Development of Dictyostelium discoideum is associated with alteration of fucosylated N-glycan structures

The social amoeba Dictyostelium discoideum has become established as a simple model for the examination of cell-cell interactions, and early studies suggested that shifts in glycosylation profiles take place during its life cycle. In the present Study, we have applied HPLC and mass spectrometric methods to show that the major N-glycans in axenic cultures of the AX3 strain are oligomannosidic forms, most of which carry core fucose and/or intersecting and bisecting N-acetylglucosamine residues, including the major structure with the composition Man(3)GlcNAc(4)Fuc(1). The postulated alpha 1,3-linkage of the core fucose correlates with the cross-reactivity of Dictyostelium glycoproteins with a horseradish peroxidase antiserum; a corresponding core alpha 1,3-fucosyltransferase activity capable of modifying oligomannosidic N-glycans wits detected in axenic Dictyostelium extracts. The presence of fucose oil the N-glycans and the reactivity to the antiserum, but not the fucosyltransferase activity, are abolished in the fucose-deficient HL250 strain. In later stages of development, N-glycans at the mound and culmination stages show a reduction in both the size and the degree of modification by intersecting/bisecting residues compared with mid-exponential phase Cultures, consistent with file hypothesis that glycosidase and glycosyltransferase expression levels lire altered during the slime mould life cycle.