Protein Engineering vol. 16 no. 8 pp. 577-587, 2003
© 2003 Oxford University Press
Molecular docking of substrates and inhibitors in the catalytic site of CYP6B1, an insect cytochrome P450 monooxygenase
1School of Chemical Sciences, 2Department of Entomology and 3Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, 190 ERML, 1201 West Gregory Drive, Urbana, IL 61801, USA
4 To whom correspondence should be addressed. e-mail: maryschu{at}uiuc.edu
Furanocoumarins represent plant toxins that are used in the treatment of a variety of skin diseases and are metabolized by cytochrome P450 monooxygenases (P450s) existing in insects such as Papilio polyxenes (the black swallowtail). To elucidate the active site in the CYP6B1 protein that is the principal P450 existing in this species, we have constructed a homology model of it based on sequence and structure alignments with the bacterial CYP102 protein whose crystal structure has been defined and with the insect CYP6B4 protein that also metabolizes furanocoumarins. In the derived CYP6B1 model, Phe116 and His117 in SRS1, Phe371 in SRS5 and Phe484 in SRS6 contribute to the formation of a resonant network that stabilizes the P450’s catalytic site and allows for interactions with its furanocoumarin substrates. The first two of these residues are absolutely conserved in all members of the insect CYP6B subfamily and the last two are variable in different members of the CYP6B subfamily. A combination of theoretical and experimental docking analyses of two substrates (xanthotoxin and bergapten) and two inhibitors (coumarin and pilocarpine) of this P450 provide significant information on the positioning of furanocoumarins within this catalytic pocket. Molecular replacement models based on the results of variations at two of these critical amino acids provide support for our furanocoumarin-docked model and begin to rationalize the altered substrate reactivities observed in experimental analyses.
Received December 4, 2002; revised June 8, 2003; accepted June 23, 2003.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  M. R. Berenbaum and A. R. Zangerl Facing the Future of Plant-Insect Interaction Research: Le Retour a la "Raison d'Etre" Plant Physiology, March 1, 2008; 146(3): 804 - 811. [Full Text] [PDF]
|
|
|
|
 |
|
 W. Mao, S. G. Rupasinghe, A. R. Zangerl, M. R. Berenbaum, and M. A. Schuler Allelic Variation in the Depressaria pastinacella CYP6AB3 Protein Enhances Metabolism of Plant Allelochemicals by Altering a Proximal Surface Residue and Potential Interactions with Cytochrome P450 Reductase J. Biol. Chem., April 6, 2007; 282(14): 10544 - 10552. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Larbat, S. Kellner, S. Specker, A. Hehn, E. Gontier, J. Hans, F. Bourgaud, and U. Matern Molecular Cloning and Functional Characterization of Psoralen Synthase, the First Committed Monooxygenase of Furanocoumarin Biosynthesis J. Biol. Chem., January 5, 2007; 282(1): 542 - 554. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Z. Wen, S. Rupasinghe, G. Niu, M. R. Berenbaum, and M. A. Schuler CYP6B1 and CYP6B3 of the Black Swallowtail (Papilio polyxenes): Adaptive Evolution through Subfunctionalization Mol. Biol. Evol., December 1, 2006; 23(12): 2434 - 2443. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Baudry, S. Rupasinghe, and M. A. Schuler Class-dependent sequence alignment strategy improves the structural and functional modeling of P450s Protein Eng. Des. Sel., August 1, 2006; 19(8): 345 - 353. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z. Wen, J. Baudry, M. R. Berenbaum, and M. A. Schuler Ile115Leu mutation in the SRS1 region of an insect cytochrome P450 (CYP6B1) compromises substrate turnover via changes in a predicted product release channel Protein Eng. Des. Sel., April 1, 2005; 18(4): 191 - 199. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 X. Li, J. Baudry, M. R. Berenbaum, and M. A. Schuler Structural and functional divergence of insect CYP6B proteins: From specialist to generalist cytochrome P450 PNAS, March 2, 2004; 101(9): 2939 - 2944. [Abstract] [Full Text] [PDF]
|
|