The conserved two-component systems orchestrate the pathophysiology of Mycobacterium tuberculosis

Pathogenic bacteria have to adapt to the various microenvironmental conditions encountered during its infective cycle. Therefore, an efficient transcriptional regulatory mechanism becomes a precondition to ensure survival of bacteria inside the host. Intracellular pathogenic bacteria basically rely on two-component signalling systems (TCSs) for this purpose. However, the reductive evolution of Mycobacterium tuberculosis (Mtb) complex encompassed a significant reduction in the number of TCSs. Nevertheless, the 11 conserved TCSs, selected under the evolutionary pressure of Mtb, play crucial roles in the successful establishment of TB infection. The basic histidine-aspartate phosphorelay mechanism and structural aspects of the TCSs have been reviewed. It has also been discussed how the conserved histidine kinases tune the transcription of specific bacterial genes in response to environmental stimulus and ensures the intracellular survival of Mtb.