Maiti Atanu, Matsuo Hiroshi
Cancer Innovation Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA.
Biomolecules. 2024 Nov 30;14(12):1538. doi: 10.3390/biom14121538.
The nucleocapsid (N) protein is one of the four structural proteins in SARS-CoV-2, playing key roles in viral assembly, immune evasion, and stability. One of its primary functions is to protect viral RNA by forming the nucleocapsid. However, the precise mechanisms by which the N protein interacts with viral RNA and assembles into a nucleocapsid remain unclear. Compared to other SARS-CoV-2 components, targeting the N protein has several advantages: it exhibits higher sequence conservation, lower mutation rates, and stronger immunogenicity, making it an attractive target for antiviral drug development and diagnostics. Therefore, a detailed understanding of the N protein's structure is essential for deciphering its role in viral assembly and developing effective therapeutics. In this study, we report the expression and purification of a soluble recombinant N protein, along with a 1.55 Å resolution crystal structure of its nucleic acid-binding domain (N-NTD) in complex with ssDNA. Our structure revealed new insights into the conformation and interaction of the flexible N-arm, which could aid in understanding nucleocapsid assembly. Additionally, we identified residues that are critical for ssDNA interaction.
核衣壳（N）蛋白是严重急性呼吸综合征冠状病毒2（SARS-CoV-2）的四种结构蛋白之一，在病毒组装、免疫逃逸和稳定性方面发挥着关键作用。其主要功能之一是通过形成核衣壳来保护病毒RNA。然而，N蛋白与病毒RNA相互作用并组装成核衣壳的确切机制仍不清楚。与SARS-CoV-2的其他成分相比，靶向N蛋白有几个优点：它表现出更高的序列保守性、更低的突变率和更强的免疫原性，使其成为抗病毒药物开发和诊断的有吸引力的靶点。因此，详细了解N蛋白的结构对于破译其在病毒组装中的作用和开发有效的治疗方法至关重要。在本研究中，我们报告了可溶性重组N蛋白的表达和纯化，以及其核酸结合结构域（N-NTD）与单链DNA（ssDNA）复合物的1.55埃分辨率晶体结构。我们的结构揭示了对柔性N臂的构象和相互作用的新见解，这有助于理解核衣壳的组装。此外，我们鉴定了对ssDNA相互作用至关重要的残基。
