FIGURE 9.

IS10-Kan transposition is derepressed in E. coli encoding Y25A and K56A forms of Hfq. E. coli cells (hfq⁺ or hfq⁻) were cotransformed with pDH602 (encodes IS10-Kan) and a compatible plasmid encoding untagged Hfq (WT, K56A, or Y25A) or the corresponding “empty vector” control. Relative transposition frequencies were measured using the conjugal mating out assay (see Materials and Methods for details). An average transposition frequency (4.03 × 10⁻³ events per mL of mating mixture) was calculated for the hfq⁺ strain (hfq⁺/emp.vect.) from 15 independent “donor” colonies across four independent experiments, and this value was set at 1. All other transposition values are expressed relative to this value where Hfq-directed repression of transposition is at its maximal level. Bars indicate the mean; the error bars indicate standard error on the mean. From left to right, the n value for each treatment group is 15, 15, 14, 16, and 11—these were compiled from at least two (and up to four) independent experiments. An asterisk (*) indicates that means were significantly different from the hfq⁺ control group; P values are indicated above the corresponding bars.