Multiple Nucleic Acid Binding Sites and Intrinsic Disorder of Severe Acute Respiratory Syndrome Coronavirus Nucleocapsid Protein: Implications for Ribonucleocapsid Protein Packaging
Multiple Nucleic Acid Binding Sites and Intrinsic Disorder of Severe Acute Respiratory Syndrome Coronavirus Nucleocapsid Protein: Implications for Ribonucleocapsid Protein Packaging
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DOI：
10.1128/jvi.02001-08
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发表时间：
2009-03-01
影响因子：
5.4
通讯作者：
Huang, Tai-Huang
中科院分区：
文献类型：
--
作者：
Chang, Chung-Ke;Hsu, Yen-Lan;Huang, Tai-Huang
严重急性呼吸综合征冠状病毒(SARS-CoV)的核衣壳蛋白(N)包装病毒基因组RNA，对病毒的生存至关重要。然而，人们对RNA结合机制知之甚少。我们以前已经证明，N蛋白包含两个结构域-N-末端结构域(NTD；第45至181位)和C-末端二聚结构域(CTD；248至365位)-两侧是一长段无序区域，几乎占整个序列的一半。小角X射线散射数据表明，该蛋白具有延伸的构象，SARS-CoV N蛋白的两个结构域相距较远。NTD和CTD都已被证明与RNA结合。在这里，我们证明了所有无序区域也能够与RNA结合。含有多个RNA结合区的构建体显示Hill系数大于1，表明N蛋白与RNA协同结合。这种效应可以用“耦合变构”模型来解释，该模型被设计用来解释多领域调控系统中的变构效应。虽然不同冠状病毒的N蛋白序列同源性很低，但上述物理化学特征可能在不同的冠状病毒组中保守。目前的结果强调了多位点核酸结合和内在紊乱在N蛋白功能和RNP包装中的重要作用。
The nucleocapsid protein (N) of the severe acute respiratory syndrome coronavirus (SARS-CoV) packages the viral genomic RNA and is crucial for viability. However, the RNA-binding mechanism is poorly understood. We have shown previously that the N protein contains two structural domains-the N-terminal domain (NTD; residues 45 to 181) and the C-terminal dimerization domain (CTD; residues 248 to 365)-flanked by long stretches of disordered regions accounting for almost half of the entire sequence. Small-angle X-ray scattering data show that the protein is in an extended conformation and that the two structural domains of the SARS-CoV N protein are far apart. Both the NTD and the CTD have been shown to bind RNA. Here we show that all disordered regions are also capable of binding to RNA. Constructs containing multiple RNA-binding regions showed Hill coefficients greater than 1, suggesting that the N protein binds to RNA cooperatively. The effect can be explained by the "coupled-allostery" model, devised to explain the allosteric effect in a multidomain regulatory system. Although the N proteins of different coronaviruses share very low sequence homology, the physicochemical features described above may be conserved across different groups of Coronaviridae. The current results underscore the important roles of multisite nucleic acid binding and intrinsic disorder in N protein function and RNP packaging.