title: Fish β-parvalbumin acquires allergenic properties by amyloid assembly.
abstract: BACKGROUND
  Amyloids are highly cross-β-sheet-rich aggregated states that confer protease resistance, membrane activity and multivalence properties to proteins, all essential features for the undesired preservation of food proteins transiting the gastrointestinal tract and causing type I allergy.
  
  
  METHODS
  Amyloid propensity of β-parvalbumin, the major fish allergen, was theoretically analysed and assayed under gastrointestinal-relevant conditions using the binding of thioflavin T, the formation of sodium dodecyl sulphate- (SDS-) resistant aggregates, circular dichroism spectroscopy and atomic force microscopy fibril imaging. Impact of amyloid aggregates on allergenicity was assessed with dot blot.
  
  
  RESULTS
  Sequences of β-parvalbumin from species with commercial value contain several adhesive hexapeptides capable of driving amyloid formation. Using Atlantic cod β-parvalbumin (rGad m 1) displaying high IgE cross-reactivity, we found that formation of amyloid fibres under simulated gastrointestinal conditions accounts for the resistance to acid and neutral proteases, for the presence of membrane active species under gastrointestinal relevant conditions and for the IgE-recognition in the sera of allergic patients. Incorporation of the anti-amyloid compound epigallocatechin gallate prevents rGad m 1 fibrillation, facilitates its protease digestion and impairs its recognition by IgE.
  
  
  CONCLUSIONS
  the formation of amyloid by rGad m 1 explains its degradation resistance, its facilitated passage across the intestinal epithelial barrier and its epitope architecture as allergen.
authors.affiliation: Instituto Química-Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Martínez
authors.affiliation: Instituto Química-Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Sánchez
authors.affiliation: Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Milagros
authors.initials: M
authors.lastname: Castellanos
authors.affiliation: Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Fernández-Escamilla
authors.affiliation: Allergy Department, Hospital Clínico San Carlos, IdISSC, Madrid, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Vázquez-Cortés
authors.affiliation: Allergy Department, Hospital Clínico San Carlos, IdISSC, Madrid, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Fernández-Rivas
authors.affiliation: Instituto Química-Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Gasset
mesh_terms: D000682:Amyloid / Q000096:biosynthesis* / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D003429:Cross Reactions / Q000276:immunology; D019286:Endopeptidase K / Q000378:metabolism; D029941:Fish Proteins / Q000737:chemistry* / Q000276:immunology*; D005399:Fishes / Q000276:immunology; D005512:Food Hypersensitivity / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000737:chemistry / Q000276:immunology*; D010320:Parvalbumins / Q000737:chemistry* / Q000276:immunology*; D010434:Pepsin A / Q000378:metabolism; D017747:Seafood / Q000009:adverse effects*
chemical_list: D000682:Amyloid; D029941:Fish Proteins; D010320:Parvalbumins; D007073:Immunoglobulin E; D002392:Catechin; C045651:epigallocatechin gallate; D019286:Endopeptidase K; D010434:Pepsin A