title: Multidrug Transporters and Alterations in Sterol Biosynthesis Contribute to Azole Antifungal Resistance in Candida parapsilosis.
abstract: While much is known concerning azole resistance in Candida albicans, considerably less is understood about Candida parapsilosis, an emerging species of Candida with clinical relevance. We conducted a comprehensive analysis of azole resistance in a collection of resistant C. parapsilosis clinical isolates in order to determine which genes might play a role in this process within this species. We examined the relative expression of the putative drug transporter genes CDR1 and MDR1 and that of ERG11. In isolates overexpressing these genes, we sequenced the genes encoding their presumed transcriptional regulators, TAC1, MRR1, and UPC2, respectively. We also sequenced the sterol biosynthesis genes ERG3 and ERG11 in these isolates to find mutations that might contribute to this phenotype in this Candida species. Our findings demonstrate that the putative drug transporters Cdr1 and Mdr1 contribute directly to azole resistance and suggest that their overexpression is due to activating mutations in the genes encoding their transcriptional regulators. We also observed that the Y132F substitution in ERG11 is the only substitution occurring exclusively among azole-resistant isolates, and we correlated this with specific changes in sterol biosynthesis. Finally, sterol analysis of these isolates suggests that other changes in sterol biosynthesis may contribute to azole resistance in C. parapsilosis.
authors.affiliation: Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA Children's Foundation Research Center at Le Bonheur Children's Medical Center, Memphis, Tennessee, USA.
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Berkow
authors.affiliation: Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA Children's Foundation Research Center at Le Bonheur Children's Medical Center, Memphis, Tennessee, USA.
authors.forename: Kayihura
authors.initials: K
authors.lastname: Manigaba
authors.affiliation: Institute of Life Science, Swansea University Medical School, Swansea, Wales, United Kingdom.
authors.forename: Josie E
authors.initials: JE
authors.lastname: Parker
authors.affiliation: Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA Children's Foundation Research Center at Le Bonheur Children's Medical Center, Memphis, Tennessee, USA.
authors.forename: Katherine S
authors.initials: KS
authors.lastname: Barker
authors.affiliation: Institute of Life Science, Swansea University Medical School, Swansea, Wales, United Kingdom.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Kelly
authors.affiliation: Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA Children's Foundation Research Center at Le Bonheur Children's Medical Center, Memphis, Tennessee, USA progers3@uthsc.edu.
authors.forename: P David
authors.initials: PD
authors.lastname: Rogers
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000935:Antifungal Agents / Q000494:pharmacology; D002175:Candida / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D002177:Candidiasis / Q000382:microbiology; D025141:Drug Resistance, Fungal / Q000235:genetics*; D015725:Fluconazole / Q000494:pharmacology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D017422:Sequence Analysis, DNA; D058886:Sterol 14-Demethylase / Q000235:genetics / Q000378:metabolism; D013261:Sterols / Q000819:agonists / Q000096:biosynthesis*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D000935:Antifungal Agents; D005656:Fungal Proteins; D013261:Sterols; D015534:Trans-Activators; D015725:Fluconazole; D010088:Oxidoreductases; D058886:Sterol 14-Demethylase; C039306:sterol delta-5 desaturase