Targeting trans-translation to kill M. tuberculosis non-replicating persister cells

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PROJECT SUMMARY/ABSTRACT The emergence of Mycobacterium tuberculosis (MTB) strains that are resistant to most or all available antibiotics has created a severe problem for treating tuberculosis. One of the critical impediments to developing drugs that are effective against these deadly MTB strains is the lack of new antibiotic targets. The trans-translation pathway for resolving stalled ribosomes is a potential target for drug development because it is required for growth of MTB in culture. The recent identification of small molecule inhibitors of trans-translation provides essential tools to determine if trans-translation can be an antibiotic target. The long-term goal of this project is to understand the role of trans-translation in MTB and to exploit this pathway for antibiotic development. The overall objective of this proposal is to evaluate the role of trans-translation during MTB infection in vivo. The central hypothesis of this work is that inhibition of trans-translation during MTB infection will lead to death of all populations of bacteria, including actively replicating cells and non-replicating persister bacilli. The rationale that underlies the proposed research is that validation of trans-translation as an anti-TB target will lead to rapid development of new antibiotics that will dramatically shorten TB treatment times and lead to sterilization of infected tissues. The proposed research will also make significant contributions to the fundamental scientific understanding of MTB physiology by determining the role of trans-translation in this organism. The specific aims of this proposal are to identify the molecular targets of trans-translation inhibitors in MTB, to evaluate the essential role of trans- translation in survival of MTB under host-relevant conditions, and to characterize the anti-tubercular activity of acylaminooxadiazole compounds. The proposed experiments use genetic tools and small molecule inhibitors of trans-translation to determine if trans-translation is required under conditions that approximate normal MTB physiology, such as growth in macrophages and during infection in mice. The results of these experiments will provide the basis for understanding the role of trans-translation during stress and infection in bacteria as well as determining if this pathway can be targeted for drug development. Biochemical and genetic approaches will be used to identify the molecular targets of active compounds, and structural studies will reveal the molecular basis of activity. Results from these studies will allow future high-level optimization of drug candidates. By targeting a pathway that has not been used for antibiotic development, this project will yield new compounds that can be used individually or in combination with existing tuberculosis therapies.