Chemical Genetic Interaction Profiling Reveals Determinants of Intrinsic Antibiotic Resistance in Mycobacterium tuberculosis

Antimicrob Agents Chemother. 2017 Nov 22;61(12):e01334-17. doi: 10.1128/AAC.01334-17. Print 2017 Dec.


Chemotherapy for tuberculosis (TB) is lengthy and could benefit from synergistic adjuvant therapeutics that enhance current and novel drug regimens. To identify genetic determinants of intrinsic antibiotic susceptibility in Mycobacterium tuberculosis, we applied a chemical genetic interaction (CGI) profiling approach. We screened a saturated transposon mutant library and identified mutants that exhibit altered fitness in the presence of partially inhibitory concentrations of rifampin, ethambutol, isoniazid, vancomycin, and meropenem, antibiotics with diverse mechanisms of action. This screen identified the M. tuberculosis cell envelope to be a major determinant of antibiotic susceptibility but did not yield mutants whose increase in susceptibility was due to transposon insertions in genes encoding efflux pumps. Intrinsic antibiotic resistance determinants affecting resistance to multiple antibiotics included the peptidoglycan-arabinogalactan ligase Lcp1, the mycolic acid synthase MmaA4, the protein translocase SecA2, the mannosyltransferase PimE, the cell envelope-associated protease CaeA/Hip1, and FecB, a putative iron dicitrate-binding protein. Characterization of a deletion mutant confirmed FecB to be involved in the intrinsic resistance to every antibiotic analyzed. In contrast to its predicted function, FecB was dispensable for growth in low-iron medium and instead functioned as a critical mediator of envelope integrity.

Keywords: Mycobacterium tuberculosis; antibiotic resistance; cell envelope; mutational studies.

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism
  • Antitubercular Agents / pharmacology*
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Cell Wall / drug effects*
  • Cell Wall / genetics
  • Cell Wall / metabolism
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Ethambutol / pharmacology
  • Galactans / biosynthesis
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial*
  • Humans
  • Ion Pumps / deficiency
  • Ion Pumps / genetics
  • Isoniazid / pharmacology
  • Ligases / genetics
  • Ligases / metabolism
  • Mannosyltransferases / genetics
  • Mannosyltransferases / metabolism
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism
  • Meropenem
  • Microbial Sensitivity Tests
  • Mycobacterium tuberculosis / drug effects*
  • Mycobacterium tuberculosis / genetics
  • Mycobacterium tuberculosis / metabolism
  • Mycolic Acids / metabolism
  • Peptidoglycan / biosynthesis
  • Rifampin / pharmacology
  • Serine Proteases / genetics*
  • Serine Proteases / metabolism
  • Thienamycins / pharmacology
  • Vancomycin / pharmacology


  • Antitubercular Agents
  • Bacterial Proteins
  • Galactans
  • Ion Pumps
  • Membrane Transport Proteins
  • Mycolic Acids
  • Peptidoglycan
  • Thienamycins
  • arabinogalactan-peptidoglycan complex
  • Vancomycin
  • Ethambutol
  • Mannosyltransferases
  • Hip1 protein, Mycobacterium tuberculosis
  • Serine Proteases
  • Adenosine Triphosphatases
  • SecA2 protein, Mycobacterium
  • Ligases
  • Meropenem
  • Isoniazid
  • Rifampin