13C Metabolic Flux Analysis Identifies an Unusual Route for Pyruvate Dissimilation in Mycobacteria which Requires Isocitrate Lyase and Carbon Dioxide Fixation
2011

New Pathway for Pyruvate Breakdown in Mycobacteria

publication Evidence: moderate

Author Information

Author(s): Dany J. V. Beste, Bhushan Bonde, Nathaniel Hawkins, Jane L. Ward, Michael H. Beale, Stephan Noack, Katharina Nöh, Nicholas J. Kruger, R. George Ratcliffe, Johnjoe McFadden

Primary Institution: School of Biomedical and Molecular Sciences, University of Surrey, Guildford, United Kingdom

Hypothesis

Isocitrate lyase (ICL) plays a crucial role in the metabolism of Mycobacterium tuberculosis beyond lipid metabolism.

Conclusion

The study identifies a novel metabolic pathway for pyruvate dissimilation in Mycobacterium tuberculosis that involves isocitrate lyase and carbon dioxide fixation.

Supporting Evidence

  • Isocitrate lyase is essential for the survival of Mycobacterium tuberculosis in nutrient-limited conditions.
  • The study demonstrates that ICL is involved in carbohydrate metabolism, not just fat metabolism.
  • Deletion of the icl1 gene impairs the growth of Mycobacterium bovis BCG in a glycerol-limited chemostat.
  • Carbon dioxide fixation was confirmed as a significant metabolic process in Mycobacterium tuberculosis.
  • The GAS pathway utilizes the glyoxylate shunt and anaplerotic reactions for pyruvate oxidation.

Takeaway

Researchers found a new way that Mycobacterium tuberculosis breaks down pyruvate, which is important for its survival, especially when food is scarce.

Methodology

The study used 13C metabolic flux analysis to investigate the metabolic pathways in Mycobacterium bovis BCG and Mycobacterium tuberculosis under different growth conditions.

Limitations

The flux values could not be determined unambiguously from the available labeling data, leading to multiple possible solutions.

Digital Object Identifier (DOI)

10.1371/journal.ppat.1002091

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