title: Restoration of mutant cytochrome P450 reductase activity by external flavin.
abstract: Cytochrome P450 oxidoreductase (POR) supplies electrons from NADPH to steroid and drug metabolizing reactions catalyzed by the cytochrome P450s located in endoplasmic reticulum. Mutations in human POR cause a wide spectrum of disease ranging from disordered steroidogenesis to sexual differentiation. Previously we and others have shown that POR mutations can lead to reduced activities of steroidogenic P450s CYP17A1, CYP19A1 and CYP21A1. Here we are reporting that mutations in the FMN binding domain of POR may reduce CYP3A4 activity, potentially influencing drug and steroid metabolism; and the loss of CYP3A4 activity may be correlated to the reduction of cytochrome b(5) by POR. Computational molecular docking experiments with a FMN free structural model of POR revealed that an external FMN could be docked in close proximity to the FAD moiety and receive electrons donated by NADPH. Using FMN supplemented assays we have demonstrated restoration of the defective POR activity in vitro.
authors.affiliation: Pediatric Endocrinology, Diabetology and Metabolism, Department of Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: Catherine
authors.initials: C
authors.lastname: Nicolo
authors.forename: Christa E
authors.initials: CE
authors.lastname: Flück
authors.forename: Primus E
authors.initials: PE
authors.lastname: Mullis
authors.forename: Amit V
authors.initials: AV
authors.lastname: Pandey
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects*; D005415:Flavins / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009154:Mutation; D051381:Rats; D016415:Sequence Alignment
chemical_list: D005415:Flavins; D003577:Cytochrome P-450 Enzyme System; C473667:cytochrome P-450 CYP3A45