Extended Data Fig. 7: Structural comparison of apo, binary and ternary CasX samples.
From: CasX enzymes comprise a distinct family of RNA-guided genome editors
a, Drift-corrected image of apoCasX obtained with a 70° phase shift and defocus of 0.5 μm. Scale bar, 50 nm. b, Drift-corrected image of CasX–guide RNA complex with a defocus of −1.5 μm. c, Drift-corrected image of CasX–guide RNA–DNA complex with a defocus of −1.5 μm. Representative reference-free 2D class averages are shown in the bottom panels for the three samples (scale bar for bottom panels, 20 nm). d, Cryo-EM reconstruction of apo-CasX. Three representative orientations are shown with coloured domains. OBD, aquamarine; NTSB, red; helical I, yellow; helical II, orange; RuvC, dark green; TSL, light pink; and bridge helix, blue. e, BS3 cross-linking signals revealed by mass spectrometry for the apo-CasX sample. The two lysines within a cross-linked pair are connected with a purple curve. f, g, As for d and e, for the CasX–guide RNA binary complex. h, i, As for d and e, for the CasX–guide RNA–DNA ternary complex. j, k, Accessibility of target-strand DNA by the RuvC domain in state I and state II. Distance between the TS DNA cleavage region and RuvC active site as calculated using Pymol is 43.8 Å for state I (j) and 10.9 Å for state II (k).
