Three-dimensional models of 14α-sterol demethylase (Cyp51A) from and : an insight into differences in voriconazole interaction

Laura Alcazar-Fuoli (1) , Isabel Cuesta (1) , Juan L. Rodriguez-Tudela (1) , Manuel Cuenca-Estrella (1) , Dominique Sanglard (2) , Emilia Mellado (1)

1 ISC - Instituto de Salud Carlos III [Madrid]
2 UNIL - Université de Lausanne = University of Lausanne

, an sibling species, is increasingly reported in corticosteroid-treated patients. Its clinical significance is unknown, but the fact that shows reduced antifungal susceptibility, mainly to voriconazole, is of serious concern. Heterologous expression of from and was performed in to assess differences in the interaction of Cyp51A with the azole drugs. The absence of endogenous was efficiently complemented in by the expression of either allele. There was a marked difference between azole minimum inhibitory concentration (MIC) values of the clones expressing each spp. . clones expressing alleles showed higher MICs to all of the azoles tested, supporting the hypothesis that the intrinsic azole resistance of could be associated with Cyp51A. Homology models of and Cyp51A protein based on the crystal structure of Cyp51p from in complex with fluconazole were almost identical owing to their mutual high sequence identity. Molecular dynamics (MD) was applied to both three-dimensional protein models to refine the homology modelling and to explore possible differences in the Cyp51A-voriconazole interaction. After 20ns of MD modelling, some critical differences were observed in the putative closed form adopted by the protein upon voriconazole binding. A closer study of the and voriconazole putative binding site in Cyp51A suggested that some major differences in the protein's BC loop could differentially affect the lock-up of voriconazole, which in turn could correlate with their different azole susceptibility profiles.

Mots clés: spp.; Azole resistance; Cyp51A; 3D models; spp

Domaines: Microbiologie et Parasitologie

Laura Alcazar-Fuoli, Isabel Cuesta, Juan L. Rodriguez-Tudela, Manuel Cuenca-Estrella, Dominique Sanglard, et al.. Three-dimensional models of 14α-sterol demethylase (Cyp51A) from and : an insight into differences in voriconazole interaction. International Journal of Antimicrobial Agents, 2011, 38 (5), pp.426. ⟨10.1016/j.ijantimicag.2011.06.005⟩. ⟨hal-00736737⟩