Fig. 4.

(A) Coomassie-stained SDS-PAGE gel showing DC3000 Fur after purification. (B) EMSA of Fur targets, regions upstream of pvdS and prrF2, and region between PSPTO_0069 and PSPTO_0070. As a negative control, Fur binding to the PSPTO_1900 promoter (not predicted to be bound by Fur) was also assessed. Unbound probes are shown in the first lane and reduced mobility is observed with increasing Fur concentrations for all three Fur targets. Competition assays with specific unlabeled probe were performed and resulted in a loss of band shift (see Fig. S1 in the supplemental material). (C) Fragment analysis from nonradioactive footprinting assays. In each case, the lower panel shows the fragments obtained after DNase I digestion of the probe alone, while in the top panel the probes were incubated with 25 nM Fur prior to DNase I digestion. Protection by Fur can be seen in the boxed regions.