The Hfq-binding small RNA PqsS regulates Pseudomonas aeruginosa pqs quorum sensing system and virulence

Abstract Pseudomonas aeruginosa is a widespread nosocomial pathogen with a significant capacity to cause both severe acute infections and biofilm-related chronic infections. Small RNAs (sRNAs) are noncoding regulatory molecules that are stabilized by the RNA chaperone Hfq, triggering various signaling pathways. Here, we identified an Hfq-binding sRNA in P. aeruginosa PAO1, named PqsS, which promoted bacterial pathogenicity and the pseudomonas quinolone signal quorum sensing (pqs QS) system. Specifically, PqsS enhanced bacterial acute infections by inducing host cell death and promoting rhamnolipid-regulated swarming motility. Meanwhile, PqsS reduced chronic infection traits including biofilm formation, antibiotic resistance, macrophage survival, and ROS production. Moreover, PqsS repressed the pqsL transcript, leading to the increased PQS levels for pqs QS system, while a PQS-rich condition promoted PqsS expression, thus forming a positive feedback loop. Furthermore, we demonstrated that the PqsS-Hfq complex interacts with and destabilizes the pqsL mRNA by recruiting RNase E to drive degradation. Finally, PqsS promotes membrane vesicles (MVs) production and is abundantly detected in MVs. Our work revealed a novel Hfq-binding sRNA PqsS signaling pathway, which enhances pqs QS and acute infections in P. aeruginosa. These findings provide insights for future research on P. aeruginosa pathogenesis and targeted treatment strategies.