The Host E3-Ubiquitin Ligase TRIM6 Ubiquitinates the Ebola Virus VP35 Protein and Promotes Virus Replication
The Host E3-Ubiquitin Ligase TRIM6 Ubiquitinates the Ebola Virus VP35 Protein and Promotes Virus Replication
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DOI：
10.1128/jvi.00833-17
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发表时间：
2017-09-01
影响因子：
5.4
通讯作者：
Rajsbaum, Ricardo
中科院分区：
文献类型：
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作者：
Bharaj, Preeti;Atkins, Colm;Rajsbaum, Ricardo
埃博拉病毒(EBOV)是丝状病毒科的成员，是一种高致病性病毒，可在人类中引起严重出血热，并导致撒哈拉以南非洲、中部和西非的疫情。EBOV基因组编码VP35，VP35是一种重要的病毒蛋白，参与病毒复制，是病毒聚合酶的重要辅助因子，也是宿主抗病毒I型干扰素系统的强大拮抗剂。通过质谱分析和免疫共沉淀分析，我们发现VP35在位于其干扰素拮抗区的赖氨酸309(K309)上是泛素化的。我们还发现VP35与TRIM6相互作用，TRIM6是E3-泛素连接酶三部分基序(TRIM)家族的成员。我们最近报道，TRIM6促进未锚定的K48连接的多泛素链的合成，这些多泛素链不与任何蛋白质共价连接，以诱导有效的抗病毒干扰素-I介导的反应。与这一概念一致，VP35还与多泛素链非共价结合，并抑制TRIM6介导的干扰素-I的诱导。有趣的是，我们还发现TRIM6在微型基因组分析中增强了EBOV聚合酶的活性，并且TRIM6敲除细胞减少了感染性EBOV的复制，这表明VP35通过泛素化劫持TRIM6来促进EBOV的复制。我们的工作提供了证据，证明TRIM6是促进EBOV复制的重要宿主细胞因子，未来的研究将集中在TRIM6是否可以作为针对EBOV感染的治疗干预的靶点。由于其高致病性和缺乏获得许可的抗病毒药物和疫苗，EBOV被列为一级选择剂风险第4组病原体。EBOV感染严重程度的一个重要机制是其对先天性免疫反应的抑制。EBOV VP35蛋白是病毒聚合酶的重要辅助因子，也是天然免疫的强效拮抗剂，参与了EBOV VP35的发病过程。然而，VP35的功能如何由宿主细胞因子调节却知之甚少。在这里，我们报告了宿主E3-泛素连接酶TRIM6促进VP35泛素化，并对有效的病毒复制是重要的。因此，我们的研究确定了一个新的宿主因子TRIM6，作为开发抗EBOV药物的潜在靶点。
Ebola virus (EBOV), a member of the Filoviridae family, is a highly pathogenic virus that causes severe hemorrhagic fever in humans and is responsible for epidemics throughout sub-Saharan, central, and West Africa. The EBOV genome encodes VP35, an important viral protein involved in virus replication by acting as an essential cofactor of the viral polymerase as well as a potent antagonist of the host antiviral type I interferon (IFN-I) system. By using mass spectrometry analysis and co-immunoprecipitation assays, we show here that VP35 is ubiquitinated on lysine 309 (K309), a residue located on its IFN antagonist domain. We also found that VP35 interacts with TRIM6, a member of the E3-ubiquitin ligase tripartite motif (TRIM) family. We recently reported that TRIM6 promotes the synthesis of unanchored K48-linked polyubiquitin chains, which are not covalently attached to any protein, to induce efficient antiviral IFN-I-mediated responses. Consistent with this notion, VP35 also associated noncovalently with polyubiquitin chains and inhibited TRIM6-mediated IFN-I induction. Intriguingly, we also found that TRIM6 enhances EBOV polymerase activity in a minigenome assay and TRIM6 knockout cells have reduced replication of infectious EBOV, suggesting that VP35 hijacks TRIM6 to promote EBOV replication through ubiquitination. Our work provides evidence that TRIM6 is an important host cellular factor that promotes EBOV replication, and future studies will focus on whether TRIM6 could be targeted for therapeutic intervention against EBOV infection.IMPORTANCE EBOV belongs to a family of highly pathogenic viruses that cause severe hemorrhagic fever in humans and other mammals with high mortality rates (40 to 90%). Because of its high pathogenicity and lack of licensed antivirals and vaccines, EBOV is listed as a tier 1 select-agent risk group 4 pathogen. An important mechanism for the severity of EBOV infection is its suppression of innate immune responses. The EBOV VP35 protein contributes to pathogenesis, because it serves as an essential cofactor of the viral polymerase as well as a potent antagonist of innate immunity. However, how VP35 function is regulated by host cellular factors is poorly understood. Here, we report that the host E3-ubiquitin ligase TRIM6 promotes VP35 ubiquitination and is important for efficient virus replication. Therefore, our study identifies a new host factor, TRIM6, as a potential target in the development of antiviral drugs against EBOV.