Induction of the PA3552–PA3559 and PA4773–PA4777 operons under Mg2+ limitation. The PA3552–PA3559 likely encodes an LPS modification operon that is strongly induced within hours of growth in Mg2+-limiting medium. (A) Transcriptional luxCDABE fusions to PA3553, PA3555, and PA3559 are shown. The PA4773–PA4777 operon that encodes pmrAB is strongly induced in the late stages of growth in Mg2+-limiting medium. (B) Transcriptional luxCDABE fusions to PA4773, PA4774, and PA4775 are shown. Luminescence (RLU) and OD620 were measured every 30 min throughout growth. All luminescence values were divided by the OD620 values to correct for growth and the ratio of normalized relative light units (RLU) in low to high Mg2+ conditions are plotted. All values shown are the mean of triplicate samples. Standard deviations were within 10% of the means.
