Involvement of a Nonstructural Protein in Poliovirus Capsid Assembly
Involvement of a Nonstructural Protein in Poliovirus Capsid Assembly
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DOI：
10.1128/jvi.01447-18
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发表时间：
2019-03-01
影响因子：
5.4
通讯作者：
Stonehouse, Nicola J.
中科院分区：
文献类型：
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作者：
Adeyemi, Oluwapelumi O.;Sherry, Lee;Stonehouse, Nicola J.
病毒衣壳蛋白必须发挥多种作用。这些包括自我组装和在具有挑战性的环境条件下保持稳定性，同时保持必要的构象灵活性，以揭开病毒基因组的外壳并将其输送到宿主细胞中。履行这些角色可能会对蛋白质序列中编码的先天能力施加相互冲突的限制。在之前的一项研究中，我们在脊髓灰质炎病毒(PV)衣壳编码序列中发现了一些突变，这些突变是在通过在逐步较高的温度下进行连续处理来选择更高热稳定性的过程中在种群中建立的。在早期获得的VP1蛋白的两个突变在整个选择过程中保持不变。其中一个突变在被引入野生型(Wt)感染性克隆时阻止了病毒粒子的组装。在这里，我们通过对热选择的病毒粒子衣壳编码区之外的测序表明，在2A蛋白酶的编码区内出现了两个突变。这两个突变在整个选择过程中都保持不变。通过定点突变将这些突变引入wt感染性克隆，大大减少了复制。然而，他们允许低水平的传染性病毒粒子组装，这些病毒粒子包含VP1中否则致命的突变。进一步证明，2A(Pro)突变可以减缓病毒多蛋白加工的动力学，我们认为这种延迟促进了突变衣壳前体蛋白的正确折叠，以允许病毒粒子组装。重要的RNA病毒，包括脊髓灰质炎病毒，由于参与基因组复制的聚合酶容易出错的性质，进化迅速。优势突变的固定可能需要获得互补突变，这些突变可以协同作用来获得有利的表型。这项研究强调了非结构调节蛋白2A(PRO)对结构VP1蛋白的致命突变的补偿作用，以促进耐热性的增加。研究病毒如何对选择压力做出反应，对于理解支持耐药性产生的机制非常重要，并可应用于未来抗病毒药物和疫苗的开发。
Virus capsid proteins must perform a number of roles. These include self-assembly and maintaining stability under challenging environmental conditions, while retaining the conformational flexibility necessary to uncoat and deliver the viral genome into a host cell. Fulfilling these roles could place conflicting constraints on the innate abilities encoded within the protein sequences. In a previous study, we identified a number of mutations within the capsid-coding sequence of poliovirus (PV) that were established in the population during selection for greater thermostability by sequential treatment at progressively higher temperatures. Two mutations in the VP1 protein acquired at an early stage were maintained throughout this selection procedure. One of these mutations prevented virion assembly when introduced into a wild-type (wt) infectious clone. Here we show, by sequencing beyond the capsid-coding region of the heat-selected virions, that two mutations had arisen within the coding region of the 2A protease. Both mutations were maintained throughout the selection process. Introduction of these mutations into a wt infectious clone by site-directed mutagenesis considerably reduced replication. However, they permitted a low level of assembly of infectious virions containing the otherwise lethal mutation in VP1. The 2A(pro) mutations were further shown to slow the kinetics of viral polyprotein processing, and we suggest that this delay improves the correct folding of the mutant capsid precursor protein to permit virion assembly.IMPORTANCE RNA viruses, including poliovirus, evolve rapidly due to the error-prone nature of the polymerase enzymes involved in genome replication. Fixation of advantageous mutations may require the acquisition of complementary mutations which can act in concert to achieve a favorable phenotype. This study highlights a compensatory role of a nonstructural regulatory protein, 2A(pro), for an otherwise lethal mutation of the structural VP1 protein to facilitate increased thermal resistance. Studying how viruses respond to selection pressures is important for understanding mechanisms which underpin emergence of resistance and could be applied to the future development of antiviral agents and vaccines.