Fig. 5: The conformational changes associated with transitions from the pre-dicing to active dicing and to post-dicing states.

a, Overview of the Dcr-2–Loqs-PD–50 bp dsRNA complex in the active dicing state. Dcr-2 (672–1722) is shown in surface mode. The siRNA region is coloured in gold. b, The distortion of dsRNA in the active dicing state. The axes of free dsRNA and active dicing dsRNA are coloured in yellow and hot pink, respectively. The torsion position induced by Dcr-2 is labelled. c, Overview of the pre-dicing model. The display mode is the same as in a. The conformational change from the pre-dicing state (c) to the active dicing state (a) is marked by purple, green and grey arrows in c. d, The distance between Cα atoms of Q580 from DUF283 and both RIIIDs (E1213 and E1472) in the pre-dicing (mid-translocation) and active dicing states. Cα atoms are labelled as spheres. RIIIDs are shown as transparent surface. The conformational change of DP-linker is marked by the orange-red box. e, Magnified view of the spring helix α1 of the superimposed structures in the mid-translocation state (grey) and the active dicing state (coloured) aligned by RIIIDs, corresponding to the orange-red box in d. The first half of α1 is coloured in red for the mid-translocation state and orange for the active dicing state, respectively. f, Cross-section of the processing centre of the superimposed mid-translocation state (grey) and active dicing state (coloured) aligned by RIIIDs. g, Overview of the post-dicing state. The display mode is the same as in a and c. The break in the dsRNA is labelled by the red arrow. h, Superposition of the structures in the active dicing and post-dicing state shown as a transparent cryo-EM map. The conformational change from the active dicing state to the post-dicing state is labelled by the black arrow. i, The distance between Gln580 of DUF283 and both RIIIDs (Glu1213 and Glu1472) in the post-dicing state as in d. The spring helix α1 is marked by orange-red arrow.