FIG. 6.
PhoP-PhoQ but not PmrA-PmrB regulates the pmrD gene. PmrA−, PmrAc, PhoPc, and Phop− strains containing a single-copy pmrD::luc fusion were assayed in logarithmic phase (OD600, 0.6) for firefly luciferase activity (expressed as relative light units [RLU]). Results are expressed as ratios of firefly luciferase activity in PmrAc versus PmrA− backgrounds and in PhoPc versus PhoP− backgrounds.