Domain-Swapping of a GT-B Glycosyltransferase Broadens Its Sugar Donor Range for Glycodiversification of Natural Products.

Glycosylation of natural compounds modulates their bioactivity as well as their physicochemical properties, making glycodiversification a valuable strategy for identifying glycosidic derivatives with improved functional profiles. However, the use of glycosyltransferases (GTs) for their synthesis is constrained by stringent sugar nucleotide donor selectivity, which limits the structural diversity of accessible glycosides. The chimeric NB1//CC1, constituted of 2 self-assembled domains originating from plant glycosyltransferases, was previously demonstrated to transfer glucose onto a wider range of natural compounds than its parental enzymes. This study demonstrates that this chimeric enzyme also exhibits a relaxed selectivity toward sugar nucleotide donors. This donor promiscuity can further be enhanced by the Mg2+ cation, which increases the sugar transfer rate for the chimeric enzyme. NB1//CC1 can therefore be used as a single biocatalyst to generate a library of glycosidic variants of a given natural glycosylated compound.