Figure 3.

FlgM interferes with specific binding of Eσ²⁸ to the fliC promoter. Filter binding assays were used to evaluate the effect of FlgM on promoter binding by Eσ²⁸. Proteins indicated above each lane were incubated together for 10 min prior to the addition of labeled promoter DNA. In lane 5 (A) and lanes 2 and 3 (B), proteins enclosed in brackets were preincubated for 10 min before the addition of the third protein; reactions were incubated a further 5 min before DNA was added. The hatched bars indicate s.d. (assays performed in triplicate). (A) Noncompeted binding of the fliC promoter by σ²⁸, core RNAP (E), and FlgM. (B) The effect of FlgM on specific binding of Eσ²⁸ to the fliC promoter. Samples were chased with unlabeled sheared salmon sperm DNA (a competitor for nonspecific DNA binding) prior to sampling, so promoter DNA retained on filters represents only that bound specifically by protein.