Multiple O-glycoforms on the spore coat protein SP96 in Dictyostelium discoideum. Fuc(alpha1-3)GlcNAc-alpha-1-P-Ser is the major modification

J Biol Chem. 2000 Apr 21;275(16):12164-74. doi: 10.1074/jbc.275.16.12164.


A decreased level of fucosylation on certain spore coat proteins of Dictyostelium discoideum alters the permeability of the spore coat. Here the post-translational modifications of a major spore coat protein, SP96, are studied in a wild type strain (X22) and a fucosylation-defective mutant (HU2470). A novel phosphoglycan structure on SP96 of the wild type strain, consisting of Fuc(alpha1-3)GlcNAc-alpha-1-P-Ser(,) was identified by electrospray ionization mass spectrometry and NMR. It was shown using monosaccharide and gas chromatography mass spectrometry analysis that SP96 in the mutant HU2470 contained approximately 20% of wild type levels of fucose, as a result of a missing terminal fucose on the novel glycan structure. The results support previous predictions, based on inhibition studies on different fucose-deficient strains, about the nature of monoclonal antibody epitopes identified by monoclonal antibodies MUD62 and MUD166, which are known to identify O-linked glycans (Champion, A., Griffiths, K., Gooley, A. A., Gonzalez, B. Y., Gritzali, M., West, C. M., and Williams, K. L. (1995) Microbiology 141, 785-797). Quantitative studies on wild type SP96 indicated that there were approximately 60 sites with phosphodiester-linked N-acetylglucosamine-fucose disaccharide units and a further approximately 20 sites with fucose directly linked to the protein. Over 70% of the serine sites are modified, with less than 1% of these sites as phosphoserine. Threonine and tyrosine residues were not found to be modified.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / analysis
  • Animals
  • Antibodies, Monoclonal / metabolism
  • Carbohydrate Sequence
  • Chromatography, Liquid
  • Dictyostelium / chemistry*
  • Fucose / metabolism
  • Models, Chemical
  • Molecular Sequence Data
  • Molecular Weight
  • Permeability
  • Phosphoamino Acids / analysis
  • Phosphorylation
  • Protein Processing, Post-Translational
  • Protozoan Proteins / chemistry*
  • Protozoan Proteins / metabolism
  • Spectrometry, Mass, Secondary Ion
  • Structure-Activity Relationship


  • Amino Acids
  • Antibodies, Monoclonal
  • Phosphoamino Acids
  • Protozoan Proteins
  • spore coat proteins, Dictyostelium
  • Fucose