Figure 1.

Kinetics of open complex formation at the malTp1 promoter in the presence of CRP. (a) UV laser footprints of the core promoter region. The samples at t = 0 min have been irradiated before addition of RNA polymerase. For the other samples, the time shown above the lanes indicates the incubation time before UV irradiation. The intensity of the band at −9 correlates with DNA melting (open complex formation). (b) UV laser footprints of the upstream promoter region. The band at −94 characterizes the interaction of upstream DNA with RNA polymerase; the band at −60 decreases in intensity upon interaction between CRP and RNA polymerase. (c) Time course of open complex formation at the malTp1 promoter. The normalized band intensity is plotted as a function of time. Filled circles, band at −9, +CRP; open circles, band at −9, no CRP; squares, band at −94, +CRP.