Homology modelling of the major peanut allergen Ara h 2 and surface mapping of IgE-binding epitopes.
Three-dimensional models built for the peanut Ara h 2 allergen and other structurally-related 2S albumin allergens of dietary nuts exhibited an overall three-dimensional fold stabilized by disulphide bridges well conserved among all the members of the 2S albumin superfamily. Conformational analysis of the linear IgE-binding epitopes mapped on the molecular surface of Ara h 2 showed no structural homology with the corresponding regions of the walnut Jug r 1, the pecan nut Car i 1 or the Brazil nut Ber e 1 allergens. The absence of epitopic community does not support the allergenic cross-reactivity observed between peanut and walnut or Brazil nut, which presumably depends on other ubiquitous seed storage protein allergens, namely the vicilins. However, the major IgE-binding epitope identified on the molecular surface of the walnut Jug r 1 allergen shared a pronounced structural homology with the corresponding region of the pecan nut Car i 1 allergen. With the exception of peanut, 2S albumins could thus account for the IgE-binding cross-reactivity observed between some other dietary nuts, e.g. walnut and pecan nut.
Barre
Annick
A
Surfaces Cellulaires et Signalisation chez les Végétaux, UMR-CNRS 5546, Pôle de Biotechnologie végétale, 24 Chemin de Borde Rouge, 31326 Castanet-Tolosan, France.
Borges
Jean-Philippe
JP
Culerrier
Raphaël
R
Rougé
Pierre
P
D055516:2S Albumins, Plant; D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D052179:Antigens, Plant / Q000276:immunology*; D010367:Arachis / Q000276:immunology*; D003429:Cross Reactions; D018604:Epitope Mapping; D006023:Glycoproteins / Q000737:chemistry / Q000276:immunology*; D007073:Immunoglobulin E / Q000276:immunology*; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology*; D017433:Protein Structure, Secondary; D016415:Sequence Alignment
D055516:2S Albumins, Plant; D000485:Allergens; D052179:Antigens, Plant; C500890:Ara h 2 allergen, Arachis hypogaea; C078642:Ara h II protein, Arachis hypogaea; D006023:Glycoproteins; D010940:Plant Proteins; D007073:Immunoglobulin E