Fig 3. RsbR1 can act independently of its paralogues to transduce the low pH signals to activate σB and enhance acid tolerance.
Expression of σB-dependent genes (A) lmo2230 and (B) lmo0596, obtained from mid-log phase cultures of wild type and rsbR1-only strains untreated (-) and treated (+) for 15 min in pH 5.0 at 37°C. Gene expression is expressed as Log2 relative gene expression. (C) Acid challenge of mid-log phase cultures treated in pH 5.0 for 15 min at 37°C, as previously described in Fig 2D. Survival data is expressed as Log10 (CFU.mL-1). The rsbR1-only genotype consists on the following mutations, ΔrsbR2; ΔrsbR3; ΔrsbR4; rsbL (C56A). Statistical analysis was performed using a paired Student’s t-test relative to the wild type untreated after 15 min, for RT-qPCR data, and untreated wild type at time 0 min, for acid challenge data (*, P value of <0.05; **, P value of <0.01; ***, P value of <0.001).