A simple screen for murein transglycosylase inhibitors

A simple assay for detection of compounds that bind to the active site in the transglycosylation domain of the essential bifunctional transglycosylase and transpeptidase penicillin-binding proteins (PBPs) is reported. The method is based on a competition with the specific transglycosylase inhibitor moenomycin. With moenomycin coupled to Affi-Gel beads, a simple filtration procedure allows the amount of labeled PBPs that bind to moenomycin beads in the presence of test substances to be determined. The PBPs can easily be labeled by the covalent binding of penicillin derivatives. Crude membrane extracts can be used as a source for the PBPs, and different kinds of labels for the penicillin-PBP complexes can be used. The assay can be adapted to high-throughput screens.