Figure 5.

Activities of purified DivL (WT), DivL^Y550H, and DivL^Y550H proteins. (A) Kinase activity assays. Experiments were carried out with C-terminal 299 aa of DivL (WT) (lanes 1 and 2), DivL^Y550H (lanes 4 and 5), or DivL^Y550F (lanes 7 and 8). The conditions for autophosphorylation of DivL and for phosphorylation of CtrA by DivL are the same as in Figs. 3 and 4. (B) Phosphatase activity assay. The CtrA protein was ³²P-labeled by the DivL (WT) protein and purified as described in Materials and Methods. The dephosphorylation of ³²P-CtrA was measured in the presence or absence of the DivL protein (200 pmol) as indicated. The reaction mixtures were incubated at 25°C, and samples (15 μl) were withdrawn at the time intervals indicated.