Dual modes of RNA-silencing suppression by Flock House virus protein B2.
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.
Chao
Jeffrey A
JA
Department of Molecular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, California 92037, USA.
Lee
June Hyung
JH
Chapados
Brian R
BR
Debler
Erik W
EW
Schneemann
Anette
A
Williamson
James R
JR
D003461:Crystallography; D019281:Dimerization; D008958:Models, Molecular; D030381:Nodaviridae / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D043244:Ribonuclease III / Q000378:metabolism; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism
D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D014764:Viral Proteins; D043244:Ribonuclease III