title: Amino acid substitutions in Erg11p of azole-resistant Candida glabrata: Possible effective substitutions and homology modelling.
abstract: Understanding the mechanisms responsible for fluconazole resistance in Candida glabrata is not only crucial for the development of new antifungals but is also important in choosing appropriate antifungals for patients at the earliest stages. The aim of this study was to determine the Erg11p amino acid substitutions in fluconazole-resistant C. glabrata isolates. Sixty clinical isolates of C. glabrata were investigated. In vitro antifungal activities of fluconazole, itraconazole and voriconazole were determined using the broth microdilution reference method. The ERG11 gene for resistant (n=4) and susceptible (n=1) isolates were sequenced and multi-aligned using MEGA6 software. A homology model of the C. glabrata ERG11 gene was created by SWISS-MODEL software using the crystal structure of Saccharomyces cerevisiae Erg11p as a template, and the predicted binding sites to fluconazole were investigated. Fluconazole and multi-azole resistance were observed in 6.7% and 3.3% of the isolates, respectively. Several amino acid substitutions were identified, among which some were also identified in susceptible isolates. The amino acid substitution G236V was at the binding site, and substitutions H146Q and D234E were near to the binding site of triazoles according to the SWISS-MODEL. According to the homology modelling results, the amino acid substitution G236V is highly likely to play a key role in azole resistance development.
authors.affiliation: Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Nabili
authors.affiliation: Invasive Fungi Research Centre/Department of Medical Mycology and Parasitology, School of Medicine, Mazandaran University of Medical Sciences, 20th km of Khazar Abad Road, P.O. Box 4847191971, Sari, Iran.
authors.forename: Atefeh
authors.initials: A
authors.lastname: Abdollahi Gohar
authors.affiliation: Invasive Fungi Research Centre/Department of Medical Mycology and Parasitology, School of Medicine, Mazandaran University of Medical Sciences, 20th km of Khazar Abad Road, P.O. Box 4847191971, Sari, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Badali
authors.affiliation: Department of Medical Parasitology and Mycology, School of Medicine and Infectious Diseases/Tropical Medicine Research Centre, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Rasoul
authors.initials: R
authors.lastname: Mohammadi
authors.affiliation: Invasive Fungi Research Centre/Department of Medical Mycology and Parasitology, School of Medicine, Mazandaran University of Medical Sciences, 20th km of Khazar Abad Road, P.O. Box 4847191971, Sari, Iran. Electronic address: moazeni.maryam@gmail.com.
authors.forename: Maryam
authors.initials: M
authors.lastname: Moazeni
mesh_terms: D019943:Amino Acid Substitution; D000935:Antifungal Agents / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology*; D041221:Candida glabrata / Q000187:drug effects / Q000235:genetics*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D025141:Drug Resistance, Fungal / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics*; D008826:Microbial Sensitivity Tests
chemical_list: D000935:Antifungal Agents; D001393:Azoles; D005656:Fungal Proteins; D003577:Cytochrome P-450 Enzyme System
keywords: Candida glabrata; Erg11p; Fluconazole; Homology modelling; Mutation