title: Mechanism of action of N-phenyl-N'-(2-chloroethyl)ureas in the colchicine-binding site at the interface between alpha- and beta-tubulin.
abstract: Computational tools such as CoMSIA and CoMFA models reported in a recent study revealed the structure-activity relationships ruling the interactions occurring between hydrophobic N-phenyl-N'-(2-chloroethyl)ureas (CEU) and the colchicine-binding site (C-BS) on beta(II)-tubulin. Here, we describe the mechanisms involved in the covalent binding of three subsets of CEU derivatives to the C-BS. The FlexiDock experiments confirmed that the interaction of non-covalent portions of the CEU auxophore moiety of CEU is involved in the binding of the drug to the C-BS facilitate the nucleophilic attack of Glu-beta198 rather than Cys-beta239. In addition, these studies suggest that Cys-beta239 together with Asn-alpha99, Ser-alpha176, Thr-alpha177, Leu-beta246, Asn-beta247, Ala-beta248, Lys-beta252 and Asn-beta256 are implicated in the stabilization of a C-BS-CEU complex prior to the acylation of Glu-beta198 by CEU. Our molecular models propose the formation of a stabilized C-BS-CEU complex before the completion of the Glu-beta198 acylation; acylation triggering conformational changes of beta-tubulin, microtubule depolymerization and anoikis. The computational models presented here might be useful to the design of selective and more potent C-BS inhibitors. Of interest, in vivo acylation of acidic amino acid residues by xenobiotics is an unusual reaction and may open new approaches for the design of irreversible protein inhibitors such as tubulin.
authors.affiliation: Unité des Biotechnologies et de Bioingénierie, Centre de recherche, C.H.U.Q., Hôpital Saint-François d'Assise, Université Laval, Québec, Canada G1L 3L5. sebastien.fortin.1@ulaval.ca
authors.forename: Sébastien
authors.initials: S
authors.lastname: Fortin
authors.forename: Lianhu
authors.initials: L
authors.lastname: Wei
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Moreau
authors.forename: Philippe
authors.initials: P
authors.lastname: Labrie
authors.forename: Eric
authors.initials: E
authors.lastname: Petitclerc
authors.forename: Lakshmi P
authors.initials: LP
authors.lastname: Kotra
authors.forename: René
authors.initials: R
authors.lastname: C-Gaudreault
mesh_terms: D001665:Binding Sites; D045744:Cell Line, Tumor; D003078:Colchicine / Q000737:chemistry / Q000378:metabolism*; D003198:Computer Simulation; D006801:Humans; D008956:Models, Chemical; D008958:Models, Molecular; D013329:Structure-Activity Relationship; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*; D050257:Tubulin Modulators / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D014404:Tubulin; D050257:Tubulin Modulators; D014508:Urea; D003078:Colchicine