Part of a signaling pathway that enables adaptation to osmotic stress through cell wall remodeling and virulence factor production. Key microbial factor required for central nervous system tuberculosis. Required for invasion of host brain endothelia, but not macrophages, lung epithelia or other endothelia. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Dimerization activates the kinase domain of unphosphorylated PknD via an allosteric mechanism, triggering autophosphorylation and phosphorylation of target proteins. Phosphorylated PknD is fully active even in the absence of dimerization. Homodimer (By similarity). The extracellular domain interacts with host laminin (PubMed:22243650). Autophosphorylated. Dephosphorylated by PstP. Mutants display defective invasion and reduced survival in brain endothelia. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.