Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: REDUCING THE ALLERGENIC PROPERTIES OF PEANUTS

Location: Food Processing and Sensory Quality Research

Title: Identification and characterization of a hypoallergenic ortholog of Ara h 2.01.

Authors
item Ramos, Laura - UNIV. OF GEORGIA
item Huntley, James - NAT. CTR. GENOME RESEARCH
item MALEKI, SOHEILA
item Ozias-Akins, Peggy - UNIV. OF GEORGIA

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 29, 2008
Publication Date: February 1, 2009
Citation: Ramos, L.M., Huntley, J.J., Maleki, S.J., Ozias-Akins, P. 2009. Identification and characterization of a hypoallergenic ortholog of Ara h 2.01. Journal of Agricultural and Food Chemistry. 69(3):325-335.

Interpretive Summary: Peanut seeds can elicit allergy, becoming the most common cause of fatal food-induced reactions. Strict avoidance is the only effective means of dealing with peanut allergy. Ara h 2 has been identified as the most potent peanut allergen recognized by approximately 90% of peanut hypersensitive individuals in the U.S. The aim of this study was to use a gene-targeting method to search for variants of Ara h 2 genes in peanut, and to characterize the different forms found for potentially reduced allergenicity. Thirty types of wild type peanuts were screened. Computer modeling of the allergen structure was used to predict the possible impact of amino acid changes found with our screening method. Also, individual sera from peanut-sensitive patients were used to determine if the variant allergens identified in screening had reduced allergenic potential. Seven out of thirty with changes in the amino acid sequence of Ara h 2 were identified. The computer model of Ara h 2 structure predicted that the location and nature of amino acid variations was not anticipated to result in any major structural alterations in Ara h 2 protein. However, the Ara h 2 variety with a specific amino acid was found to have 56%-99% reduction in IgE-binding activity or potential allergenicity.

Technical Abstract: Peanut seeds can elicit type I allergy, becoming the most common cause of fatal food-induced anaphylactic reactions. Strict avoidance is the only effective means of dealing with peanut allergy. Ara h 2 has been identified as the most potent peanut allergen recognized by approximately 90% of peanut hypersensitive individuals in the U.S. The aim of this study was to use Ecotilling to search for variant alleles of Ara h 2 in a putative diploid progenitor of peanut, and to characterize different isoforms for potential hypoallergenicity. Thirty accessions of the wild diploid were screened by Ecotilling. Molecular modeling was used to predict the impact of amino acid changes. Individual sera from peanut-sensitive patients were used for immunoblotting. Seven out of thirty accessions with mutations in the open reading frame of Ara h 2 were identified. Five of eight point mutations were missense mutations. An Ara h 2 homology model was built. The location and nature of amino acid variation/mutation was not anticipated to result in any major conformational or structural alterations. However, the isoform with a polymorphism in epitope #7 (S73T) showed 56%-99% reduction in IgE-binding activity. This modification did not affect dominant regions responsible for T cell activation.

Last Modified: 9/10/2014