FIG. 3.

Effect of various E. coli proteases on the EDF response. E. coli strains MC4100relA1 (WT), MC4100relA1ΔclpP (ΔclpP), MC4100relA1ΔclpA (ΔclpA), MC4100relA1ΔclpX (ΔclpX), and MC4100relA1Δlon (Δlon) were grown as described in Materials and Methods. When the cultures reached a density of 2.5 × 10⁸ cells/ml, duplicate samples were removed and diluted to 3 × 10⁴ cells/ml in prewarmed (37°C) M9 medium containing chemically synthesized EDF (0.05 μg/ml). The samples were incubated without shaking at 37°C for 10 min. Samples were further incubated without shaking at 37°C with rifampin (25 μg/ml). For the rest of the experiment, see Materials and Methods.