ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Transiently by pathogenic bacteria Pseudomonas syringae. Faster level reduction following induction by treatment with the virulent compatible DC3000 strain than with avirulent incompatible strains. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.