FIG 3.

HilD and SlyA are not required for expression of ssrAB during growth in LB when H-NS is inactivated. Expression of the ssrAB-cat−302/+478 transcriptional fusion carried by the pssrAB-cat-302/+478 plasmid was determined in the WT S. Typhimurium strain and its derivative ΔhilD ΔslyA mutant containing the pMPM-T6Ω vector, as well as in the ΔhilD ΔslyA mutant containing the pT6-HNS-WT or pT6-HNS-G113D plasmid, which expresses WT H-NS or the H-NS^G113D dominant negative mutant, respectively, from an arabinose-inducible promoter. CAT-specific activity was determined from samples of bacterial cultures grown for 9 h in LB at 37°C. Expression of WT H-NS or H-NS^G113D from plasmids pT6-HNS-WT and pT6-HNS-G113D, respectively, was induced by adding 0.1% l-arabinose to the medium (+ arabinose). Data represent the mean with standard deviation of the results from three independent experiments done in duplicate. Statistically different values are indicated (***, P < 0.001).