Figure 2. Gel shift assay of the Fis binding to the lapF promoter DNA containing the wild-type Fis binding site Fis-F2 and the mutated site Fis-F2-mut.

2×10¹⁰ molecules of radioactively labelled PCR products containing Fis-F2 (lanes 1–10) and Fis-F2-mut site (lanes 11–20) were used for Fis binding. Fis was outcompeted from Fis-DNA complex with unlabelled PCR product containing the Fis binding site (LF2) and PCR product without Fis-binding site (RF1). Added unlabelled DNA was calculated in molecules. 0.46 µM Fis was used in each reaction mixture except mixtures without Fis in lanes 2 and 12.