Open AccessThree-dimensional structure of NADPH–cytochrome P450 reductase: Prototype for FMN- and FAD-containing enzymes
Author(s) -
Ming Wang,
David L. Roberts,
Rosemary Paschke,
Thomas M. Shea,
Bettie Sue Siler Masters,
Jung Ja P. Kim
Publication year - 1997
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.94.16.8411
Subject(s) - flavin adenine dinucleotide , flavin group , flavodoxin , flavin mononucleotide , reductase , chemistry , cytochrome p450 reductase , binding site , heme , stereochemistry , flavoprotein , cytochrome , ferredoxin , docking (animal) , biochemistry , enzyme , cytochrome c , cofactor , coenzyme q – cytochrome c reductase , medicine , nursing , mitochondrion
Microsomal NADPH–cytochrome P450 reductase (CPR) is one of only two mammalian enzymes known to contain both FAD and FMN, the other being nitric-oxide synthase. CPR is a membrane-bound protein and catalyzes electron transfer from NADPH to all known microsomal cytochromes P450. The structure of rat liver CPR, expressed inEscherichia coli and solubilized by limited trypsinolysis, has been determined by x-ray crystallography at 2.6 Å resolution. The molecule is composed of four structural domains: (from the N- to C- termini) the FMN-binding domain, the connecting domain, and the FAD- and NADPH-binding domains. The FMN-binding domain is similar to the structure of flavodoxin, whereas the two C-terminal dinucleotide-binding domains are similar to those of ferredoxin–NADP+ reductase (FNR). The connecting domain, situated between the FMN-binding and FNR-like domains, is responsible for the relative orientation of the other domains, ensuring the proper alignment of the two flavins necessary for efficient electron transfer. The two flavin isoalloxazine rings are juxtaposed, with the closest distance between them being about 4 Å. The bowl-shaped surface near the FMN-binding site is likely the docking site of cytochromec and the physiological redox partners, including cytochromes P450 andb 5 and heme oxygenase.