Communication Between an Allosteric Inhibitor Binding Site and the Active Site in Beta-Lactamase

Abstract

Listen

Translate article

Beta-lactamases hydrolyze the beta-lactam ring of antibiotics, rendering them ineffective. Understanding the inhibitor recognition mechanism of beta-lactamases will give important information toward the fight against beta-lactamase mediated antibiotic resistance. Most inhibitors of beta-lactamase bind to the active site and thus inhibit beta-lactamase in a competitive manner. An allosteric inhibitor binding site, near the H10 helix (residues 218-230), has also been discovered in TEM-1 and KPC-2 beta-lactamases. Multiple sequence alignment of beta-lactamases shows that Trp 229, which resides on the H10 helix, is a highly conserved residue within the beta-lactamase family. In this study, computational mutagenesis of Trp 229 on two clinically relevant beta-lactamases, TEM-1 and SHV-1, was performed. Beta-lactamase inhibitor protein (BLIP) is known to bind TEM-1 with 1000 fold higher affinity than it binds to SHV-1. Molecular dynamics simulations were carried out on the unbound and BLIP bound forms of the wild type and W229A mutant beta-lactamases. The simulation trajectories were analyzed to obtain information about the changes in mobility. The binding free energies of the beta-lactamase - BLIP complexes were obtained and the individual energy terms contributing to the difference in affinity in the different mutants were determined. The results were compared for TEM-1 and SHV-1 to elucidate the difference in affinity toward BLIP. The change in binding dynamics upon mutation of Trp 229 was examined.