The ''Mycobacterium tuberculosis'' complex (MTC or MTBC) is a genetically related group of ''

Mycobacterium ''Mycobacterium'' is a genus of over 190 species in the phylum Actinomycetota, assigned its own family, Mycobacteriaceae. This genus includes pathogens known to cause serious diseases in mammals, including tuberculosis ('' M. tuberculosis'') ...

'' species that can cause

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, ...

in humans or other animals. It includes: * ''

Mycobacterium tuberculosis ''Mycobacterium tuberculosis'' (M. tb) is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, ''M. tuberculosis'' has an unusual, waxy coating on it ...

'' * '' Mycobacterium africanum'' * '' Mycobacterium orygis'' * ''

Mycobacterium bovis ''Mycobacterium bovis'' is a slow-growing (16- to 20-hour generation time) aerobic bacterium and the causative agent of tuberculosis in cattle (known as bovine TB). It is related to ''Mycobacterium tuberculosis'', the bacterium which causes tub ...

and the Bacillus Calmette–Guérin strain'' * '' Mycobacterium microti'' * '' Mycobacterium canetti'' * '' Mycobacterium caprae'' * '' Mycobacterium pinnipedii'' * ''

Mycobacterium suricattae ''Mycobacterium suricattae'' is a species of the tuberculosis complex of the genus ''Mycobacterium''. It causes tuberculosis in meerkats, and was first identified from South African animals in 2013. Prior to this, it was considered to be synonym ...

'' * '' Mycobacterium mungi'' In addition, two branches exist which have phylogenetic similarities but are not completely described: the dassie and oryx bacilli. Oryx bacilli has been recently reclassified into a separate subspecies, orygis. Members of the MTC can be distinguished from all other bacteria by the presence of 63 conserved signature indels (CSIs) present in diverse proteins that are exclusively shared by these pathogens. Due to their exclusivity for the MTC complex and presence in highly conserved regions of proteins, these CSIs provide novel means for functional and diagnostic studies (including potential targets for development of novel therapeutics).

Phylogenetics

As MTBC diverged into different lineages, so did the expression of key and metabolic pathogenic genes, as a result of mutations introducing new TANNNT Pribnow boxes and mutations that impair the function of repressors Transcripcionales. This provides clear evidence that MTBC lineages probably reflect adaptation to different human populations. In fact, modifying gene expression could be a rapid mechanism for physiological adaptation to a new environment without the need to substantially change the genome. This can be seen reflected in the way that the different MTBC clades have their own transcriptomic signature. Even single-point mutations can completely change the transcriptional profile of a strain. An example is the N1177 strain, which carries a single mutation in the rpoB gene that confers resistance to rifampicin that modified transcription levels of multiple genes. The role of methylation is more elusive, the mutation inactivation pattern seems to confirm that methylases are not preserved throughout mtBC. Transcriptional adaptation can allow M. tuberculosis isolates to optimize their infectivity and transmission in subtly different environments provided by different human host populations. CC-BY icon

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References

tuberculosis complex Tuberculosis {{Mycobacterium-stub

Phylogenetics

See also

References