RstAB activates type 1 fimbriae to promote uropathogenic Escherichia coli bladder invasion

Urinary tract infections (UTIs), primarily caused by uropathogenic Escherichia coli (UPEC), are a significant public health problem. UPEC relies on type 1 fimbria to invade bladder epithelial cells (BECs), which is a crucial step in the successful establishment of UTIs. In this study, we found that a two-component system, RstAB, was required for UPEC CFT073 colonization of the mouse bladder, by contributing to bacterial invasion during acute UTIs. Our results demonstrated that RstAB promoted UPEC invasion of BECs and enhanced virulence by activating type 1 fimbria, with RstA directly binding to fimS to facilitate its phase-ON orientation. This study identified a pathway regulating type 1 fimbria activation in UPEC CFT073, providing mechanistic insights into its virulence and a potential strategy for UTI treatment.