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 such as FtsZ and MurD. Shows a strong preference for Thr versus Ser as the phosphoacceptor. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated by magnesium or manganese. Inhibited by vanadate. Interacts with FtsZ and MurD. The kinase domain and the juxtamembrane region constitute the catalytic core of PknA. Interaction between core and C-terminal domains is crucial for activity. Autophosphorylated. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.