An explorative study on Staphylococcus aureus MurE inhibitor: induced fit docking, binding free energy calculation,...

Staphylococcus aureus MurE enzyme catalyzes the addition of l-lysine as third residue of the peptidoglycan peptide moiety. Due to the high substrate specificity and its ubiquitous nature among bacteria, MurE enzyme is considered as one of the potential target for the development of new therapeutic agents. In the present work, induced fit docking (IFD), binding free energy calculation, and molecular dynamics (MD) simulation were carried out to elucidate the inhibition potential of 2-thioxothiazolidin-4-one based inhibitor 1 against S. aureus MurE enzyme. The inhibitor 1 formed majority of hydrogen bonds with the central domain residues Asn151, Thr152, Ser180, Arg187, and Lys219. Binding free-energy calculation by MM-GBSA approach showed that van der Waals (ΔG_vdW, -57.30 kcal/mol) and electrostatic solvation (ΔG_solv, -36.86 kcal/mol) energy terms are major contributors for the inhibitor binding. Further, 30-ns MD simulation was performed to validate the stability of ligand-protein complex and also to get structural insight into mode of binding. Based on the IFD and MD simulation results, we designed four new compounds D1-D4 with promising binding affinity for the S. aureus MurE enzyme. The designed compounds were subjected to the extra-precision docking and binding free energy was calculated for complexes. Further, a 30-ns MD simulation was performed for D1/4C13 complex.