Nature's carbohydrate chemists: The enzymatic glycosylation of bioactive bacterial metabolites

A recent estimate suggests roughly 70% of current lead compounds in modern drug discovery derive directly from the natural products, many of which are glycosylated bacterial metabolites. Thus, bacterial glycosyltransferases and their corresponding sugar substrates contribute significantly to the diversity of pharmaceutically important metabolites. This review summarizes (i) the role that carbohydrates contribute to biologically active bacterial metabolites, (ii) a sequence homology classification of known glycosyltransferases from these systems and (iii) the potential impact pathway engineering and combinatorial biocatalysis may have on increasing carbohydrate-ligand diversity. While the number of glycosylated bacterial metabolites is vast, this review limits itself to glycosides with considerable published information pertaining to biological activity and biosynthesis.