Phosphorylates a specific serine in the N-terminus of a myosin light chain (By similarity). Phosphorylates regulatory myosin light chain (mlcR) during chemotaxis (PubMed:16546177). mlcR phosphorylation increases the motility and actin-activated ATPase activity of myosin, contributing to chemotaxis (PubMed:16546177). ATP + L-seryl-[myosin light chain] = ADP + H(+) + O-phospho-L-seryl-[myosin light chain] ATP + L-threonyl-[myosin light chain] = ADP + H(+) + O-phospho-L-threonyl-[myosin light chain] Possesses an autoinhibitory domain. Autophosphorylation appears to increase the enzymatic activity. Activation is gbdC-dependent. Does not have a calmodulin-binding domain. Autophosphorylated. Transiently phosphorylated on Thr-166 and Thr-289. This phosphorylation is gbpC-dependent. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. CaMK subfamily.