Mutational epitope analysis of Pru av 1 and Api g 1, the major allergens of cherry (Prunus avium) and celery (Apium graveolens): correlating IgE reactivity with three-dimensional structure.
Birch pollinosis is often accompanied by adverse reactions to food due to pollen-allergen specific IgE cross-reacting with homologous food allergens. The tertiary structure of Pru av 1, the major cherry (Prunus avium) allergen, for example, is nearly identical with Bet v 1, the major birch (Betula verrucosa) pollen allergen. In order to define cross-reactive IgE epitopes, we generated and analysed mutants of Pru av 1 and Api g 1.0101, the major celery (Apium graveolens) allergen, by immunoblotting, EAST (enzyme allergosorbent test), CD and NMR spectroscopy. The mutation of Glu45 to Trp45 in the P-loop region, a known IgE epitope of Bet v 1, significantly reduced IgE binding to Pru av 1 in a subgroup of cherry-allergic patients. The backbone conformation of Pru av 1 wild-type is conserved in the three-dimensional structure of Pru av 1 Trp45, demonstrating that the side chain of Glu45 is involved in a cross-reactive IgE epitope. Accordingly, for a subgroup of celery-allergic patients, IgE binding to the homologous celery allergen Api g 1.0101 was enhanced by the mutation of Lys44 to Glu. The almost complete loss of IgE reactivity to the Pru av 1 Pro112 mutant is due to disruption of its tertiary structure. Neither the mutation Ala112 nor deletion of the C-terminal residues 155-159 influenced IgE binding to Pru av 1. In conclusion, the structure of the P-loop partially explains the cross-reactivity pattern, and modulation of IgE-binding by site-directed mutagenesis is a promising approach to develop hypo-allergenic variants for patient-tailored specific immunotherapy.
Neudecker
Philipp
P
Lehrstuhl für Biopolymere, Universitaet Bayreuth, Universitätsstrasse 30, 95440 Bayreuth, Germany. philipp.neudecker@uni-bayreuth.de
Lehmann
Katrin
K
Nerkamp
Jörg
J
Haase
Tanja
T
Wangorsch
Andrea
A
Fötisch
Kay
K
Hoffmann
Silke
S
Rösch
Paul
P
Vieths
Stefan
S
Scheurer
Stephan
S
D000485:Allergens / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D052179:Antigens, Plant; D004252:DNA Mutational Analysis; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D005512:Food Hypersensitivity / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D011487:Protein Conformation; D027861:Prunus / Q000276:immunology; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D016415:Sequence Alignment
D000485:Allergens; D000911:Antibodies, Monoclonal; D052179:Antigens, Plant; C096695:Api g 1 protein, Apium graveolens; D000939:Epitopes; D010940:Plant Proteins; C479400:Pru av 1 allergen, Prunus avium; D011994:Recombinant Proteins; D007073:Immunoglobulin E