title: Erg11 mutations associated with azole resistance in clinical isolates of Candida albicans.
abstract: The widespread use of azoles has led to increasing azole resistance among Candida albicans strains. One mechanism of azole resistance involves point mutations in the ERG11 gene, which encodes the target enzyme (cytochrome P450 lanosterol 14α-demethylase). In the present study, we amplified and sequenced the ERG11 gene of 23 C. albicans clinical isolates. Seventeen mutations encoding distinct amino acid substitutions were found, of which seven (K143Q, Y205E, A255V, E260V, N435V, G472R, and D502E) were novel. We further verified the contribution of the amino acid substitutions to azole resistance using site-directed mutagenesis of the ERG11 gene to recreate these mutations for heterologous expression in Saccharomyces cerevisiae. We observed that substitutions A114S, Y132H, Y132F, K143R, Y257H, and a new K143Q substitution contributed to significant increases (≧fourfold) in fluconazole and voriconazole resistance; changes in itraconazole resistance were not significant (≦twofold).
authors.affiliation: Department of Immunology, Shanghai Jiao Tong University School of Medicine, and Department of Laboratory Medicine, Ruijin Hospital, Shanghai, China.
authors.forename: Ming-Jie
authors.initials: MJ
authors.lastname: Xiang
authors.forename: Jin-Yan
authors.initials: JY
authors.lastname: Liu
authors.forename: Pei-Hua
authors.initials: PH
authors.lastname: Ni
authors.forename: Shengzheng
authors.initials: S
authors.lastname: Wang
authors.forename: Ce
authors.initials: C
authors.lastname: Shi
authors.forename: Bing
authors.initials: B
authors.lastname: Wei
authors.forename: Yu-Xing
authors.initials: YX
authors.lastname: Ni
authors.forename: Hai-Liang
authors.initials: HL
authors.lastname: Ge
mesh_terms: D019943:Amino Acid Substitution; D000935:Antifungal Agents / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D002177:Candidiasis / Q000382:microbiology; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D025141:Drug Resistance, Fungal; D006801:Humans; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D017422:Sequence Analysis, DNA
chemical_list: D000935:Antifungal Agents; D001393:Azoles; D004271:DNA, Fungal; D050505:Mutant Proteins; D003577:Cytochrome P-450 Enzyme System