Oxidative stress-activated zinc cluster protein Stb5 has dual activator/repressor functions required for pentose phosphate pathway regulation and NADPH production.
In Saccharomyces cerevisiae, zinc cluster protein Pdr1 can form homodimers as well as heterodimers with Pdr3 and Stb5, suggesting that different combinations of these proteins may regulate the expression of different genes. To gain insight into the interplay among these regulators, we performed genome-wide location analysis (chromatin immunoprecipitation with hybridization to DNA microarrays) and gene expression profiling. Unexpectedly, we observed that Stb5 shares only a few target genes with Pdr1 or Pdr3 in rich medium. Interestingly, upon oxidative stress, Stb5 binds and regulates the expression of most genes of the pentose phosphate pathway as well as of genes involved in the production of NADPH, a metabolite required for oxidative stress resistance. Importantly, deletion of STB5 results in sensitivity to diamide and hydrogen peroxide. Our data suggest that Stb5 acts both as an activator and as a repressor in the presence of oxidative stress. Furthermore, we show that Stb5 activation is not mediated by known regulators of the oxidative stress response. Integrity of the pentose phosphate pathway is required for the activation of Stb5 target genes but is not necessary for the increased DNA binding of Stb5 in the presence of diamide. These data suggest that Stb5 is a key player in the control of NADPH production for resistance to oxidative stress.
Larochelle
Marc
M
Department of Medicine, Room H7.83, Royal Victoria Hospital, McGill University, 687 Pine Ave. West, Montréal, Québec, Canada.
Drouin
Simon
S
Robert
François
F
Turcotte
Bernard
B
D020816:Amino Acid Motifs; D004271:DNA, Fungal / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D003958:Diamide / Q000494:pharmacology; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D046228:Microarray Analysis; D008957:Models, Genetic; D009249:NADP / Q000096:biosynthesis*; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress; D010427:Pentose Phosphate Pathway / Q000187:drug effects / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D016877:Oxidants; C085480:PDR1 protein, S cerevisiae; C089261:PDR3 protein, S cerevisiae; D012333:RNA, Messenger; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C488251:Stb5 protein, S cerevisiae; D015534:Trans-Activators; D014157:Transcription Factors; D003958:Diamide; D009249:NADP