Structure and Zeatin Binding of the Peach Allergen Pru p 1

Abstract

Peach ( Prunus persica ) is among the fruits most frequently reported to cause food allergies. Allergic reactions commonly result from previous sensitization to the birch pollen allergen Bet v 1, followed by immunological cross-reactivity of IgE antibodies to structurally related proteins in peach. In this study, we present the three-dimensional NMR solution structure of the cross-reactive peach allergen Pru p 1 (isoform Pru p 1.0101). This 17.5 kDa protein adopts the canonical Bet v 1 fold, composed of a seven-stranded β-sheet and three α-helices enclosing an internal cavity. In Pru p 1 , the inner surface of the cavity contains an array of hydroxyl-bearing amino acids surrounded by a hydrophobic patch, constituting a docking site for amphiphilic molecules. NMR-guided docking of the cytokinin molecule zeatin to the internal cavity of Pru p 1 provides a structure-based rationale for the effect that zeatin binding has on the protein’s RNase activity.

The Structural Flexibility of PR-10 Food Allergens

“…The compilation of the data presented here clearly illustrates that the structural flexibility in PR-10 allergens is not evenly distributed along the protein backbone. The glycine-rich loop, which has been identified as a cross-reactive IgE epitope in some of these allergens, is particularly rigid and highly conserved, and it has a conformation that is compatible with antibody binding [ 15 , 35 , 39 ]. This is contrasted by the C-terminal helix α3, in which the conformational flexibility is pronounced, and the variation in the primary sequence is high.…”

“…The tertiary fold of PR-10 proteins comprises a large internal cavity of a vastly variable size, with volumes up to ~4000 Å 3 [ 5 ]. While the cavity is, in large parts, formed by hydrophobic amino acids, several hydrophilic amino acids with hydrogen-bond donor/acceptor capacities confer a certain degree of amphiphilicity to its surface [ 15 ]. Entrances to the cavity are located between helix α3 and loops L3, L5, and L7 (ε1, the largest opening), and in some PR-10 proteins, between helix α3 and strand β1 (ε2) [ 5 , 16 ].…”

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

“…Other amino acid residues, such as Thr-10, Thr-57, Ser111, and Thr-112 were also found to play an important role in IgE binding of Mal d 1 [71,72]. In a preliminary study, the binding of zeatin to the PR-10 peach allergen Pru p 1 did not result in any conformational changes of the glycine-rich region [73]. The binding of deoxycholate was reported to stabilize Bet v 1 without modulating its conformational epitopes, suggesting that patients are normally exposed to both ligand-bound and unbound Bet v 1 during the sensitization phase [74].…”

Identification of Major B-Cell Linear Epitopes of Peach Allergen Pru p 3 Using Immune Slot-Blot Microarray Assay

“…It is usually accompanied by symptoms such as urticaria, oral allergic syndrome (OAS), and, in severe cases, shock or lifethreatening allergic reactions, which usually last for the rest of the patient's life. 4,5 Five food-borne allergen proteins including Pru p 1, Pru p 2, Pru p 3, Pru p 4, and Pru p 7 were found in peach. 6 Pru p 3 is the major peach allergen protein, which is derived from a family of nonspecific lipid transfer proteins (nsLTPs) that induce positive reactions in over 90% of peach-allergic patients.…”

“…Like other food allergies, peach allergy arises through ingestion, inhalation, or exposure to allergens. It is usually accompanied by symptoms such as urticaria, oral allergic syndrome (OAS), and, in severe cases, shock or life-threatening allergic reactions, which usually last for the rest of the patient’s life. , …”