MRC/NHLS/UCT Molecular Mycobacteriology Research Unit & DST/NRF Center of Excellence for Biomedical TB Research, Institute of Infectious Disease & Molecular Medicine & Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Observatory 7925, Cape Town, South Africa.
Future Microbiol. 2013 Nov;8(11):1405-18. doi: 10.2217/fmb.13.113.
Mycobacterium tuberculosis is included among a select group of bacteria possessing the capacity for de novo biosynthesis of vitamin B12, the largest and most complex natural organometallic cofactor. The bacillus is also able to scavenge B12 and related corrinoids utilizing an ATP-binding cassette-type protein that is distinct from the only known bacterial B12-specific transporter, BtuFCD. Consistent with the inferred requirement for vitamin B12 for metabolic function, the M. tuberculosis genome encodes two B12 riboswitches and three B12-dependent enzymes. Two of these enzymes have been shown to operate in methionine biosynthesis (MetH) and propionate utilization (MutAB), while the function of the putative nrdZ-encoded ribonucleotide reductase remains unknown. Taken together, these observations suggest that M. tuberculosis has the capacity to regulate core metabolic functions according to B12 availability - whether acquired via endogenous synthesis or through uptake from the host environment - and, therefore, imply that there is a role for vitamin B12 in pathogenesis, which remains poorly understood.
结核分枝杆菌属于能够从头生物合成维生素 B12 的一组精选细菌之列，维生素 B12 是最大和最复杂的天然有机金属辅因子。该杆菌还能够利用一种与唯一已知的细菌 B12 特异性转运蛋白 BtuFCD 不同的 ATP 结合盒型蛋白来摄取 B12 和相关的类钴胺素。与推断的维生素 B12 对代谢功能的要求一致，结核分枝杆菌基因组编码两个 B12 核糖开关和三个 B12 依赖性酶。这两种酶已被证明在蛋氨酸生物合成（MetH）和丙酸利用（MutAB）中起作用，而假定的 nrdZ 编码的核苷酸还原酶的功能仍然未知。综上所述，这些观察结果表明，结核分枝杆菌具有根据 B12 可用性调节核心代谢功能的能力——无论是通过内源性合成还是通过从宿主环境摄取获得，因此，这意味着维生素 B12 在发病机制中发挥作用，但这方面的作用仍知之甚少。
