Figure 5. cI Binds to the pckA Promoter Region.
In these experiments, affinity-purified cI was added in variable (0 μM, 1.15 μM, and 4.6 μM, lanes 1, 2, and 3, respectively) or constant (4.6 μM, lanes 4–12) amounts to 32P-labeled upstream pckA DNA (pPckA*, 0.83 nM each lane). In lanes 4–5, a 5-, 10-, and 30-fold excess of unlabeled pckA DNA was added as competitor. In lanes 7–9, a 10-, 30-, and 60-fold excess of unlabeled λ OR DNA was the competitor. In lanes 10–12, a 10-, 30-, and 60-fold excess of unlabeled random λ OR1 sequence (nonspecific) was added (see Materials and Methods).
