Functional characterization of Schistosoma mansoni fucosyltransferases in Nicotiana benthamiana plants.

Helminth parasites secrete a wide variety of immunomodulatory proteins and lipids to dampen host immune responses. Many of these immunomodulatory compounds are modified with complex sugar structures (or glycans), which play an important role at the host-parasite interface. As an example, the human blood fluke Schistosoma mansoni produces highly fucosylated glycan structures on glycoproteins and glycolipids. Up to 20 different S. mansoni fucosyltransferase (SmFucT) genes can be found in genome databases, but thus far only one enzyme has been functionally characterized. To unravel the synthesis of highly fucosylated N-glycans by S. mansoni, we examined the ability of ten selected SmFucTs to modify N-glycans upon transient expression in Nicotiana benthamiana plants. All enzymes were localized in the plant Golgi apparatus, which allowed us to identify the SmFucTs involved in core fucosylation and the synthesis of complex antennary glycan motifs. This knowledge provides a starting point for investigations into the role of specific fucosylated glycan motifs of schistosomes in parasite-host interactions. The functionally characterized SmFucTs can also be applied to synthesize complex N-glycan structures on recombinant proteins to study their contribution to immunomodulation. Furthermore, this plant expression system will fuel the development of helminth glycoproteins for pharmaceutical applications or novel anti-helminth vaccines.