Dual targeting DNA gyrase B (GyrB) and topoisomerse IV (ParE) inhibitors: A review.

GyrB and ParE are type IIA topoisomerases and found in most bacteria. Its function is vital for DNA replication, repair and decatenation. The highly conserved ATP-binding subunits of DNA GyrB and ParE are structurally related and have been recognized as prime candidates for the development of dual-targeting antibacterial agents with broad-spectrum potential. However, no natural product or small molecule inhibitors targeting ATPase catalytic domain of both GyrB and ParE enzymes have succeeded in the clinic. Moreover, no inhibitors of these enzymes with broad-spectrum antibacterial activity against Gram-negative pathogens have been reported. Availability of high resolution crystal structures of GyrB and ParE made it possible for the design of many different classes of inhibitors with dual mechanism of action. Among them benzimidazoles, benzothiazoles, thiazolopyridines, imidiazopyridazoles, pyridines, indazoles, pyrazoles, imidazopyridines, triazolopyridines, pyrrolopyrimidines, pyrimidoindoles as well as related structures are disclosed in literatures. Unfortunately most of these inhibitors are found to be active against Gram-positive pathogens. In the present review we discuss about studies on novel dual targeting ATPase inhibitors.

Pharmacophore modeling, atom based 3D-QSAR, molecular docking and molecular dynamics studies on Escherichia coli ParE inhibitors.

ATP dependent ParE enzyme is as an attractive target for the development of antibacterial agents. Atom based 3D-QSAR model AADHR.187 was developed based on the thirty eight Escherichia coli ParE inhibitors. The generated model showed statistically significant coefficient of determinations for the training (R2 = 0.985) and test (R2 = 0.86) sets. The cross-validated correlation coefficient (q2) was 0.976. The utility of the generated model was validated by the enrichment study. The model was also validated with structurally diverse external test set of ten compounds. Contour plot analysis of the generated model unveiled the chemical features necessary for the E. coli ParE enzyme inhibition. Extra-precision docking result revealed that hydrogen bonding and ionic interactions play a major role in ParE protein-ligand binding. Binding free energy was computed for the data set inhibitors to validate the binding affinity. A 30-ns molecular dynamics simulation showed high stability and effective binding of inhibitor 34 within the active site of ParE enzyme. Using the best fitted model AADHR.187, pharmacophore-based high-throughput virtual screening was performed to identify virtual hits. Based on the above studies three new molecules are proposed as E. coli ParE inhibitors with high binding affinity and favourable ADME properties.