FIG. 1.

The effect of E. coli rpoS on mazEF-mediated cell death during stationary growth phase following the inhibition of transcription or translation. MC4100relA⁺ (WT) and its derivatives, MC4100relA⁺ΔmazEF::kan (ΔmazEF), MC4100relA⁺ΔrpoS::tet (ΔrpoS), MC4100relA⁺ΔrpoS::tet carrying plasmid pQEkatE (ΔrpoS+KatE), and MC4100relA⁺ΔrpoSΔmazEF (ΔrpoS ΔmazEF) were grown aerobically at 37°C until stationary phase (OD₆₀₀ = 1.3 to 1.4). Stressful conditions were induced by incubation of cells at 37°C, without shaking them, with rifampin (20 μg/ml) for 10 min (A); spectinomycin (1 mg/ml) for 10 min (B); chloramphenicol (50 μg/ml) for 20 min (C); or serine hydroxamate (0.2 mg/ml) for 1 h (D); for the rest of the experimental details, see the text. The results represent the ratio of CFU of treated cells versus that of untreated cells. (E) CFU/ml of all untreated strains at stationary phase.