Protein kinase that regulates many aspects of mycobacterial physiology. Is a key component of a signal transduction pathway that regulates cell growth, cell shape and cell division via phosphorylation of target proteins. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Homodimer. Autophosphorylated. Dephosphorylated by PstP (By similarity). Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.