Crystal structures of coronaviral main proteases in complex with the non-covalent inhibitor X77.
Jiang, H., Li, W., Zhou, X., Zhang, J., Li, J.(2024) Int J Biol Macromol 276: 133706-133706
- PubMed: 38981557 
- DOI: https://doi.org/10.1016/j.ijbiomac.2024.133706
- Primary Citation of Related Structures:  
8YKJ, 8YKK, 8YKL, 8YKM, 8YKN, 8YKO, 8YKP, 8YKQ - PubMed Abstract: 
Main proteases (M pro s) are a class of conserved cysteine hydrolases among coronaviruses and play a crucial role in viral replication. Therefore, M pro s are ideal targets for the development of pan-coronavirus drugs. X77, previously developed against SARS-CoV M pro , was repurposed as a non-covalent tight binder inhibitor against SARS-CoV-2 M pro during COVID-19 pandemic. Many novel inhibitors with favorable efficacy have been discovered using X77 as a reference, suggesting that X77 could be a valuable scaffold for drug design. However, the broad-spectrum performance of X77 and underlying mechanism remain less understood. Here, we reported the crystal structures of M pro s from SARS-CoV-2, SARS-CoV, and MERS-CoV, and several M pro mutants from SARS-CoV-2 variants bound to X77. A detailed analysis of these structures revealed key structural determinants essential for interaction and elucidated the binding modes of X77 with different coronaviral M pro s. The potencies of X77 against these investigated M pro s were further evaluated through molecular dynamic simulation and binding free energy calculation. These data provide molecular insights into broad-spectrum inhibition against coronaviral M pro s by X77 and the similarities and differences of X77 when bound to various M pro s, which will promote X77-based design of novel antivirals with broad-spectrum efficacy against different coronaviruses and SARS-CoV-2 variants.
Organizational Affiliation: 
School of Basic Medical Sciences, Jiangxi Medical College, Nanchang University, Nanchang 330031, China.