title: Biosynthesis of methylphosphomannosyl residues in the oligosaccharides of Dictyostelium discoideum glycoproteins. Evidence that the methyl group is derived from methionine.
abstract: The phosphorylated oligosaccharides of Dictyostelium discoideum contain methylphosphomannosyl residues which are stable to mild-acid and base hydrolysis (Gabel, C. A., Costello, C. E., Reinhold, V. N., Kurtz, L., and Kornfeld, S. (1984) J. Biol. Chem. 259, 13762-13769). Here we present evidence that these methyl groups are derived from [methyl-3H]methionine, in vivo and [methyl-3H]S-adenosylmethionine in vitro. About 18% of the macromolecules secreted from vegetative cells labeled with [methyl-3H]methionine are released by digestion with preparations of endoglycosidase/peptide N-glycosidase F. The majority of the released molecules are sulfated, anionic high mannose-type oligosaccharides. Strong acid hydrolysis of the [3H]methyl-labeled molecules yields [3H]methanol with kinetics of release similar to those found for the generation of Man-6-P from chemically synthesized methylphosphomannose methylglycoside. Treatment of the [3H]methyl-labeled molecules with a phosphodiesterase from Aspergillus niger which is known to cleave this phosphodiester also releases [3H]methanol from a portion of the oligosaccharides. In vitro incorporation of [methyl-3H]S-adenosylmethionine into endogenous acceptors found in membrane preparations shows that the [3H]methyl group of the methylphosphomannose residues can be derived from this molecule.
authors.forename: H H
authors.initials: HH
authors.lastname: Freeze
authors.forename: D
authors.initials: D
authors.lastname: Wolgast
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004023:Dictyostelium / Q000378:metabolism*; D006023:Glycoproteins / Q000096:biosynthesis*; D006026:Glycoside Hydrolases / Q000378:metabolism; D006600:Hexosephosphates / Q000096:biosynthesis*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008360:Mannosephosphates / Q000096:biosynthesis*; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D008715:Methionine / Q000378:metabolism*; D008745:Methylation; D009844:Oligosaccharides / Q000096:biosynthesis*; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D010766:Phosphorylation; D012436:S-Adenosylmethionine / Q000378:metabolism
chemical_list: D006023:Glycoproteins; D006600:Hexosephosphates; D008360:Mannosephosphates; D009844:Oligosaccharides; C027693:mannose-6-phosphate; D012436:S-Adenosylmethionine; D008715:Methionine; D006026:Glycoside Hydrolases; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase