Open AccessStructural analysis of the endogenous glycoallergen Hev b 2 (endo‐β‐1,3‐glucanase) from Hevea brasiliensis and its recognition by human basophils
Author(s) -
RodríguezRomero Adela,
HernándezSantoyo Alejandra,
FuentesSilva Deyanira,
Palomares Laura A.,
MuñozCruz Samira,
YépezMulia Lilian,
OrozcoMartínez Socorro
Publication year - 2014
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s1399004713027673
Subject(s) - epitope , degranulation , immunoglobulin e , hevea brasiliensis , basophil activation , chemistry , biochemistry , glycosylation , antibody , glycan , allergen , basophil , biology , immunology , glycoprotein , allergy , natural rubber , receptor , organic chemistry
Endogenous glycosylated Hev b 2 (endo‐β‐1,3‐glucanase) from Hevea brasiliensis is an important latex allergen that is recognized by IgE antibodies from patients who suffer from latex allergy. The carbohydrate moieties of Hev b 2 constitute a potentially important IgE‐binding epitope that could be responsible for its cross‐reactivity. Here, the structure of the endogenous isoform II of Hev b 2 that exhibits three post‐translational modifications, including an N‐terminal pyroglutamate and two glycosylation sites at Asn27 and at Asn314, is reported from two crystal polymorphs. These modifications form a patch on the surface of the molecule that is proposed to be one of the binding sites for IgE. A structure is also proposed for the most important N ‐glycan present in this protein as determined by digestion with specific enzymes. To analyze the role of the carbohydrate moieties in IgE antibody binding and in human basophil activation, the glycoallergen was enzymatically deglycosylated and evaluated. Time‐lapse automated video microscopy of basophils stimulated with glycosylated Hev b 2 revealed basophil activation and degranulation. Immunological studies suggested that carbohydrates on Hev b 2 represent an allergenic IgE epitope. In addition, a dimer was found in each asymmetric unit that may reflect a regulatory mechanism of this plant defence protein.