Two novel types of O-glycans on the mugwort pollen allergen Art v 1 and their role in antibody binding.
Art v 1, the major allergen of mugwort (Artemisia vulgaris) pollen contains galactose and arabinose. As the sera of some allergic patients react with natural but not with recombinant Art v 1 produced in bacteria, the glycosylation of Art v 1 may play a role in IgE binding and human allergic reactions. Chemical and enzymatic degradation, mass spectrometry, and 800 MHz (1)H and (13)C nuclear magnetic resonance spectroscopy indicated the proline-rich domain to be glycosylated in two ways. We found a large hydroxyproline-linked arabinogalactan composed of a short beta1,6-galactan core, which is substituted by a variable number (5-28) of alpha-arabinofuranose residues, which form branched side chains with 5-, 2,5-, 3,5-, and 2,3,5-substituted arabinoses. Thus, the design of the Art v 1 polysaccharide differs from that of the well known type II arabinogalactans, and we suggest it be named type III arabinogalactan. The other type of glycosylation was formed by single (but adjacent) beta-arabinofuranoses linked to hydroxyproline. In contrast to the arabinosylation of Ser-Hyp(4) motifs in other hydroxyproline-rich glycoproteins, such as extensins or solanaceous lectins, no oligo-arabinosides were found in Art v 1. Art v 1 and parts thereof produced by alkaline degradation, chemical deglycosylation, proteolytic degradation, and/or digestion with alpha-arabinofuranosidase were used in enzyme-linked immunosorbent assay and immunoblot experiments with rabbit serum and with the sera of patients. Although we could not observe antibody binding by the polysaccharide, the single hydroxyproline-linked beta-arabinose residues appeared to react with the antibodies. Mono-beta-arabinosylated hydroxyproline residues thus constitute a new, potentially cross-reactive, carbohydrate determinant in plant proteins.
Leonard
Renaud
R
Division of Biochemistry, Department of Chemistry, Universitaet fuer Bodenkultur Wien, Muthgasse 18, A-1190 Vienna, Austria.
Petersen
Bent O
BO
Himly
Martin
M
Kaar
Waltraud
W
Wopfner
Nicole
N
Kolarich
Daniel
D
van Ree
Ronald
R
Ebner
Christof
C
Duus
Jens Ø
JØ
Ferreira
Fátima
F
Altmann
Friedrich
F
D000485:Allergens / Q000737:chemistry* / Q000378:metabolism; D000906:Antibodies / Q000737:chemistry*; D052179:Antigens, Plant; D002241:Carbohydrates / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D002853:Chromatography, Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005685:Galactans / Q000737:chemistry; D008040:Genetic Linkage; D006020:Glycopeptides / Q000737:chemistry; D006023:Glycoproteins / Q000737:chemistry; D006031:Glycosylation; D006909:Hydroxyproline / Q000737:chemistry; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008956:Models, Chemical; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D011058:Pollen / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D011392:Proline / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000485:Allergens; D000906:Antibodies; D052179:Antigens, Plant; C102724:Art v 1 protein, mugwort; D002241:Carbohydrates; D005685:Galactans; D006020:Glycopeptides; D006023:Glycoproteins; D010940:Plant Proteins; D011134:Polysaccharides; D007073:Immunoglobulin E; D002244:Carbon; D011392:Proline; D006909:Hydroxyproline; C005653:arabinogalactan