A Region of the Cellobiohydrolase I Promoter from the Filamentous FungusTrichoderma reeseiMediates Glucose Repression inSaccharomyces cerevisiae,Dependent on Mitochondrial Activity

Abstract

The upstream activating region that controls cellulose-induced expression of the glucose-repressible cellobiohydrolase I gene (UARcb1) of the filamentous fungusTrichoderma reeseiis shown to mediate transcription and glucose repression of a reporter gene inSaccharomyces cerevisiae,a unicellular microorganism that lacks the genes required for the utilization of cellulose. Glucose-controlled transcription mediated byUARcb1requires the products of the genesSNF1andSSN6,a protein kinase and a repressor, respectively, that regulate glucose-repressible yeast genes. Previously, it has been shown that mitochondrial function is implicated in cellobiohydrolase I gene expression inT. reeseiand this sensitivity to the metabolic state of the mitochondria was shown to be transcriptionally controlled by the 5′-flanking sequence of thecbh1gene [Abrahão-Netoet al.(1995)Biochemistry 34,10456–10462]. Remarkably, transcription of the reporter gene controlled byUARcb1inS. cerevisiaealso showed a requirement for active mitochondria, suggesting that a common mechanism involving mitochondrial activity controls glucose-repressible genes in both microorganisms.