FtsZ moves bidirectionally around the mature-septal division plane with filament/bundle velocities similar to those determined in nascent FtsZ rings. FtsZ moves bidirectionally around the mature-septal division plane with filament/bundle velocities similar to those determined in nascent FtsZ rings. IU9985 cells expressing FtsZ-sfGFP were immobilized vertically, and FtsZ-sfGFP dynamics (Movie S3) was determined as described in SI Appendix, Experimental Procedures. (A, Upper) Representative snapshot images of FtsZ-sfGFP septal rings with typical diameters used in analyses. Images in SI Appendix, Fig. S11 illustrate the range of cell diameters observed. (Lower) Kymographs around cell circumference showing multiple FtsZ-sfGFP filaments/bundles treadmilling in both directions. Time-lapse images of the ring circumference were unwrapped into lines (black arrow, Upper Left) to generate the kymograph rows. (Scale bars, 500 nm.) (B–D) Individual filament/bundle tracks in kymographs were quantified from 29 cells (SI Appendix, Fig. S10) to give distributions of FtsZ-sfGFP filament treadmilling speed (B; n = 605), processivity (C; n = 544), and lifetime (D; n = 544). Mean ± SD; speed = 30.5 ± 9.3 nm/s; processivity = 515 ± 544 nm; lifetime = 17.1 ± 9.4 s. Amilcar J. Perez et al. PNAS 2019;116:8:3211-3220 ©2019 by National Academy of Sciences