title: Recombinant prespore-specific antigen from Dictyostelium discoideum is a beta-sheet glycoprotein with a spacer peptide modified by O-linked N-acetylglucosamine.
abstract: Prespore-specific antigen (PsA) is a putative cell-adhesion molecule of the cellular slime mould Dictyostelium discoideum, which has a similar molecular architecture to several mammalian cell-surface proteins. It has an N-terminal globular domain presented to the extracellular environment on an O-glycosylated stem (glycopeptide) that is attached to the cell membrane through a glycosyl-PtdIns anchor. The sequence of PsA suggests that PsA may belong to a new family of cell-surface molecules and here we present information on the structure of the N-terminal globular domain and determine the reducing-terminal linkage of the O-glycosylation. To obtain a sufficient amount of pure protein, a secreted recombinant form of PsA (rPsA), was expressed in D. discoideum and characterised. 1H-NMR spectra of rPsA contained features consistent with a high degree of beta-sheet in the N-terminal globular domain, a feature commonly observed in cell-adhesion proteins. Solid-phase Edman degradation of the glycopeptide of rPsA indicated that 14 of the 15 threonines and serines in the spacer region were glycosylated. The chemical structures of the O-glycosylations were determined to be single N-acetylglucosamine residues.
authors.affiliation: Macquarie University Centre for Analytical Biotechnology, Sydney, Australia.
authors.forename: N E
authors.initials: NE
authors.lastname: Zachara
authors.forename: N H
authors.initials: NH
authors.lastname: Packer
authors.forename: M D
authors.initials: MD
authors.lastname: Temple
authors.forename: M B
authors.initials: MB
authors.lastname: Slade
authors.forename: D R
authors.initials: DR
authors.lastname: Jardine
authors.forename: P
authors.initials: P
authors.lastname: Karuso
authors.forename: C J
authors.initials: CJ
authors.lastname: Moss
authors.forename: B C
authors.initials: BC
authors.lastname: Mabbutt
authors.forename: P M
authors.initials: PM
authors.lastname: Curmi
authors.forename: K L
authors.initials: KL
authors.lastname: Williams
authors.forename: A A
authors.initials: AA
authors.lastname: Gooley
mesh_terms: D000117:Acetylglucosamine / Q000032:analysis; D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan; D000954:Antigens, Surface / Q000737:chemistry* / Q000235:genetics; D002236:Carbohydrate Conformation; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D004023:Dictyostelium / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D006020:Glycopeptides / Q000737:chemistry; D006031:Glycosylation; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D015800:Protozoan Proteins; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D014357:Trypsin / Q000378:metabolism
chemical_list: D000953:Antigens, Protozoan; D000954:Antigens, Surface; D005656:Fungal Proteins; D006020:Glycopeptides; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C074496:prespore-specific antigen, Dictyostelium discoideum; D014357:Trypsin; D000117:Acetylglucosamine