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Molecular and Cellular Biology, September 2006, p. 6690-6701, Vol. 26, No. 17
0270-7306/06/$08.00+0 doi:10.1128/MCB.02450-05
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
Simon Drouin,4,
François Robert,4 and
Bernard Turcotte1,2,3*
Departments of Medicine,1 Biochemistry,2 Microbiology and Immunology, Royal Victoria Hospital, McGill University, Montréal, Québec, Canada H3A 1A1,3 Institut de recherches cliniques de Montréal, Montréal, Québec, Canada H2W 1R74
Received 22 December 2005/ Returned for modification 30 January 2006/ Accepted 13 June 2006
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.
Supplemental material for this article may be found at http://mcb.asm.org/.
M.L. and S.D. contributed equally to this work.
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