Covalent polyphenol modification of a reactive cysteine in the major apple allergen Mal d 1. (1st June 2023)

• Record Type: Journal Article
• Authors: Unterhauser, Jana; Ahammer, Linda; Rainer, Tobias; Eidelpes, Reiner; Führer, Sebastian; Nothegger, Bettina; Covaciu, Claudia E.; Cova, Valentina; Kamenik, Anna S.; Liedl, Klaus R.; Müller, Thomas; Breuker, Kathrin; Eisendle, Klaus; Reider, Norbert; Letschka, Thomas; Tollinger, Martin
• Is Part Of: Food chemistry. Volume 410(2023)
• Publication Date: 2023-06-01
• Subjects: CSP chemical shift perturbation -- ELISA Enzyme-Linked Immunosorbent Assay -- ESI electrospray ionization -- FT-ICR Fourier-transform ion cyclotron resonance -- IgE Immunoglobulin E -- MTSL (2, 2, 5, 5-tetramethyl-2, 5-dihydro-1H-pyrrol-3-yl)methylmethanesulfonothiolate -- PPO polyphenol oxidase -- PRE paramagnetic relaxation enhancement -- PR-10 pathogenesis-related protein 10; Chlorogenic acid -- Chemical modification -- Mass spectrometry -- Three-dimensional structure -- Antigen binding epitope; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2022.135374
• Languages: English
• ISSNs: 0308-8146

Abstract

Graphical abstract: Highlights: Mal d 1 is prone to spontaneous covalent modification by polyphenols. A surface-exposed cysteine residue in Mal d 1 is the primary modification site. Covalent modification does not perturb or unfold the three-dimensional structure. An immunorelevant binding epitope on the allergen surface is masked. Abstract: Naturally occurring polyphenols can modify the molecular properties of food allergens. For the major apple allergen Mal d 1 it has been postulated that chemical reactions with polyphenols cause permanent changes in the tertiary structure, causing a loss of conformational IgE epitopes and reducing allergenicity. In our study, we investigated the effect that reactions with oxidized polyphenols have on the structure of Mal d 1 by mass spectrometry and NMR spectroscopy. We showed that a surface-exposed cysteine residue in this allergen spontaneously reacts with oxidized polyphenols under formation of a defined covalent adduct. Chemical modification of Mal d 1 did not destabilize or perturb the three-dimensional fold, nor did it interfere with ligand binding to its internal pocket. A structural model of the chemically modified apple allergen is presented, which reveals that the bound polyphenol partially covers a conformational IgE epitope on the protein surface.