FIG. 5.

Reporter enzyme activity of an ackA::lacZ transcriptional fusion construct in response to phosphate starvation. Cells of each strain were prepared and assayed as described in Materials and Methods. Reporter enzyme levels (in Miller units) for strains RmMSU4 (ackA::Tn5B22) (□), RmMSU5 (pta::Ω ackA::Tn5B22) (●), and RmMSU7 (ackA::Tn5B22 phoB::Ω) (○) are shown. Data points are the averages of data from duplicate cultures from one of three independent experiments documenting these responses. Reporter enzyme levels failed to increase when washed cells of all three strains were resuspended in high-phosphate medium (results not shown to simplify presentation).