Processing of the hepatitis E virus polyprotein can be mediated by a cellular protease
Processing of the hepatitis E virus polyprotein can be mediated by a cellular protease
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戊型肝炎病毒多蛋白的加工可以由细胞蛋白酶介导
DOI：
10.1101/2022.12.05.519104
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Pierce D
中科院分区：
文献类型：
--
作者：
Pierce D
正义型RNA病毒的基因组编码对控制病毒复制至关重要的多蛋白。这些病毒多蛋白必须经过蛋白分解(也称为多蛋白加工)才能产生功能蛋白单位。这种蛋白分解可以由病毒编码的蛋白水解酶和宿主细胞蛋白水解酶执行，通常被认为是调节病毒复制的关键步骤。戊型肝炎病毒(HEV)是急性病毒性肝炎的主要病因之一，它翻译其阳性RNA基因组产生一种称为pORF1的多蛋白，这是病毒基因组复制所必需的，也是足够的。然而，HEV中多蛋白加工的机制仍有待确定。在这项研究中，我们旨在通过体外翻译实验和HEV亚基因组复制相结合的方法来了解这种多蛋白的加工及其在病毒复制中的作用。我们的数据表明没有证据表明存在病毒编码的蛋白酶或自身蛋白分解活性，因为体外翻译主要产生未处理的病毒多蛋白前体。然而，多聚蛋白中的七个裂解位点(生物信息学分析表明)对宿主细胞蛋白水解酶凝血酶敏感。使用亚基因组复制子系统，我们证明了这些位点的突变可以防止复制，就像药物对丝氨酸蛋白酶的抑制一样。总体而言，我们的数据支持HEV使用宿主蛋白酶支持其复制的模型，并且可能已经独特地进化为不依赖于病毒编码的蛋白酶进行复制。作者摘要正链RNA病毒产生的多蛋白被控制病毒复制的蛋白酶切割。所有研究良好的正链病毒的多蛋白都以一种高度受控的方式进行蛋白分解，以产生功能蛋白并调节从翻译到RNA复制的过渡。病毒多蛋白的蛋白分解一般是由病毒编码的蛋白水解酶完成的，尽管有些病毒使用宿主细胞蛋白水解酶。在这份报告中，我们提供的证据表明，戊型肝炎病毒是一种重要的医学上的人类病原体，它不编码蛋白酶，而且与其他病毒多蛋白不同的是，它不能进行自动催化加工。相反，我们提供的证据表明，该多聚蛋白容易被宿主细胞蛋白水解酶降解，这对病毒复制是必不可少的。我们的数据与之前的阳性病毒复制教条相矛盾，并提出了一种模型，在该模型中，这种病毒已经进化为使用宿主蛋白酶来控制病毒的复制和趋向性。
The genomes of positive-sense RNA viruses encode polyproteins that are essential for controlling viral replication. These viral polyproteins must undergo proteolysis (also termed polyprotein processing) to generate functional protein units. This proteolysis can be performed by virally-encoded proteases as well as host cellular proteases, and is generally believed to be a key step in regulating viral replication. Hepatitis E virus (HEV), a leading cause of acute viral hepatitis, translates its positive-sense RNA genome to generate a polyprotein, termed pORF1, which is necessary and sufficient for viral genome replication. However, the mechanism of polyprotein processing in HEV remains to be determined. In this study, we aimed to understand processing of this polyprotein and its role in viral replication using a combination ofin vitrotranslation experiments and HEV sub-genomic replicons.Our data suggest no evidence for a virally-encoded protease or auto-proteolytic activity asin vitrotranslation predominantly generates unprocessed viral polyprotein precursors. However, seven cleavage sites within the polyprotein (suggested by bioinformatic analysis) are susceptible to the host cellular protease, thrombin. Using a sub-genomic replicon system, we demonstrate that mutagenesis of these sites prevents replication, as does pharmacological inhibition of serine proteases. Overall, our data supports a model where HEV uses host proteases to support its replication and could have uniquely evolved not to rely on a virally-encoded protease for replication.Author summaryPositive-strand RNA viruses produce polyproteins that are cleaved by proteases that control viral replication. The polyproteins of all well studied positive-strand viruses undergo proteolysis in a highly controlled manner to generate functional proteins and regulate the transition from translation to RNA replication. Proteolysis of viral polyproteins is generally performed by virally-encoded proteases, although host cell proteases are used by some viruses. In this report, we provide evidence that suggests that hepatitis E virus, a medically important human pathogen, does not encode a protease and unlike other viral polyproteins cannot undergo auto-catalytic processing. Instead, we provide evidence that the polyprotein is susceptible to proteolysis by host cell proteases and that this is essential for viral replication. Our data contradict the previous dogma of positive-sense viral replication and suggests a model where this virus has evolved to use a host protease to control viral replication and tropism.
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DOI：
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