Characterization of an AP-1-like transcription factor that mediates an oxidative stress response in Kluyveromyces lactis.

The KlYAP1 gene, encoding the transcription factor Yap1p from Kluyveromyces lactis, was cloned by functional complementation of the cadmium hypersensitivity phenotype of a Saccharomyces cerevisiae strain lacking functional YAP1 and YAP2 genes. The KlYAP1 gene product is 41% identical to Yap1p, the sequence similarity being centered on the bZip domain and extending into the C-terminal portion of both proteins. When expressed in S. cerevisiae, this gene efficiently complements some of the phenotypes associated with both yap1 and yap2 mutations and also mediates AP-1 response element-dependent transcriptional activation in response to H2O2. Gene disruption experiments in K. lactis indicated that the KlYAP1 gene is involved in both the oxidative and cadmium response pathways. We also demonstrate the existence in K. lactis of inducible protective stress responses to both peroxides and superoxides and investigate the role of the Klyap1p protein in these responses.