Volume 6 Supplement 1

2nd WAO International Scientific Conference (WISC 2012), Abstracts

Open Access

Food allergy and anaphylaxis – 2046. Cloning and characterization of the gene for acidic thaumatin-like protein, an important allergen from sapodilla plum (manilkara zapota)

  • YP Venkatesh1,
  • HG Ashok Kumar1,
  • VL Hegde1 and
  • SM Shetty1
World Allergy Organization Journal20136:415

https://doi.org/10.1186/1939-4551-6-S1-P131

Published: 23 April 2013

Background

Allergic reactions to sapodilla ingestion are rare; a 21 kD protein was recognized as an allergen in sapodilla extracts by IgE-immunoblot [1]. Further, the allergen was identified as a basic thaumatin-like protein (TLP) by its N-terminal sequence (ATFDIQNNC-) and isoelectric point. The major purpose of this study was to identify additional allergens from this tropical fruit.

Methods

A case of oral allergy syndrome to sapodilla and custard apple was investigated following approval by Institutional Ethics Committee. Sapodilla allergy was confirmed by diagnostic tests (SPT and allergen-specific IgE). Sapodilla proteins were separated on SP-Sepharose by adsorption at pH 4 followed by step elution at pH 5 (SP1), and with increasing NaCl – 0.1 M (SP2) and 0.2 M (SP3). Forward primers and nested reverse primers specific to the SP1 component were designed based on its N-terminal sequence and conserved regions of homologous plant TLPs. PCR was performed using sapodilla (cv. cricket ball) leaf genomic DNA as template.

Results

SPT and allergen-specific IgE were positive. ELISA revealed that IgE from allergic serum recognized two 21 kD proteins – one in the SP1 pool and the other in the SP2 pool; the 21 kD protein in SP2 was identified as basic TLP. The N-terminal sequence of SP1 component was found to be ATFDVVNQCTFTVWAGASPGGGKQL- which was identified as an additional TLP. Sequence analysis of overlapping PCR products revealed an almost full-length gene (603 bases; GenBank accession JN624813.1) corresponding to acidic TLP (residues 8–207 of sapodilla acidic TLP and lacking the N-terminal 7 residues). Phylogenetic analysis shows that sapodilla acidic TLP is evolutionarily related to the allergenic TLPs from olive and kiwi fruits, all belonging to the order Ericales.

Conclusions

A partial gene coding for sapodilla acidic TLP representing 97% of the mature sequence has been cloned. Sapodilla acidic TLP has weak β-1,3-glucanase activity and is an important allergen belonging to the TLP family of pollen and fruit allergens [2].

Authors’ Affiliations

(1)
Biochemistry & Nutrition, Csir-Central Food Technological Research Institute

References

  1. Hegde VL, Venkatesh YP: Oral allergy syndrome to sapodilla (Achras zapota). J Allergy Clin Immunol. 2002, 110: 533-534. 10.1067/mai.2002.126816.View ArticlePubMedGoogle Scholar
  2. Breiteneder H: Thaumatin-like proteins – a new family of pollen and fruit allergens. Allergy. 2004, 59: 479-481. 10.1046/j.1398-9995.2003.00421.x.View ArticlePubMedGoogle Scholar

Copyright

© Venkatesh et al; licensee BioMed Central Ltd. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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