Structural Basis of Double-Stranded RNA Recognition by the RIG-I Like Receptor MDA5

Arch Biochem Biophys. 2009 Aug 1;488(1):23-33. doi: 10.1016/ Epub 2009 Jun 14.


RIG-I, MDA5 and LGP2 are cytosolic pattern recognition receptors detecting single-stranded or double-stranded RNA in virally infected cells. The activation of RIG-I or MDA5 stimulates the secretion of type I interferons that play key roles in antiviral immune responses. The C-terminal domains (CTD) of RIG-I and LGP2 are responsible for RNA binding; however, it is not clear how MDA5 binds RNA. To understand the structural basis of dsRNA recognition by MDA5, we have determined the 1.45A resolution structure of the C-terminal domain of human MDA5. The structure revealed a highly conserved fold similar to the structures of RIG-I and LGP2 CTDs. NMR titration of MDA5 CTD with dsRNA demonstrated that a positively charged surface is involved in dsRNA binding. Mutagenesis and RNA binding studies showed that electrostatic interactions play primary roles in dsRNA recognition by MDA5. Like RIG-I and LGP2, MDA5 CTD preferentially binds dsRNA with blunt ends, but does not associate with dsRNA with either 5' or 3' overhangs. Molecular modeling of MDA5 CTD/dsRNA complex suggests that MDA5 CTD may recognize the first turn of blunt-ended dsRNA in a similar manner as LGP2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Crystallography, X-Ray
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases / chemistry*
  • DEAD-box RNA Helicases / metabolism*
  • Humans
  • Interferon-Induced Helicase, IFIH1
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Binding
  • Protein Structure, Tertiary
  • RNA Helicases / chemistry
  • RNA Helicases / metabolism
  • RNA, Double-Stranded / chemistry*
  • RNA, Double-Stranded / genetics
  • RNA, Double-Stranded / metabolism*
  • Sequence Homology, Amino Acid
  • Static Electricity
  • Surface Properties


  • RNA, Double-Stranded
  • DHX58 protein, human
  • DDX58 protein, human
  • IFIH1 protein, human
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases
  • Interferon-Induced Helicase, IFIH1
  • RNA Helicases

Associated data

  • PDB/3GA3