Comparative analysis of high-throughput assays of family-1 plant glycosyltransferases

The ability of glycosyltransferases (GTs) to reduce volatility, increase solubility, and thus alter the bioavailability of small molecules through glycosylation has attracted immense attention in pharmaceutical, nutraceutical, and cosmeceutical industries. The lack of GTs known and the scarcity of high-throughput (HTP) available methods, hinders the extrapolation of further novel applications. In this study, the applicability of new GT-assays suitable for HTP screening was tested and compared with regard to harmlessness, robustness, cost-effectiveness and reproducibility. The UDP-Glo GT-assay, Phosphate GT Activity assay, pH-sensitive GT-assay, and UDP²-TR-FRET assay were applied and tailored to plant UDP GTs (UGTs). Vitis vinifera (UGT72B27) GT was subjected to glycosylation reaction with various phenolics. Substrate screening and kinetic parameters were evaluated. The pH-sensitive assay and the UDP²-TR-FRET assay were incomparable and unsuitable for HTP plant GT-1 family UGT screening. Furthermore, the UDP-Glo GT-assay and the Phosphate GT Activity assay yielded closely similar and reproducible K_M, v_max, and k_cat values. Therefore, with the easy experimental set-up and rapid readout, the two assays are suitable for HTP screening and quantitative kinetic analysis of plant UGTs. This research sheds light on new and emerging HTP assays, which will allow for analysis of novel family-1 plant GTs and will uncover further applications.