The RyfA small RNA serves as a master regulator of stress responses and virulence in uropathogenic Escherichia coli

Urinary tract infections (UTIs) are a very common bacterial infectious disease in humans, and uropathogenic Escherichia coli (UPEC) are the most frequent cause of UTIs. During infection, UPEC must cope with a variety of stressful conditions in the urinary tract. Here, we demonstrated that the small RNA (sRNA) RyfA of UPEC strains was required for resistance to oxidative and osmotic stresses. Inactivation of ryfA in UPEC strain CFT073 decreased urinary tract colonization in CBA/J mice and the ryfA mutant also had reduced production of type 1 and P fimbriae, which are known to be important for UTI. Transcriptomic analysis of the ryfA mutant showed changes in expression of genes associated with general stress responses, metabolism, biofilm formation and genes coding for cell surface proteins. Furthermore, loss of ryfA also reduced UPEC survival in human macrophages. Thus, ryfA plays a key regulatory role in UPEC adaptation to stress, that contributes to UTI and survival in macrophages. Examination of transcriptome of CFT073 vs ΔryfA in LB at O.D 0.6