Two component signaling systems in Mycobacterium tuberculosis

Mycobacterium tuberculosis is one of fearful pathogens and has the ability to persist within its host. Its successful survival is due to alterations in gene expression in response to environmental changes by two component systems (TCS), which consist of sensor histidine kinases (HK) and their cognate response regulators (RR). M. tuberculosis has twelve TCSs and five orphan RRs. A typical TCS involves sensing of internal or external signals by a HK, leading to its autophosphorylation, by phosphoryl transfer to the cognate RR, which functions as a transcriptional activator. To understand the function and the mechanism of M. tuberculosis TCSs, the components of HKs and RRs are subjected on the structural studies and the results could be useful for new antituberculosis drug development. Here, structural features of HKs and RRs currently revealed from M. tuberculosis are summarized. Those include GAF and PAS domains for senor domains and ATP binding domains from HKs, and the receiver and effector domains from RRs.