Retraction motor ATPase activity is required for MSHA surface piliation.

(A) Representative images of piliated cells containing the indicated mutations to their retraction motor ATPases. Phase images (top) show cell boundaries and fluorescence images (bottom) show AF488-mal labeled pili. Scale bar = 1 μm. (B) Quantification of piliation in strains from A. Cells were categorized as either having no pili (white bars), 1–2 pili (light gray bars), or at least 3 pili (dark gray bars). n = 300 cells analyzed from three independent biological replicates for all samples. Data for the parent and ΔpilT strains are identical to that presented in Fig 1C and are included again here for ease of comparison. (C) Quantification of retraction in strains from A. Graphs display the percentage of cells in each replicate that exhibited any pilus retraction during a three-minute timelapse. n ≥ 25 piliated cells analyzed for each of the three biological replicates. All data are displayed as the mean ± SD. Parent and ΔpilT data from Fig 1C are included for comparison.