title: The glycoinositolphospholipids from Leishmania panamensis contain unusual glycan and lipid moieties.
abstract: The cell surface of Leishmania parasites is coated by glycosylphosphatidylinositol (GPI)-anchored macromolecules (glycoproteins and a lipophosphoglycan) and a polymorphic family of free GPI glycolipids or glycoinositolphospholipids (GIPLs). Here we show that GIPLs with unusual glycan and lipid moieties are likely to be major cell surface components of L. panamensis (subgenus Viannia) promastigotes. These glycolipids were purified by high performance thin layer chromatography and their structures determined by gas-liquid chromatography-mass spectrometry, fast-atom bombardment mass spectrometry, methylation analysis and chemical and enzymatic sequencing of the glycan headgroups. The major GIPLs contained two glycan core sequences, Manalpha1-3Manalpha1-4GlcN-phosphatidylinositol (type-2 series) or Manalpha1-3[Manalpha1-2Manalpha1-6]Manalpha1- 4GlcN-phosphatidylinosit ol (hybrid series), which were elaborated with Galalpha1-2Galbeta1- or Galalpha1-2/3Galalpha1-2Galbeta1- extensions that were attached to the 3-position of the alpha1-3 linked mannose. The phosphatidylinositol moiety contained exclusively diacylglycerol with palmitoyl, stearoyl and heptadecanoyl chains. Non-galactosylated GIPL species with the same core structures were also found. The galactose extensions and the presence of diacylglycerol in the lipid moieties are novel features for the GIPLs of Leishmania spp. The implications of these structures for the biosynthesis of leishmanial GIPLs and their putative function in the mammalian host are discussed.
authors.affiliation: Departments of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3052, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Zawadzki
authors.forename: C
authors.initials: C
authors.lastname: Scholz
authors.forename: G
authors.initials: G
authors.lastname: Currie
authors.forename: G H
authors.initials: GH
authors.lastname: Coombs
authors.forename: M J
authors.initials: MJ
authors.lastname: McConville
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D002851:Chromatography, High Pressure Liquid; D006028:Glycosphingolipids / Q000737:chemistry; D017261:Glycosylphosphatidylinositols / Q000737:chemistry*; D018334:Leishmania guyanensis / Q000737:chemistry* / Q000254:growth & development; D008055:Lipids / Q000737:chemistry*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000737:chemistry*
chemical_list: D006028:Glycosphingolipids; D017261:Glycosylphosphatidylinositols; D008055:Lipids; D011134:Polysaccharides; C008290:lipophosphonoglycan