FIG. 6.

Effect of Hfq and Lon via the downstream silencer in an hns mutant. The expression level directed by the bgl-downstream silencer-lacZ reporter constructs carrying the bglG coding region (Fig. 5D) was determined in hfq hns, lon hns, and stpA hns mutants and compared to the expression level in the hns strain tested previously (9). Cultures were grown in NB medium to an OD₆₀₀ of 0.5. The hfq hns double mutant was grown in LB medium. β-Galactosidase activity is shown for the following strains from top to bottom: S1258 (hns-206::Ap^r) (9), S1828 (hfq1::Ω hns-206::Ap^r), S1432 (Δlon-510 sulA3 hns-206::Ap^r), and S1767 (stpA::Tc^r hns-206::Ap^r).