Effects of PrrA phosphorylation and nonspecific competitor DNA addition on PrrA binding properties. EMSA results showing binding by increasing concentrations of either P-PrrA (lanes 3, 5, 7, and 9) or U-PrrA (lanes 2, 4, 6, and 8) to RSP3361 gene PrrA site 2. The analysis is performed in the presence (A) and absence (B) of the nonspecific competitive inhibitor poly(dA) · poly(dT), which was added at an 80 ng/μl concentration. (C) Effects of increasing concentrations of poly(dA) · poly(dT) on P-PrrA-DNA complex formation at a constant P-PrrA concentration. The amounts shown in each case refer to the total amount added to the reaction. The plus sign refers to addition of 0.57 μmol of P-PrrA. In all panels, lane 1 contains DNA only. The minus sign indicates that there was no addition of the specific compound.