Regulation of the expression of the Kluyveromyces lactis PDC1 gene: carbon source responsive elements and autoregulation.

The yeast Kluyveromyces lactis has a single structural gene coding for pyruvate decarboxylase (KlPDC1). In order to study the regulation of the expression of KlPDC1, we have sequenced (EMBL Accession No. Y15435) its promoter and have fused the promoter to the reporter gene lacZ from E. coli. Transcription analysis in a Klpdc1delta strain showed that KlPDC1 expression is subject to autoregulation. The PDC1 gene from Saccharomyces cerevisiae was able to complement the Rag- phenotype of the Klpdc1delta mutant strain and it could also repress transcription of the KlPDC1–lacZ fusion on glucose. A deletion analysis of the promoter region was performed to study carbon source-dependent regulation and revealed that at least two cis-acting regions are necessary for full induction of gene expression on glucose. Other cis-elements mediate repression on ethanol.