Molecular recognition and electron transfer in mitochondrial steroid hydroxylase systems.
Mitochondrial monooxygenase systems are involved in the biosynthesis of glucocorticoids, mineralocorticoids, bile acids, and 1,25-dihydroxyvitamin D. The reactions are catalyzed by specific P450 enzymes that receive reducing equivalents via NADPH-ferredoxin oxidoreductase (adrenodoxin reductase) and ferredoxin (adrenodoxin). Although the three-dimensional structures of the individual components have not yet been solved, methods of expressing recombinant forms of these enzymes in Escherichia coli have allowed the use of site-directed mutagenesis to investigate the roles of specific amino acids in protein binding interactions, electron transfer, and catalysis. These studies have identified key charged residues in NADPH-ferredoxin oxidoreductase, ferredoxin, and P450scc, which are involved in electrostatic interactions critical for recognition, high-affinity binding, and electron transfer. The finding that the binding sites on ferredoxin for NADPH-ferredoxin oxidoreductase and P450 show significant overlap supports the proposed function for ferredoxin as a mobile electron shuttle between the reductase and P450 enzymes and is consistent with ferredoxin's role in serving multiple P450 isoforms.
Vickery
L E
LE
Department of Physiology and Biophysics, University of California, Irvine 92697-4560, USA.
D000595:Amino Acid Sequence; D001665:Binding Sites; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004579:Electron Transport; D005287:Ferredoxin-NADP Reductase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005288:Ferredoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D005288:Ferredoxins; D011994:Recombinant Proteins; D002786:Cholesterol Side-Chain Cleavage Enzyme; D005287:Ferredoxin-NADP Reductase