SGER: Discovery of Substrates and Inhibitors of the Anthrax Lethal Factor using Peptide Libraries

Beth Israel Deaconess Medical Center, Boston MA

Investigators

Abstract

`Inhalational anthrax is nearly always fatal unless antibiotic treatment begins early in the course of the disease. There is therefore an urgent need for novel agents to treat the disease in the event of further terrorist use of anthrax. Fatality from anthrax is attributable to a toxin produced by the bacteria called lethal toxin. Much attention has turned to the development of agents which target lethal toxin as an adjunct to antibiotic therapy. The enzymatically active component of lethal toxin is a zinc-dependent metalloprotease called lethal factor (LF). LF causes the activation and lysis of macrophages as a consequence of the specific cleavage of proteins in the cell cytosol. Data on the cleavage site specificity of LF is at this point limited, and no specific inhibitors of LF have thus far been reported. The substrate specificity of LF will be determined using recently developed peptide library methodology. Data from peptide library screens will be used to prepare model substrates for monitoring LF activity both in vitro and in living cells. Peptide analogous inhibitors based on the optimal cleavage motif will be prepared. Improved inhibitors will be generated based on additional peptide library screens incorporating non-proteogenic "unnatural" amino acids, thus allowing a virtually unlimited source of chemical diversity to be tapped in an unprecedented manner. Such inhibitors can serve as lead compounds in the development of novel anthrax drugs. The technologies developed will be generally applicable to the design of substrates and inhibitors for proteases essential for the pathogenesis of other infectious diseases.