5-Fluorouracil modulates motility and biofilm-associated gene expression in Pseudomonas aeruginosa

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen in which motility, biofilm formation, and stress adaptation contribute to virulence. Drug repurposing represents a practical strategy for identifying compounds that influence these processes. In this study, the effects of 5-fluorouracil (5-FU) on motility, extracellular DNA (eDNA) production, and gene expression were examined in P. aeruginosa PAO1. Swimming, swarming, and twitching motility assays were performed in the presence of increasing concentrations of 5-FU. Transcriptional responses of motility, rhamnolipid, and DNA repair-associated genes were evaluated using quantitative real-time PCR. eDNA levels were quantified using fluorescence-based assays and visualized by confocal laser scanning microscopy. Exposure to 5-FU resulted in concentration-dependent reductions in swimming, swarming, and twitching motility. These changes were associated with downregulation of multiple genes involved in flagellar and type IV pili function, including motA , flhA , fliD , pilA , and pilI , and reduced expression of lasB and rhlAB . At 24 h, eDNA levels were decreased relative to untreated controls, whereas at 48 h, higher concentrations of 5-FU were associated with increased eDNA accumulation and upregulation of several DNA repair genes, including xthA , nth , recJ , sbcB , and eddB . These results indicate the multifaceted effects of 5-FU on important virulence factors of P. aeruginosa.