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Glucose-responsive and oleic acid-responsive elements in the gene encoding the peroxisomal trifunctional enzyme of
J A Sloots1, J D Aitchison, R A Rachubinski
1Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada.
Abstract:
We have investigated the regulation of expression of the gene (HDE), encoding the peroxisomal trifunctional enzyme hydratase-dehydrogenase-epimerase (HDE), of the diploid yeast Candida tropicalis. Heterologous expression in Saccharomyces cerevisiae of constructs containing deletions in the upstream region of the HDE gene has allowed for determination of regions responsible for the control of expression of the HDE gene. Expression was monitored by immunoblot analysis of yeast lysates with anti-HDE serum. Regions have been identified that are responsible for both repression by glucose and induction by oleic acid. A glucose-responsive region lies between nucleotides (nt) -526 and -393. An oleic acid-responsive region lies between nt -393 and -341. An additional region controlling derepression by nonfermentable carbon sources is located downstream from nt -341. Comparison of the nt sequences of these regions to upstream regions of other oleic acid-responsive genes of C. tropicalis has identified possible consensus nt sequences for glucose- and oleic acid-responsive upstream elements in these genes. The regulation of the HDE gene in S. cerevisiae closely resembles that found in C. tropicalis, suggesting that similar mechanisms of transcriptional control operate in both yeasts.