Enhanced Pru p 3 IgE-binding activity by selective free fatty acid-interaction

Abstract

interaction with pruritogens, including SP and compound 48/80, we evaluated LL-37-induced itch using the mouse cheek model. As opposed to pruritogens, which induce scratching in this model, LL-37 does not induce scratching (see Fig E8 in this article's Online Repository at www.jacionline.org).The data presented here demonstrate that SP and compound 48/ 80 activate native Mrgprs but fail to activate Mrgprs in which a single amino acid residue was mutated. In contrast, LL-37 activates both native receptor and mutant receptors. This finding indicates that the site(s) of Mrgpr activation for the pruritogens SP and compound 48/80 differs from the activation site(s) for LL-37. Furthermore, an Mrgpr antagonist, QWF, 2 inhibits the interaction of SP and compound 48/80 with MRGPRX2 but not that between LL-37 and the receptor.These findings have several implications. First, they reveal that the Glu and Asn residues at the end of the fourth TMD and beginning of the fourth extracellular loop of Mrgprs are necessary for the interaction of SP and compound 48/80 with members of this receptor family. Second, not all compounds that activate Mrgprs or induce mast-cell degranulation result in itch. It is possible that LL-37 may interact with other cells such as keratinocytes and additional receptors to induce the release of molecules with antipruritic properties such as semaphorin 3A. 11 Another possibility is that activation of MRGPRX2 on mast cells by SP versus LL-37 may result in differential release of granules and their associated mediators from mast cells. Third, at least some Mrgprs appear to have more than 1 site for signaling followed by distinct behavioral effects. Fourth, although MrgprB2 has been proposed as the mouse ortholog of human MRGPRX2, modeling demonstrates that mouse MrgprA1 and human MRGPRX2 also exhibit topological similarities (see Fig E9 in this article's Online Repository at www.jacionline.org). Taken together, these data provide further support for the possibility that antagonists of MRGPRX2 may be useful for the treatment of itch and inflammation while providing guidance with respect to the development of receptor antagonists.

Impact of lipid binding on the tertiary structure and allergenic potential of Jug r 3, the non-specific lipid transfer protein from walnut

“…Although tertiary structures of some nsLTPs have already been resolved, there is still a lack of experimental knowledge regarding the impact of ligands on the protein 3D structure. Since it has been shown that the ligand binding specificity can vary among protein family members 10,20 and that this is an important factor regarding nsLTP allergenicity 30 , we investigated the ligand binding ability of the major allergen from walnut, Jug r 3. We also investigated the interaction of Jug r 3 with OLE by NMR technique and an in silico docking program to model the Jug r 3-OLE complex.…”

“…It has been shown that the interaction between free fatty acids and nsLTPs affects the local conformation of the protein 29 . We have recently demonstrated that in Pru p 3 such interactions increase also the allergenic potential of the protein 30 . However, experimental structural data on the atomic level remained limited.…”

Interaction of Non-Specific Lipid-Transfer Proteins With Plant-Derived Lipids and Its Impact on Allergic Sensitization

“…Of note, unsaturated FA (oleic, linoleic, and elaidic acid) and short chain saturated lauric acid (C12) were confirmed to bind to Pru p 3 by 1,8-ANS-competition assays ( 31 ). Binding of oleic but not stearic acid (saturated C18) increased IgE-reactivity and basophil activation by conformational changes.…”

“…In summary, several FAs, likewise saturated lauric acid and unsaturated oleic acid ( 31 ) as well as palmitic acid ( 29 ), and phytosphingosine ( 33 ) were described as ligands for Pru p 3 (Table 1 ). The conjugation of lipids to nsLTPs may influence the IgE-binding capacity by structural modification of allergens ( 31 ). So far, the effect of lipids on the stability of allergens is discussed controversially.…”

iNEXT: a European facility network to stimulate translational structural biology

“…Understanding how to reduce side effects during immunotherapy is a highly relevant topic which was addressed by a research group from the Medical University of Vienna . In particular, the work focused on the characterization by NMR, at the CERM facility, of the lipid binding properties of the major peach allergen named Pru p 3, providing evidence that upon ligand binding, the allergen undergoes local structural changes which modulate its allergenic activity.…”