Brunotte Linda, Flies Joe, Bolte Hardin, Reuther Peter, Vreede Frank, Schwemmle Martin
From the Institute for Virology, University Medical Center Freiburg, Hermann-Herder-Str. 11, 79104 Freiburg, Germany and.
the Sir William Dunn School of Pathology, University of Oxford, South Parks Rd., Oxford OX 3RE, United Kingdom.
J Biol Chem. 2014 Jul 18;289(29):20067-77. doi: 10.1074/jbc.M114.569178. Epub 2014 Jun 2.
In influenza A virus-infected cells, replication and transcription of the viral genome occurs in the nucleus. To be packaged into viral particles at the plasma membrane, encapsidated viral genomes must be exported from the nucleus. Intriguingly, the nuclear export protein (NEP) is involved in both processes. Although NEP stimulates viral RNA synthesis by binding to the viral polymerase, its function during nuclear export implicates interaction with viral ribonucleoprotein (vRNP)-associated M1. The observation that both interactions are mediated by the C-terminal moiety of NEP raised the question whether these two features of NEP are linked functionally. Here we provide evidence that the interaction between M1 and the vRNP depends on the NEP C terminus and its polymerase activity-enhancing property for the nuclear export of vRNPs. This suggests that these features of NEP are linked functionally. Furthermore, our data suggest that the N-terminal domain of NEP interferes with the stability of the vRNP-M1-NEP nuclear export complex, probably mediated by its highly flexible intramolecular interaction with the NEP C terminus. On the basis of our data, we propose a new model for the assembly of the nuclear export complex of Influenza A vRNPs.
在甲型流感病毒感染的细胞中，病毒基因组的复制和转录发生在细胞核内。为了在质膜处被包装进病毒颗粒，被衣壳化的病毒基因组必须从细胞核输出。有趣的是，核输出蛋白（NEP）参与了这两个过程。虽然NEP通过与病毒聚合酶结合来刺激病毒RNA合成，但其在核输出过程中的功能意味着它与病毒核糖核蛋白（vRNP）相关的M1相互作用。NEP的这两种相互作用均由其C末端介导，这一发现引发了一个问题，即NEP的这两个特性在功能上是否相关联。在此，我们提供证据表明，M1与vRNP之间的相互作用取决于NEP的C末端及其增强vRNP核输出的聚合酶活性特性。这表明NEP的这些特性在功能上是相关联的。此外，我们的数据表明，NEP的N末端结构域会干扰vRNP-M1-NEP核输出复合物的稳定性，这可能是由其与NEP C末端高度灵活的分子内相互作用介导的。基于我们的数据，我们提出了一种甲型流感病毒vRNP核输出复合物组装的新模型。
