Extended Data Fig. 4: Numerical model of FtsZ WT - quantitative analysis and parameter refinement.
From: Chiral and nematic phases of flexible active filaments
a-b, d-g, Quantitative comparison of ring density (a), lifetime (b,d,e) and diameter (f,g) between large-scale simulations with varying parameters (flexure number, filament attraction and Peclet number) and experiments. The thick red line corresponds to the best match of simulation parameters to experiments. Dotted lines represent the mean, the shaded area the 95% confidence interval and the error bars of experimentally determined values represent the standard deviation. The number of rings was determined from 4, 4, 9, 11 and 3 independent experiments at Φ = 0.12, 0.23, 0.4, 0.5 and 0.6. The lifetime was quantified from 18, 24, 16, 33 and 24 rings, while the ring diameter was measured from n = 27, 15, 63, 65 and 17 randomly chosen rings from experiments at increasing packing fractions. c, Comparison of ring lifetime distributions between the simulations (ℱ = 40) and experiments at corresponding densities. The lifetime from experimental rings was quantified from 18, 24, 16, 33 and 24 rings. The thick black line extends from the mean and covers the range from the 25–75th percentile. h, Representative micrograph of TIRF experiment and the quantification of ring diameter. The line profile on the right corresponds to the orange dashed line. i, Example illustrating the automatic detection of rings. Left box depicts a simulation snapshot with filaments forming rings and bands (with filaments are colored according to the orientation of the bond vectors between beads), while the right box shows the result of clustering of filament rotation centers in space after applying all cutoffs (see Material & Methods). j, Result of the ring detection algorithm for the whole simulation after applying the time clustering algorithm to detect the rings in all calculated simulation snapshots. k, Analysis of filament persistence in the numerical simulations based on the distribution of local curvatures. Persistence length was extracted from variance of Gaussian function fitted to the data. l, Single filament trajectories (10 independent simulations) with varying Peclet number. m, Comparison of distributions of single-filament trajectories analysed in Fig. 1b and simulations with different Peclet numbers. 100 rings of each Peclet number were analysed in simulations, 105 rings were analysed in experiments. The thick black line extends from the mean and covers the range from the 25–75th percentile. n, Probability of antiparallel alignment of FtsZ bundles as a function of collision angle in experiment (corresponds to Extended Data Fig. 2c) and simulations. o, Mean of antiparallel alignment distribution as a function of filament curvature in simulations. p, Treadmilling velocities of single filaments from simulations at different densities and flexure number.
