FIG 7.

Positive controls for cat reporter assays in the ΔssrB and ΔphoP mutants. (A and C) Expression of the ssaG-cat transcriptional fusion carried by the pssaG-cat plasmid was determined in the WT S. Typhimurium strain and its isogenic ΔssrB mutant containing the pMPM-K3 vector or the pK3-SsrB plasmid that expresses SsrB from a constitutive promoter. (B and D) Expression of the pagK-cat transcriptional fusion carried by the ppagK-cat plasmid was determined in the WT S. Typhimurium strain and its isogenic ΔphoP mutant containing the pMPM-K3 vector or the pK3-PhoP plasmid that expresses PhoP from a constitutive promoter. The CAT-specific activity was determined from samples of bacterial cultures grown for 9 h in LB (A and B) or 6 h in N-MM (C and D) at pH 5.8 and 37°C. Data represent the mean with standard deviation of the results from three independent experiments performed in duplicate. Statistically different values are indicated (***, P < 0.001; ****, P < 0.0001).