Deletion of a dehydratase important for intracellular growth and cording renders rough Mycobacterium abscessus avirulent

Proc Natl Acad Sci U S A. 2016 Jul 19;113(29):E4228-37. doi: 10.1073/pnas.1605477113. Epub 2016 Jul 6.


Mycobacterium abscessus (Mabs) is a rapidly growing Mycobacterium and an emerging pathogen in humans. Transitioning from a smooth (S) high-glycopeptidolipid (GPL) producer to a rough (R) low-GPL producer is associated with increased virulence in zebrafish, which involves the formation of massive serpentine cords, abscesses, and rapid larval death. Generating a cord-deficient Mabs mutant would allow us to address the contribution of cording in the physiopathological signs of the R variant. Herein, a deletion mutant of MAB_4780, encoding a dehydratase, distinct from the β-hydroxyacyl-ACP dehydratase HadABC complex, was constructed in the R morphotype. This mutant exhibited an alteration of the mycolic acid composition and a pronounced defect in cording. This correlated with an extremely attenuated phenotype not only in wild-type but also in immunocompromised zebrafish embryos lacking either macrophages or neutrophils. The abolition of granuloma formation in embryos infected with the dehydratase mutant was associated with a failure to replicate in macrophages, presumably due to limited inhibition of the phagolysosomal fusion. Overall, these results indicate that MAB_4780 is required for Mabs to successfully establish acute and lethal infections. Therefore, targeting MAB_4780 may represent an attractive antivirulence strategy to control Mabs infections, refractory to most standard chemotherapeutic interventions. The combination of a dehydratase assay with a high-resolution crystal structure of MAB_4780 opens the way to identify such specific inhibitors.

Keywords: M. abscessus; cording; dehydratase; virulence; zebrafish.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Embryo, Nonmammalian / enzymology
  • Embryo, Nonmammalian / immunology
  • Embryo, Nonmammalian / microbiology
  • Hydro-Lyases / physiology*
  • Macrophages / immunology
  • Macrophages / microbiology
  • Mice
  • Mycobacterium / pathogenicity*
  • Mycobacterium Infections / enzymology*
  • Mycobacterium Infections / microbiology
  • Neutrophils / immunology
  • Virulence
  • Zebrafish / immunology
  • Zebrafish / metabolism
  • Zebrafish / microbiology
  • Zebrafish Proteins / physiology*


  • Zebrafish Proteins
  • Hydro-Lyases

Associated data

  • PDB/5I7N