HAP1 and ROX1 form a regulatory pathway in the repression of HEM13 transcription in Saccharomyces cerevisiae.
AUTOR(ES)
Keng, T
RESUMO
HEM13 of Saccharomyces cerevisiae encodes coproporphyrinogen oxidase, an enzyme in the heme biosynthetic pathway. Expression of HEM13 is repressed by oxygen and heme. This study investigated the regulatory pathway responsible for the regulation of HEM13 expression. The transcriptional activator HAP1 is demonstrated to be required for the full-level expression of HEM13 in the absence of heme. It is also shown that the repression of HEM13 transcription caused by heme involves the HAP1 and ROX1 gene products; a mutation in either gene results in derepression of HEM13 expression. The heme-dependent expression of ROX1 was found to require functional HAP1, leading one to propose that repression of HEM13 results from a pathway involving HAP1-mediated regulation of ROX1 transcription in response to heme levels followed by ROX1-mediated repression of HEM13 transcription. In support of this model, expression of ROX1 under control of the GAL promoter was found to result in repression of HEM13 transcription in a hap1 mutant strain. The ability of ROX1 encoded by the galactose-inducible ROX1 construct to function in the absence of HAP1 indicates that the only role of HAP1 in repression of HEM13 is to activate ROX1 transcription.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=364455Documentos Relacionados
- A Novel Allele of Hap1 Causes Uninducible Expression of Hem13 in Saccharomyces Cerevisiae
- The HMG domain of the ROX1 protein mediates repression of HEM13 through overlapping DNA binding and oligomerization functions.
- ROX1 encodes a heme-induced repression factor regulating ANB1 and CYC7 of Saccharomyces cerevisiae.
- Synergistic repression of anaerobic genes by Mot3 and Rox1 in Saccharomyces cerevisiae
- ROX1 and ERG Regulation in Saccharomyces cerevisiae: Implications for Antifungal Susceptibility