title: Crystal structures of bovine odorant-binding protein in complex with odorant molecules.
abstract: The structure of bovine odorant-binding protein (bOBP) revealed a striking feature of a dimer formed by domain swapping [Tegoni, M., Ramoni, R., Bignetti, E., Spinelli, S. & Cambillau, C. (1996) Nat. Struct. Biol.3, 863-867; Bianchet, M.A., Bains, G., Pelosi, P., Pevsner, J., Snyder, S.H., Monaco, H.L. & Amzel, L.M. (1996) Nat. Struct. Biol.3, 934-939] and the presence of a naturally occuring ligand [Ramoni, R., Vincent, F., Grolli, S., Conti, V., Malosse, C., Boyer, F.D., Nagnan-Le Meillour, P., Spinelli, S., Cambillau, C. & Tegoni, M. (2001) J. Biol. Chem.276, 7150-7155]. These features led us to investigate the binding of odorant molecules with bOBP in solution and in the crystal. The behavior of odorant molecules in bOBP resembles that observed with porcine OBP (pOBP), although the latter is monomeric and devoid of ligand when purified. The odorant molecules presented K(d) values with bOBP in the micromolar range. Most of the X-ray structures revealed that odorant molecules interact with a common set of residues forming the cavity wall and do not exhibit specific interactions. Depending on the ligand and on the monomer (A or B), a single residue--Phe89--presents alternate conformations and might control cross-talking between the subunits. Crystal data on both pOBP and bOBP, in contrast with binding and spectroscopic studies on rat OBP in solution, reveal an absence of significant conformational changes involving protein loops or backbone. Thus, the role of OBP in signal triggering remains unresolved.
authors.affiliation: Architecture et Fonction des Macromolécules Biologiques, UMR 6098, CNRS, 13402 Marseille, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Vincent
authors.forename: Roberto
authors.initials: R
authors.lastname: Ramoni
authors.forename: Silvia
authors.initials: S
authors.lastname: Spinelli
authors.forename: Stefano
authors.initials: S
authors.lastname: Grolli
authors.forename: Mariella
authors.initials: M
authors.lastname: Tegoni
authors.forename: Christian
authors.initials: C
authors.lastname: Cambillau
mesh_terms: D000447:Aldehydes / Q000378:metabolism*; D000818:Animals; D000873:Anthracenes / Q000378:metabolism*; D001577:Benzophenones / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D002417:Cattle; D018360:Crystallography, X-Ray; D019281:Dimerization; D004876:Ergot Alkaloids / Q000378:metabolism*; D008024:Ligands; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D051381:Rats; D018035:Receptors, Odorant / Q000737:chemistry* / Q000378:metabolism*; D013552:Swine
chemical_list: D000447:Aldehydes; D000873:Anthracenes; D001577:Benzophenones; C043481:DHM 32-550; D004876:Ergot Alkaloids; D008024:Ligands; D018035:Receptors, Odorant; C045648:odorant-binding protein; C047723:benzophenone; C049062:1-aminoanthracene; C479548:undecanal