title: Molecular motions as a drug target: mechanistic simulations of anthrax toxin edema factor function led to the discovery of novel allosteric inhibitors.
abstract: Edema Factor (EF) is a component of Bacillus anthracis toxin essential for virulence. Its adenylyl cyclase activity is induced by complexation with the ubiquitous eukaryotic cellular protein, calmodulin (CaM). EF and its complexes with CaM, nucleotides and/or ions, have been extensively characterized by X-ray crystallography. Those structural data allowed molecular simulations analysis of various aspects of EF action mechanism, including the delineation of EF and CaM domains through their association energetics, the impact of calcium binding on CaM, and the role of catalytic site ions. Furthermore, a transition path connecting the free inactive form to the CaM-complexed active form of EF was built to model the activation mechanism in an attempt to define an inhibition strategy. The cavities at the surface of EF were determined for each path intermediate to identify potential sites where the binding of a ligand could block activation. A non-catalytic cavity (allosteric) was found to shrink rapidly at early stages of the path and was chosen to perform virtual screening. Amongst 18 compounds selected in silico and tested in an enzymatic assay, 6 thiophen ureidoacid derivatives formed a new family of EF allosteric inhibitors with IC50 as low as 2 micromolars.
authors.affiliation: Laboratoire de Biologie et de Pharmacologie Appliquée, Ecole Normale Supérieure de Cachan, 61 Avenue du Président Wilson, 94235 Cachan Cedex, France. elodie.laine@lbpa.ens-cachan.fr
authors.forename: Elodie
authors.initials: E
authors.lastname: Laine
authors.forename: Leandro
authors.initials: L
authors.lastname: Martínez
authors.forename: Daniel
authors.initials: D
authors.lastname: Ladant
authors.forename: Thérèse
authors.initials: T
authors.lastname: Malliavin
authors.forename: Arnaud
authors.initials: A
authors.lastname: Blondel
mesh_terms: D000495:Allosteric Site; D000942:Antigens, Bacterial / Q000737:chemistry* / Q000378:metabolism; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D008958:Models, Molecular; D008968:Molecular Conformation
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D002147:Calmodulin; C030325:anthrax toxin; D002118:Calcium