Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA; Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.
Biochem Biophys Res Commun. 2020 Apr 30;525(2):259-264. doi: 10.1016/j.bbrc.2020.02.059. Epub 2020 Feb 19.
Influenza A virus nucleoprotein (NP) is a structural component that encapsulates the viral genome into the form of ribonucleoprotein complexes (vRNPs). Efficient assembly of vRNPs is critical for the virus life cycle. The assembly route from RNA-free NP to the NP-RNA polymer in vRNPs has been suggested to require a cellular factor UAP56, but the mechanism is poorly understood. Here, we characterized the interaction between NP and UAP56 using recombinant proteins and showed that UAP56 features two NP binding sites. In addition to the UAP56 core comprised of two RecA domains, we identified the N-terminal extension (NTE) of UAP56 as a previously unknown NP binding site. In particular, UAP56-NTE recognizes the nucleic acid binding region of NP. This corroborates our observation that binding of UAP56-NTE and RNA to NP is mutually exclusive. Collectively, our results reveal the molecular basis for how UAP56 acts on RNA-free NP, and provide new insights into NP-mediated influenza genome packaging.
甲型流感病毒核蛋白（NP）是一种结构成分，将病毒基因组包裹成核糖核蛋白复合物（vRNP）的形式。vRNP 的有效组装对病毒生命周期至关重要。从无 RNA 的 NP 到 vRNP 中的 NP-RNA 聚合体的组装途径被认为需要一种细胞因子 UAP56，但机制尚不清楚。在这里，我们使用重组蛋白表征了 NP 和 UAP56 之间的相互作用，并表明 UAP56 具有两个 NP 结合位点。除了由两个 RecA 结构域组成的 UAP56 核心外，我们还确定了 UAP56 的 N 端延伸（NTE）作为一个以前未知的 NP 结合位点。特别是，UAP56-NTE 识别 NP 的核酸结合区域。这证实了我们的观察结果，即 UAP56-NTE 和 RNA 与 NP 的结合是相互排斥的。总的来说，我们的结果揭示了 UAP56 如何作用于无 RNA 的 NP 的分子基础，并为 NP 介导的流感基因组包装提供了新的见解。
