Fig 5.

Overproduced GreA activates PdksA::lacZ and increases DksA level in ppGpp⁰ cells. (A to C) PgreA::lacZ, PgreB::lacZ, and PdksA::lacZ activities in ppGpp⁰ cells carrying the pGreA plasmid were monitored by β-galactosidase assays throughout growth at 37°C in LB medium. When present, IPTG was added to 0.1 mM at the beginning of the experiment. (D) GreA and DksA protein levels assessed by Western blotting under the same conditions as in panels A to C. The samples for the Western analysis were collected at OD₆₀₀ of 0.4 and 2. Protein levels were normalized for each blot separately to the level found in the sample obtained at an OD₆₀₀ of 0.4 without IPTG; the alpha subunit of RNAP was used as the loading control.