Transcript analysis of 203 novel genes from Saccharomyces cerevisiae in hap1 and rox1 mutant backgrounds

Hap1 and Rox1 are transcriptional regulators that bind regulatory sites in the promoters of oxygen-regulated genes in Saccharomyces cerevisiae. Hap1 i s a heme-responsive activator of genes induced in aerobic conditions and Ro x1 is a repressor of hypoxic genes in aerobic conditions. We have studied t ranscriptional regulation of a pool of 203 open reading frames (ORFs) from chromosomes IV, VII, and XIV in wild-type, hap1, and rox1 mutant genetic ba ckgrounds in an attempt to extend the family of oxygen and heme regulated g enes. Only three ORFs are significantly repressed by Rox1 but they cannot b e considered as typical hypoxic genes because they are not overexpressed du ring hypoxia.