FIG. 2.

DNA mobility shift assays of CRP binding to sites 1, 2, 3, and 4. The fragment containing CRP site 1⁺ was PCR amplified using primers 742 and 744. The upstream primer 896 was used to generate fragments with sites 2⁺3⁺4⁺ and site 2⁺, with primers 1170 and 2165 used as downstream primers, respectively. Primers 742 and 896 were ³²P labeled. The major band in the second lane in each set is at the position of the wells. Approximately 1 ng of ³²P-labeled DNA fragment was added to each reaction mixture. The approximate CRP concentrations per reaction were the following: for the first lane in each set, F, none; for the second lane in each set, 8.4 μM CRP; for the third lane in each set, 2.1 μM CRP; and for the fourth lane in each set, 0.21 μM CRP.