SARS-CoV-2 RNA, nsP3c (non-structural Protein3c) spans the sequence of the so-called SARS Unique Domains (SUDs), first observed in SARS-CoV. Although the function of this viral protein is not fully elucidated, it is believed that it is crucial for the formation of the replication/transcription viral complex (RTC) and of the interaction of various viral “components” with the host cell; thus, it is essential for the entire viral life cycle. The first two SUDs, the so-called SUD-N (the N-terminal domain) and SUD-M (domain following SUD-N) domains, exhibit topological and conformational features that resemble the nsP3b macro (or “X”) domain. Indeed, they are all folded in a three-layer α/β/α sandwich structure, as revealed through crystallographic structural investigation of SARS-CoV SUDs, and they have been attributed to different substrate selectivity as they selectively bind to oligonucleotides. On the other hand, the C-terminal SUD (SUD-C) exhibit much lower sequence similarities compared to the SUD-N & SUD-M, as reported in previous crystallographic and NMR studies of SARS-CoV. In the absence of the 3D structures of SARS-CoV-2, we report herein the almost complete NMR backbone and side-chain resonance assignment (¹H,¹³C,¹⁵N) of SARS-CoV-2 SUD-M and SUD-C proteins, and the NMR chemical shift-based prediction of their secondary structure elements. These NMR data will set the base for further understanding at the atomic-level conformational dynamics of these proteins and will allow the effective screening of a large number of small molecules as binders with potential biological impact on their function.

SARS-CoV-2 RNA、nsP3c（非结构蛋白 3c）跨越了所谓的 SARS 独特域（SUDs）的序列，首次在 SARS-CoV 中观察到。尽管这种病毒蛋白的功能尚未完全阐明，但据信它对于复制/转录病毒复合物 (RTC) 的形成以及各种病毒“成分”与宿主细胞的相互作用至关重要；因此，它对于整个病毒生命周期至关重要。前两个 SUD，即所谓的 SUD-N（N 端域）和 SUD-M（SUD-N 之后的域）域，表现出类似于 nsP3b 宏（或“X”）域的拓扑和构象特征。事实上，它们都折叠成三层 α/β/α 夹层结构，正如通过对 SARS-CoV SUD 的晶体结构研究所揭示的那样，并且它们被归因于不同的底物选择性，因为它们选择性地结合寡核苷酸。另一方面，与 SUD-N 和 SUD-M 相比，C 末端 SUD (SUD-C) 的序列相似性要低得多，正如之前对 SARS-CoV 的晶体学和 NMR 研究所报道的那样。在没有 SARS-CoV-2 的 3D 结构的情况下，我们在此报告了几乎完整的 NMR 主链和侧链共振分配（^{SARS-CoV-2 SUD-M 和 SUD-C 蛋白的1} H, ¹³ C, ¹⁵ N) 及其二级结构元素的基于 NMR 化学位移的预测。这些 NMR 数据将为进一步了解这些蛋白质的原子级构象动力学奠定基础，并将允许有效筛选大量小分子作为粘合剂，这些小分子可能对其功能产生生物学影响。