Involved in the regulation of secondary metabolism by phosphorylating, on both Ser and Thr, the AfsR global regulatory protein involved in the control of secondary metabolism. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts (via the N-terminal kinase domain) with KbpA; the interaction prevents autophosphorylation of AfsK. Autophosphorylated mainly on threonine residues. Some phosphorylation on serine residues. Autophosphorylation on Thr-168 is the major site enhancing kinase activity towards AfsR, and is regulated though interaction with KbpA. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.