Screening of Novel Inhibitors Targeting the Non-ATP-binding Domain of Staphylococcus aureus SecA1

Objective: Staphylococcus aureus (S. aureus) has been one of the pathogenic bacteria for clinical infections, and there is an urgent need for the development of novel anti-S. aureus drugs. SecA is a conserved and essential protein in bacteria and is considered as an ideal target for development. Current screening of inhibitors against SecA has focused on the ATP-binding structural domain, which increases the risk of drug side effects, so a novel screening strategy based on the non-ATP-binding structural domain was chosen in this paper. Methods: A three-dimensional structural model of S. aureus SecA1N75 was constructed, and molecular docking was utilized to screen small molecules with strong interactions with the non- ATP binding domains from a compound library, and four candidate compounds were finally targeted. Molecular dynamics simulations of the candidate molecules were performed to evaluate their drug potential. Results: The four candidate compounds formed stable interactions with key residues of the SecA binding pocket. Molecular dynamics simulations further showed that the candidate molecules bound to the receptor in a stable conformation with nM-level inhibition constants, displaying potent SecA inhibitory activity. It lays the foundation of a lead compound for the development of antimicrobial drugs targeting SecA. Conclusion: In this thesis, an inhibitor screening strategy based on non-ATP binding structural domains was successfully constructed, which breaks through the limitations of traditional methods to screen candidate molecules with high activity and low risk of potential side effects, and provides an innovative solution to meet the challenge of S. aureus drug resistance.