Identification of small covalent inhibitors targeting DsbA using virtual screening, covalent docking, and molecular dynamics simulations

Antimicrobial resistance (AMR) is a growing global health threat, highlighting the urgent need for new therapeutic strategies. The development of bacterial antivirulence agents and antibiotic adjuvants offers two promising strategies for combating bacterial infections. The DsbA protein is crucial for bacterial virulence and resistance, catalyzing the formation of disulfide bonds in bacterial proteins, making it an attractive target for novel antibiotics. In this study, we employed virtual screening, covalent docking, and molecular dynamics simulations to screen a library of 69,579 compounds for inhibitors targeting Cys30, a key nucleophilic residue in the CXXC catalytic motif of DsbA. We identified four small molecule covalent inhibitors that form covalent bonds with DsbA. The MM/PBSA results indicate that three covalent compounds (Cov28322, Cov16876, and Cov64052) have lower binding energies than the positive control. However, covalent binding typically offers superior target specificity and durability. These inhibitors primarily interact with key regions of DsbA, including the CXXC motif and L2 loop, suggesting their potential to disrupt DsbA's catalytic activity. This study provides a theoretical basis for designing DsbA covalent inhibitors as antibiotic adjuvants, presenting a promising strategy to combat bacterial infections and AMR.