The Structural Flexibility of PR-10 Food Allergens

• Published in: International journal of molecular sciences Vol. 23; no. 15; p. 8252
• Main Authors: Führer, Sebastian, Unterhauser, Jana, Zeindl, Ricarda, Eidelpes, Reiner, Fernández-Quintero, Monica L., Liedl, Klaus R., Tollinger, Martin
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 26-07-2022; MDPI
• Subjects: Allergens; Allergic reactions; Allergies; Amino acids; Antibodies; conformational breathing; Cross-reactivity; Dispersion; Flexibility; Food; Food allergies; Food sources; Helices; Homology; Immunoglobulin E; ligand binding; Ligands; NMR; NMR spectroscopy; Nuclear magnetic resonance; Pollen; protein flexibility; Protein structure; Proteins; relaxation dispersion; Shape; Spectroscopy; Spectrum analysis
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms23158252

PR-10 proteins constitute a major cause of food allergic reactions. Birch-pollen-related food allergies are triggered by the immunologic cross-reactivity of IgE antibodies with structurally homologous PR-10 proteins that are present in birch pollen and various food sources. While the three-dimensional structures of PR-10 food allergens have been characterized in detail, only a few experimental studies have addressed the structural flexibility of these proteins. In this study, we analyze the millisecond-timescale structural flexibility of thirteen PR-10 proteins from prevalent plant food sources by NMR relaxation-dispersion spectroscopy, in a comparative manner. We show that all the allergens in this study have inherently flexible protein backbones in solution, yet the extent of the structural flexibility appears to be strikingly protein-specific (but not food-source-specific). Above-average flexibility is present in the two short helices, α1 and α2, which form a V-shaped support for the long C-terminal helix α3, and shape the internal ligand-binding cavity, which is characteristic for PR-10 proteins. An in-depth analysis of the NMR relaxation-dispersion data for the PR-10 allergen from peanut reveals the presence of at least two subglobal conformational transitions on the millisecond timescale, which may be related to the release of bound low-molecular-weight ligands from the internal cavity.