Three-Dimensional Model of Lanosterol 14-Demethylase from Cryptococcus neoformans: Active-Site Characterization and

Cryptococcus neoformans is one of the most important causes of life-threatening fungal infections in immu-nocompromised patients. Lanosterol 14-demethylase (CYP51) is the target of azole antifungal agents. This study describes, for the first time, the 3-dimensional model of CYP51 from Cryptococcus neoformans (CnCYP51). The model was further refined by energy minimization and molecular-dynamics simulations. The active site of CnCYP51 was well characterized by multiple-copy simultaneous-search calculations, and four functional regions important for rational drug design were identified. The mode of binding of the natural substrate and azole antifungal agents with CnCYP51 was identified by flexible molecular docking. A G484S substitution mechanism for azole resistance in CnCYP51, which might be important for the conformation of the heme environment, is suggested. Lanosterol 14-demethylase (CYP51, P45014DM, Erg11) is a member of the cytochrome P450 superfamily, which catalyzes the oxidative removal of the 14-methyl group (C-32) of lanos-terol to give 14,15-desaturated intermediates in ergosterol bio-synthesis (2). During the catalytic cycle, a substrate undergoes three successive monooxygenation reactions, resulting in th