title: Mannosamine can replace glucosamine in glycosylphosphatidylinositols of Plasmodium falciparum in vitro.
abstract: Mannosamine (2-deoxy-2-amino-D-mannose) is unable to block GPI biosynthesis in Plasmodium falciparum: neither parasite development nor GPI biosynthesis were blocked by mannosamine treatment in P. falciparum cultures. Further, it was shown by metabolic labeling with [3H]mannosamine and subsequent monosaccharide analysis by high pH anion exchange chromatography that mannosamine is converted at a high rate into glucosamine. Both mannosamine and glucosamine are incorporated into P. falciparum glycolipids, but the characterization of mannosamine-labeled glycolipids synthesized in vivo proved difficult. Therefore, a cell-free system was developed to investigate the incorporation of [3H]mannosamine into glycolipids in P. falciparum. It was observed that mannosamine is incorporated in vitro into P. falciparum glycolipids, which possess a phosphate group. Chemical (nitrous acid deamination, mild acid hydrolysis and alkaline hydrolysis) and enzymatic (PI-PLC) treatments of [3H]mannosamine-labeled glycolipids synthesized in vitro showed the presence of GPIs. Further analyses by Bio-Gel P4 size-exclusion chromatography and HPAEC demonstrated the presence of a mannosamine-containing GPI-like structures, where mannosamine is incorporated instead of glucosamine, i.e. Man3-ManN-PI. This utilization of mannosamine is novel and not been described for any other cellular or parasitic system.
authors.affiliation: Institut für Virologie, Med. Zentrum für Hygiene und Medizinische Mikrobiologie, Philipps-Universität Marburg, Robert-Koch-Strasse 17, D-35037 Marburg, Germany.
authors.forename: Nahid
authors.initials: N
authors.lastname: Azzouz
authors.forename: Cristiana Santos
authors.initials: CS
authors.lastname: de Macedo
authors.forename: Michael A J
authors.initials: MA
authors.lastname: Ferguson
authors.forename: Terry K
authors.initials: TK
authors.lastname: Smith
authors.forename: Ralph T
authors.initials: RT
authors.lastname: Schwarz
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D005944:Glucosamine / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols / Q000096:biosynthesis*; D006595:Hexosamines / Q000378:metabolism*; D010963:Plasmodium falciparum / Q000378:metabolism*; D014316:Tritium / Q000378:metabolism
chemical_list: D017261:Glycosylphosphatidylinositols; D006595:Hexosamines; D014316:Tritium; C008322:mannosamine; D005944:Glucosamine