The stationary phase-specific sRNAfimR2is a multifunctional regulator of bacterial motility, biofilm formation and virulence

Abstract

SummaryBacterial pathogens employ a plethora of virulence factors for host invasion, and their use is tightly regulated to maximize infection efficiency and manage resources in a nutrient-limited environment. Here we show that duringEscherichia colistationary phase the small non-coding RNAfimR2regulates fimbrial and flagellar biosynthesis at the post-transcriptional level, leading to biofilm formation as the dominant mode of survival under conditions of nutrient depletion.fimR2interacts with the translational regulator CsrA, antagonizing its functions and firmly tightening control over motility and biofilm formation. Generated through RNase E cleavage,fimR2regulates stationary phase biology independently of the chaperones Hfq and ProQ. TheSalmonella entericaversion offimR2induces effector protein secretion by the type III secretion system and stimulates infection, thus linking the sRNA to virulence. This work reveals the importance of bacterial sRNAs in modulating various aspects of bacterial physiology including stationary phase and virulence.HighlightsfimR2expression causes biofilm formation and alters bacterial outer membrane architecturefimR2modulates CsrA activity and sequesters it from its targetsTheSalmonella fimR2variant is functional inE. colifimR2is generated through RNase E processing and enhances infectivity