RT Journal Article
SR Electronic
T1 Crystal Structure of a Cytochrome P450 2B6 Genetic Variant in Complex with the Inhibitor 4-(4-Chlorophenyl)imidazole at 2.0-Å Resolution
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 529
OP 538
DO 10.1124/mol.109.062570
VO 77
IS 4
A1 Gay, Sean C.
A1 Shah, Manish B.
A1 Talakad, Jyothi C.
A1 Maekawa, Keiko
A1 Roberts, Arthur G.
A1 Wilderman, P. Ross
A1 Sun, Ling
A1 Yang, Jane Y.
A1 Huelga, Stephanie C.
A1 Hong, Wen-Xu
A1 Zhang, Qinghai
A1 Stout, C. David
A1 Halpert, James R.
YR 2010
UL http://molpharm.aspetjournals.org/content/77/4/529.abstract
AB The structure of the K262R genetic variant of human cytochrome P450 2B6 in complex with the inhibitor 4-(4-chlorophenyl)imidazole (4-CPI) has been determined using X-ray crystallography to 2.0-Å resolution. Production of diffraction quality crystals was enabled through a combination of protein engineering, chaperone coexpression, modifications to the purification protocol, and the use of unique facial amphiphiles during crystallization. The 2B6-4-CPI complex is virtually identical to the rabbit 2B4 structure bound to the same inhibitor with respect to the arrangement of secondary structural elements and the placement of active site residues. The structure supports prior P450 2B6 homology models based on other mammalian cytochromes P450 and is consistent with the limited site-directed mutagenesis studies on 2B6 and extensive studies on P450 2B4 and 2B1. Although the K262R genetic variant shows unaltered binding of 4-CPI, altered binding affinity, kinetics, and/or product profiles have been previously shown with several other ligands. On the basis of new P450 2B6 crystal structure and previous 2B4 structures, substitutions at residue 262 affect a hydrogen-bonding network connecting the G and H helices, where subtle differences could be transduced to the active site. Docking experiments indicate that the closed protein conformation allows smaller ligands such as ticlopidine to bind to the 2B6 active site in the expected orientation. However, it is unknown whether 2B6 undergoes structural reorganization to accommodate bulkier molecules, as previously inferred from multiple P450 2B4 crystal structures.Copyright © 2010 The American Society for Pharmacology and Experimental Therapeutics