FIGURE 13.

The rpoEP3 promoter is positively regulated by the CRP activator protein. A, cultures of the wild-type strain carrying the rpoEP3 promoter fusion and its four independent Δcrp transductants were grown in LB medium at 30 °C and analyzed for β-galactosidase activity after different intervals. B, interaction of CRP with DNA containing the P3 promoter and upstream DNA region. A 118-bp DNA fragment covering the P3 promoter region was incubated with increasing concentrations of CRP activated by cAMP (lanes 2–5) and complexes were resolved on a 6% native gel. Lane 1 serves as a negative control with DNA alone. Arrows show the position of free dsDNA and CRP-DNA complex.