Dual modes of RNA-silencing suppression by Flock House virus protein B2

Nat Struct Mol Biol. 2005 Nov;12(11):952-7. doi: 10.1038/nsmb1005.


As a counter-defense against antiviral RNA silencing during infection, the insect Flock House virus (FHV) expresses the silencing suppressor protein B2. Biochemical experiments show that B2 binds to double-stranded RNA (dsRNA) without regard to length and inhibits cleavage of dsRNA by Dicer in vitro. A cocrystal structure reveals that a B2 dimer forms a four-helix bundle that binds to one face of an A-form RNA duplex independently of sequence. These results suggest that B2 blocks both cleavage of the FHV genome by Dicer and incorporation of FHV small interfering RNAs into the RNA-induced silencing complex.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crystallography
  • Dimerization
  • Models, Molecular*
  • Nodaviridae / chemistry*
  • Protein Binding
  • Protein Conformation
  • RNA Interference*
  • RNA, Double-Stranded / genetics
  • RNA, Double-Stranded / metabolism*
  • RNA, Small Interfering / metabolism
  • RNA-Binding Proteins / chemistry*
  • RNA-Binding Proteins / metabolism
  • Ribonuclease III / metabolism
  • Structure-Activity Relationship
  • Viral Proteins / chemistry*
  • Viral Proteins / metabolism


  • RNA, Double-Stranded
  • RNA, Small Interfering
  • RNA-Binding Proteins
  • Viral Proteins
  • Ribonuclease III

Associated data

  • PDB/2AZ0
  • PDB/2AZ2