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Title: Structural analysis of the endogenous glycoallergen Hev b 2 (endo-β-1,3-glucanase) from Hevea brasiliensis and its recognition by human basophils

This study describes the three-dimensional structure of the endogenous glycosylated allergen Hev b 2 (endo-β-1,3-glucanase), which exhibits three post-translational modifications that form a patch on the surface of the molecule that is proposed to be an allergenic IgE epitope. 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 Hevmore » 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.« less
Authors:
; ;  [1] ;  [2] ; ;  [3] ;  [4] ;  [5]
  1. Universidad Nacional Autónoma de México, Circuito Exterior, CU, 04310 Coyoacán, DF (Mexico)
  2. Universidad Nacional Autónoma de México, Apartado Postal 510-3, 62250 Cuernavaca, MOR (Mexico)
  3. Centro Médico Nacional Siglo XXI, IMSS, Avenida Cuauhtémoc 330, Colonia Doctores, Mexico, DF (Mexico)
  4. Instituto Nacional de Pediatría, Insurgentes Sur 3700C, 04530 Cuicuilco, DF (Mexico)
  5. (Mexico)
Publication Date:
OSTI Identifier:
22351309
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Crystallographica. Section D: Biological Crystallography; Journal Volume: 70; Journal Issue: Pt 2; Other Information: PMCID: PMC3940204; PMID: 24531467; PUBLISHER-ID: mn5038; OAI: oai:pubmedcentral.nih.gov:3940204; Copyright (c) International Union of Crystallography 2014; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
Denmark
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTALS; DIMERS; LATEX; MICROSCOPY; MODIFICATIONS; MOLECULES; REACTIVITY; SURFACES