Structure of a cytochrome P450–redox partner electron-transfer complex

Structure of a cytochrome P450–redox partner electron-transfer complex

^*University of California, Department of Molecular Biology and Biochemistry, 3205 Bio Sci II, Irvine, CA 92697-3900; and ^†Howard Hughes Medical Institute and ^‡Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75235-9038

Communicated by Lowell P. Hager, University of Illinois, Urbana, IL (received for review September 29, 1998)

Abstract

The crystal structure of the complex between the heme- and FMN-binding domains of bacterial cytochrome P450BM-3, a prototype for the complex between eukaryotic microsomal P450s and P450 reductase, has been determined at 2.03 Å resolution. The flavodoxin-like flavin domain is positioned at the proximal face of the heme domain with the FMN 4.0 and 18.4 Å from the peptide that precedes the heme-binding loop and the heme iron, respectively. The heme-binding peptide represents the most efficient and coupled through-bond electron pathway to the heme iron. Substantial differences between the FMN-binding domains of P450BM-3 and microsomal P450 reductase, observed around the flavin-binding sites, are responsible for different redox properties of the FMN, which, in turn, control electron flow to the P450.

Footnotes

↵ § To whom reprint requests should be addressed. e-mail: poulos{at}uci.edu.
Data deposition: The atomic coordinates reported in this paper have been deposited in the Protein Data Bank, Biology Department, Brookhaven National Laboratory, Upton, NY 11973 (ID code 1BVY).
ABBREVIATIONS:

P450BM-3,

the soluble P450 isolated from Bacillus megaterium (the product of the CYP102 gene);

BMP,

the recombinantly expressed heme domain of P450BM-3;

BMP/FMN,

the recombinantly expressed heme- and FMN-binding domain of P450BM-3;

FMN domain or BM3-FMN,

the recombinantly expressed FMN-binding domain of P450BM-3;

FMN sq,

one-electron reduced FMN semiquinone;

FMN hq,

two-electron reduced FMN hydroquinone;

CPR,

NADPH-cytochrome P450 reductase;

CPR-FMN,

the FMN-binding domain of CPR