Proteomic Screening Points to the Potential Importance of Ara h 3 Basic Subunit in Allergenicity of Peanut

Abstract

Peanuts are complex storage proteins with high contents and have been identified as one of the most allergenic foods. In this review, we summarize some of the latest findings and the potential importance of the Ara h 3 basic subunit, which has been overlooked as an allergen in early literature. Some recent studies indicate that Ara h 3 basic subunit may be as significant as or even a more important allergen than the acidic subunit. For example, one clinical study found a group of children with peanut allergy who were specifically sensitized to the basic subunit of Ara h 3. Although, proteomic analysis of total peanut storage proteins has revealed limited polymorphic profiles of major proteins in diverse peanut germplasm accessions, a study reported a peanut breeding line 'GT-C9' lacking several seed protein peptides, in which the missed major proteins were basic subunits of Ara h 3. This breeding line was shown to exhibit significantly lower levels of advanced glycation end (AGE) products and IgE binding by the sera of peanut allergic patients, which implies a role for the basic subunit of Ara h 3 in the allergenicity of peanuts. Further studies are needed to investigate the contribution of Ara h 3 basic subunits to peanut allergenicity.

Influence of Enzymatic Hydrolysis on the Allergenicity of Roasted Peanut Protein Extract

“…This finding was not in agreement with previous studies [24] indicating that allergenic epitopes occurred only in the acidic Ara h 3 subunit. However, other studies [25,26,27] have shown that Ara h 3 basic subunits may be important allergenic peptides. The resistance of the 11S globulin basic subunit to enzymatic hydrolysis has been reported previously in soybeans [28].…”

Can we explain the allergenicity of peanuts on the basis of the three-dimensional structure of its allergens and use the information to devise means of eliminating peanut allergy?

“…There are three independently determined sequences for the less-allergenic isoform of Ara h 3 (GenBank Entries AAT39430 [7], ABI17154 [14], and ADQ53859 [15]). This strongly suggests that the existence of this isoform is not uncommon.…”

The Molecular Basis of Peanut Allergy

“…This cleavage appears to be required for hexamer formation as this loop needs to be removed for the two trimers to form the hexameric interface. The two cupin domains are known as the acidic and basic subunit and can be readily separated by isolectric focusing [19]. Certain cultivars of peanuts lacking the basic subunit of Ara h 3 have been studied as potentially less allergenic [20].…”