Mapping conformational IgE epitopes of arginine kinase in Oratosquilla oratoria

Abstract

Arginine kinase (AK) is a major allergen found in Oratosquilla oratoria. However, the information about the formation of its conformational epitopes is limited. In this study, the three-dimensional structures of O. oratoria AK and eight conformational mimotopes were predicted using bioinformatic methods. All key amino acids of the predicted conformational mimotopes were individually deleted using site-directed mutagenesis, and changes in IgE-binding capacity were measured. Relative to native AK, the IgE-binding capacities of the three mutants were significantly reduced, confirming the presence of three conformational epitopes: O-AK-1, O-AK-2, and O-AK-3. Structural analyses indicated that the deletion of key residues induced subtle changes in secondary structure, surface hydrophobicity, and electrostatic potential, which may be responsible for localized structural distortions in the epitope regions. Furthermore, a comparison across shellfish species found that O-AK-1 and O-AK-2 were conserved within crustacean species and that O-AK-3 was conserved across crustaceans and mollusks. Overall, three conformational IgE epitopes were identified, and the deletion of key amino acids reduced IgE-binding capacity owing to localized structural alterations. The conserved epitopes suggest a potential molecular basis for cross-reactivity among shellfish. Collectively, these findings provide a foundation for epitope-based allergen-specific therapeutic strategies.

Keywords

Oratosquilla oratoria / Allergen / Arginine kinase / Conformational IgE epitope / Structure / Cross-reactivity

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