Heme levels switch the function of Hap1 of Saccharomyces cerevisiae between transcriptional activator and transcriptional repressor.

ABSTRACT: Changes in oxygen levels cause widespread changes in gene expression in organisms ranging from bacteria to humans. In Saccharomyces cerevisiae, this response is mediated in part by Hap1, originally identified as a heme-dependent transcriptional activator that functions during aerobic growth. We show here that Hap1 also plays a significant and direct role under hypoxic conditions, not as an activator, but as a repressor. The repressive activity of Hap1 controls several genes, including three ERG genes required for ergosterol biosynthesis. Chromatin immunoprecipitation experiments showed that Hap1 binds to the ERG gene promoters, while additional experiments showed that the corepressor Tup1/Ssn6 is recruited by Hap1 and is also required for repression. Furthermore, mutational analysis demons

SUBMITTER: Hickman MJ 

PROVIDER: S-EPMC2169065 | biostudies-literature | 2007 Nov

REPOSITORIES: biostudies-literature