title: Dual modes of RNA-silencing suppression by Flock House virus protein B2.
abstract: 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.
authors.affiliation: Department of Molecular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, California 92037, USA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Chao
authors.forename: June Hyung
authors.initials: JH
authors.lastname: Lee
authors.forename: Brian R
authors.initials: BR
authors.lastname: Chapados
authors.forename: Erik W
authors.initials: EW
authors.lastname: Debler
authors.forename: Anette
authors.initials: A
authors.lastname: Schneemann
authors.forename: James R
authors.initials: JR
authors.lastname: Williamson
mesh_terms: 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
chemical_list: D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D014764:Viral Proteins; D043244:Ribonuclease III