Optimization of the Expression, Purification, and Crystallization of SARS-CoV-2 Nonstructural Protein 13

The SARS-CoV-2 nonstructural protein 13 (nsp13) is a helicase essential for viral replication, making it a promising antiviral target. The goal of this study is to optimize the expression, purification, and crystallization of recombinant nsp13. An Escherichia coli host was transformed with a plasmid containing an N-terminal His6-Zb-TEV-tagged nsp13 gene. Expression of nsp13 protein was then induced in the transformed bacteria. Protein purification involved immobilized metal affinity chromatography, ion-exchange chromatography, and size exclusion chromatography. SDS-PAGE confirmed successful purification, showing a distinct band at the expected molecular weight. TEV protease cleavage removed the His6-Zb tag, followed by further purification to obtain pure cleaved nsp13. The resulting high-purity nsp13 was suitable for crystallization trials. This study presents a reproducible protocol for the efficient expression and purification of nsp13, facilitating the way for structural characterization. Successful production of pure nsp13 protein lays the foundation for future biochemical studies to identify helicase-targeting inhibitors.