High-Throughput "FP-Tag" Assay for the Identification of Glycosyltransferase Inhibitors

Bacterial capsular polysaccharides are important virulence factors. Capsular polysaccharides from several important Gram-negative pathogens share a conserved glycolipid terminus containing 3-deoxy-β-d- manno-oct-2-ulosonic acid (β-Kdo). The β-Kdo glycosyltransferases responsible for synthesis of this conserved glycolipid belong to a new family of glycosyltransferases that shares little homology with other such enzymes, thereby representing an attractive antivirulence target. Here, we report the development of a fluorescence polarization-based, high-throughput screening assay (FP-tag) for β-Kdo glycosyltransferases, and use it to identify a class of marine natural products as lead inhibitors. This "FP-tag" assay should be readily adaptable to high-throughput screens of other glycosyltransferases.