Discovery of New Small Molecule Inhibitors of the Bacterial Cell Division Protein FtsZ
University of California, Davis
FtsZ is the prokaryotic homologue of tubulin and plays an important role in mediating bacterial cell division. Despite the existence of reported FtsZ inhibitors, many of these molecules were found to have irreproducible activity or formed drug aggregates in enzymatic assays. To circumvent this problem, a fragment-based discovery approach is employed through a disulfide-tethered screening assay. FtsZ from Escherichia coli or Bacillus subtilis is mutated to install a cysteine moiety near one of the allosteric pockets of the protein. Mutated FtsZ is incubated with a library of disulfide-containing compounds in the presence of a reducing agent, such as _-mercaptoethanol, to identify small chemical fragments that have binding affinity toward the protein. Subsequent mass spectrometry and crystallographic analyses on the fragment-inhibitor protein complex are employed to identify the important interactions between the fragment and the binding pocket. Ultimately, information provided by the screen will guide us in the rational design of more potent modulators of FtsZ that can be further developed into potential antibiotic candidates.