Fig. 3.

Effects of hfq mutations on sRNA-dependent repression of flhD, chiP, sodB and sdhC. (a) Derivatives of NRD688 (P_BAD-flhD-lacZ) carrying a plasmid expressing McaS were grown on a lactose MacConkey plate containing 50 µg/ml ampicillin and 0.001% arabinose for 24 h. (c) Derivatives of DJS2677 (P_BAD-chiP-lacZ) were grown on lactose MacConkey plates with 0.0005% arabinose for 11 h at 37 °C. (e) Derivatives of DJS2546 (fur::kan) were grown in MOPS EZ rich defined medium with 0.4% glycerol to late exponential phase at 37 °C, and RNA was extracted and sodB RNA levels were analyzed as described in Materials and Methods. (g) The same strains as for (e) were grown in minimal succinate medium at 37° C overnight and growth determined by OD₆₀₀ normalized to growth in minimal glucose medium. (b, d, f, h) β-galactosidase activity measured in wild-type and a subset of hfq mutants shown in (a, c, e, g). Strains in (a, c), derivatives of DJS2676 (P_BAD-sodB-lacZ) overexpressing RyhB, and derivatives of DJS2729 (P_BAD-sdhC-lacZ) overexpressing RyhB were grown in LB medium containing 100 µg/ml ampicillin, 100 µM IPTG, 0.0002% arabinose at 37 °C to early stationary phase (OD₆₀₀ ~ 1.0) and assayed for β-galactosidase activity. Data is an average of three assays and brackets denote the standard deviation of the mean.