cDNA Cloning and Sequencing Reveal the Major Horse Allergen Equ c1 to Be a Glycoprotein Member of the Lipocalin Superfamily

Grégoire, Christophe; Rosinski‐Chupin, Isabelle; Rabillon, J.; Alzari, Pedro M.; David, B.; Dandeu, J P

doi:10.1074/jbc.271.51.32951

Cited by 87 publications

(77 citation statements)

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“…Crystallization and Data Collection-Protein expression, purification, and crystallization of recombinant sublingual gland (rSLG) Equ c 1 have been previously described (3,4). Briefly, rSLG Equ c 1 was expressed as a His-tagged protein in Escherichia coli, purified by metalion affinity chromatography, treated with factor Xa to excise the His tag, and concentrated to 6.0 mg/ml for crystallization.…”

Section: Methodsmentioning

confidence: 99%

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Crystal Structure of the Allergen Equ c 1

Lascombe¹,

Grégoire²,

Poncet³

et al. 2000

Journal of Biological Chemistry

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The three-dimensional structure of the major horse allergen Equ c 1 has been determined at 2.3 Å resolution by x-ray crystallography. Equ c 1 displays the typical fold of lipocalins, a ␤-barrel flanked by a C-terminal ␣-helix. The space between the two ␤-sheets of the barrel defines an internal cavity that could serve, as in other lipocalins, for the binding and transport of small hydrophobic ligands. Equ c 1 crystallizes in a novel dimeric form, which is distinct from that observed in other lipocalin dimers and corresponds to the functional form of the allergen. Binding studies of point mutants of the allergen with specific monoclonal antibodies raised in mouse and IgE serum from horse allergic patients allowed to identify putative B cell antigenic determinants. In addition, total inhibition of IgE serum recognition by a single specific monoclonal antibody revealed the restricted nature of the IgE binding target on the molecular surface of Equ c 1.The incidence of allergic diseases is increasing in developed countries resulting from growing exposure to allergens, altered stimulation of the immune system during development, and probably facilitating an adjuvant effect of the environment. Allergy to animals is distinguishable by its intensity and the possibility of sensitization by a limited contact with danders or hair. The animals responsible for allergy are obviously familiar domestic cats and dogs, but also the horse, which is often incriminated. Five main horse allergens have been isolated and purified (1, 2). Among these, the Equ c 1 protein (molecular mass 21.5 kDa, 187 amino acids, pI ϭ 4.5) has been defined as a major allergen, because it induces an IgE-mediated type I allergic reaction in a majority of the patients allergic to horses.Equ c 1 belongs to the lipocalin family (3, 4). Although members of this family display low sequence similarity (often lower than 20% of amino acid identities), all share a conserved folding pattern, an 8-stranded ␤-barrel flanked by an ␣-helix at the C-terminal end of the polypeptide chain. The lipocalin ␤-barrel often defines a central apolar cavity that serves for the binding and transport of small hydrophobic molecules such as retinol (retinol-binding protein (5, 6)), odorant molecules (bovine odorant-binding protein (7, 8)), or pheromones (mouse major urinary protein, mMUP 1 (9), and rat urinary ␣2-globulin (10)). Several lipocalins have been described as allergenic proteins, among which the mouse major urinary protein mMUP (11), rat urinary ␣2-globulin rat urinary ␣2-globulin (12), bovine ␤-lactoglobulin (13), cockroach allergen Bla g 4 (14), dog allergens Can f 1 and Can f 2 (15), and bovine allergen Bos d 2 (16).Whether a protein exhibits special structural characteristics that are responsible for its allergenic properties is an issue that remains poorly understood. Although the three-dimensional structures of some allergenic lipocalins are known (mMUP (9), rat urinary ␣2-globulin (10), bovine ␤-lactoglobulin (17, 18), and Bos d 2 (19)), little information is availa...

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Section: Methodsmentioning

confidence: 99%

“…Equ c 1 belongs to the lipocalin family (3,4). Although members of this family display low sequence similarity (often lower than 20% of amino acid identities), all share a conserved folding pattern, an 8-stranded ␤-barrel flanked by an ␣-helix at the C-terminal end of the polypeptide chain.…”

mentioning

confidence: 99%

Crystal Structure of the Allergen Equ c 1

Lascombe¹,

Grégoire²,

Poncet³

et al. 2000

Journal of Biological Chemistry

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“…The allergens are found in the mane, transpiration and urine. The major allergen of horse dander is Equ c1 (455,456). Cross-sensitization can sometimes be found with other equidae (pony, mule, donkey and zebra) and with cat, dog and guinea pig albumins.…”

Section: Other Mitesmentioning

confidence: 99%

Allergic Rhinitis and its Impact on Asthma (ARIA) 2008*

Bousquet¹,

Khaltaev²,

Cruz³

et al. 2008

Allergy

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“…In recent years, a number of allergens have been identified that stimulate IgE production and cause IgEmediated disease (6)(7)(8)(9). Although considerable information exists on the identification, purification, and cloning of inhaled allergens (pollens, dust mites, animal danders, insects, and fungi), few food allergens have been identified and studied.…”

Section: Introductionmentioning

confidence: 99%