Figure 2.

Cooperative binding of ω protein to the promoter region of copS (shaded squares), δ (filled circles), and ω (empty rhomboids). DNA fragments spanning the promoter region of copS, δ, and ω genes (0.2 nM) were radiolabeled and incubated with 1 μg of poly [d(I/C)] as nonspecific competitor DNA and an increasing concentration of the ω protein (0.2–200 nM) in buffer C containing 50 mM NaCl for 15 min at 37°C. The signals present in the protein–DNA complex and in the free DNA were determined by densitometry.