FIGURE 7.

Gel mobility shift assay for binding of IHF to the vvpE regulatory region. The 201-bp DNA fragment of the vvpE upstream region was radioactively labeled and then used as a probe DNA. Lanes 1–5, the radiolabeled fragments (7 nm) were mixed with increasing amounts of IHF (0, 100, 200, 300, and 400 nm in lanes 1–5, respectively) and then resolved on a 5% polyacrylamide gel. Lanes 6–9, for a competition analysis, the same yet unlabeled 201-bp DNA fragment was used as a self-competitor DNA. Various amounts of the self-competitor DNA were added to the reaction mixture containing 7 nm of the labeled DNA prior to the addition of 400 nm of IHF. Lanes 6–9, probe DNA incubated with 35, 70, 175, and 350 nm of competitor DNA, respectively. B, bound DNA; F, free DNA.