FIG. 4.

Regulation of virulence factor gene expression in CsrS mutant strains. Compared to results for the corresponding CsrR mutant strains, hybridizations of RNA from CsrS mutant strains 515ΔcsrS and 2603ΔcsrS demonstrate similar, but less marked, increases in cylE (beta-hemolysin) and scpB (C5a peptidase) transcripts and a less marked reduction in cfb (CAMP factor) transcript. Hybridizations were performed as described in the legend to Fig. 3. No significant difference was observed between wild-type and mutant strains in expression of control genes recA and rpsL. Each blot is representative of two to four independent experiments.