Cell surface oligosaccharides participate in cohesion during aggregation of Dictyostelium discoideum.

Abstract

Plasma membrane glycoproteins from Dictyostelium discoideum amoebae at three stages of early development were digested with Pronase and endoglycosidase H and fractionated by gel filtration. This gave three classes of glycans (polysaccharides, endoglycosidase H-resistant glycopeptides, and endoglycosidase H-released oligosaccharides), which were tested for their ability to block agglutination of amoebae from vegetative, aggregation (8-hr), and late-aggregation (13-hr) stages of development. The endoglycosidase H-resistant glycopeptides from 8-hr cells inhibited agglutination of disaggregated 8-hr cells but not vegetative or 13-hr cells. The 8-hr polysaccharide and endo H-sensitive oligosaccharides did not inhibit. The glycopeptides from 8-hr cells were resolved into five species by electrophoresis in borate-containing buffer. Two of these had agglutination-inhibiting activity, and three did not. None of the glycan fractions from vegetative or 13-hr cells inhibited agglutination of vegetative, 8-, or 13-hr cells. These data implicate specific cell surface glycans in aggregation-stage intercellular cohesion and suggest that both these glycans and receptors for them are developmentally regulated.