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Hypoallergenic variant of the major egg white allergen gal d 1 produced by disruption of cysteine bridges

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Version 2 2024-06-03, 12:45
Version 1 2017-04-07, 12:52
journal contribution
posted on 2024-06-17, 22:58 authored by P Dhanapala, D Withanage-Dona, MLK Tang, T Doran, Cenk SuphiogluCenk Suphioglu
BACKGROUND: Gal d 1 (ovomucoid) is the dominant allergen in the chicken egg white. Hypoallergenic variants of this allergen can be used in immunotherapy as an egg allergy treatment approach. We hypothesised that disruption of two of the nine cysteine-cysteine bridges by site-directed mutagenesis will allow the production of a hypoallergenic variant of the protein; Methods: Two cysteine residues at C192 and C210 in domain III of the protein were mutated to alanine using site-directed mutagenesis, to disrupt two separate cysteine-cysteine bridges. The mutated and non-mutated proteins were expressed in Escherichia coli (E. coli) by induction with isopropyl β-d-1-thiogalactopyranoside (IPTG). The expressed proteins were analysed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting to confirm expression. Immunoglobulin E (IgE) reactivity of the two proteins was analysed, by immunoblotting, against a pool of egg-allergic patients' sera. A pool of non-allergic patients' sera was also used in a separate blot as a negative control; Results: Mutant Gal d 1 showed diminished IgE reactivity in the immunoblot by showing lighter bands when compared to the non-mutated version, although there was more of the mutant protein immobilised on the membrane when compared to the wild-type protein. The non-allergic negative control showed no bands, indicating an absence of non-specific binding of secondary antibody to the proteins; Conclusion: Disruption of two cysteine bridges in domain III of Gal d 1 reduces IgE reactivity. Following downstream laboratory and clinical testing, this mutant protein can be used in immunotherapy to induce tolerance to Gal d 1 and in egg allergy diagnosis.

History

Journal

Nutrients

Volume

9

Article number

ARTN 171

Pagination

1 - 11

Location

Switzerland

Open access

  • Yes

ISSN

2072-6643

eISSN

2072-6643

Language

English

Publication classification

C Journal article, C1 Refereed article in a scholarly journal

Copyright notice

2017, by the authors

Issue

2

Publisher

MDPI