Regulates the activity of endogenous beta-lactamase or related enzymes, by blocking their secretion by phosphorylation, in response to an external signal yet to be identified. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.