Candida glabrata PDR1, a transcriptional regulator of a pleiotropic drug resistance network, mediates azole resistance in clinical isolates and petite mutants.
Candida glabrata, a yeast with intrinsically low susceptibility to azoles, frequently develops increased azole resistance during prolonged treatment. Transposon mutagenesis revealed that disruption of CgPDR1 resulted in an 8- to 16-fold increase in fluconazole susceptibility of C. glabrata. CgPDR1 is a homolog of Saccharomyces cerevisiae PDR1, which encodes a transcriptional regulator of multidrug transporters. Northern blot analyses indicated that CgPDR1 regulated both constitutive and drug-induced expression of CgCDR1, a multidrug transporter gene. In agreement with the Northern analysis, the Cgpdr1 mutant had increased rhodamine accumulation, in contrast to the decreased accumulation in the CgPDR1-overexpressing strain. Northern analyses also indicated the importance of CgPDR1 in fluconazole resistance arising during therapy. Two clinically resistant isolates had higher expression of CgPDR1 and CgCDR1 compared to their paired susceptible isolates. Integrative transformation of CgPDR1 from the two resistant isolates converted the Cgpdr1 mutant into azole-resistant strains with upregulated CgPDR1 expression. Two different amino acid substitutions, W297S in one isolate and F575L in the other, accounted for the upregulated CgPDR1 expression and the resistance. Finally, CgPDR1 was shown to be required for the azole resistance due to mitochondrial deficiency. Thus, CgPDR1 encodes a transcriptional regulator of a pleiotropic drug resistance network and contributes to the azole resistance of clinical isolates and petite mutants.
Clinical Mycology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD 20892, USA.
Huei-Fung
HF
Tsai
Anna A
AA
Krol
Kelly E
KE
Sarti
John E
JE
Bennett
D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000935:Antifungal Agents / Q000494:pharmacology*; D001483:Base Sequence; D041221:Candida glabrata / Q000187:drug effects* / Q000235:genetics; D003062:Codon; D004268:DNA-Binding Proteins / Q000502:physiology; D025141:Drug Resistance, Fungal; D015725:Fluconazole / Q000494:pharmacology*; D005656:Fungal Proteins / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012235:Rhodamines / Q000493:pharmacokinetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology; D015534:Trans-Activators / Q000502:physiology*; D014157:Transcription Factors
D018528:ATP-Binding Cassette Transporters; D000935:Antifungal Agents; D003062:Codon; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C085480:PDR1 protein, S cerevisiae; D012235:Rhodamines; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C026188:rhodamine 6G; D015725:Fluconazole