Fig. 2
From: Direct visualization of human myosin II force generation using DNA origami-based thick filaments
Direct observation of a two-step and reversible powerstroke by high-speed AFM. a Successive AFM images showing actin sliding along thick filaments. Arrows indicate the sliding direction. Scale bar, 100 nm. b Successive AFM images showing conformational changes of S1 on actin. Scale bar, 20 nm. Lower cartoon shows the myosin shape in the images. c, d Histograms of the angle θ in b with or without 190 nM ATP. Angles were globally fit to two Gaussian distributions for 190 nM ATP (peaks were 58 ± 14o and 97 ± 8o, n = 402) (c) and rigor (peaks 58 ± 20o and 97 ± 9o, n = 96) (mean ± SD) (d). e Histograms of Gaussian-fitted powerstroke sizes (head displacements) from the pre- to first post-powerstroke state (3.9 ± 1.1 nm, mean ± SD, n = 76) and from the pre- to second post-powerstroke state (7.9 ± 2.6 nm, mean ± SD, n = 28). AFM images and cartoons on the right show the head displacement. Scale bar, 20 nm. f A schematic of a two-step powerstroke based on the data in c–e. g Successive AFM images showing a reversal powerstroke from the first post- to pre-powerstroke state. Data were obtained from at least ten independent experiments. Scale bar, 20 nm.
