Application of Fragment-Based Drug Discovery against DNA Gyrase B

Bacterial resistance to antibiotics remains a serious threat to global health. The gyraseB enzyme is a well-validated target for developing antibacterial drugs. Despite being an attractive target for antibiotic development, there are currently no gyraseB inhibitory drugs on the market. A fragment screen using 1,800compounds identified 14fragments that bind to Escherichia coli (E.coli) gyraseB. The detailed characterization of binding is described for all 14fragments. With the aid of X-ray crystallography, modifications on a low-affinity fragment (K-D=253M, IC50=634M) has led to the development of a new class of potent phenyl aminopyrazole inhibitors against E.coli gyraseB (IC50=160nM). The study presented here combines the use of a set of biophysical techniques including differential scanning fluorimetry, nuclear magnetic resonance, isothermal titration calorimetry, and X-ray crystallography to methodically identify, quantify, and optimize fragments into new chemical leads.