Abstract
The spread of carbapenem-resistant Enterobacteriaceae (CRE) has weakened control of severe hospital infections. These strains evade nearly all last-resort antibiotics, making targeted β-lactamase inhibitors indispensable for β-lactam treatment. Existing carbapenem-bicyclic boronate derivative combinations show broad-spectrum activity, with confirmed efficacy against Class A serine carbapenemases represented by KPC-2. Using KPC-2 as a model for serine β-lactamases (SBLs), we performed non-covalent and covalent docking to compare substrate and inhibitor competition for the active site and acyl-enzyme formation. The bicyclic boronate inhibitors Taniborbactam and Ledaborbactam show stronger binding affinities than the monocyclic Vaborbactam, with affinities comparable to those of Imipenem. Beyond the catalytic residues Ser70, Lys73, and Glu166, shared hydrogen-bonding interactions involving Ser130, Asn132, Arg220, and Thr237 in KPC-2 with both carbapenems and cyclic boronates indicate direct active-site competition. These findings clarify how inhibition competes with catalysis and provide a theoretical framework for inhibitor optimization.