Structure of the Rift Valley fever virus nucleocapsid protein reveals another architecture for RNA encapsidation
Structure of the Rift Valley fever virus nucleocapsid protein reveals another architecture for RNA encapsidation
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DOI：
10.1073/pnas.1001760107
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发表时间：
2010-06-29
影响因子：
11.1
通讯作者：
Smith, Janet L.
中科院分区：
文献类型：
--
作者：
Raymond, Donald D.;Piper, Mary E.;Smith, Janet L.
裂谷热病毒（RVFV）是一种负义RNA病毒（白蛉病毒属，布尼亚病毒科），可感染牲畜和人类，是撒哈拉以南非洲的一种特有病毒。与所有负义病毒一样，裂谷热病毒的片段RNA基因组被核衣壳蛋白(N)封装。RVFV N的1.93埃晶体结构和核糖核蛋白（RNP）的电子显微图显示其被封装的基因组与其他负义RNA病毒家族的组织结构有很大不同。在病毒RNP和由纯化的N与确定的RNA重组的RNP的电子显微照片中，RNP聚合物具有扩展的结构，没有螺旋对称。通过穷尽核糖核酸酶处理病毒RNP，重组表达N，纯化N和RNA寡聚物重组，获得了表观分子量接近100 kda的N-RNA种，其组成不均匀。通过变性和再折叠获得的无rna N具有新颖的全螺旋折叠，在N端和C端都紧凑且有序。与其他负义RNA病毒的N不同，RVFV N没有带正电荷的表面裂缝用于RNA结合，也没有突出的末端或环来稳定定义的N-RNA寡聚物或RNP螺旋。在一个保守的疏水口袋中发现了一个潜在的蛋白质相互作用位点。白蛉病毒RNP的非螺旋外观、类似于100 kda N-RNA多聚体的异质性和N折叠与其他负义RNA病毒家族的RNP和N有很大不同，这为白蛉病毒基因组的封壳结构提供了有价值的见解。
Rift Valley fever virus (RVFV) is a negative-sense RNA virus (genus Phlebovirus, family Bunyaviridae) that infects livestock and humans and is endemic to sub-Saharan Africa. Like all negative-sense viruses, the segmented RNA genome of RVFV is encapsidated by a nucleocapsid protein (N). The 1.93-angstrom crystal structure of RVFV N and electron micrographs of ribonucleoprotein (RNP) reveal an encapsidated genome of substantially different organization than in other negative-sense RNA virus families. The RNP polymer, viewed in electron micrographs of both virus RNP and RNP reconstituted from purified N with a defined RNA, has an extended structure without helical symmetry. N-RNA species of similar to 100-kDa apparent molecular weight and heterogeneous composition were obtained by exhaustive ribonuclease treatment of virus RNP, by recombinant expression of N, and by reconstitution from purified N and an RNA oligomer. RNA-free N, obtained by denaturation and refolding, has a novel all-helical fold that is compact and well ordered at both the N and C termini. Unlike N of other negative-sense RNA viruses, RVFV N has no positively charged surface cleft for RNA binding and no protruding termini or loops to stabilize a defined N-RNA oligomer or RNP helix. A potential protein interaction site was identified in a conserved hydrophobic pocket. The nonhelical appearance of phlebovirus RNP, the heterogeneous similar to 100-kDa N-RNA multimer, and the N fold differ substantially from the RNP and N of other negative-sense RNA virus families and provide valuable insights into the structure of the encapsidated phlebovirus genome.