FIG. 3.

Interaction of the dad promoters from E. coli and K. aerogenes with NAC. pCB888, which contains the dad promoter from K. aerogenes, and pCB889, which contains the dad promoter from E. coli, were digested and radiolabeled as described in Materials and Methods. Each was then incubated with buffer 6 (19) or increasing amounts of purified NAC (0, 16.5, 22, 33, and 66 nM) for 20 min. The bound and unbound fragments were then separated by electrophoresis on a 4% TE–polyacrylamide gel run for 2 h at 13.3 V/cm at 4°C. The gel was dried, and the DNA was visualized by exposure to X-ray film. Unbound vector and dad promoter bands are indicated by labeled arrows; the unlabeled arrow indicates the NAC-dadAp complex.