Cleavage of the C-Terminal Fragment of Reovirus μ1 Is Required for Optimal Infectivity.
Cleavage of the C-Terminal Fragment of Reovirus μ1 Is Required for Optimal Infectivity.
复制标题
为了获得最佳感染性，需要切割呼肠孤病毒 μ1 的 C 末端片段。
DOI：
10.1128/jvi.01848-17
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发表时间：
2018
影响因子：
5.4
通讯作者：
Danthi,Pranav
中科院分区：
文献类型：
--
作者：
Snyder,AnthonyJ;Danthi,Pranav
哺乳动物正呼肠孤病毒（呼肠孤病毒）的外衣壳由200 μ1/σ3异六聚体和最多12个σ1三聚体组成，包含了附着和进入宿主细胞所需的所有蛋白质。在附着之后，呼肠孤病毒通过受体介导的内吞作用内化，酸依赖性组织蛋白酶降解σ3蛋白。这一过程产生了一种亚稳态中间体，称为感染性亚病毒颗粒（ISVP）， μ1膜穿透蛋白暴露在其中。isvp经历第二次结构重排，将包含基因组的核心沉积到宿主细胞质中。构象改变的粒子称为ISVP*。ISVP-to-ISVP*转化的高潮是释放μ1N和c端片段，分别为μ1N和Φ。释放的μ1N被认为通过在内体膜内产生大小选择性孔来促进核递送，而Φ的确切作用，特别是在病毒进入的背景下，尚不明确。在本报告中，我们描述了一种重组呼肠孤病毒，它不能在体外从μ1中切割Φ。Φ裂解不是ISVP-to-ISVP*转化所必需的，它增强了对脂质体膜的破坏，促进了ISVP*s聚集到孔形成部位。此外，Φ裂解缺陷菌株启动宿主细胞感染的效率低于亲本菌株。这些结果表明μ1N和Φ参与呼肠孤病毒的孔形成活性。宿主膜是防止感染的物理屏障。为了克服这一屏障，病毒利用不同的策略，如膜融合或膜破坏，进入细胞的内部成分。这些策略的特点是离散的蛋白质-蛋白质和蛋白质-脂质相互作用。哺乳动物正呼肠孤病毒（呼肠孤病毒）的外衣壳经历一系列明确的构象变化，最终形成孔并传递病毒遗传物质。在本报告中，我们描述了小的呼肠孤病毒衍生Φ肽在孔隙形成中的作用。Φ外衣壳的裂解增强了膜的破坏，促进了病毒粒子向膜相关孔的募集。此外，Φ裂解促进了感染的开始。总之，这些结果揭示了呼肠孤病毒孔形成装置的另一个组成部分，并强调了穿透宿主膜的策略。
The mammalian orthoreovirus (reovirus) outer capsid, which is composed of 200 μ1/σ3 heterohexamers and a maximum of 12 σ1 trimers, contains all of the proteins that are necessary for attaching to and entering host cells. Following attachment, reovirus is internalized by receptor-mediated endocytosis and acid-dependent cathepsin proteases degrade the σ3 protein. This process generates a metastable intermediate, called infectious subviral particle (ISVP), in which the μ1 membrane penetration protein is exposed. ISVPs undergo a second structural rearrangement to deposit the genome-containing core into the host cytoplasm. The conformationally altered particle is called ISVP*. ISVP-to-ISVP* conversion culminates in the release of μ1 N- and C-terminal fragments, μ1N and Φ, respectively. Released μ1N is thought to facilitate core delivery by generating size-selective pores within the endosomal membrane, whereas the precise role of Φ, particularly in the context of viral entry, is undefined. In this report, we characterize a recombinant reovirus that fails to cleave Φ from μ1in vitro. Φ cleavage, which is not required for ISVP-to-ISVP* conversion, enhances the disruption of liposomal membranes and facilitates the recruitment of ISVP*s to the site of pore formation. Moreover, the Φ cleavage-deficient strain initiates infection of host cells less efficiently than the parental strain. These results indicate that μ1N and Φ contribute to reovirus pore forming activity.IMPORTANCEHost membranes represent a physical barrier that prevents infection. To overcome this barrier, viruses utilize diverse strategies, such as membrane fusion or membrane disruption, to access internal components of the cell. These strategies are characterized by discrete protein-protein and protein-lipid interactions. The mammalian orthoreovirus (reovirus) outer capsid undergoes a series of well-defined conformational changes, which conclude with pore formation and delivery of the viral genetic material. In this report, we characterize the role of the small, reovirus-derived Φ peptide in pore formation. Φ cleavage from the outer capsid enhances membrane disruption and facilitates the recruitment of virions to membrane-associated pores. Moreover, Φ cleavage promotes the initiation of infection. Together, these results reveal an additional component of the reovirus pore forming apparatus and highlight a strategy for penetrating host membranes.