Structural Basis for Coronaviral Main Proteases Inhibition by the 3CLpro Inhibitor GC376.
Lin, C., Zhu, Z., Jiang, H., Zou, X., Zeng, X., Wang, J., Zeng, P., Li, W., Zhou, X., Zhang, J., Wang, Q., Li, J.(2024) J Mol Biol 436: 168474-168474
- PubMed: 38311236 
- DOI: https://doi.org/10.1016/j.jmb.2024.168474
- Primary Citation of Related Structures:  
8IG4, 8IG5, 8IG6, 8IG7, 8IG8, 8IG9, 8IGA, 8IGB - PubMed Abstract: 
The main protease (M pro ) of coronaviruses participates in viral replication, serving as a hot target for drug design. GC376 is able to effectively inhibit the activity of M pro , which is due to nucleophilic addition of GC376 by binding covalently with Cys145 in M pro active site. Here, we used fluorescence resonance energy transfer (FRET) assay to analyze the IC 50 values of GC376 against M pro s from six different coronaviruses (SARS-CoV-2, HCoV-229E, HCoV-HUK1, MERS-CoV, SARS-CoV, HCoV-NL63) and five M pro mutants (G15S, M49I, K90R, P132H, S46F) from SARS-CoV-2 variants. The results showed that GC376 displays effective inhibition to various coronaviral M pro s and SARS-CoV-2 M pro mutants. In addition, the crystal structures of SARS-CoV-2 M pro (wide type)-GC376, SARS-CoV M pro -GC376, MERS-CoV M pro -GC376, and SARS-CoV-2 M pro mutants (G15S, M49I, S46F, K90R, and P132H)-GC376 complexes were solved. We found that GC376 is able to fit into the active site of M pro s from different coronaviruses and different SARS-CoV-2 variants properly. Detailed structural analysis revealed key molecular determinants necessary for inhibition and illustrated the binding patterns of GC376 to these different M pro s. In conclusion, we not only proved the inhibitory activity of GC376 against different M pro s including SARS-CoV-2 M pro mutants, but also revealed the molecular mechanism of inhibition by GC376, which will provide scientific guidance for the development of broad-spectrum drugs against SARS-CoV-2 as well as other coronaviruses.
Organizational Affiliation: 
College of Pharmacy, Gannan Medical University, Ganzhou 341000, China.