Inverse relation between structural flexibility and IgE reactivity of Cor a 1 hazelnut allergens

Abstract

A major proportion of allergic reactions to hazelnuts (Corylus avellana) are caused by immunologic cross-reactivity of IgE antibodies to pathogenesis-related class 10 (PR-10) proteins. Intriguingly, the four known isoforms of the hazelnut PR-10 allergen Cor a 1, denoted as Cor a 1.0401–Cor a 1.0404, share sequence identities exceeding 97% but possess different immunologic properties. In this work we describe the NMR solution structures of these proteins and provide an in-depth study of their biophysical properties. Despite sharing highly similar three-dimensional structures, the four isoforms exhibit remarkable differences regarding structural flexibility, hydrogen bonding and thermal stability. Our experimental data reveal an inverse relation between structural flexibility and IgE-binding in ELISA experiments, with the most flexible isoform having the lowest IgE-binding potential, while the isoform with the most rigid backbone scaffold displays the highest immunologic reactivity. These results point towards a significant entropic contribution to the process of antibody binding.

Structure and Zeatin Binding of the Peach Allergen Pru p 1

“…Moreover, NMR RD experiments show that this segment is rigid and structurally homogeneous in solution (Supporting Information Figure S7), irrespective of whether the internal cavity is loaded with the ligand cargo or not. This is noteworthy in light of a recent study of the major hazelnut allergens Cor a 1.04, which revealed that antibody IgE binding and structural flexibility of these PR-10 proteins are correlated . Structural flexibility might represent a critical determinant that relates ligand binding of PR-10 allergens to immunologic reactions …”

“…This is noteworthy in light of a recent study of the major hazelnut allergens Cor a 1.04, which revealed that antibody IgE binding and structural flexibility of these PR-10 proteins are correlated. 50 Structural flexibility might represent a critical determinant that relates ligand binding of PR-10 allergens to immunologic reactions. 51 …”

The Structural Flexibility of PR-10 Food Allergens

“…RD data contain quantitative information about the structural flexibility that occurs on the millisecond timescale on a per-residue basis [ 29 ]. As noted previously for PR-10 allergens from birch pollen and hazelnut, these proteins are remarkably flexible, with a significant portion of the backbone amides showing nonflat relaxation-dispersion curves [ 21 , 22 ]. Figure 3 A compares the backbone amide 15 N relaxation-dispersion amplitudes (ΔR 2,eff values) of the thirteen PR-10 proteins in this study, in detail.…”

“…The biophysical research on PR-10 allergens in the last decades has focused on ligand binding and structure elucidation by NMR spectroscopy or X-ray crystallography, and on understanding how the structural properties of these proteins are related to the observed allergenic behavior [ 16 ]. Only a few studies have addressed the structural flexibility of these proteins, which is a feature that may be related to the affinity of low-molecular-weight ligands binding to the internal cavity, and IgE binding to the outer surfaces of these proteins [ 21 , 22 , 23 , 24 ]. In this work, we provide a thorough and quantitative comparison of the structural flexibilities of 12 PR-10 food allergens from apple, hazelnut, peach, kiwi, peanut, and plum, along with—and in comparison to—the sensitizing birch-pollen allergen, as observed by solution NMR spectroscopy.…”

Microscale Thermophoresis Reveals Oxidized Glutathione as High-Affinity Ligand of Mal d 1

“…Dynamic protein structures may be important for an optimal configuration of epitope residues and the Fc RI cross-linkage [75,76]. Recently, a study of the hazelnut allergen Cor a 1.04 isoforms reported an inverse relation between the conformational flexibility and IgE binding [77]. The IgE reactivity correlated with the rigidification of the protein backbone, where the highest IgE binding was observed for Cor a 1.0401, with the most rigid backbone scaffold, whereas the lowest IgE binding potential was determined for the most structurally flexible isoform Cor a 1.0404.…”