FIG. 4.
CpxR directly regulates the genes containing the consensus sequence. The expression of wild-type fusions (grey bars) of sidM::lacZ (A) and lvgA::lacZ (B), as well as the same fusions containing a mutation in the CpxR regulatory element (open bars), was examined in E. coli having a deletion in the cpxR gene (PAD215). The bacteria examined contained a plasmid with the L. pneumophila cpxR gene cloned under control of the Ptac promoter (activated by IPTG), and they were grown in media containing different concentrations of IPTG (indicated below the bars). Bacteria containing the same lacZ fusions without the cpxR gene were used as controls (left columns in both panels). β-Galactosidase activity was determined as described in Materials and Methods. The data are the averages ± standard deviations (error bars) of at least three different experiments. MU, Miller units.