Purification and Inhibitor Screening of the Full-Length SARS-CoV-2 Nucleocapsid Protein

Severe acute respiratory syndrome coronavirus 2 has undergone several mutations since 2020, and novel variants continue to emerge to this day. The immune escape ability of the emerging mutants is enhanced and results in robust transmissibility. The neutralizing ability of the antibodies produced in...

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Main Authors: Chen Chen, Zhengfu Zhang, Qiao Zheng, Yingshun Zhou, Shujun Zhang
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/13/2679
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author Chen Chen
Zhengfu Zhang
Qiao Zheng
Yingshun Zhou
Shujun Zhang
author_facet Chen Chen
Zhengfu Zhang
Qiao Zheng
Yingshun Zhou
Shujun Zhang
author_sort Chen Chen
collection DOAJ
description Severe acute respiratory syndrome coronavirus 2 has undergone several mutations since 2020, and novel variants continue to emerge to this day. The immune escape ability of the emerging mutants is enhanced and results in robust transmissibility. The neutralizing ability of the antibodies produced in the human body during previous infections is decreased against some of these mutants, which poses a severe challenge to the preventive and therapeutic effectiveness of vaccines and antibody drugs. The nucleocapsid protein is one of the main structural proteins of the coronavirus and plays an important role in the life cycle of the novel coronavirus. This protein is one of the key targets for drug development, and the first major step in drug development is to obtain pure nucleocapsid proteins. However, since nucleocapsid proteins have a nucleic acid-binding function and automatically undergo liquid–liquid phase separation and agglomeration, the purification of full-length nucleocapsids is challenging. In this context, a set of easy-to-operate processes was developed in this study for the purification of nucleocapsid proteins. Finally, a pure full-length nucleocapsid protein without nucleic acid contamination was obtained, which exhibited significantly enhanced accessibility for structural and functional virological studies, vaccine development, and related research applications. Further, the nucleic acid-binding domain of the nucleocapsid protein was targeted, and potential severe acute respiratory syndrome coronavirus 2 inhibitors were identified using virtual screening and biolayer interferometry technology. Notably, the eukaryotically expressed nucleocapsid protein demonstrated a significantly greater binding affinity for Light Green SF Yellowish (K<sub>D</sub> = 119.7 nM) compared to that demonstrated by its prokaryotic counterpart (K<sub>D</sub> = 19.9 × 10<sup>3</sup> nM). The findings of this study suggest the importance of considering both protein source and post-translational modifications of the target proteins to be used in drug screening workflows. Therefore, this compound not only represents a novel therapeutic candidate for COVID-19 but also a critical tool for elucidating antiviral mechanisms.
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spelling doaj-art-e5b654d14f274dc6a3d805cc1ec02bfb2025-08-20T02:36:32ZengMDPI AGMolecules1420-30492025-06-013013267910.3390/molecules30132679Purification and Inhibitor Screening of the Full-Length SARS-CoV-2 Nucleocapsid ProteinChen Chen0Zhengfu Zhang1Qiao Zheng2Yingshun Zhou3Shujun Zhang4Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, ChinaDepartment of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, ChinaDepartment of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, ChinaDepartment of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, ChinaDepartment of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, ChinaSevere acute respiratory syndrome coronavirus 2 has undergone several mutations since 2020, and novel variants continue to emerge to this day. The immune escape ability of the emerging mutants is enhanced and results in robust transmissibility. The neutralizing ability of the antibodies produced in the human body during previous infections is decreased against some of these mutants, which poses a severe challenge to the preventive and therapeutic effectiveness of vaccines and antibody drugs. The nucleocapsid protein is one of the main structural proteins of the coronavirus and plays an important role in the life cycle of the novel coronavirus. This protein is one of the key targets for drug development, and the first major step in drug development is to obtain pure nucleocapsid proteins. However, since nucleocapsid proteins have a nucleic acid-binding function and automatically undergo liquid–liquid phase separation and agglomeration, the purification of full-length nucleocapsids is challenging. In this context, a set of easy-to-operate processes was developed in this study for the purification of nucleocapsid proteins. Finally, a pure full-length nucleocapsid protein without nucleic acid contamination was obtained, which exhibited significantly enhanced accessibility for structural and functional virological studies, vaccine development, and related research applications. Further, the nucleic acid-binding domain of the nucleocapsid protein was targeted, and potential severe acute respiratory syndrome coronavirus 2 inhibitors were identified using virtual screening and biolayer interferometry technology. Notably, the eukaryotically expressed nucleocapsid protein demonstrated a significantly greater binding affinity for Light Green SF Yellowish (K<sub>D</sub> = 119.7 nM) compared to that demonstrated by its prokaryotic counterpart (K<sub>D</sub> = 19.9 × 10<sup>3</sup> nM). The findings of this study suggest the importance of considering both protein source and post-translational modifications of the target proteins to be used in drug screening workflows. Therefore, this compound not only represents a novel therapeutic candidate for COVID-19 but also a critical tool for elucidating antiviral mechanisms.https://www.mdpi.com/1420-3049/30/13/2679SARS-CoV-2COVID-19nucleocapsid proteinexpression and purificationvirtual screeninginhibitor
spellingShingle Chen Chen
Zhengfu Zhang
Qiao Zheng
Yingshun Zhou
Shujun Zhang
Purification and Inhibitor Screening of the Full-Length SARS-CoV-2 Nucleocapsid Protein
Molecules
SARS-CoV-2
COVID-19
nucleocapsid protein
expression and purification
virtual screening
inhibitor
title Purification and Inhibitor Screening of the Full-Length SARS-CoV-2 Nucleocapsid Protein
title_full Purification and Inhibitor Screening of the Full-Length SARS-CoV-2 Nucleocapsid Protein
title_fullStr Purification and Inhibitor Screening of the Full-Length SARS-CoV-2 Nucleocapsid Protein
title_full_unstemmed Purification and Inhibitor Screening of the Full-Length SARS-CoV-2 Nucleocapsid Protein
title_short Purification and Inhibitor Screening of the Full-Length SARS-CoV-2 Nucleocapsid Protein
title_sort purification and inhibitor screening of the full length sars cov 2 nucleocapsid protein
topic SARS-CoV-2
COVID-19
nucleocapsid protein
expression and purification
virtual screening
inhibitor
url https://www.mdpi.com/1420-3049/30/13/2679
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