Crystal structures of cytochrome P450 2B4 in complex with the inhibitor 1-biphenyl-4-methyl-1H-imidazole: ligand-induced structural response through alpha-helical repositioning.
Primary Citation of Related Structures: 3G5N, 3G93
PubMed Abstract:
Two different ligand occupancy structures of cytochrome P450 2B4 (CYP2B4) in complex with 1-biphenyl-4-methyl-1H-imidazole (1-PBI) have been determined by X-ray crystallography. 1-PBI belongs to a series of tight binding, imidazole-based CYP2B4 inhibitors ...
Two different ligand occupancy structures of cytochrome P450 2B4 (CYP2B4) in complex with 1-biphenyl-4-methyl-1H-imidazole (1-PBI) have been determined by X-ray crystallography. 1-PBI belongs to a series of tight binding, imidazole-based CYP2B4 inhibitors. 1-PBI binding to CYP2B4 yields a type II spectrum with a K(s) value of 0.23 microM and inhibits enzyme activity with an IC(50) value of 0.035 microM. Previous CYP2B4 structures have shown a large degree of structural movement in response to ligand size. With two phenyl rings, 1-PBI is larger than 1-(4-chlorophenyl)imidazole (1-CPI) and 4-(4-chlorophenyl)imidazole (4-CPI) but smaller than bifonazole, which is branched and contains three phenyl rings. The CYP2B4-1-PBI complex is a structural intermediate to the closed CPI and the open bifonazole structures. The B/C-loop reorganizes itself to include two short partial helices while closing one side of the active site. The F-G-helix cassette pivots over the I-helix in direct response to the size of the ligand in the active site. A cluster of Phe residues at the fulcrum of this pivot point allows for dramatic repositioning of the cassette with only a relatively small amount of secondary structure rearrangement. Comparisons of ligand-bound CYP2B4 structures reveal trends in plastic region mobility that could allow for predictions of their position in future structures based on ligand shape and size.
Related Citations:
Structural and thermodynamic consequences of 1-(4-chlorophenyl)imidazole binding to cytochrome P450 2B4. Zhao, Y., Sun, L., Muralidhara, B.K., Kumar, S., White, M.A., Stout, C.D., Halpert, J.R. (2007) Biochemistry 46: 11559
Structure of mammalian cytochrome P450 2B4 complexed with 4-(4-chlorophenyl)imidazole at 1.9 {angstrom} resolution: Insight into the range of P450 conformations and coordination of redox partner binding. Scott, E.E., White, M.A., He, Y.A., Johnson, E.F., Stout, C.D., Halpert, J.R. (2004) J Biol Chem 279: 27294
Structure of microsomal cytochrome P450 2B4 complexed with the antifungal drug bifonazole: insight into P450 conformational plasticity and membrane interaction. Zhao, Y., White, M.A., Muralidhara, B.K., Sun, L., Halpert, J.R., Stout, C.D. (2006) J Biol Chem 281: 5973
An open conformation of mammalian cytochrome P450 2B4 at 1.6 A resolution. Scott, E.E., He, Y.A., Wester, M.R., White, M.A., Chin, C.C., Halpert, J.R., Johnson, E.F., Stout, C.D. (2003) Proc Natl Acad Sci U S A 100: 13196
Organizational Affiliation:
Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, California 92093, USA. scgay@ucsd.edu
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