Type IV pili interact with PelA deposited on a surface. (a) Sketch of setup (left) and typical sequence of trapped P. aeruginosa (right). Bacteria were incubated on a glass surface for 70 to 80 min. An escape was defined by displacement of the cell body by at least 300 nm from the center of the laser trap (e.g., event starting at 7 s). Bar, 2 μm. (b) Escape probabilities within 30 s of the ΔflgK, ΔroeA ΔflgK, ΔpelA ΔflgK, and ΔpelA ΔpilA ΔflgK mutants. Error bars, standard errors. (c) Distribution of times elapsed before escape for the ΔflgK, ΔroeA ΔflgK, and ΔpelA ΔflgK mutants.