HfqLMO is able to restore several key defects associated with Hfq in E. coli. (A) Growth curves of E. coli wild-type (SØ928) carrying the empty vector pNDM-220, and E. coli hfq−1 carrying pNDM-220, pNDM-hfqECO or pNDM-hfqLMO. Cells were cultivated in LB medium in the presence of 1 mM IPTG. The data shown are the result of three independent experiments each conducted in duplicate. (B) Resistance to oxidative stress. Overnight cultures were spread on agar plates and tested for their tolerance towards hydrogen peroxide by disk diffusion assay. Here, the averages of three independent experiments each conducted in triplicate are shown. The presence of three asterisks above a bar indicate a significant difference as compared to the hfq− strain with P < 0.001. (C) Western blot analysis of the level of σS and GroEL (control). Cells were grown in LB medium containing 1 mM IPTG and cells were harvested at various time points during growth. E, exponential; T, transition phase; S, stationary phase. (D) Northern blot showing Hfq-dependent stabilization of RyhB and degradation of sodB mRNA. Cells were grown in LB medium containing 1 mM IPTG. At OD600 = 0.4, the cultures were split and 2,2′-Dipyridyl (DIP) was added to one of the cultures. After 10 min, cells were harvested for RNA extractions, and RhyB RNA, sodB mRNA and 5S rRNA levels were analysed by northern blotting.