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.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Crystallography
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Dimerization
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Models, Molecular*
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Nodaviridae / chemistry*
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Protein Binding
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Protein Conformation
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RNA Interference*
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RNA, Double-Stranded / genetics
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RNA, Double-Stranded / metabolism*
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RNA, Small Interfering / metabolism
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RNA-Binding Proteins / chemistry*
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RNA-Binding Proteins / metabolism
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Ribonuclease III / metabolism
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Structure-Activity Relationship
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Viral Proteins / chemistry*
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Viral Proteins / metabolism
Substances
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RNA, Double-Stranded
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RNA, Small Interfering
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RNA-Binding Proteins
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Viral Proteins
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Ribonuclease III