Member of the two-component regulatory system LytR/LytS that regulates genes involved in autolysis, programmed cell death, biofilm formation and cell wall metabolism (PubMed:19502411). Participates also in sensing and responding to host defense cationic antimicrobial peptides (CAMPs) (PubMed:23733465). Functions as a sensor protein kinase which is autophosphorylated at a histidine residue and transfers its phosphate group to the conserved aspartic acid residue in the regulatory domain of LytR (PubMed:25491472). In turn, LytR binds to the upstream promoter regions of target genes including lrgA and lrgB, to positively regulate their expression. Possesses also a phosphatase activity that dephosphorylates and thus inactivates LytR (PubMed:25491472). ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Autophosphorylated on His-390. Deletion significantly reduces target tissue survival during calcium-daptomycin treatment and increases susceptibility to host defense cationic antimicrobial peptides.