Biochemical characterization of SARS-CoV-2 nucleocapsid protein

• Published in: Biochemical and biophysical research communications Vol. 527; no. 3; pp. 618 - 623
• Main Authors: Zeng, Weihong, Liu, Guangfeng, Ma, Huan, Zhao, Dan, Yang, Yunru, Liu, Muziying, Mohammed, Ahmed, Zhao, Changcheng, Yang, Yun, Xie, Jiajia, Ding, Chengchao, Ma, Xiaoling, Weng, Jianping, Gao, Yong, He, Hongliang, Jin, Tengchuan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 30.06.2020; Published by Elsevier Inc
• Subjects: ambient temperature; Antibodies, Viral - blood; Antigenicity; antigens; Betacoronavirus - chemistry; chromatography; Coronavirus Infections; COVID-19; COVID-19 infection; diagnostic techniques; fluorescence; Humans; immunity; Nucleic Acids; nucleocapsid; Nucleocapsid protein; nucleocapsid proteins; Nucleocapsid Proteins - chemistry; Pandemics; Pneumonia, Viral; Protein Binding; Protein Multimerization; Protein Structure, Tertiary; RNA packaging; SARS-CoV-2; SAXS; Scattering, Small Angle; Severe acute respiratory syndrome coronavirus 2; small-angle X-ray scattering; Structure and function; virion; X-Ray Diffraction; COVID-19; SARS-CoV-2; Antigenicity; Nucleocapsid protein; Structure and function; SAXS
• ISSN: 0006-291X; 1090-2104; 1090-2104
• DOI: 10.1016/j.bbrc.2020.04.136

The nucleocapsid (N) protein is an important antigen for coronavirus, which participate in RNA package and virus particle release. In this study, we expressed the N protein of SARS-CoV-2 and characterized its biochemical properties. Static light scattering, size exclusive chromatography, and small-angle X-ray scattering (SAXS) showed that the purified N protein is largely a dimer in solution. CD spectra showed that it has a high percentage of disordered region at room temperature while it was best structured at 55 °C, suggesting its structural dynamics. Fluorescence polarization assay showed it has non-specific nucleic acid binding capability, which raised a concern in using it as a diagnostic marker. Immunoblot assays confirmed the presence of IgA, IgM and IgG antibodies against N antigen in COVID-19 infection patients’ sera, proving the importance of this antigen in host immunity and diagnostics. •SARS-CoV-2 nucleocapsid protein is full of coils and highly disordered.•SARS-CoV-2 N protein forms a dimer by CTD-CTD interaction.•SARS-CoV-2 N protein can bind with non-specific nucleic acid with high affinity.•SARS-CoV-2 N protein can be a good antigen for serological test of COVID-19.