Cryo-EM Structure of Human Dicer and Its Complexes with a Pre-miRNA Substrate

Cell. 2018 May 17;173(5):1191-1203.e12. doi: 10.1016/j.cell.2018.03.080. Epub 2018 Apr 26.

Abstract

Human Dicer (hDicer) is a multi-domain protein belonging to the RNase III family. It plays pivotal roles in small RNA biogenesis during the RNA interference (RNAi) pathway by processing a diverse range of double-stranded RNA (dsRNA) precursors to generate ∼22 nt microRNA (miRNA) or small interfering RNA (siRNA) products for sequence-directed gene silencing. In this work, we solved the cryoelectron microscopy (cryo-EM) structure of hDicer in complex with its cofactor protein TRBP and revealed the precise spatial arrangement of hDicer's multiple domains. We further solved structures of the hDicer-TRBP complex bound with pre-let-7 RNA in two distinct conformations. In combination with biochemical analysis, these structures reveal a property of the hDicer-TRBP complex to promote the stability of pre-miRNA's stem duplex in a pre-dicing state. These results provide insights into the mechanism of RNA processing by hDicer and illustrate the regulatory role of hDicer's N-terminal helicase domain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cryoelectron Microscopy
  • DEAD-box RNA Helicases / chemistry*
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / metabolism
  • Electrophoretic Mobility Shift Assay
  • Humans
  • MicroRNAs / chemistry*
  • MicroRNAs / metabolism
  • Nuclear Receptor Coactivators / chemistry
  • Nuclear Receptor Coactivators / genetics
  • Nuclear Receptor Coactivators / metabolism
  • Nucleic Acid Conformation
  • Protein Binding
  • Protein Domains
  • Protein Structure, Quaternary
  • RNA Cleavage
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Ribonuclease III / chemistry*
  • Ribonuclease III / genetics
  • Ribonuclease III / metabolism

Substances

  • MicroRNAs
  • NCOA6 protein, human
  • Nuclear Receptor Coactivators
  • Recombinant Proteins
  • DICER1 protein, human
  • Ribonuclease III
  • DEAD-box RNA Helicases