IngentaConnect Molecular characterization of Dau c 1, the Bet v 1 homologous pro...

Authors: HOFFMANN-SOMMERGRUBER¹; O'RIORDAIN¹; AHORN²; EBNER¹; DA CAMARA MACHADO,³; PÜHRINGER³; SCHEINER¹; BREITENEDER¹

Source: Clinical & Experimental Allergy, Volume 29, Number 6, June 1999 , pp. 840-847(8)

Publisher: Blackwell Publishing

Abstract:

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.

Keywords: Dau c 1; Bet v 1; Api g 1; food allergen; carrot; IgE-binding; recombinant allergen

Document Type: Research article

DOI: 10.1046/j.1365-2222.1999.00529.x

Affiliations: 1: Department of General and Experimental Pathology, University of Vienna, 2: Ernst Böhringer Institute, Vienna, 3: Institute of Applied Microbiology, University of Agricultural Sciences, Vienna, Austria

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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