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Three-dimensional structure of NADPH-cytochrome P450 reductase: prototype for FMN- and FAD-containing enzymes

M Wang1, D L Roberts, R Paschke

  • 1Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA.

Proceedings of the National Academy of Sciences of the United States of America
|August 5, 1997
PubMed

Insights

Microsomal NADPH-cytochrome P450 reductase (CPR) is a key enzyme for electron transfer. Its crystal structure reveals four domains crucial for flavin alignment and interaction with other proteins.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Enzymology

Background:

  • Microsomal NADPH-cytochrome P450 reductase (CPR) is a vital mammalian enzyme containing both FAD and FMN.
  • CPR facilitates electron transfer from NADPH to microsomal cytochromes P450, essential for various metabolic processes.

Purpose of the Study:

  • To determine the high-resolution crystal structure of rat liver CPR.
  • To elucidate the structural basis for CPR's function in electron transfer and its interactions with redox partners.

Main Methods:

  • X-ray crystallography was used to determine the structure of rat liver CPR at 2.6 Å resolution.
  • The enzyme was expressed in Escherichia coli and solubilized via limited trypsinolysis.

Main Results:

  • The CPR structure comprises four domains: FMN-binding, connecting, FAD-binding, and NADPH-binding.
  • The FMN-binding domain resembles flavodoxin, while the FAD- and NADPH-binding domains are similar to ferredoxin-NADP+ reductase (FNR).
  • A connecting domain orients the flavin-binding domains for efficient electron transfer, with flavin rings juxtaposed approximately 4 Å apart.

Conclusions:

  • The determined structure provides insights into the mechanism of electron transfer mediated by CPR.
  • The FNR-like domains and the connecting domain are critical for CPR's enzymatic activity and substrate binding.
  • The structure suggests a docking site for CPR's physiological redox partners, including cytochromes P450.

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