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Bacterial protein-O-mannosylating enzyme is crucial for virulence of Mycobacterium tuberculosis

Chia-Fang Liu1, Laure Tonini, Wladimir Malaga

  • 1Centre National de la Recherche Scientifique, Institut de Pharmacologie et de Biologie Structurale, F-31077 Toulouse, France.

Proceedings of the National Academy of Sciences of the United States of America
|April 4, 2013
PubMed

Insights

Protein O-mannosylation is crucial for Mycobacterium tuberculosis (Mtb) virulence. Disrupting this process severely impacts Mtb growth and pathogenicity, highlighting its role in host infection.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Posttranslational Modifications

Background:

  • Protein O-mannosylation, essential in eukaryotes, occurs in Mycobacterium tuberculosis (Mtb) and related actinobacteria.
  • The specific role and prevalence of O-mannosylation in Mtb pathogenesis remain unexplored.

Purpose of the Study:

  • To investigate the biological significance of protein O-mannosylation in Mtb and Mycobacterium smegmatis.
  • To determine the impact of disrupting O-mannosylation on Mtb virulence and growth.

Main Methods:

  • Inactivation of putative protein mannosyl transferase genes (Msmeg_5447 and Rv1002c) in M. smegmatis and Mtb.
  • Mass spectrometry-based glycoproteomics to confirm loss of O-mannosylation.
  • Phenotypic analysis of mutant strains in vitro, in cellulo, and in immunocompromised mice.

Main Results:

  • Loss of protein O-mannosylation was confirmed in both M. smegmatis and Mtb mutant strains.
  • M. smegmatis lacking O-mannosylation showed no significant phenotypic changes.
  • Mtb mutants exhibited severely impaired growth and significantly reduced pathogenicity in vivo.

Conclusions:

  • Protein O-mannosylation is biologically significant in mycobacteria.
  • This posttranslational modification is critical for Mtb virulence and host colonization.

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