Recombinant prespore-specific antigen from Dictyostelium discoideum is a beta-sheet glycoprotein with a spacer peptide modified by O-linked N-acetylglucosamine.
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.
Zachara
N E
NE
Macquarie University Centre for Analytical Biotechnology, Sydney, Australia.
Packer
N H
NH
Temple
M D
MD
Slade
M B
MB
Jardine
D R
DR
Karuso
P
P
Moss
C J
CJ
Mabbutt
B C
BC
Curmi
P M
PM
Williams
K L
KL
Gooley
A A
AA
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
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