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The cross‐reactive calcium‐binding pollen allergen, Phl p 7, reveals a novel dimer assembly
Author(s) -
Verdino Petra,
Westritschnig Kerstin,
Valenta Rudolf,
Keller Walter
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdf526
Subject(s) - biology , allergen , dimer , calcium , pollen , botany , immunology , allergy , medicine , physics , nuclear magnetic resonance
The timothy grass pollen allergen Phl p 7 assembles most of the IgE epitopes of a novel family of 2 EF‐hand calcium‐binding proteins and therefore represents a diagnostic marker allergen and vaccine candidate for immunotherapy. Here we report the first three‐dimensional structure of a representative of the 2 EF‐hand allergen family, Phl p 7, in the calcium‐bound form. The protein occurs as a novel dimer assembly with unique features: in contrast to well known EF‐hand proteins such as calmodulin, parvalbumin or the S100 proteins, Phl p 7 adopts an extended conformation. Two protein monomers assemble in a head‐to‐tail arrangement with domain‐swapped EF‐hand pairing. The intertwined dimer adopts a barrel‐like structure with an extended hydrophobic cavity providing a ligand‐binding site. Calcium binding acts as a conformational switch between an open and a closed dimeric form of Phl p 7. These findings are interesting in the context of lipid‐ and calcium‐dependent pollen tube growth. Furthermore, the structure of Phl p 7 allows for the rational development of vaccine strategies for treatment of sensitized allergic patients.