Fig. 3: Cryo-EM reconstructions of mechanically deformed F-actin reveal bend–twist coupling.
From: Bending forces and nucleotide state jointly regulate F-actin structure
a, Representative cryo-EM micrograph of ADP–F-actin filaments featuring high-curvature regions, low-pass filtered to 30 Å. Picked segments are coloured by estimated curvature as indicated. Scale bar, 100 nm. b, Normalized curvature histograms of ADP–F-actin (blue, n = 374,942) and ADP-Pi–F-actin (orange, n = 470,625) filament segments, compared using a two-tailed Mann–Whitney U-test. The dashed lines indicate curvature thresholds for straight (≤2.0 μm−1) and bent (≥2.5 μm−1) segments. The colour bars correspond to the curvature key in a. c, Helically symmetric ADP–F-actin (left map) and cryoDRGN reconstructions sampling continuous bending of ADP–F-actin (right three maps), low-pass filtered to 8 Å. Strands are coloured in shades of blue. Scale bar, 10 nm. d, Stitched volumes of straight and bent maps from c, aligned to the bottom 16 protomers. Scale bar, 100 nm. e, Schematic of twist and rise measurements along a bent filament axis. Protomer numbering is indicated. f, Twist and rise measurements of cryoDRGN reconstructions sampled along the major variability component. The solid and dashed curves correspond to measurements from even-to-odd and odd-to-even protomer indices, respectively.
