FIG. 3.

ComK negatively affects transcription of ywcC and tig. β-Galactosidase (Betagal) assays were performed to verify the negative effects of ComK production on transcription of ywcC and tig, using a P_ywcC-lacZ fusion (A) and a P_tig-lacZ fusion (B) as reporters, respectively. As a control for significant regulation, the mild effect of ComK on P_ctrA-lacZ, which just missed the arbitrary cutoff level, was determined (C). At the end of the exponential growth phase, expression of wtComK or ComKΔC25 was induced. β-Galactosidase activity was determined at 30-min intervals until 2 h after induction. For each strain, four independent cultures were grown, and the average activity (in Miller units) is shown along with the standard deviation for the average. Symbols: ⧫, no ComK (empty plasmid pNZ8048); ▴, wtComK; ▪, ComKΔC25.