title: Regulation of hypoxic gene expression in yeast.
abstract: Baker's yeast, Saccharomyces cerevisiae, can adapt to growth under severe oxygen limitation. Two regulatory systems are described here that control this adaptation. The first involves a heme-dependent repression mechanism. Cells sense hypoxia through the inability to maintain oxygen-dependent heme biosynthesis. Under aerobic conditions, heme accumulates and serves as an effector for the transcriptional activator Hap1. The heme-Hap1 complex activates transcription of the ROX1 gene that encodes a repressor of one set of hypoxic genes. Under hypoxic conditions, heme levels fall, and a heme-deficient Hap1 complex represses ROX1 expression. As a consequence, the hypoxic genes are derepressed. The second regulatory system activates gene expression in response to a variety of stress conditions, including oxygen limitation. Oxygen sensing in this system is heme-independent. The same DNA sequence mediates transcriptional activation of each stress signal.
authors.affiliation: Department of Biological Sciences, University at Albany/SUNY, USA. RZI44@CNSVAX.ALBANY.EDU
authors.forename: R S
authors.initials: RS
authors.lastname: Zitomer
authors.forename: P
authors.initials: P
authors.lastname: Carrico
authors.forename: J
authors.initials: J
authors.lastname: Deckert
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D016384:Consensus Sequence; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D006418:Heme / Q000378:metabolism; D056892:Mediator Complex; D010100:Oxygen / Q000378:metabolism*; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D056892:Mediator Complex; D012331:RNA, Fungal; D012333:RNA, Messenger; C083348:ROX1 protein, S cerevisiae; C103856:ROX3 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D006418:Heme; D012319:RNA Polymerase II; D010100:Oxygen