title: Small molecule inhibitors of Bacillus anthracis protective antigen proteolytic activation and oligomerization.
abstract: Protective antigen (PA), lethal factor, and edema factor, the protein toxins of Bacillus anthracis , are among its most important virulence factors and play a key role in infection. We performed a virtual ligand screen of a library of 10000 members to identify compounds predicted to bind to PA and prevent its oligomerization. Four of these compounds slowed PA association in a FRET-based oligomerization assay, and two of those protected cells from intoxication at concentrations of 1-10 μM. Exploration of the protective mechanism by Western blot showed decreased SDS-resistant PA oligomer on cells and, surprisingly, decreased amounts of activated PA. In vitro assays showed that one of the inhibitors blocked furin-mediated cleavage of PA, apparently through its binding to the PA substrate. Thus, we have identified inhibitors that can independently block both PA's cleavage by furin and its subsequent oligomerization. Lead optimization on these two backbones may yield compounds with high activity and specificity for the anthrax toxins.
authors.affiliation: Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 33 North Drive, Bethesda, Maryland 20892, USA.
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Wein
authors.forename: Brian N
authors.initials: BN
authors.lastname: Williams
authors.forename: Shihui
authors.initials: S
authors.lastname: Liu
authors.forename: Boris
authors.initials: B
authors.lastname: Ermolinsky
authors.forename: Daniele
authors.initials: D
authors.lastname: Provenzano
authors.forename: Ruben
authors.initials: R
authors.lastname: Abagyan
authors.forename: Andrew
authors.initials: A
authors.lastname: Orry
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Leppla
authors.forename: Michael
authors.initials: M
authors.lastname: Peredelchuk
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000737:chemistry* / Q000378:metabolism* / Q000633:toxicity; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism* / Q000633:toxicity; D002460:Cell Line; D019295:Computational Biology; D004353:Drug Evaluation, Preclinical; D006801:Humans; D051379:Mice; D062105:Molecular Docking Simulation; D016062:Porosity; D055503:Protein Multimerization / Q000187:drug effects*; D020836:Protein Structure, Quaternary; D059748:Proteolysis / Q000187:drug effects*; D054852:Small Molecule Libraries / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D054852:Small Molecule Libraries; C030325:anthrax toxin