title: Azole drugs trap cytochrome P450 EryK in alternative conformational states.
abstract: EryK is a bacterial cytochrome P450 that catalyzes the last hydroxylation occurring during the biosynthetic pathway of erythromycin A in Streptomyces erythraeus. We report the crystal structures of EryK in complex with two widely used azole inhibitors: ketoconazole and clotrimazole. Both of these ligands use their imidazole moiety to coordinate the heme iron of P450s. Nevertheless, because of the different chemical and structural properties of their N1-substituent group, ketoconazole and clotrimazole trap EryK, respectively, in a closed and in an open conformation that resemble the two structures previously described for the ligand-free EryK. Indeed, ligands induce a distortion of the internal helix I that affects the accessibility of the binding pocket by regulating the kink of the external helix G via a network of interactions that involves helix F. The data presented thus constitute an example of how a cytochrome P450 may be selectively trapped in different conformational states by inhibitors.
authors.affiliation: Department of Biochemical Sciences, Sapienza University of Rome and CNR Institute of Molecular Biology and Pathology, Piazzale A. Moro 5, Rome, Italy.
authors.forename: Linda Celeste
authors.initials: LC
authors.lastname: Montemiglio
authors.forename: Stefano
authors.initials: S
authors.lastname: Gianni
authors.forename: Beatrice
authors.initials: B
authors.lastname: Vallone
authors.forename: Carmelinda
authors.initials: C
authors.lastname: Savino
mesh_terms: D001393:Azoles / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000187:drug effects; D020134:Catalytic Domain; D003022:Clotrimazole / Q000737:chemistry; D018360:Crystallography, X-Ray; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry* / Q000187:drug effects; D007654:Ketoconazole / Q000737:chemistry; D011487:Protein Conformation / Q000187:drug effects; D016930:Saccharopolyspora / Q000737:chemistry*
chemical_list: D001393:Azoles; D001426:Bacterial Proteins; D003577:Cytochrome P-450 Enzyme System; D003022:Clotrimazole; D007654:Ketoconazole