Ethanol‐induced and glucose‐insensitive alcohol dehydrogenase activity in the yeast Kluyveromyces lactis

Publisher Website
Google Scholar
Abstract
The alcohol dehydrogenase (ADH) system in the yeast Kluyveromyces lactis is encoded by four ADH genes. In this paper we report evidence that at least three of these genes are transcribed and transcribed into protein. KIADH1 and KIADH2, which encode cytoplasmic activities, are preferentially expressed in glucose-grown cells with respect to ethanol-grown cells. KIADH4, which encodes one of the two activities localized within mitochondria, is induced at the transcriptional level in the presence of ethanol as is the ADH2 gene in Saccharomyces cerevlslae. However the regulation of the expression of the K. lactis gene is completely different from that of ADH2 and of other known ADH genes in that KIADH4 is insensitive to glucose repression and is not expressed on non-fermentabie carbon sources other than ethanol. This km6 of regulation can be clearly observed in non-fermenting strains, where the induction of KIADH4 is dependent on the addition of ethanol to the medium. On the contrary, in fermenting strains KIADH4 is always induced by ethanol or acetaldehyde produced endocellularly and this results in constitutive expression of the gene aiso in the presence of glucose. The mitochondrial localization of the activity encoded by KIADH4 and the peculiar regulation of this gene could be related to the fact that K. lactis is a petite negative yeast in which some mitochondrial functions seem to be essential for cell viability.

This publication has 33 references indexed in Scilit: