Regulation of Inducible Potassium Transporter KdpFABC by the KdpD/KdpE Two-Component System in Mycobacterium smegmatis

Kdp-ATPase is an inducible high affinity potassium uptake system that is widely distributed in bacteria, and is generally regulated by the KdpD/KdpE two-component system (TCS). In this study, conducted on , the (encoding Kdp-ATPase) expression was found to be affected by low concentration of K , high concentrations of Na , and/or [Formula: see text] of the medium. The KdpE was found to be a transcriptional regulator that bound to a specific 22-bp sequence in the promoter region of operon to positively regulate expression. The KdpE binding motif was highly conserved in the promoters of among the mycobacterial species. 5'-RACE data indicated a transcriptional start site (TSS) of the operon within the coding sequence of , which comprised a 120-bp long 5'-UTR and an open reading frame of the 87-bp gene. The deletion resulted in altered growth rate under normal and low K conditions. Furthermore, under K limiting conditions, a single transcript ( ) spanning and operons was observed. This study provided the first insight into the regulation of operon by the KdpD/KdpE TCS in .