Extended Data Fig. 8: Cryo-EM analysis of DICER–pre-mir-517a_GU.
From: DICER cleavage fidelity is governed by 5′-end binding pockets
a, Data processing workflow. From 4,024 + 5,460 + 4,760 movies, particles were subjected to motion correction, CTF estimation, curated exposure selection, blob/template picking, iterative 2D/3D classification, ab initio reconstruction, non-uniform refinement, and CryoTEN map sharpening. Two conformational groups were resolved: pre-dicing (1,272,937 particles; 3.00 Å) and dicing (475,650 particles; 3.21 Å). Representative 2D classes and GS-FSC curves are shown. b, Pre-dicing state. Composite map with segmented densities for domains: Helicase, DUF283, dsRBD, D-linker, Connector helix, Platform, PAZ, RIIIDa, RIIIDb, and the pre-mir-517a_GU. c, Dicing state. Overall map and individual domain segments as in b, highlighting rearrangements accompanying catalytic engagement. d, Secondary-structure model of pre-mir-517a_GU indicating terminal ends and DC21. e, Active-site views. Close-ups around the cleavage centre in RIIIDa/RIIIDb show coordination of catalytic residues and metal ions with nearby nucleotides. Residues are labelled; putative scissile-bond positions are indicated.
