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Molecular characterization of Dau c 1, the Bet v 1 homologous protein from carrot and its cross‐reactivity with Bet v 1 and Api g 1
Author(s) -
Karin HoffmannSommergruber,
O'riordain,
Ahorn,
Ebner,
Da Camara Machado,
Pühringer,
Scheiner,
Breiteneder
Publication year - 1999
Publication title -
clinical and experimental allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 154
eISSN - 1365-2222
pISSN - 0954-7894
DOI - 10.1046/j.1365-2222.1999.00529.x
Subject(s) - daucus carota , recombinant dna , complementary dna , allergen , cross reactivity , escherichia coli , immunoglobulin e , open reading frame , microbiology and biotechnology , biology , food allergy , epitope , biochemistry , allergy , chemistry , peptide sequence , gene , antibody , immunology , botany , cross reactions
Background Up to 70% of patients with birch pollen allergy exhibit the so‐called oral allergy syndrome, an IgE‐mediated food allergy. The most frequent and therefore best characterized pollen–fruit syndrome is apple allergy in patients suffering from tree pollen‐induced pollinosis. The occurrence of adverse reactions to proteins present in vegetables such as celery and carrots in patients suffering from pollen allergy has also been reported. cDNAs for Bet v 1 homologous proteins have been cloned from celery, apple and cherry. Objective The aim of the study was to identify Bet v 1 homologues from carrot ( Daucus carota ), to isolate the respective cDNA, to compare the IgE‐binding capacity of the natural protein to the recombinant allergen and determine the cross‐reactivity to Api g 1 and Bet v 1. Methods Molecular characterization of the carrot allergen was performed using IgE‐immunoblotting, cross‐inhibition assays, N‐terminal sequencing, PCR‐based cDNA cloning and expression of the recombinant protein in Escherichia coli . Results A 16‐kDa protein from carrot was identified as a major IgE‐binding component and designated Dau c 1. Sequencing corresponding cDNAs revealed three extremely similar sequences (Dau c 1.1, 1.2 and 1.3) with an open reading frame of 462 bp coding for 154 amino acid residues. Conclusions Purified recombinant Dau c 1.2 was tested in immunoblots displaying IgE‐binding capacity comparable to its natural counterpart. Cross‐inhibition assays verified the existence of common B‐cell epitopes present on Dau c 1, Api g 1 as well as on Bet v 1.