Structural Analysis of dsRNA Binding to Anti-viral Pattern Recognition Receptors LGP2 and MDA5

Mol Cell. 2016 May 19;62(4):586-602. doi: 10.1016/j.molcel.2016.04.021.

Abstract

RIG-I and MDA5 sense virus-derived short 5'ppp blunt-ended or long dsRNA, respectively, causing interferon production. Non-signaling LGP2 appears to positively and negatively regulate MDA5 and RIG-I signaling, respectively. Co-crystal structures of chicken (ch) LGP2 with dsRNA display a fully or semi-closed conformation depending on the presence or absence of nucleotide. LGP2 caps blunt, 3' or 5' overhang dsRNA ends with 1 bp longer overall footprint than RIG-I. Structures of 1:1 and 2:1 complexes of chMDA5 with short dsRNA reveal head-to-head packing rather than the polar head-to-tail orientation described for long filaments. chLGP2 and chMDA5 make filaments with a similar axial repeat, although less co-operatively for chLGP2. Overall, LGP2 resembles a chimera combining a MDA5-like helicase domain and RIG-I like CTD supporting both stem and end binding. Functionally, RNA binding is required for LGP2-mediated enhancement of MDA5 activation. We propose that LGP2 end-binding may promote nucleation of MDA5 oligomerization on dsRNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / metabolism
  • Adenosine Triphosphatases / chemistry
  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism*
  • Adenosine Triphosphate / metabolism
  • Animals
  • Avian Proteins / chemistry
  • Avian Proteins / genetics
  • Avian Proteins / metabolism*
  • Binding Sites
  • Cell Line
  • Chickens
  • DEAD Box Protein 58 / chemistry
  • DEAD Box Protein 58 / genetics
  • DEAD Box Protein 58 / metabolism*
  • Humans
  • Hydrolysis
  • Interferon-Induced Helicase, IFIH1 / chemistry
  • Interferon-Induced Helicase, IFIH1 / genetics
  • Interferon-Induced Helicase, IFIH1 / metabolism*
  • Models, Molecular
  • Nucleic Acid Conformation
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • RNA, Double-Stranded / chemistry
  • RNA, Double-Stranded / genetics
  • RNA, Double-Stranded / metabolism*
  • RNA-Binding Proteins / chemistry
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Receptors, Pattern Recognition / chemistry
  • Receptors, Pattern Recognition / genetics
  • Receptors, Pattern Recognition / metabolism*
  • Structure-Activity Relationship
  • Transfection

Substances

  • Avian Proteins
  • RNA, Double-Stranded
  • RNA-Binding Proteins
  • Receptors, Pattern Recognition
  • Adenosine Diphosphate
  • Adenosine Triphosphate
  • Adenosine Triphosphatases
  • DEAD Box Protein 58
  • Interferon-Induced Helicase, IFIH1