Involved in the regulation of capsular polysaccharide biosynthesis. Autophosphorylation of CpsD attenuates its activity and reduces the level of encapsulation. May be part of a complex that directs the coordinated polymerization and export to the cell surface of the capsular polysaccharide (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Dephosphorylated and activated by CpsB. Capsule biogenesis; capsule polysaccharide biosynthesis. Autophosphorylated. Belongs to the CpsD/CapB family. Was originally called CpsC.