Identification of potentially cross-reactive peanut-lupine proteins by computer-assisted search for amino acid sequence homology.
BACKGROUND
Allergic cross-reactions are an issue of major concern because of implications for public health. The molecular basis of cross-allergy is the similarity of epitopes belonging to proteins of different organisms. Lupine is an emerging cause of food allergy, which has become a 'hot topic' because of recent large-scale introduction into processed foods and frequent cross-reactions with other members of the legume family. However, no lupine allergen has been characterized thus far. Prompted by a recently reported case of peanut-lupine cross-allergy, we wished to identify the possible cross-reactive allergen(s) between the two vegetal species.


METHODS
We used computer-aided amino acid sequence comparison, a well-established technique for the study of protein homology, and followed the FAO/WHO guidelines for the identification of potential allergens. We also performed a three-dimensional modeling of the suspected cross-reactive proteins to compare their molecular surfaces.


RESULTS
We found a highly significant sequence homology and molecular similarity between allergen Ara h 8 of peanut and pathogenesis-related protein PR-10 of white lupine. Another protein of lupine, the beta-conglutin precursor, was found to be significantly homologous to the Ara h 1 allergen of peanut. The molecular surfaces of Ara h 8 and PR-10 were remarkably similar.


CONCLUSIONS
Our in silico data allow to predict the allergenicity of PR-10 and beta-conglutin precursor of white lupine according to FAO/WHO guidelines. Amino acid sequence homology also suggests that these proteins could be responsible, at least in part, for some of the allergic cross-reactions between peanut and lupine reported in the literature.
Guarneri
Fabrizio
F
Istituto di Dermatologia, Policlinico Gaetano Martino, Messina, Italia. f.guarneri@tiscali.it
Guarneri
Claudio
C
Benvenga
Salvatore
S
D000485:Allergens; D000595:Amino Acid Sequence; D052179:Antigens, Plant / Q000235:genetics / Q000276:immunology*; D010367:Arachis / Q000235:genetics / Q000276:immunology*; D037222:Collectins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D003429:Cross Reactions / Q000276:immunology; D006023:Glycoproteins; D031297:Lupinus / Q000235:genetics / Q000276:immunology*; D008565:Membrane Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D012712:Serum Globulins / Q000737:chemistry / Q000235:genetics / Q000276:immunology
D000485:Allergens; D052179:Antigens, Plant; C500889:Ara h 1 protein, Arachis hypogaea; D037222:Collectins; D006023:Glycoproteins; D008565:Membrane Proteins; D010940:Plant Proteins; D012712:Serum Globulins; C024014:conglutinin; C053376:pathogenesis-related proteins, plant