Fig 4.

PgreA::lacZ, PgreB::lacZ, and PdksA::lacZ activities in different backgrounds reveal complex regulation of the three factors. The experiments were performed in wild-type or ppGpp⁰ cells also carrying a greA, greB, or dksA deletion. Activities of the promoters, as indicated on the figure, were monitored by β-galactosidase assays at early exponential phase (OD₆₀₀ of <0.4) and early stationary growth (OD₆₀₀ of ≥2).