(A) Time course of OmpR phosphorylation. OmpR (7.5 μM) was incubated with 25 mM acetyl phosphate in the presence (triangles) or absence (circles) of a 2-fold molar excess of C1 DNA. At 5, 15, 30, 60, 90, 120, 150, and 180 min, 50-μl samples were withdrawn from the phosphorylation reaction and injected onto a C4 column and separated by reverse-phase HPLC. OmpR-P is plotted as a percentage of total protein versus time. (B) Time course of OmpR-P dephosphorylation. OmpR is phosphorylated as described for A, and after 180 min, the acetyl phosphate is removed by gel filtration. OmpR-P is monitored via C4 reverse-phase HPLC, and this value represents 100% at time zero. OmpR-P is plotted in the presence (triangles) and absence (circles) of C1 DNA at the times indicated.