Asp159 is a critical core amino acid of an IgE-binding and cross-reactive epitope of a dust mite allergen Der f 7

Mol Immunol. 2011 Sep;48(15-16):2130-4. doi: 10.1016/j.molimm.2011.07.004. Epub 2011 Aug 5.


Der f 7 and Der p 7 are important house dust mite allergens with known structure and suggested biological function recently. However, their IgE-binding determinants remain unknown. The purpose of this study is to identify the IgE-reactive epitopes of Der f 7 and the determinants of IgE-mediated cross-reactivity between Der f 7 and Der p 7. IgE-reactive determinants were identified by immunodot blot inhibition using synthetic overlapping peptides, allergen mutants, and a Der f 7 structural model. Our results showed that synthetic peptides with sequence (156)SILDP(160) on Der f 7 bind IgE in two of the 30 asthmatic serum samples tested. Recombinant Der f 7 I157A, L158A, or D159A mutants have reduced IgE-binding activity. Inhibition experiments confirmed Asp159 as a critical core residue for IgE-binding. Among Der p 7, Der f 7 and Der f 7 mutants with single substitution between residues 156 and 160, only the D159A mutant cannot inhibit significantly IgE-binding against Der p 7. Therefore, Asp159 contributes to IgE-mediated cross-reactivity between Der f 7 and Der p 7. The structural model constructed for Der f 7 suggests that the IgE-binding epitope forms a loop-like structure on the surface of the molecule. In conclusion, Asp 159 is a critical core residue of an IgE-binding and IgE-mediated cross-reactive epitope (156)SILDP(160) of Der f 7. Results obtained from this study provide more information on molecular and structural features related to allergenicity, underlying basis of IgE cross-reactivity between allergens, and in designing safer immunotherapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Dermatophagoides / chemistry*
  • Antigens, Dermatophagoides / genetics
  • Antigens, Dermatophagoides / immunology
  • Arthropod Proteins
  • Aspartic Acid / chemistry*
  • Aspartic Acid / immunology
  • Base Sequence
  • Cross Reactions / immunology
  • Epitope Mapping
  • Epitopes, B-Lymphocyte / chemistry*
  • Epitopes, B-Lymphocyte / genetics
  • Epitopes, B-Lymphocyte / immunology
  • Humans
  • Immunoblotting
  • Immunoglobulin E / immunology*
  • Models, Molecular*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Mutation
  • Protein Conformation


  • Antigens, Dermatophagoides
  • Arthropod Proteins
  • Dermatophagoides farinae antigen f 7
  • Dermatophagoides pteronyssinus antigen p 7
  • Epitopes, B-Lymphocyte
  • Aspartic Acid
  • Immunoglobulin E