title: PDR16-mediated azole resistance in Candida albicans.
abstract: Many Candida albicans azole-resistant (AR) clinical isolates overexpress the CDR1 and CDR2 genes encoding homologous multidrug transporters of the ATP-binding cassette family. We show here that these strains also overexpress the PDR16 gene, the orthologue of Saccharomyces cerevisiae PDR16 encoding a phosphatidylinositol transfer protein of the Sec14p family. It has been reported that S. cerevisiae pdr16Delta mutants are hypersusceptible to azoles, suggesting that C. albicans PDR16 may contribute to azole resistance in these isolates. To address this question, we deleted both alleles of PDR16 in an AR clinical strain overexpressing the three genes, using the mycophenolic acid resistance flipper strategy. Our results show that the homozygous pdr16Delta/pdr16Delta mutant is approximately twofold less resistant to azoles than the parental strain whereas reintroducing a copy of PDR16 in the mutant restored azole resistance, demonstrating that this gene contributes to the AR phenotype of the cells. In addition, overexpression of PDR16 in azole-susceptible (AS) C. albicans and S. cerevisiae strains increased azole resistance by about twofold, indicating that an increased dosage of Pdr16p can confer low levels of azole resistance in the absence of additional molecular alterations. Taken together, these results demonstrate that PDR16 plays a role in C. albicans azole resistance.
authors.affiliation: Institut de recherche en immunologie et en cancérologie, Université de Montréal, QC, Canada.
authors.forename: Saloua
authors.initials: S
authors.lastname: Saidane
authors.forename: Sandra
authors.initials: S
authors.lastname: Weber
authors.forename: Xavier
authors.initials: X
authors.lastname: De Deken
authors.forename: Guy
authors.initials: G
authors.lastname: St-Germain
authors.forename: Martine
authors.initials: M
authors.lastname: Raymond
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000483:Alleles; D001393:Azoles / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics*; D025141:Drug Resistance, Fungal / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D026901:Membrane Transport Proteins / Q000235:genetics; D049294:Phospholipid Transfer Proteins / Q000235:genetics / Q000502:physiology*; D015854:Up-Regulation
chemical_list: D018528:ATP-Binding Cassette Transporters; D001393:Azoles; C094693:CDR1 protein, Candida albicans; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D049294:Phospholipid Transfer Proteins