Chao Jeffrey A, Lee June Hyung, Chapados Brian R, Debler Erik W, Schneemann Anette, Williamson James R
Department of Molecular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, California 92037, USA.
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.
作为感染期间对抗病毒RNA沉默的一种反防御机制，昆虫 flock House病毒（FHV）表达沉默抑制蛋白B2。生化实验表明，B2可与双链RNA（dsRNA）结合，且不考虑其长度，并在体外抑制Dicer对dsRNA的切割。一种共晶体结构显示，B2二聚体形成一个四螺旋束，该四螺旋束独立于序列与A-form RNA双链体的一个面结合。这些结果表明，B2既能阻断Dicer对FHV基因组的切割，又能阻止FHV小干扰RNA掺入RNA诱导沉默复合体。
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