functions in many cellular processes, including deoxyribonucleotide synthesis, repair of oxidatively damaged proteins, protein folding and sulphur metabolism. This review describes recent findings in the lower eukaryote Saccharomyces cerevisiae that are leading to a better understanding of their role in redox homeostasis in eukaryotic cell metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02283.x
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  • 5
    Electronic Resource
    Electronic Resource
    Candida albicans and three other Candida species contain an elongation factor structurally and functionally analogous to elongation factor 3 (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 80 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A cell-free poly(U)-dependent translation elongation system from Candida albicans is ATP-dependent due to the presence of an elongation factor 3 (EF3)-like activity. Saccharomyces cerevisiae ribosomes added to a C. albicans post-ribosomal supernatant (PRS) supported poly(U)-dependent elongation, suggesting that the C. albicans lysate contained a soluble translation factor functionally analogous to the S. cerevisiae translation factor EF-3. The presence of EF-3 in C. albicans was confirmed by Western blotting using an antibody raised against S. cerevisiae EF-3. This antibody was also used to screen a selection of Candida species, all of which possessed EF-3 with molecular mass in the range of 110–130 kDa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04634.x
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  • 6
    Electronic Resource
    Electronic Resource
    Regulation of redox homeostasis in the yeast Saccharomyces cerevisiae (2004)
    Oxford, UK; Malden , USA : Munksgaard International Publishers
    Physiologia plantarum 120 (2004), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: An increasingly important area of research is based on sulphydryl chemistry, since the oxidation of -SH groups is one of the earliest observable events during oxidant-mediated damage and -SH groups play a critical role in the function of many macromolecular structures including enzymes, transcription factors and membrane proteins. Glutaredoxins and thioredoxins are small heat-stable oxidoreductases, conserved throughout evolution, which play key roles in maintaining the cellular redox balance. Much progress has been made in analysing these systems in the yeast Saccharomyces cerevisiae which is a very useful model eukaryote due to its ease of genetic manipulation, its compact genome, the availability of the entire genome sequence, and the current rate of progress in gene function research. Yeast, like all eukaryotes, contains a number of glutaredoxin and thioredoxin isoenzymes located in both the cytoplasm and the mitochondria. This review describes recent findings made in yeast that are leading to a better understanding of the regulation and role of redox homeostasis in eukaryotic cell metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0031-9317.2004.0193.x
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  • 7
    Electronic Resource
    Electronic Resource
    Glutathione regulates the expression of γ-glutamylcysteine synthetase via the Met4 transcription factor (2002)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 46 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Our previous studies have shown that glutathione is an essential metabolite in the yeast Saccharomyces cerevisiae because a mutant deleted for GSH1, encoding the first enzyme in γ-l-glutamyl-l-cysteinylglycine (GSH) biosynthesis, cannot grow in its absence. In contrast, strains deleted for GSH2, encoding the second step in GSH synthesis, grow poorly as the dipeptide intermediate, γ-glutamylcysteine, can partially substitute for GSH. In this present study, we identify two high copy suppressors that rescue the poor growth of the gsh2 mutant in the absence of GSH. The first contains GSH1, indicating that γ-glutamylcysteine can functionally replace GSH if it is present in sufficiently high quantities. The second contains CDC34, encoding a ubiquitin conjugating enzyme, indicating a link between the ubiquitin and GSH stress protective systems. We show that CDC34 rescues the growth of the gsh2 mutant by inducing the Met4-dependent expression of GSH1 and elevating the cellular levels of γ-glutamylcysteine. Furthermore, this mechanism normally operates to regulate GSH biosynthesis in the cell, as GSH1 promoter activity is induced in a Met4-dependent manner in a gsh1 mutant which is devoid of GSH, and the addition of exogenous GSH represses GSH1 expression. Analysis of a cis2 mutant, which cannot breakdown GSH, confirmed that GSH and not a metabolic product, serves as the regulatory molecule. However, this is not a general mechanism affecting all Met4-regulated genes, as MET16 expression is unaffected in a gsh1 mutant, and GSH acts as a poor repressor of MET16 expression compared with methionine. In summary, GSH biosynthesis is regulated in parallel with sulphate assimilation by activity of the Met4 protein, but GSH1-specific mechanisms exist that respond to GSH availability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.03174.x
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  • 8
    Electronic Resource
    Electronic Resource
    Role of thioredoxins in the response of Saccharomyces cerevisiae to oxidative stress induced by hydroperoxides (2002)
    Oxford, UK : Blackwell Science Ltd.
    Molecular microbiology 43 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Glutaredoxins and thioredoxins are highly conserved, small, heat-stable oxidoreductases. The yeast Saccharomyces cerevisiae contains two gene pairs encoding cytoplasmic glutaredoxins (GRX1, GRX2) and thioredoxins (TRX1, TRX2), and we have used multiple mutants to determine their roles in medi-ating resistance to oxidative stress caused by hydroperoxides. Our data indicate that TRX2 plays the predominant role, as mutants lacking TRX2 are hypersensitive, and mutants containing TRX2 are resistant to these oxidants. However, the requirement for TRX2 is only apparent during stationary phase growth, and we present three lines of evidence that the thioredoxin isoenzymes actually have redundant activities as antioxidants. First, the trx1 and trx2 mutants show wild-type resistance to hydroperoxide during exponential phase growth; secondly, overexpression of either TRX1 or TRX2 leads to increased resistance to hydroperoxides; and, thirdly, both Trx1 and Trx2 are equally able to act as cofactors for the thioredoxin peroxidase, Tsa1. The antioxidant activity of thioredoxins is required for both the survival of yeast cells as well as protection against oxidative stress during stationary phase growth, and correlates with an increase in the expression of both TRX1 and TRX2. We show that the requirement for thioredoxins during this growth phase is dependent on their activity as cofactors for the antioxidant enzyme Tsa1, and for regulation of the redox state and protein-bound levels of the low-molecular-weight antioxidant glutathione.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.02795.x
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  • 9
    Electronic Resource
    Electronic Resource
    Thioredoxins are required for protection against a reductive stress in the yeast Saccharomyces cerevisiae (2002)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 46 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Thioredoxins are small, highly conserved oxidoreductases that are required to maintain the redox homeostasis of the cell. They have been best characterized for their role as antioxidants in protection against reactive oxygen species. We show here that thioredoxins (TRX1, TRX2) and thioredoxin reductase (TRR1) are also required for protection against a reductive stress induced by exposure to dithiothreitol (DTT). This sensitivity to reducing conditions is not a general property of mutants affected in redox control, as mutants lacking components of the glutathione/glutaredoxin system are unaffected. Furthermore, TRX2 gene expression is induced in response to DTT treatment, indicating that thioredoxins form part of the cellular response to a reductive challenge. Our data indicate that the sensitivity of thioredoxin mutants to reducing stress appears to be a consequence of elevated glutathione levels, which is present predominantly in the reduced form (GSH). The elevated GSH levels also result in a constitutively high unfolded protein response (UPR), indicative of an accumulation of unfolded proteins in the endoplasmic reticulum (ER). However, there does not appear to be a general defect in ER function in thioredoxin mutants, as oxidative protein folding of the model protein carboxypeptidase Y occurs with similar kinetics to the wild-type strain, and trx1 trx2 mutants are unaffected in sensitivity to the glycosylation inhibitor tunicamycin. Furthermore, trr1 mutants are resistant to tunicamycin, consistent with their high UPR. The high UPR seen in trr1 mutants can be abrogated by the GSH-specific reagent 1-chloro-2,4-dinitrobenzene. In summary, thioredoxins are required to maintain redox homeostasis in response to both oxidative and reductive stress conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.03216.x
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  • 10
    Electronic Resource
    Electronic Resource
    Stationary-phase regulation of the Saccharomyces cerevisiaeSOD2 gene is dependent on additive effects of HAP2/3/4/5- and STRE-binding elements (1997)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: SOD2, encoding manganese superoxide dismutase (MnSOD), is essential for stationary-phase survival of yeast cells. In addition, stationary-phase cells are more resistant to oxidative stress than exponential-phase cells. The use of a SOD2::lacZ fusion construct in this study shows that transcription of SOD2 increases 6.5-fold as cells enter stationary phase in rich, glucose medium. The increase in SOD2 expression appears to be due to two phenomena — the switch to a non-fermentable carbon source and nutrient limitation. Analysis of SOD2 transcription in mutant Saccharomyces cerevisiae strains showed that the gene was negatively regulated by intracellular cAMP levels which decrease as cells enter stationary phase. Mutation of ‘stress-responsive’ (STRE) elements in the SOD2 promoter which respond to cAMP levels resulted in the loss of cAMP-dependent expression but only partially reduced the increase in expression as cells entered stationary phase. A putative Yap1p-binding site was found to be inactive and mutation of YAP1 had no effect on the STRE-mediated expression. To fully eliminate the stationary-phase response, it was necessary to mutate a HAP2/3/4/5 complex binding site in addition to the STRE elements. It is postulated that the effects of the STRE sites and the HAP2/3/4/5 complex binding site are additive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.2121581.x
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