6C94

Structure Of Cytochrome P450 4B1 (CYP4B1) Complexed with the Inhibitor HET0016

Summary for 6C94

• Entry DOI: 10.2210/pdb6c94/pdb
• Related: 5T6Q
• Descriptor: Cytochrome P450 4B1, PROTOPORPHYRIN IX CONTAINING FE, N-(4-butyl-2-methylphenyl)-N'-hydroxyimidoformamide, ... (4 entities in total)
• Functional Keywords: cytochrome p450, fatty acid omega-hydroxylase, cyp4b1, inhibitor, het0016, oxidoreductase, oxidoreductase-inhibitor complex, oxidoreductase/inhibitor
• Biological source: Oryctolagus cuniculus (Rabbit)
• Total number of polymer chains: 1
• Total formula weight: 58670.15

Authors

Hsu, M.-H.,Johnson, E.F. (deposition date: 2018-01-25, release date: 2018-06-20, Last modification date: 2024-10-30)

Primary citation

Jennings, G.K.,Hsu, M.H.,Shock, L.S.,Johnson, E.F.,Hackett, J.C.
Noncovalent interactions dominate dynamic heme distortion in cytochrome P450 4B1.
J. Biol. Chem., 293:11433-11446, 2018

PubMed Abstract: Cytochrome P450 4B1 (4B1) functions in both xenobiotic and endobiotic metabolism. An ester linkage between Glu-310 in 4B1 and the 5-methyl group of heme facilitates preferential hydroxylation of terminal (ω) methyl groups of hydrocarbons (HCs) and fatty acids compared with ω-1 sites bearing weaker C-H bonds. This preference is retained albeit diminished 4-fold for the E310A mutant, but the reason for this is unclear. Here, a crystal structure of the E310A-octane complex disclosed that noncovalent interactions maintain heme deformation in the absence of the ester linkage. Consistent with the lower symmetry of the heme, resonance Raman (RR) spectroscopy revealed large enhancements of RR peaks for high-spin HC complexes of 4B1 and the E310A mutant relative to P450 3A4. Whereas these enhancements were diminished in RR spectra of a low-spin 4B1--hydroxy-'-(4-butyl-2-methylphenyl)formamidine complex, a crystal structure indicated that this inhibitor does not alter heme ruffling. RR spectra of Fe-CO HC complexes revealed larger effects of HC length in E310A than in 4B1, suggesting that reduced rigidity probably underlies increased E310A-catalyzed (ω-1)-hydroxylation. Diminished effects of the HC on the position of the Fe-CO stretching mode in 4B1 suggested that the ester linkage limits substrate access to the CO. Heme ruffling probably facilitates autocatalytic ester formation by reducing inhibitory coordination of Glu-310 with the heme iron. This also positions the 5-methyl for a reaction with the proposed glutamyl radical intermediate and potentially enhances oxo-ferryl intermediate reactivity for generation of the glutamyl radical to initiate ester bond formation and ω-hydroxylation.

PubMed: 29858244
DOI: 10.1074/jbc.RA118.004044

Experimental method

X-RAY DIFFRACTION (2.72 Å)