STRUCTURAL VARIATION IN THE GLYCOINOSITOLPHOSPHOLIPIDS OF DIFFERENT STRAINS OF TRYPANOSOMA-CRUZI

The structures of the glycoinositolphospholipids (GIPLs) from five str ains of the protozoan parasite Trypanosoma cruzi have been determined. Two series of structures were identified, all but one containing the same Man(4)(AEP)GlcN-Ins-PO4 core. Series 1 oligosaccharides are subst ituted at the third mannose distal to inositol (Man 3) by ethanolamine -phosphate or 2-aminoethylphosphonic acid, as are some glycosyl-phosph atidylinositol-protein anchors of T. cruzi. The core can be further su bstituted by terminal (1-3)-linked beta-galactofuranose units. In cont rast, Series 2 oligosaccharides do not have additional phosphorus-cont aining groups attached to Man 3, the latter being substituted instead by a single side chain unit of beta-galactofuranose. Series 1 oligosac charides are present in all strains (G, G-645, Tulahuen CL, and Y) whe reas Series 2 structures are present mainly in CL and Y strains. The l ipid moiety in the GIPLs from the G, G-645 and Tulahuen strains is pre dominantly ceramide, as reported for the Y strain, whilst that from th e CL strain is a mixture of ceramide and alkylacylglycerol species. Th e lipid moiety of the GIPLs, and probably also the phosphoinositol-oli gosaccharide structures may play an important immunomodulatory role in infection by T. cruzi.