In vitro activities of the KdpD-Usp chimeras. KdpD-autokinase and KdpE-phosphotransferase activities (A) as well as KdpE-phosphatase activities (B) were determined as described in Methods. Data are presented as percentages of maximal accumulation of KdpD~P or KdpE~P (after 3 min, kinase as well as phosphotransferase activity) (A), respectively, or as percentages of the dephosphorylation initial rates relative to wild-type KdpD (+/- ATPγS) (B). For wild-type KdpD (100% values), the autophosphorylation activity of KdpD was determined with 14 pmol min-1 mg-1 protein. The phosphatase activity was determined with 2.1 pmol min-1 mg-1 protein. The autoradiographs represent a typical result from three independently performed experiments, whereas the values represent the averaged results of these three independent measurements.