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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
biochemistry, genetics and molecular biology
Functional characterization of a vitamin B
12
-dependent methylmalonyl pathway in Mycobacterium tuberculosis: Implications for propionate metabolism during growth on fatty acids
Journal of Bacteriology, Volume 190, No. 11, Year 2008
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Description
Mycobacterium tuberculosis is predicted to subsist on alternative carbon sources during persistence within the human host. Catabolism of odd- and branched-chain fatty acids, branched-chain amino acids, and cholesterol generates propionyl-coenzyme A (CoA) as a terminal, three-carbon (C3) product. Propionate constitutes a key precursor in lipid biosynthesis but is toxic if accumulated, potentially implicating its metabolism in M. tuberculosis pathogenesis. In addition to the well-characterized methylcitrate cycle, the M. tuberculosis genome contains a complete methylmalonyl pathway, including a mutAB-encoded methylmalonyl-CoA mutase (MCM) that requires a vitamin B 12-derived cofactor for activity. Here, we demonstrate the ability of M. tuberculosis to utilize propionate as the sole carbon source in the absence of a functional methylcitrate cycle, provided that vitamin B12 is supplied exogenously. We show that this ability is dependent on mutAB and, furthermore, that an active methylmalonyl pathway allows the bypass of the glyoxylate cycle during growth on propionate in vitro. Importantly, although the glyoxylate and methylcitrate cycles supported robust growth of M. tuberculosis on the C17 fatty acid heptadecanoate, growth on valerate (C 5) was significantly enhanced through vitamin B12 supplementation. Moreover, both wild-type and methylcitrate cycle mutant strains grew on B12-supplemented valerate in the presence of 3-nitropropionate, an inhibitor of the glyoxylate cycle enzyme isocitrate lyase, indicating an anaplerotic role for the methylmalonyl pathway. The demonstrated functionality of MCM reinforces the potential relevance of vitamin B 12 to mycobacterial pathogenesis and suggests that vitamin B 12 availability in vivo might resolve the paradoxical dispensability of the methylcitrate cycle for the growth and persistence of M. tuberculosis in mice. Copyright © 2008, American Society for Microbiology. All Rights Reserved.
Available Materials
https://efashare.b-cdn.net/share/pmc/articles/PMC2395058/bin/supp_190_11_3886__index.html
https://efashare.b-cdn.net/share/pmc/articles/PMC2395058/bin/supp_190_11_3886__1.pdf
Authors & Co-Authors
Savvi, Suzana
South Africa, Johannesburg
School of Pathology
South Africa, Johannesburg
National Health Laboratory Service
Warner, Digby F.
South Africa, Johannesburg
School of Pathology
Kana, Bavesh Davandra
South Africa, Johannesburg
School of Pathology
McKinney, John D.
Switzerland, Lausanne
École Polytechnique Fédérale de Lausanne
Mizrahi, Valerie
South Africa, Johannesburg
School of Pathology
South Africa, Johannesburg
National Health Laboratory Service
Dawes, Stephanie S.
South Africa, Johannesburg
School of Pathology
Statistics
Citations: 226
Authors: 6
Affiliations: 3
Identifiers
Doi:
10.1128/JB.01767-07
ISSN:
00219193
Research Areas
Environmental