Autoactivated KlPDR1 gene in the control of multidrug resistance in Kluyveromyces lactis.

The KlPDR1 gene encodes a zinc finger transcription factor that has recently been shown to be involved in the control of multidrug resistance of Kluyveromyces lactis. In this work, we provide evidence that the K. lactis KIPDR1 gene is under positive autoregulation by KlPdrlp, which plays a role in the activation of the main multidrug resistance transporter gene KlPDR5. Electrophoretic mobility shift assays, as well as the use of gusA reporter constructs, enabled us to identify the 5'-tataTCCGGGTAactt-3' sequence motif in the KIPDR1 promoter (in the position -326 to -319 bp) as the PDRE (pleiotropic drug responsive element) for the binding of KlPdr1p. The drug sensitivity of Klpdr1 Delta mutant cells was complemented by introducing the plasmid-born KIPDR1 gene. The KlPdr1p activated the expression of the P(KIPDR1)-gusA fusion gene, and the expression of the KlPDR1 gene was induced by fluconazole. The PDRE was also found in the promoter of KlPDR5, a gene encoding the ATP-dependent efflux pump responsible for the drug resistance phenomenon in K. lactis.