Skip to main content
. 2019 Feb 4;116(8):3211–3220. doi: 10.1073/pnas.1816018116

Fig. 1.

Fig. 1.

FtsZ filament dynamics in nascent and early equatorial rings determined by TIRFm of strain IU9985 expressing FtsZ-sfGFP. Representative data are shown from two to four independent biological replicates. (A) Summation of frames from 180-s TIRFm movies of FtsZ-sfGFP (at one frame per second). Montage of images at 9-s intervals of the cell containing the indicated “A” ring in summation. (Right) Kymographs from 1 to 180 s; top equatorial “A” ring of cell in summation; area marked “B” above septal ring in summation. The dotted lines are approximate outlines of cell shape. (B) Summation of frames from 180-s movies of bright-field images of cells and TIRFm images of FtsZ-sfGFP of mature-septal and nascent rings. Montage of images at 9-s intervals shows FtsZ-sfGFP in nascent rings above and below mature-septal ring (Movies S1 and S2). (Right) Kymographs show FtsZ-sfGFP movement in the top nascent ring plane, bottom (Btm) nascent ring plane, and middle (Mid) mature-septal plane. (C) TIRFm movie taken over 540 s of a single cell. Montage shows frames of FtsZ-sfGFP in two nascent rings and the middle mature-septal FtsZ ring at the times indicated. Kymographs of the left (L) and right (R) nascent rings and the middle (M) mature-septal ring over the 540 s (9 min) are shown. (Scale bars in A–C, 1.0 µm.) (D) Distribution of velocities of FtsZ filaments/bundles in nascent rings, early equatorial rings, and the combination of nascent and equatorial rings. Velocities of FtsZ filament/bundles were binned in intervals of 7.5 nm/s. (E) Distribution of times of reappearance of FtsZ filaments/bundles moving in the same direction in nascent and early equatorial rings. Reappearance times were determined as described in SI Appendix, Experimental Procedures from four independent biological replicate experiments (n = 164 events) and are binned in 9-s intervals (dark blue). A simulation (light blue) of the means ± SDs of random events for each reappearance interval in kymographs of 1–180 s was generated as described in SI Appendix, Experimental Procedures. The reappearance interval of FtsZ filaments/bundles matched the random simulation within 2 SDs, except at 32 s, which showed a significant difference (see Dynamics of FtsZ in Nascent Rings That Form Parallel to Mature FtsZ Septal Rings).