Fig. 2: ZapA changes the architecture of the FtsZ filament network.
a Orientation fields (red lines) for FtsZ filament network without (left) or with 6.0 μM ZapA (right) overlaying corresponding fluorescence micrographs. b Curvature maps of orientation fields; white areas correspond to areas with straight filament bundles, while the purple areas corresponds to the degree of curvature. Scale bars: large image, 5 μm; small image, 2 μm. c Time-dependent decrease of curvature for FtsZ filaments alone (left, blue gradient, light to dark) and with 6 μM ZapA (right, red gradient, light to dark). d The mean curvature, k, at each time point was given by the characteristic length scale of an exponential fit to the curvature distributions. Curves depict the mean and std as shaded error bands of independent experiments (FtsZ, n = 10, ZapA, n = 10). e Typical spatial correlation function, S(r), for an FtsZ filament network without (left, blue gradient, light to dark) or with 6 μM ZapA (right, red gradient, light to dark). For FtsZ/FtsA the curves overlapped in time while ZapA promoted a shift to higher correlation lengths. f Correlation length, ρ, was given by the intersection line where S(r) = 0.5 (insets in e) and shows that ρ remained constant for FtsZ/FtsA (blue) over time, but continuously increased with 6 μM ZapA (red). Curves show the mean and std as shaded error bands of independent experiments (FtsZ, n = 6, ZapA, n = 8). g k (gray) and ρ (black) with varying concentrations of ZapA. ZapA induced a switch-like behavior for kss and ρss (nH = 3.28 and EC50 = 0.84 μM; nH = 12.04 and EC50 = 1.05, respectively) with a saturation point close to equimolar concentrations with FtsZ. Circles depict the mean and std of independent experiments (FtsZ, n = 6, ZapA, n = 8). The 90% confidence intervals for nH and EC50 obtained from boostrapping are shown in Supplementary Table 2. h, i Mean values for ZapA I83E and R46A (light red) shows different behavior compared to wildtype ZapA (red). Source data available at Figshare [https://doi.org/10.6084/m9.figshare.10347062.v1].
