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Conformational States of Cytochrome P450cam Revealed by Trapping of Synthetic Molecular Wires

Hays, Anna-Maria A. and Dunn, Alexander R. and Chiu, Richard and Gray, Harry B. and Stout, C. David and Goodin, David B. (2004) Conformational States of Cytochrome P450cam Revealed by Trapping of Synthetic Molecular Wires. Journal of Molecular Biology, 344 (2). pp. 455-469. ISSN 0022-2836. doi:10.1016/j.jmb.2004.09.046.

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Members of the ubiquitous cytochrome P450 family catalyze a vast range of biologically significant reactions in mammals, plants, fungi, and bacteria. Some P450s display a remarkable promiscuity in substrate recognition, while others are very specific with respect to substrate binding or regio and stereo-selective catalysis. Recent results have suggested that conformational flexibility in the substrate access channel of many P450s may play an important role in controlling these effects. Here, we report the X-ray crystal structures at 1.8 Å and 1.5 Å of cytochrome P450cam complexed with two synthetic molecular wires, D-4-Ad and D-8-Ad, consisting of a dansyl fluorophore linked to an adamantyl substrate analog via an α,ω-diaminoalkane chain of varying length. Both wires bind with the adamantyl moiety in similar positions at the camphor-binding site. However, each wire induces a distinct conformational response in the protein that differs from the camphor-bound structure. The changes involve significant movements of the F, G, and I helices, allowing the substrate access channel to adapt to the variable length of the probe. Wire-induced opening of the substrate channel also alters the I helix bulge and Thr252 at the active site with binding of water that has been proposed to assist in peroxy bond cleavage. The structures suggest that the coupling of substrate-induced conformational changes to active-site residues may be different in P450cam and recently described mammalian P450 structures. The wire-induced changes may be representative of the conformational intermediates that must exist transiently during substrate entry and product egress, providing a view of how substrates enter the deeply buried active site. They also support observed examples of conformational plasticity that are believed be responsible for the promiscuity of drug metabolizing P450s. Observation of such large changes in P450cam suggests that substrate channel plasticity is a general property inherent to all P450 structures.

Item Type:Article
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URLURL TypeDescription
Dunn, Alexander R.0000-0001-6096-4600
Gray, Harry B.0000-0002-7937-7876
Additional Information:© 2004 Elsevier. Received 14 June 2004, Revised 17 September 2004, Accepted 20 September 2004, Available online 5 October 2004. Edited by R. Huber. The authors thank Dr Chris Putnam for discussion and critical reading of the manuscript. In addition, we thank Sophie Coon for providing support for PMV (TSRI). This work was supported by NSF (H.B.G.) and NIH grants GM41049 (to D.B.G.) and GM48495 (to D.B.G. and H.B.G.), and NIH NRSA postdoctoral fellowship GM20703-03 (to A.-M.A.H.). A.R.D. received support from the Fannie and John Hertz Foundation.
Funding AgencyGrant Number
NIH Predoctoral FellowshipGM20703-03
Fannie and John Hertz FoundationUNSPECIFIED
Subject Keywords:molecular wires; sensitizer linked substrates; cytochrome P450; substrate recognition; X-ray crystallography
Issue or Number:2
Record Number:CaltechAUTHORS:20170408-142602553
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75942
Deposited By: 1Science Import
Deposited On:21 Apr 2017 19:18
Last Modified:15 Nov 2021 16:56

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