Molecular Motions as a Drug Target: Mechanistic Simulations of Anthrax Toxin Edema Factor Function Led to the Discovery of Novel Allosteric Inhibitors

Toxins

Élodie Laine⁴  Leandro Martínez¹  Daniel Ladant²  Thérèse Malliavin³ 

[1] The Molecular Biotechnology Group, Institute of Physics of São Carlos, University of São Paulo, Av. Trabalhador Sãocarlense, 400, 13566-590 São Carlos, SP, Brazil;Unité de Biochimie des Interactions Macromoléculaires and CNRS UMR 3528, Département de Biologie Structurale et Chimie, Institut Pasteur, 28, rue du Dr. Roux, 75724 Paris Cedex 15, France;Unité de Bioinformatique Structurale and CNRS UMR 3528, Département de Biologie Structurale et Chimie, Institut Pasteur, 25, rue du Dr. Roux, 75724 Paris Cedex 15, France;Laboratoire de Biologie et de Pharmacologie Appliquée, Ecole Normale Supérieure de Cachan, 61, avenue du Président Wilson, 94235 Cachan cedex, France;

关键词: anthrax;    Edema factor;    molecular modeling;    virtual screening;    allostery;    transition path;   

DOI  :  10.3390/toxins4080580

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.