FIG 5.

EMSA of iron levels and the binding of HupB/IdeR to the mbtB promoter DNA. (A and B) EMSA performed with HupB (A) and IdeR (B). One μM the respective purified protein was added to the 216-bp [γ-³²P]ATP-labeled mbtB promoter DNA in the presence of various concentrations of iron. Lane 1 shows the unbound probe in both panels. The intensity of the HupB-bound probe, also detected in the absence of iron (A, lane 2), increased with iron added from 25 to 200 μM (A, lanes 3 to 6). The high level of the bound probe in lane 6 was displaced upon addition of cold probe (lanes 7 and 8). In panel B, lanes 2 to 5 represent IdeR with iron added from 100 to 500 μM. The reaction products were resolved on 4% Tris-acetate polyacrylamide gel.