title: Hydrophobic mannosides act as acceptors for trypanosome alpha-mannosyltransferases.
abstract: A series of hydrophobic mannosides were synthesized and tested for their ability to act as acceptor substrates for mannosyltransferases in a Trypanosoma brucei cell-free system. The thiooctyl alpha-mannosides and octyl alpha-mannosides all accepted single mannose residues in alpha-linkage, as judged by thin layer chromatography of the products before and after jack bean alpha-mannosidase digestion. The mannosylation reactions were inhibited by amphomycin, suggesting that the immediate donor was dolichol-phosphate-mannose (Dol-P-Man) in all cases. The transferred alpha-mannose residues were shown to be both alpha 1-2 and alpha 1-6 linked by Aspergillus phoenicis alpha-mannosidase and acetolysis treatments, respectively. These data suggest that the compounds can act as acceptor substrates for the Dol-P-Man dependent alpha 1-2 and alpha 1-6 mannosyltransferases of the GPI biosynthetic pathway and/or the dolichol-cycle of protein N-glycosylation. One of the compounds, Man alpha 1-6 Man alpha 1-O-(CH2)7CH3, inhibited endogenous GPI biosynthesis in the cell-free system, suggesting that it could be a substrate for the trypanosome Dol-P-Man:Man2GlcN-Pl alpha 1-2 mannosyltransferase.
authors.affiliation: Department of Biochemistry, University of Dundee, Scotland.
authors.forename: J R
authors.initials: JR
authors.lastname: Brown
authors.forename: M L
authors.initials: ML
authors.lastname: Güther
authors.forename: R A
authors.initials: RA
authors.lastname: Field
authors.forename: M A
authors.initials: MA
authors.lastname: Ferguson
mesh_terms: D000818:Animals; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002851:Chromatography, High Pressure Liquid; D004287:Dolichol Monophosphate Mannose / Q000378:metabolism / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006155:Guanosine Diphosphate Mannose / Q000378:metabolism / Q000494:pharmacology; D055666:Lipopeptides; D008358:Mannose / Q000737:chemistry / Q000378:metabolism; D008361:Mannosidases / Q000378:metabolism; D008362:Mannosides / Q000138:chemical synthesis / Q000378:metabolism*; D008364:Mannosyltransferases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology; D014346:Trypanosoma brucei brucei / Q000201:enzymology*; D043323:alpha-Mannosidase
chemical_list: D004791:Enzyme Inhibitors; D055666:Lipopeptides; D008362:Mannosides; D009842:Oligopeptides; D006155:Guanosine Diphosphate Mannose; C004423:amphomycin; D004287:Dolichol Monophosphate Mannose; D008364:Mannosyltransferases; D008361:Mannosidases; D043323:alpha-Mannosidase; D008358:Mannose