Department of Microbiology and Physiological Systems
Medical Subject Headings
Antitubercular Agents; Aspartic Acid Endopeptidases; Bacterial Proteins; Drug Discovery; Drug Evaluation, Preclinical; Drug Resistance, Bacterial; Models, Molecular; Molecular Structure; Mycobacterium tuberculosis; Polyketide Synthases; Sequence Analysis, DNA
Bacteriology | Immunoprophylaxis and Therapy | Pathogenic Microbiology
Identification of new drug targets is vital for the advancement of drug discovery against Mycobacterium tuberculosis, especially given the increase of resistance worldwide to first- and second-line drugs. Because traditional target-based screening has largely proven unsuccessful for antibiotic discovery, we have developed a scalable platform for target identification in M. tuberculosis that is based on whole-cell screening, coupled with whole-genome sequencing of resistant mutants and recombineering to confirm. The method yields targets paired with whole-cell active compounds, which can serve as novel scaffolds for drug development, molecular tools for validation, and/or as ligands for co-crystallization. It may also reveal other information about mechanisms of action, such as activation or efflux. Using this method, we identified resistance-linked genes for eight compounds with anti-tubercular activity. Four of the genes have previously been shown to be essential: AspS, aspartyl-tRNA synthetase, Pks13, a polyketide synthase involved in mycolic acid biosynthesis, MmpL3, a membrane transporter, and EccB3, a component of the ESX-3 type VII secretion system. AspS and Pks13 represent novel targets in protein translation and cell-wall biosynthesis. Both MmpL3 and EccB3 are involved in membrane transport. Pks13, AspS, and EccB3 represent novel candidates not targeted by existing TB drugs, and the availability of whole-cell active inhibitors greatly increases their potential for drug discovery.
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Citation: PLoS One. 2013 Sep 23;8(9):e75245. doi: 10.1371/journal.pone.0075245. eCollection 2013. Link to article on publisher's site
Ioerger, Thomas R.; O'Malley, Theresa; Liao, Reiling; Guinn, Kristine M.; Hickey, Mark J.; Mohaideen, Nilofar; Murphy, Kenan C.; Boshoff, Helena I. M; Mizrahi, Valerie; Rubin, Eric J.; Sassetti, Christopher M.; Barry, Clifton E. III; Sherman, David R.; Parish, Tanya; and Sacchettini, James C., "Identification of new drug targets and resistance mechanisms in Mycobacterium tuberculosis" (2013). University of Massachusetts Medical School Faculty Publications. 574.
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