Fig. 11.

Effects of ppGpp and DksA on the pS1 (a) and pS2 (b) promoter activity. Wild-type (WT) E. coli or ppGpp⁰ (relA spoT double mutant), DksA⁰ (dksA::kan mutant) and ppGpp⁰ DksA⁰ (relA spoT dksA triple mutant) strains were cultured in the LB medium at 37°C to exponential (exp) or stationary (st) phase of growth. Primer extension experiments were performed as described in “Materials and methods”, with the use of PS1.rev primer (left panel) and PS2.rev primer (right panel), and the products of the reactions were separated during polyacrylamide gel electrophoresis, with the products of the sequencing reaction (performed using the same primers) run at the same gel (lanes G, A, T and C). Positions corresponding to pB, pS1 and pS2 transcription start sites are shown