The tool of metabolic oligosaccharide engineering (MOE) allows the introduction of chemical reporter groups into glycan structures of various organisms, by taking advantage of the cellular machinery. The incorporated reactive groups can be further targeted through bio-orthogonal labelling reactions and allow the identification and characterization of specific carbohydrate structures.,
We developed galactose derivatives with terminal alkene groups in C2 or C6 position, which can be targeted through inverse electron demand Diels Alder reactions by using 6 Methyl-tetrazine derivatives. These new monosaccharides were used to study different aspects of changes in galactosylated glycan structures related with Malaria infection. With about 500000 deaths each year, Malaria is still one of the major global health problems and due to increasing numbers of resistances to present treatments, the development of new strategies, such as vaccinations, is crucial. Our approach uses MOE to incorporate artificial galactose derivatives in galactosylated glycan structures in different stages of a Malaria infection. First we were able to show the incorporation of these galactose derivatives into cell membrane structures of hepatic cells with and without an infection through Plasmodium berghei sporozoites. It was shown that infected cells seem to display a slightly higher uptake of the artificial galactose derivatives, due to an involvement of the up regulated GLUT1 transporter in these cells.
Having addressed the incorporation of artificial galactose derivatives in the liver stage of Malaria infection, we decided to investigate also the interplay between the mosquito host and the Plasmodium parasite with regard to galactose containing glycans. After administering the presented galactose derivative to infected mosquitoes during the feeding process, we were able to successfully label the transmitted sugar on the parasite surface. This results suggests a transmission of galactose monosaccharides from the mosquito host to the parasite and can help to answer questions about the formation of specific carbohydrate structures in this organism.
Overall, we present an approach to use MOE as a tool for investigations on important glycan structures during Malaria infection, with the final goal to identify possible carbohydrate antigens for the development of anti-malarial vaccine candidates.
- Sminia, T.J., Zuilhof, H. & Wennekes, T. Getting a grip on glycans: A current overview of the metabolic oligosaccharide engineering toolbox. Carbohyd Res 435, 121-141 (2016).
- Gilormini, P.-A., Batt, A.R., Pratt, M.R. & Biot, C. Asking more from metabolic oligosaccharide engineering. Chem Sci 9, 7585-7595 (2018).
- World Malaria Report 2018. 210 (World Health Organization, Geneve, 2018).