1 H-Benzo[ d]Imidazole Derivatives Affect MmpL3 in Mycobacterium tuberculosis

Antimicrob Agents Chemother. 2019 Sep 23;63(10):e00441-19. doi: 10.1128/AAC.00441-19. Print 2019 Oct.


1H-benzo[d]imidazole derivatives exhibit antitubercular activity in vitro at a nanomolar range of concentrations and are not toxic to human cells, but their mode of action remains unknown. Here, we showed that these compounds are active against intracellular Mycobacterium tuberculosis To identify their target, we selected drug-resistant M. tuberculosis mutants and then used whole-genome sequencing to unravel mutations in the essential mmpL3 gene, which encodes the integral membrane protein that catalyzes the export of trehalose monomycolate, a precursor of the mycobacterial outer membrane component trehalose dimycolate (TDM), as well as mycolic acids bound to arabinogalactan. The drug-resistant phenotype was also observed in the parental strain overexpressing the mmpL3 alleles carrying the mutations identified in the resistors. However, no cross-resistance was observed between 1H-benzo[d]imidazole derivatives and SQ109, another MmpL3 inhibitor, or other first-line antitubercular drugs. Metabolic labeling and quantitative thin-layer chromatography (TLC) analysis of radiolabeled lipids from M. tuberculosis cultures treated with the benzoimidazoles indicated an inhibition of trehalose dimycolate (TDM) synthesis, as well as reduced levels of mycolylated arabinogalactan, in agreement with the inhibition of MmpL3 activity. Overall, this study emphasizes the pronounced activity of 1H-benzo[d]imidazole derivatives in interfering with mycolic acid metabolism and their potential for therapeutic application in the fight against tuberculosis.

Keywords: MmpL3; Mycobacterium tuberculosis inhibitors; benzimidazole; drug resistance; tuberculosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Antitubercular Agents / chemical synthesis
  • Antitubercular Agents / pharmacology*
  • Bacterial Proteins / antagonists & inhibitors
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Benzimidazoles / chemical synthesis
  • Benzimidazoles / pharmacology*
  • Binding Sites
  • Biological Transport / drug effects
  • Cloning, Molecular
  • Cord Factors / antagonists & inhibitors*
  • Cord Factors / biosynthesis
  • Cord Factors / metabolism
  • Drug Resistance, Bacterial / drug effects*
  • Drug Resistance, Bacterial / genetics
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Galactans / metabolism
  • Gene Expression
  • Genetic Vectors / chemistry
  • Genetic Vectors / metabolism
  • Membrane Transport Proteins / chemistry
  • Membrane Transport Proteins / genetics*
  • Membrane Transport Proteins / metabolism
  • Microbial Sensitivity Tests
  • Models, Molecular
  • Mutation
  • Mycobacterium tuberculosis / drug effects*
  • Mycobacterium tuberculosis / genetics
  • Mycobacterium tuberculosis / growth & development
  • Mycobacterium tuberculosis / metabolism
  • Mycolic Acids / metabolism
  • Protein Binding
  • Protein Conformation, alpha-Helical
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Whole Genome Sequencing


  • Antitubercular Agents
  • Bacterial Proteins
  • Benzimidazoles
  • Cord Factors
  • Galactans
  • Membrane Transport Proteins
  • MmpL3 protein, Mycobacterium tuberculosis
  • Mycolic Acids
  • Recombinant Proteins
  • trehalose monomycolate
  • arabinogalactan