Allergenic relevance of nonspecific lipid transfer proteins 2: Identification and characterization of Api g 6 from celery tuber as representative of a novel IgE-binding protein family
Article first published online: 5 AUG 2013
© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Molecular Nutrition & Food Research
Volume 57, Issue 11, pages 2061–2070, November 2013
How to Cite
Vejvar, E., Himly, M., Briza, P., Eichhorn, S., Ebner, C., Hemmer, W., Ferreira, F. and Gadermaier, G. (2013), Allergenic relevance of nonspecific lipid transfer proteins 2: Identification and characterization of Api g 6 from celery tuber as representative of a novel IgE-binding protein family. Mol. Nutr. Food Res., 57: 2061–2070. doi: 10.1002/mnfr.201300085
- Issue published online: 28 OCT 2013
- Article first published online: 5 AUG 2013
- Manuscript Revised: 16 MAY 2013
- Manuscript Accepted: 16 MAY 2013
- Manuscript Received: 30 JAN 2013
- Christian-Doppler Research Association; Biomay AG, Vienna, Austria and Land Salzburg
- Apium graveolens;
- Celery tuber;
- IgE reactivity;
- Nonspecific lipid transfer protein 2;
- Plant food allergy
Apium graveolens represents a relevant food allergen source linked with severe systemic reactions. We sought to identify an IgE-binding nonspecific lipid transfer protein (nsLTP) in celery tuber.
Methods and results
A low molecular weight protein exclusively present in celery tuber was purified and designated Api g 6. The entire protein sequence was obtained by MS and classified as member of the nsLTP2 family. Api g 6 is monomeric in solution with a molecular mass of 6936 Da. The alpha-helical disulfide bond-stabilized structure confers tremendous thermal stability (Tm > 90°C) and high resistance to gastrointestinal digestion. Endolysosomal degradation demonstrated low susceptibility and the presence of a dominant peptide cluster at the C-terminus. Thirty-eight percent of A. graveolens allergic patients demonstrated IgE reactivity to purified natural Api g 6 in ELISA and heat treatment did only partially reduce its allergenic activity. No correlation in IgE binding and limited cross-reactivity was observed with Api g 2 and Art v 3, nsLTP1 from celery stalks and mugwort pollen.
Api g 6, a novel nsLTP2 from celery tuber represents the first well-characterized allergen in this protein family. Despite similar structural and physicochemical features as nsLTP1, immunological properties of Api g 6 are distinct which warrants its inclusion in molecule-based diagnosis of A. graveolens allergy.