NMR spectroscopy reveals common structural features of the birch pollen allergen Bet v 1 and the cherry allergen Pru a 1

A high percentage of birch pollen allergic patients also experience food hy persensitivity which results from common epitopes on the corresponding alle rgens. In order to analyze whether this observed cross-reactivity can be at tributed to common structural features, the major birch pollen allergen Bet v 1 and the cherry allergen Pru a I were investigated by multidimensional heteronuclear nuclear magnetic resonance (NMR) spectroscopy. For the 17 kDa Bet v 1 a three-dimensional structure was calculated on the basis of 1344 experimental restraints. The structure is well defined showing average root mean square deviations of 0.67 and 1.15 Angstrom for the backbone heavy at oms and all heavy atoms of residues 1-154, respectively. The major structur al features include a seven-stranded antiparallel beta-sheet that wraps aro und a long C-terminal alpha-helix, thereby forming a large cavity in the in terior of the protein. This structure served as template for the generation of an NMR-based model of Pru a 1 by homology modelling in conjunction with 277 experimentally derived distance restraints. Comparison to the structur e of Bet v 1 proves both structures to be highly similar concerning the ele ments of secondary structure as well as the shape and charge distribution o f the protein surface. This finding is consistent with the observed cross-r eactivity between both proteins and allows the delineation of common cross- reactive B-cell epitopes.