Identification of new drug targets and resistance mechanisms in Mycobacterium tuberculosis

PLoS One. 2013 Sep 23;8(9):e75245. doi: 10.1371/journal.pone.0075245. eCollection 2013.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antitubercular Agents / pharmacology*
  • Aspartic Acid Endopeptidases / genetics
  • Aspartic Acid Endopeptidases / metabolism
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Drug Discovery / methods*
  • Drug Evaluation, Preclinical / methods*
  • Drug Resistance, Bacterial / genetics*
  • Drug Resistance, Bacterial / physiology
  • Models, Molecular
  • Molecular Structure
  • Mycobacterium tuberculosis / drug effects
  • Mycobacterium tuberculosis / genetics*
  • Polyketide Synthases / chemistry
  • Polyketide Synthases / genetics
  • Sequence Analysis, DNA / methods

Substances

  • Antitubercular Agents
  • Bacterial Proteins
  • polyketide synthase Pks13, Mycobacterium tuberculosis
  • Polyketide Synthases
  • Aspartic Acid Endopeptidases