Member of the two-component regulatory system WalK/WalR involved in the regulation of the ftsAZ operon, the yocH and ykvT, cwlO, lytE, ydjM, yjeA, yoeB genes and the tagAB and tagDEF operons. Phosphorylates WalR. ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Homodimer. Interacts with YycH and YycI. Expressed during exponential growth and shut down at the entry into stationary phase. Autophosphorylated. The imidazole derivatives NH125, NH126 and NH127 inhibited the incorporation of phosphate from ATP at 50 ug/ml. The zerumbone derivative NH0891 inhibited WalK.