Molecular cloning and epitope analysis of the peanut allergen Ara h 3
Pat Rabjohn, … , A. Wesley Burks, Gary A. Bannon
Pat Rabjohn, … , A. Wesley Burks, Gary A. Bannon
Published February 15, 1999
Citation Information: J Clin Invest. 1999;103(4):535-542. https://doi.org/10.1172/JCI5349.
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Article

Molecular cloning and epitope analysis of the peanut allergen Ara h 3

Abstract

Peanut allergy is a significant IgE-mediated health problem because of the increased prevalence, potential severity, and chronicity of the reaction. Following our characterization of the two peanut allergens Ara h 1 and Ara h 2, we have isolated a cDNA clone encoding a third peanut allergen, Ara h 3. The deduced amino acid sequence of Ara h 3 shows homology to 11S seed-storage proteins. The recombinant form of this protein was expressed in a bacterial system and was recognized by serum IgE from ∼45% of our peanut-allergic patient population. Serum IgE from these patients and overlapping, synthetic peptides were used to map the linear, IgE-binding epitopes of Ara h 3. Four epitopes, between 10 and 15 amino acids in length, were found within the primary sequence, with no obvious sequence motif shared by the peptides. One epitope is recognized by all Ara h 3–allergic patients. Mutational analysis of the epitopes revealed that single amino acid changes within these peptides could lead to a reduction or loss of IgE binding. By determining which amino acids are critical for IgE binding, it might be possible to alter the Ara h 3 cDNA to encode a protein with a reduced IgE-binding capacity. These results will enable the design of improved diagnostic and therapeutic approaches for food-hypersensitivity reactions.

Authors

Pat Rabjohn, Erica M. Helm, J. Steven Stanley, C. Michael West, Hugh A. Sampson, A. Wesley Burks, Gary A. Bannon

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Figure 1

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Nucleotide sequence of an Ara h 3 cDNA clone. The nucleotide sequence is...
Nucleotide sequence of an Ara h 3 cDNA clone. The nucleotide sequence is on the second line. The first line is the derived amino acid sequence. Boxed amino acids correspond to the amino acid sequence determined from the NH2-terminus of the Ara h 3 protein. The numbers on the right side of the figure indicate the position of the nucleotide sequence relative to the first nucleotide in the insert. The numbers on the left side of the figure indicate the position of the amino acid sequence relative to the first determined amino acid from the protein. The underlined amino acids are found at the NH2-terminal end of the Ara h 3 protein, but are not encoded by the cDNA clone. The stop codon TAA is indicated by an asterisk. Ara h 3 GenBank accession no. AF093541.