FIG 2.

Stalling forces of P. aeruginosa PA14 T4P retraction. (a and b) Typical examples for T4P retraction events in position clamp mode. Deflections (d) of the bead from the center of the laser trap (compare with Fig. 1a) and the corresponding forces (F) are shown. (c) Distribution of stalling forces (force at which the velocity was less than 250 nm/s for at least 500 ms) (n = 103). (d) Distribution of stalling forces. First, second, and third stalling events of single pilus retractions are plotted (n > 21 for each condition). In these experiments, the P. aeruginosa PA14 ΔflgK mutant was used to eliminate any contribution of the flagellum to the adhesion or movement of the cell.