Expression of the lactate permease gene JEN1 from the yeast Saccharomyces cerevisiae

In Saccharomyces cerevisiae, lactate permease induction by lactic acid took place after transcription of JEN1. JEN1 transcripts were undetectable 10 min after the addition of a pulse of glucose to YP-lactic acid exponentially growing cells, while the permease activity ceased after 50 min. A value of 15.1 min was found for the half-life of JEN1 mRNA, showing the involvement of a glucose-induced mechanism of mRNA degradation. The rapid decline of the carrier activity upon glucose addition points to the existence of an irreversible carbon catabolite inactivation process. Isogenic strains, deleted in genes encoding enzymes involved in lactic acid metabolism, did not express JEN1, indicating an association of the intracellular metabolism of the acid to the transcription of the permease gene. The carbon sources capable of inducing JEN1 transcription were dependent on the strain, Distinct posttranslation mechanisms appeared to be involved in the lactate carrier activity. (C) 2001 Academic Press.