Send to

Choose Destination
Open Biol. 2013 Feb 13;3(2):120175. doi: 10.1098/rsob.120175.

A vitamin B₁₂ transporter in Mycobacterium tuberculosis.

Author information

MRC/NHLS/UCT Molecular Mycobacteriology Research Unit and DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, University of Cape Town, Observatory, Cape Town 7925, South Africa.


Vitamin B₁₂-dependent enzymes function in core biochemical pathways in Mycobacterium tuberculosis, an obligate pathogen whose metabolism in vivo is poorly understood. Although M. tuberculosis can access vitamin B₁₂ in vitro, it is uncertain whether the organism is able to scavenge B₁₂ during host infection. This question is crucial to predictions of metabolic function, but its resolution is complicated by the absence in the M. tuberculosis genome of a direct homologue of BtuFCD, the only bacterial B₁₂ transport system described to date. We applied genome-wide transposon mutagenesis to identify M. tuberculosis mutants defective in their ability to use exogenous B₁₂. A small proportion of these mapped to Rv1314c, identifying the putative PduO-type ATP : co(I)rrinoid adenosyltransferase as essential for B₁₂ assimilation. Most notably, however, insertions in Rv1819c dominated the mutant pool, revealing an unexpected function in B₁₂ acquisition for an ATP-binding cassette (ABC)-type protein previously investigated as the mycobacterial BacA homologue. Moreover, targeted deletion of Rv1819c eliminated the ability of M. tuberculosis to transport B₁₂ and related corrinoids in vitro. Our results establish an alternative to the canonical BtuCD-type system for B₁₂ uptake in M. tuberculosis, and elucidate a role in B₁₂ metabolism for an ABC protein implicated in chronic mycobacterial infection.

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Atypon Icon for PubMed Central
Loading ...
Support Center