The role of PilU in the surface behaviors of Pseudomonas aeruginosa

In Pseudomonas aeruginosa , the dynamic activity of type IV pilus (TFP) is essential for various bacterial behaviors. While PilU is considered a homolog of the TFP disassembling motor PilT, its specific roles remain unclear. Using pilus visualization and single‐cell tracking techniques, we characterized TFP dynamics and surface behaviors in wild‐type and Δ pilU mutants. We found that Δ pilU cells displayed increased TFP numbers but reduced cell movement and delayed microcolony formation. Interestingly, beyond affecting the twitching motility, Δ pilU cells formed a thick multilayered colony edge on semi‐solid surfaces, slowing colony expansion. Cell–cell collision responses changed from touch‐turn dominance in wild type to touch‐upright dominance in Δ pilU , affecting colony morphology and expansion. These findings expand our understanding of PilU's physiological roles and provide potential targets for developing strategies to control P. aeruginosa biofilm formation and virulence.