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

• Published in: Clinical and experimental allergy Vol. 29; no. 6; pp. 840 - 847
• Main Authors: HOFFMANN-SOMMERGRUBER, K, O'RIORDAIN, G, AHORN, H, EBNER, C, LAIMER DA CAMARA MACHADO, M, PÜHRINGER, H, SCHEINER, O, BREITENEDER, H
• Format: Journal Article
• Language: English
• Published: Oxford BSL Blackwell Science Ltd 01.06.1999; Blackwell; Wiley Subscription Services, Inc
• Subjects: Allergens; Allergic diseases; Amino Acid Sequence - genetics; Antigens, Plant; Api g 1; Base Sequence - genetics; Bet v 1; Biological and medical sciences; carrot; Cross Reactions - immunology; Dau c 1; Daucus carota - immunology; Daucus carota - metabolism; food allergen; Humans; IgE-binding; Immunoblotting; Immunoglobulin E - immunology; Immunopathology; Medical sciences; Molecular Sequence Data; Other localizations; Plant Extracts - immunology; Plant Proteins - genetics; Plant Proteins - immunology; Plant Proteins - isolation & purification; Plant Proteins - metabolism; Polymerase Chain Reaction; recombinant allergen; Recombinant Proteins; RNA, Messenger - isolation & purification; Sequence Homology; Allergy; Daucus carota; Insecta; IgE; Apidae; Apis mellifera; Apoidea; Dicotyledones; Angiospermae; Cross reaction; Tree; Betula pendula; Betulaceae; Vegetable; Aculeata; Food; Human; Immunopathology; Animal origin; Protein; Arthropoda; Spermatophyta; Umbelliferae; Hymenoptera; Invertebrata; Molecular biology; Allergen
• ISSN: 0954-7894; 1365-2222
• DOI: 10.1046/j.1365-2222.1999.00529.x

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.