Fig. 4. PapB binding to the fim regulatory DNA region. (A) Outline of the fimB, fimE, fimA regions and positions of the promoters (P). The relative positions and lengths of different PCR fragments are also indicated. (B and C) Gel mobility shift assays of His-PapB binding to DNA fragments (PCR1–6). The assays were carried out as described in Materials and methods.