Development of Antibacterials Targeting the MEP Pathway of Select Agents.

摘要

The threat of bioterrorism and the use of biological weapons against both military personnel and civilian populations has become an increasing concern for governments around the world. The 1984 Rajneeshee Salmonella attack, 2001 anthrax letter attacks, 2003 SARS outbreak, 2009 H1N1 swine flu pandemic, and the current US flu epidemic all illustrate our vulnerability to both deliberate and natural outbreaks of infectious disease and underscore the necessity of effective antimicrobial and antiviral therapeutics. The prevalence of antibiotic resistant strains and the ease by which antibiotic resistance can be engineered into bacteria further highlights the need for continued development of novel antibiotics against new bacterial targets. This research project directly addresses this need through the development of a broad spectrum inhibitor of the biothreat agents Francisella tularensis and Yersinia pestis. During this period of performance, we have successfully cloned, expressed, purified and enzymatically characterized the Yersinia pestis IspC (aka MEP synthase), a validated target for the development of new broad spectrum antibiotics. This characterization enabled us to establish conditions for screening an in-house natural product library, and through this screening effort we have identified inhibitor-leads for the enzyme. We have performed detailed kinetic evaluation of one of these leads and have deduced that this new inhibitor is the founding member of a novel class of IspC inhibitors; functioning by binding to a previously undiscovered allosteric site on the enzyme (i.e. this new inhibitor binds the enzyme at a site outside of the active site). As an allosteric site has never been described for any IspC homolog, this exciting discovery affords the development of a completely new family of antibiotics targeting the IspC enzyme.