Fig. 5.

Effects of WT-CsrA or HD-CsrA on the expression of glgC′-‘lacZ or glgCΔGGA′-‘lacZ translational fusions in S-30 coupled transcription-translation reactions. a) Reactions contained 2 μg of supercoiled plasmid pCZ3-3 (glgC′-‘lacZ) and either WT-CsrA (top panel) or HD-CsrA (bottom panel) at the concentrations indicated; right panel graphically displays quantified results. b) Similar reactions were conducted with 2 μg of supercoiled plasmid pCSB25 (glgCΔGGA′-‘lacZ). The concentration of CsrA that leads to a 50% inhibition of gene expression (IC₅₀) was calculated based on a simple point-to-point curve and a Hill-Slope (4PL) model, both of which gave similar values. Simultaneous expression from the bla gene of these plasmids (Bla) served as an internal control for nonspecific inhibition. Graphpad Prism version 3 was used for graphical representations and IC₅₀ calculations. In vitro transcription-translation assays were conducted at least twice for each set, with similar results.