Conformational equilibria and rates of localized motion within hepatitis B virus capsids
Conformational equilibria and rates of localized motion within hepatitis B virus capsids
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DOI：
10.1016/j.jmb.2007.10.044
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发表时间：
2008-01-11
影响因子：
5.6
通讯作者：
Bothner, Brian
中科院分区：
文献类型：
--
作者：
Hilmer, Jonathan K.;Zlotnick, Adam;Bothner, Brian
对乙肝病毒核心颗粒的功能分析已经将许多生物学作用与衣壳蛋白的C末端联系起来。一组功能要求C末端在衣壳的外部，而另一些功能则将这个结构域放在内部。根据衣壳的晶体结构，这段严格地位于衣壳内部，埋藏在蛋白质-蛋白质界面上。利用SDS-PAGE和质谱仪分析的一种酶消化形式--动力学水解法，已经证明了具有重要结构和生物学意义的乙肝病毒衣壳蛋白装配结构域(Cp149，残基1-149)的C-末端在二聚体和衣壳两种形式中都是动态的。乙肝病毒是一种包膜病毒，具有T=4的二十面体核心，由120个拷贝的同源二聚体衣壳蛋白组成。蛋白质的游离二聚体和组装的衣壳形式很容易被胰酶和热裂解酶水解，残基在127-128附近，这表明这个区域是动态的，暴露在衣壳表面。测得的构象平衡在自由二聚体和组装衣壳之间具有相反的温度依赖性。这项工作有助于解释前面描述的对埋藏结构域的组装和功能性质的变构调节。这些观察结果在结构、动力学和功能之间建立了关键的联系：通过对兆吨复合体的构象平衡和蛋白质构象之间转化率的首次定量测量，使之成为可能。(C)2007爱思唯尔有限公司。保留所有权利。
Functional analysis of hepatitis B virus (HBV) core particles has associated a number of biological roles with the C terminus of the capsid protein. One set of functions require the C terminus to be on the exterior of the capsid, while others place this domain on the interior. According to the crystal structure of the capsid, this segment is strictly internal to the capsid shell and buried at a protein-protein interface. Using kinetic hydrolysis, a form of protease digestion assayed by SDS-PAGE and mass spectrometry, the structurally and biologically important C-terminal region of HBV capsid protein assembly domain (Cp149, residues 1-149) has been shown to be dynamic in both dimer and capsid forms. HBV is an enveloped virus with a T = 4 icosahedral core that is composed of 120 copies of a homodimer capsid protein. Free dimer and assembled capsid forms of the protein are readily hydrolyzed by trypsin and thermolysin, around residues 127-128, indicating that this region is dynamic and exposed to the capsid surface. The measured conformational equilibria have an opposite temperature dependence between free dimer and assembled capsid. This work helps to explain the previously described allosteric regulation of assembly and functional properties of a buried domain. These observations make a critical connection between structure, dynamics, and function: made possible by the first quantitative measurements of conformational equilibria and rates of conversion between protein conformers for a megaDalton complex. (C) 2007 Elsevier Ltd. All rights reserved.