Conformational rearrangements of RIG-I receptor on formation of a multiprotein:dsRNA assembly

Nucleic Acids Res. 2013 Mar 1;41(5):3436-45. doi: 10.1093/nar/gks1477. Epub 2013 Jan 15.

Abstract

The retinoic acid inducible gene-I (RIG-I)-like family of receptors is positioned at the front line of our innate cellular defence system. RIG-I detects and binds to foreign duplex RNA in the cytoplasm of both immune and non-immune cells, and initiates the induction of type I interferons and pro-inflammatory cytokines. The mechanism of RIG-I activation by double-stranded RNA (dsRNA) involves a molecular rearrangement proposed to expose the N-terminal pair of caspase activation recruitment domains, enabling an interaction with interferon-beta promoter stimulator 1 (IPS-1) and thereby initiating downstream signalling. dsRNA is particularly stimulatory when longer than 20 bp, potentially through allowing binding of more than one RIG-I molecule. Here, we characterize full-length RIG-I and RIG-I subdomains combined with a stimulatory 29mer dsRNA using multi-angle light scattering and size-exclusion chromatography-coupled small-angle X-ray scattering, to build up a molecular model of RIG-I before and after the formation of a 2:1 protein:dsRNA assembly. We report the small-angle X-ray scattering-derived solution structure of the human apo-RIG-I and observe that on binding of RIG-I to dsRNA in a 2:1 ratio, the complex becomes highly extended and flexible. Hence, here we present the first model of the fully activated oligomeric RIG-I.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoproteins / chemistry*
  • Chromatography, Gel
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases / chemistry*
  • Humans
  • Models, Molecular
  • Peptide Fragments / chemistry
  • Protein Binding
  • Protein Structure, Quaternary
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Proteolysis
  • RNA, Double-Stranded / chemistry*
  • Scattering, Small Angle
  • Trypsin / chemistry
  • X-Ray Diffraction

Substances

  • Apoproteins
  • Peptide Fragments
  • RNA, Double-Stranded
  • Trypsin
  • DDX58 protein, human
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases