title: Mutations in transcription factor Mrr2p contribute to fluconazole resistance in clinical isolates of Candida albicans.
abstract: The Candida albicans zinc cluster proteins are a family of transcription factors (TFs) that play essential roles in the development of antifungal drug resistance. Gain-of-function mutations in several TFs, such as Tac1p, Mrr1p and Upc2p, have been previously well documented in azole-resistant clinical C. albicans isolates. Mrr2p (multidrug resistance regulator 2) is a novel TF controlling expression of the ABC transporter gene CDR1 and mediating fluconazole resistance. In this study, the relationship between naturally occurring mutations in MRR2 and fluconazole resistance in clinical C. albicans isolates was investigated. Among a group of 20 fluconazole-resistant clinical C. albicans and 10 fluconazole-susceptible C. albicans, 12 fluconazole-resistant isolates overexpressed CDR1 by at least two-fold compared with the fluconazole-susceptible isolates. Of these 12 resistant isolates, three (C7, C9, C15) contained 11 identical missense mutations, 6 of which occurred only in the azole-resistant isolates. The contribution of these mutations to CDR1 overexpression and therefore to fluconazole resistance was further verified by generating recombinant strains containing the mutated MRR2 gene. The mutated MRR2 alleles from isolate C9 contributed to an almost six-fold increase in CDR1 expression and an eight-fold increase in fluconazole resistance; the missense mutations S466L and T470N resulted in an increase in CDR1 expression of more than two-fold and a four-fold increase in fluconazole resistance. In contrast, the other four missense mutations conferred only two- to four-fold increases in fluconazole resistance, with no significant increase in CDR1 expression. These findings provide some insight into the mechanism by which MRR2 regulates C. albicans multidrug resistance.
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin No. 2 Road, Shanghai 200025, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital Luwan Branch, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Jin-Yan
authors.initials: JY
authors.lastname: Liu
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin No. 2 Road, Shanghai 200025, China.
authors.forename: Ce
authors.initials: C
authors.lastname: Shi
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin No. 2 Road, Shanghai 200025, China.
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Li
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin No. 2 Road, Shanghai 200025, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Center for New Drug Research, School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai 200433, China. Electronic address: ylansmmu@sina.com.
authors.forename: Lan
authors.initials: L
authors.lastname: Yan
authors.affiliation: Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin No. 2 Road, Shanghai 200025, China; Department of Laboratory Medicine, Ruijin Hospital Luwan Branch, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Electronic address: mjxiang123456@126.com.
authors.forename: Ming-Jie
authors.initials: MJ
authors.lastname: Xiang
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D002177:Candidiasis / Q000382:microbiology; D025141:Drug Resistance, Fungal; D015725:Fluconazole / Q000494:pharmacology*; D005656:Fungal Proteins / Q000096:biosynthesis; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D026901:Membrane Transport Proteins / Q000096:biosynthesis; D020125:Mutation, Missense; D014157:Transcription Factors / Q000235:genetics*; D015854:Up-Regulation
chemical_list: D000935:Antifungal Agents; C094693:CDR1 protein, Candida albicans; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D014157:Transcription Factors; D015725:Fluconazole
keywords: Candida albicans; Fluconazole resistance; Mutation; Transcription factor Mrr2p