Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel, highly infectious RNA virus that belongs to the coronavirus family. Replication of the viral genome is a fundamental step in the virus life cycle and SARS-CoV-2 non-structural protein 9 (Nsp9) is shown to be essential for virus replication through its ability to bind RNA in the closely related SARS-CoV-1 strain. Two recent studies revealing the three-dimensional structure of Nsp9 from SARS-CoV-2 have demonstrated a high degree of similarity between Nsp9 proteins within the coronavirus family. However, the binding affinity to RNA is very low which, until now, has prevented the determination of the structural details of this interaction. In this study, we have utilized nuclear magnetic resonance spectroscopy (NMR) in combination with surface biolayer interferometry (BLI) to reveal a distinct binding interface for both ssDNA and RNA that is different to the one proposed in the recently solved SARS-CoV-2 replication and transcription complex (RTC) structure. Based on these data, we have proposed a structural model of a Nsp9-RNA complex, shedding light on the molecular details of these important interactions.

中文翻译：

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来自 SARS-CoV-2 的 Nsp9 蛋白中独特的 ssDNA/RNA 结合界面

严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 是一种新型的、高度传染性的 RNA 病毒，属于冠状病毒家族。病毒基因组的复制是病毒生命周期中的一个基本步骤，而 SARS-CoV-2 非结构蛋白 9 (Nsp9) 通过与密切相关的 SARS-CoV- 中的 RNA 结合的能力，被证明是病毒复制所必需的。 1株。最近的两项研究揭示了来自 SARS-CoV-2 的 Nsp9 的三维结构，证明了冠状病毒家族中 Nsp9 蛋白之间的高度相似性。然而，与 RNA 的结合亲和力非常低，直到现在，这阻碍了确定这种相互作用的结构细节。在这项研究中，我们利用核磁共振波谱 (NMR) 结合表面生物层干涉仪 (BLI) 揭示了 ssDNA 和 RNA 的独特结合界面，这与最近解决的 SARS-CoV-2 复制和转录复合物中提出的结合界面不同(RTC) 结构。基于这些数据，我们提出了 Nsp9-RNA 复合物的结构模型，揭示了这些重要相互作用的分子细节。