Structure, Function, and Evolution of the Crimean-Congo Hemorrhagic Fever Virus Nucleocapsid Protein
Structure, Function, and Evolution of the Crimean-Congo Hemorrhagic Fever Virus Nucleocapsid Protein
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DOI：
10.1128/jvi.01555-12
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发表时间：
2012-10-01
影响因子：
5.4
通讯作者：
Barr, John N.
中科院分区：
文献类型：
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作者：
Carter, Stephen D.;Surtees, Rebecca;Barr, John N.
克里米亚-刚果出血热病毒（CCHFV）是布尼亚病毒科的一种新出现的蜱传病毒，可引起一种致命的人类疾病，目前尚不存在预防或治疗措施。我们以2.1埃的分辨率解析了CCHFV毒株巴格达-12核衣壳蛋白（N）的晶体结构，该蛋白是一种潜在的治疗靶点。N包含一个由N-和C-末端序列组成的大球状结构域，可能参与RNA结合，以及一个在其顶端具有保守的DEVD胱天蛋白酶-3切割位点的突出臂结构域。我们的结构与最近报道的来自菌株YL 04057的N蛋白的结构的比对显示了所有折叠的密切对应，但通过180度的旋转和40埃的平移，臂发生了显著的转位。这些观察结果表明，结构的灵活性，可能提供的基础上，在重要的功能，如RNA结合和寡聚化的交替N蛋白构象之间的切换。我们的结构揭示了可能参与RNA结合和寡聚化的表面，并且使用能够概括细胞中CCHFV特异性RNA合成的微型基因组系统鉴定了这些结构域内的功能关键残基。胱天蛋白酶-3在暴露的DEVD基序处切割多肽链;然而，切割的N蛋白保持完整的单位，可能是由于球状结构域中N-和C-末端片段的紧密结合。与现有N蛋白的结构比对表明，CCHFV最接近的亲属不是另一种布尼亚病毒，而是沙粒病毒拉沙病毒，这表明目前分段负链RNA病毒分类可能需要修订。
Crimean-Congo hemorrhagic fever virus (CCHFV) is an emerging tick-borne virus of the Bunyaviridae family that is responsible for a fatal human disease for which preventative or therapeutic measures do not exist. We solved the crystal structure of the CCHFV strain Baghdad-12 nucleocapsid protein (N), a potential therapeutic target, at a resolution of 2.1 angstrom. N comprises a large globular domain composed of both N- and C-terminal sequences, likely involved in RNA binding, and a protruding arm domain with a conserved DEVD caspase-3 cleavage site at its apex. Alignment of our structure with that of the recently reported N protein from strain YL04057 shows a close correspondence of all folds but significant transposition of the arm through a rotation of 180 degrees and a translation of 40 angstrom. These observations suggest a structural flexibility that may provide the basis for switching between alternative N protein conformations during important functions such as RNA binding and oligomerization. Our structure reveals surfaces likely involved in RNA binding and oligomerization, and functionally critical residues within these domains were identified using a minigenome system able to recapitulate CCHFV-specific RNA synthesis in cells. Caspase-3 cleaves the polypeptide chain at the exposed DEVD motif; however, the cleaved N protein remains an intact unit, likely due to the intimate association of N- and C-terminal fragments in the globular domain. Structural alignment with existing N proteins reveals that the closest CCHFV relative is not another bunyavirus but the arenavirus Lassa virus instead, suggesting that current segmented negative-strand RNA virus taxonomy may need revision.