Molecular and Functional Analysis of Soybean Allergen Proteins with a Focus on Pollen-Food Syndrome

Gly m 3 and Gly m 4 are major soybean food allergens, causing birch pollen cross-allergic reactions, particularly with Bet v 1 and Bet v 2. These allergens can mediate anaphylactic reactions; however, the causative factors are still unknown. The goals of this comparative study are to characterize (A) the structural functionality of Gly m allergens of Glycine max and Bet v allergens of Betula pendula form birch, with a focus on their immunological properties, and (B) the molecular mechanisms of cross-allergenicity involved in pollen-food syndrome. This was achieved by extensive analysis using different molecular computer-aided approaches covering (1) physicochemical properties and functional-regulatory motifs, (2) sequence analysis, 2D and 3D structural homology modeling comparative study, (3) conservational and evolutionary analysis, (4) identification of B-cell epitopes based on sequence and structure-docking, while T-cell epitopes were identified by inhibitory concentration and binding score methods. Thus, we found that particular epitopes, in addition to the conserved ones, could be responsible for eliciting cross-reactivity between Bet v 1 and Bet v 2, and their respective homolog allergens proteins found in soybean. Moreover, variable epitopes were present in the Gly m 4 and Gly m 3 structures, which may be also responsible for this causative cross-allergenicity between soybean seed and birch pollen proteins.