FIG. 6.

In vitro transcription. (A) In vitro transcription from Po in the presence and absence of IHF in response to increasing concentrations of Eς⁵⁴. Standard single-round transcription assays included 5 nM supercoiled template pVI595, 20 nM IHF, 100 nM ΔA2*-His-DmpR, 0 to 100 nM core with a threefold excess of ς⁵⁴, and either no IHF (open symbols) or 20 nM IHF (closed symbols). The results are the weighted averages of duplicate independent experiments, in which the average of the plateau values in the absence of IHF was set at 100. (B) In vitro transcription from templates with modified Po regulatory regions as schematically indicated. Standard single-round transcription assays included a 5 nM concentration of the indicated supercoiled template, 200 nM ΔA2*-His-DmpR, 20 nM core, 80 nM ς⁵⁴, and either no IHF (open bars) or 20 nM IHF (shaded bars). The results are the averages of duplicate experiments in which the average of pTE-Po in the absence of IHF is set at 100. Error bars, standard errors; Arb., arbitrary.