Investigating the Molecular Mechanism and Function of the Histidine Kinase TrcS in Mycobacterium tuberculosis.

Mycobacterium tuberculosis (Mtb) is a critical intracellular pathogen responsible for tuberculosis (TB), a highly detrimental infectious disease. For survival in the changing host environment, Mtb employs two-component systems to regulate gene expression and control protein production. Among these systems, histidine kinase TrcS plays a key role in this adaptive response. However, the functional mechanism of Mtb TrcS remains unknown. Here, we successfully obtained monomeric TrcS. G254D or G254R significantly decreased the histidine kinase activity of TrcS compared with the wild-type protein, whereas A220 V or A220I caused a slight decrease in the activity. Gene TrcS induced upregulation of MtrA/B transcript levels in WT and ΔtrcS::trcS Mtb, but downregulation in ΔtrcS Mtb. Deletion of the gene TrcS increased the virulence of Mtb. Our findings contribute to a deeper understanding of the functionality of Mtb TrcS and provide foundational insights for the future development of novel antituberculosis drugs.