title: Y132H substitution in Candida albicans sterol 14alpha-demethylase confers fluconazole resistance by preventing binding to haem.
abstract: Fungal cytochrome P450 sterol 14alpha-demethylase (CYP51) is required for ergosterol biosynthesis and is the target for azole antifungal compounds. The amino acid substitution Y132H in CYP51 from clinical isolates of Candida albicans can cause fluconazole resistance by a novel change in the protein. Fluconazole binding to the mutant protein did not involve normal interaction with haem as shown by inducing a Type I spectral change. This contrasted to the wild-type protein where fluconazole inhibition was reflected in coordination to haem as a sixth ligand and where the typical Type II spectrum was obtained. The Y132H substitution occurred without drastic perturbation of the haem environment or activity allowing resistant mutants to produce ergosterol and retain fitness, an efficient strategy for resistance in nature.
authors.affiliation: Institute of Biological Sciences, University of Wales Aberystwyth, Aberystwyth, UK. Steven.Kelly@aber.ac.uk
authors.forename: S L
authors.initials: SL
authors.lastname: Kelly
authors.forename: D C
authors.initials: DC
authors.lastname: Lamb
authors.forename: D E
authors.initials: DE
authors.lastname: Kelly
mesh_terms: D019943:Amino Acid Substitution; D000935:Antifungal Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004352:Drug Resistance, Microbial / Q000235:genetics; D015725:Fluconazole / Q000494:pharmacology*; D006418:Heme / Q000378:metabolism; D006801:Humans; D016297:Mutagenesis, Site-Directed; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D013053:Spectrophotometry; D058886:Sterol 14-Demethylase
chemical_list: D000935:Antifungal Agents; C548418:CYP51A1 protein, human; D011994:Recombinant Proteins; D006418:Heme; D015725:Fluconazole; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D058886:Sterol 14-Demethylase