Ebola virus (EBOV) causes a severe and often fatal disease for which no approved vaccines or antivirals are currently available. EBOV VP30 has been described as a viral phosphoprotein, and nonphosphorylated VP30 is essential and sufficient to support secondary transcription in an EBOV-specific minigenome system; however, phosphorylatable serine residues near the N terminus of VP30 are required to support primary viral transcription as well as the reinitiation of VP30-mediated transcription at internal EBOV genes. While the dephosphorylation of VP30 by the cellular phosphatase PP2A was found to be mediated by nucleoprotein, the VP30-specific kinases and the role of phosphorylation remain unknown. Here, we report that serine-arginine protein kinase 1 (SRPK1) and SRPK2 phosphorylate serine 29 of VP30, which is located in an N-terminal R26xxS29 motif. Interaction with VP30 via the R26xxS29 motif recruits SRPK1 into EBOV-induced inclusion bodies, the sites of viral RNA synthesis, and an inhibitor of SRPK1/SRPK2 downregulates primary viral transcription. When the SRPK1 recognition motif of VP30 was mutated in a recombinant EBOV, virus replication was severely impaired. It is presumed that the interplay between SRPK1 and PP2A in the EBOV inclusions provides a comprehensive regulatory circuit to ensure the activity of VP30 in EBOV transcription. Thus, the identification of SRPK1 is an important mosaic stone that completes our picture of the players involved in Ebola virus transcription regulation.IMPORTANCE The largest Ebola virus (EBOV) epidemic in West Africa ever caused more than 28,000 cases and 11,000 deaths, and the current EBOV epidemic in the Democratic Republic of the Congo continues, with more than 3,000 cases to date. Therefore, it is essential to develop antivirals against EBOV. Recently, an inhibitor of the cellular phosphatase PP2A-mediated dephosphorylation of the EBOV transcription factor VP30 has been shown to suppress the spread of Ebola virus. Here, we identified the protein kinase SRPK1 as a VP30-specific kinase that phosphorylates serine 29, the same residue that is dephosphorylated by PP2A. SRPK1-mediated phosphorylation of serine 29 enabled primary viral transcription. Mutation of the SRPK1 recognition motif in VP30 resulted in significant growth inhibition of EBOV. Similarly, elevation of the phosphorylation status of serine 29 by overexpression of SRPK1 inhibited EBOV growth, highlighting the importance of reversible phosphorylation of VP30 as a potential therapeutic target.

中文翻译：

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丝氨酸精氨酸蛋白激酶1调节埃博拉病毒转录。

埃博拉病毒（EBOV）导致一种严重且往往致命的疾病，目前尚无批准的疫苗或抗病毒药物。EBOV VP30被描述为一种病毒磷蛋白，非磷酸化的VP30是必不可少的，足以支持EBOV特异性微型基因组系统中的二次转录。但是，需要VP30 N末端附近的磷酸化丝氨酸残基来支持初级病毒转录以及内部EBOV基因上VP30介导的转录的重新启动。虽然发现细胞磷酸酶PP2A对VP30的去磷酸化是由核蛋白介导的，但VP30特异性激酶和磷酸化的作用仍然未知。在这里，我们报告丝氨酸精氨酸蛋白激酶1（SRPK1）和SRPK2磷酸化VP30的丝氨酸29，它位于N端R26xxS29主题。通过R26xxS29基序与VP30的相互作用将SRPK1募集到EBOV诱导的包涵体，病毒RNA合成的位点和SRPK1 / SRPK2的抑制剂下调了初级病毒转录。当在重组EBOV中突变VP30的SRPK1识别基序时，病毒复制受到严重损害。据推测，EBOV包涵体中SRPK1和PP2A之间的相互作用提供了一个全面的调节电路，以确保VP30在EBOV转录中的活性。因此，鉴定SRPK1是重要的镶嵌石，这使我们对参与埃博拉病毒转录调控的参与者的了解更加完整。要点西非最大的埃博拉病毒（EBOV）流行病曾导致28,000多例病例和11,000例死亡，目前刚果民主共和国的EBOV流行继续，迄今为止，已有3,000多个案例。因此，开发针对EBOV的抗病毒药物至关重要。近来，已经证明细胞磷酸酶PP2A介导的EBOV转录因子VP30的去磷酸化抑制剂抑制了埃博拉病毒的传播。在这里，我们确定蛋白激酶SRPK1为VP30特异性激酶，可磷酸化丝氨酸29，该残基与被PP2A磷酸化的残基相同。SRPK1介导的丝氨酸29磷酸化使初级病毒转录成为可能。VP30中SRPK1识别基序的突变导致EBOV的显着生长抑制。同样，通过过度表达SRPK1来提高丝氨酸29的磷酸化状态会抑制EBOV的生长，突出了VP30可逆磷酸化作为潜在治疗靶点的重要性。因此，开发针对EBOV的抗病毒药物至关重要。近来，已经证明细胞磷酸酶PP2A介导的EBOV转录因子VP30的去磷酸化抑制剂抑制了埃博拉病毒的传播。在这里，我们确定蛋白激酶SRPK1为VP30特异性激酶，可磷酸化丝氨酸29，该残基与被PP2A磷酸化的残基相同。SRPK1介导的丝氨酸29磷酸化使初级病毒转录成为可能。VP30中SRPK1识别基序的突变导致EBOV的显着生长抑制。同样，通过过度表达SRPK1来提高丝氨酸29的磷酸化状态会抑制EBOV的生长，突出了VP30可逆磷酸化作为潜在治疗靶点的重要性。因此，开发针对EBOV的抗病毒药物至关重要。近来，已经证明细胞磷酸酶PP2A介导的EBOV转录因子VP30的去磷酸化抑制剂抑制了埃博拉病毒的传播。在这里，我们确定蛋白激酶SRPK1为VP30特异性激酶，可磷酸化丝氨酸29，该残基与被PP2A磷酸化的残基相同。SRPK1介导的丝氨酸29磷酸化使初级病毒转录成为可能。VP30中SRPK1识别基序的突变导致EBOV的显着生长抑制。同样，通过过度表达SRPK1来提高丝氨酸29的磷酸化状态会抑制EBOV的生长，突出了VP30可逆磷酸化作为潜在治疗靶点的重要性。细胞磷酸酶PP2A介导的EBOV转录因子VP30的去磷酸化抑制剂可抑制埃博拉病毒的传播。在这里，我们确定蛋白激酶SRPK1为VP30特异性激酶，可磷酸化丝氨酸29，该残基被PP2A磷酸化。SRPK1介导的丝氨酸29磷酸化使初级病毒转录成为可能。VP30中SRPK1识别基序的突变导致EBOV的显着生长抑制。同样，通过过度表达SRPK1来提高丝氨酸29的磷酸化状态会抑制EBOV的生长，突出了VP30可逆磷酸化作为潜在治疗靶点的重要性。细胞磷酸酶PP2A介导的EBOV转录因子VP30的去磷酸化抑制剂可抑制埃博拉病毒的传播。在这里，我们确定蛋白激酶SRPK1为VP30特异性激酶，可磷酸化丝氨酸29，该残基与被PP2A磷酸化的残基相同。SRPK1介导的丝氨酸29磷酸化使初级病毒转录成为可能。VP30中SRPK1识别基序的突变导致EBOV的显着生长抑制。同样，通过过度表达SRPK1来提高丝氨酸29的磷酸化状态会抑制EBOV的生长，突出了VP30可逆磷酸化作为潜在治疗靶点的重要性。