Calcium-dependent immunoglobulin E recognition of the apo- and calcium- bound form of a cross-reactive two EF-hand timothy grass pollen allergen, Phl p 7

Verena Niederberger, Brigitte Hayek, Susanne Vrtala, Sylvia Laffer, Anna Twardosz, Luca Vangelista, Wolfgang R. Sperr, Peter Valent, Helmut Rumpold, Dietrich Kraft, Klaus Ehrenberger, Rudolf Valenta, Susanne Spitzauer

Research output: Contribution to journalArticlepeer-review

92 Citations (Scopus)


Type I allergy, an immunodisorder that affects almost 20% of the population worldwide, is based on the immunoglobulin E (IgE) recognition of per se innocuous antigens (allergens). Pollen from wind-pollinated plants belong to the most potent allergen sources. We report the isolation of a cDNA coding for a 8.6 kDa two EF-hand calcium binding allergen, Phl p 7, from a timothy grass (Phleum pratense) pollen expression cDNA library, using serum IgE from a grass pollen allergic patient. Sequence analysis identified Phl p 7 as a member of a recently discovered subfamily of pollen-specific calcium binding proteins. Recombinant Phl p 7 was expressed in Escherichia coli and purified to homogeneity as determined by mass spectroscopy. Approximately 10% of pollen allergic patients displayed IgE reactivity to rPhl p 7 and Phl p 7- homologous allergens present in pollens of monocotyledonic and dicotyledonic plants. Circular dichroism analysis of the calcium-bound and apo-rPhl p 7 indicated that differences in IgE recognition may be due to calcium-induced changes in the protein conformation. The fact that patients mount IgE antibodies against different protein conformations is interpreted as a footprint of a preferential sensitization against either form. The biological activity of rPhl p 7 was demonstrated by its ability to induce basophil histamine release and immediate type skin reactions in sensitized individuals. In conclusion, IgE binding to Phl p 7 represents an example for the conformation-dependent IgE recognition of an allergen. Recombinant Phl p 7 may be used for diagnosis and perhaps treatment of a group of patients who suffer from allergy to pollens of many unrelated plant species.

Original languageEnglish
Pages (from-to)843-856
Number of pages14
JournalFASEB Journal
Issue number8
Publication statusPublished - Jan 1 1999


  • Allergen
  • Circular dichroism spectroscopy
  • Conformational epitopes
  • Cross-reactivity
  • EF-hand protein
  • Pollen-specific expression
  • Type I allergy

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics

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