Constitutive activation of the PDR16 promoter in a Candida albicans azole-resistant clinical isolate overexpressing CDR1 and CDR2.

Candida albicans azole-resistant clinical isolates overexpressing the CDR1 and CDR2 genes (multidrug transporters) also overexpress the PDR16 gene (phosphatidylinositol transfer protein). We show here that the PDR16 promoter displays higher transcriptional activity following integration in an azole-resistant isolate than in the matched azole-susceptible one. Thus, the upregulation of PDR16 in the resistant strain results from a mutation acting in trans.