Enzymatic Synthesis of the C-Glycosidic Moiety of Nogalamycin R

Carbohydrate moieties are essential for the biological activity of anthracycline anticancer agents such as nogalamycin, which contains L-nogalose and L-nogalamine units. The former of these is attached through a canonical O-glycosidic linkage, but the latter is connected via an unusual dual linkage composed of C-C and O-glycosidic bonds. In this work, we have utilized enzyme immobilization techniques and synthesized L-rhodosamine-thymidine diphosphate (TDP) from alpha-D-glucose-1-TDP using seven enzymes. In a second step, we assembled the dual linkage system by attaching the aminosugar to an anthracycline aglycone acceptor using the glycosyl transferase SnogD and the a-ketoglutarate dependent oxygenase SnoK. Furthermore, our work indicates that the auxiliary P450-type protein SnogN facilitating glycosylation is surprisingly associated with attachment of the neutral sugar L-nogalose rather than the aminosugar L-nogalamine in nogalamycin biosynthesis.