The functional Hfq-binding module of bacterial sRNAs consists of a double or single hairpin preceded by a U-rich sequence and followed by a 3′ poly(U) tail

Effects of mutations in internal stem–loop on expression and silencing ability of SgrS. (A) Properties of SgrS variants expressed from pQE80L-series plasmids. IT1568 (hfq⁺) and TM589 (Δhfq) cells harboring indicated plasmids were grown in LB medium in the presence of 0.1 mM IPTG. Total RNAs and proteins were prepared. The RNA samples were subjected to Northern blot analysis using SgrS probe 1 and a ptsG probe. The following amounts of RNAs were loaded: SgrS variants, 0.1 μg; ptsG mRNA, 10 μg. Protein samples equivalent to 0.04 A₆₀₀ units were subjected to Western blot analysis. (B) Properties of SgrS variants expressed from pMW218- and pTWV228-series plasmids. pMW218 is a low-copy, and pTWV228 is a high-copy plasmid. IT1568 cells harboring indicated plasmids were grown in the presence of 0.2% (for preparation of total RNAs) or 1% (for preparation of total proteins) arabinose. Total RNAs and proteins were prepared. RNA samples were subjected to Northern blot analysis using SgrS probe 1 and a ptsG probe. The following amounts of RNAs were loaded: SgrS variants, 0.25 μg; ptsG mRNA, 10 μg. Protein samples equivalent to 0.04 A₆₀₀ units were subjected to Western blot analysis.