The transcriptional activity of SsrB-regulated virulence genes is affected by an rpoE deletion. Wild type and ΔrpoE cells carrying single-copy chromosomal transcriptional reporters of (A) PsseA::pPsseA-lacZ, (B) PssaB::pPssaB-lacZ, (C) PssaG::pPssaG-lacZ, (D) PsifA::pPsifA-lacZ, (E) PsseL::pPsseL-lacZ and (F) PsrfN::pPsrfN-lacZ were grown in LPM (pH 5.8). At the indicated time β-galactosidase activity was measured and expressed as relative light units (RLU) normalized to optical density of the culture. Wild type and ΔrpoE cells lacking the transcriptional reporters were used as controls in each experiment. Data are the means with standard error from triplicate determinations from three independent experiments.