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Removal and Replacement of Endogenous Ligands from Lipid-Bound Proteins and Allergens
Published on: February 24, 2021
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Taro raphide-associated proteins: Allergens and crystal growth
Robert E Paull1, Dessireé Zerpa-Catanho2, Nancy J Chen1
1Tropical Plant and Soil Sciences University of Hawaii at Manoa Honolulu HI USA.
Plant Direct
|September 12, 2022
Summary
Calcium oxalate crystals in taro plants are associated with proteins, including profilins, which may cause acridity. Profilin variants with specific inserts show increased allergenicity, suggesting screening methods to reduce irritation.
Area of Science:
- Plant biology
- Biochemistry
- Food science
Background:
- Calcium oxalate raphide crystals in idioblast cells of many plants, including taro (Colocasia esculenta), are linked to acridity.
- Acridity, an irritant sensation, occurs when raw or undercooked taro tissues are consumed.
- The presence of associated toxins or allergens, rather than just crystals, is hypothesized due to variable acridity and inactivation by cooking/proteases.
Purpose of the Study:
- To investigate the biochemical composition of calcium oxalate raphides in taro.
- To identify proteins associated with raphides and explore their potential role in acridity.
- To assess the allergenic potential of identified proteins, particularly profilins.
Main Methods:
- Purification of raphide crystals from taro.
- Two-dimensional (2D) gel electrophoresis and mass spectrometry (MS) for peptide sequencing.
- Taro apex transcriptome sequencing.
- Bioinformatic analysis of protein sequences and epitope prediction.
Main Results:
- Proteins associated with mitochondria (ATP synthase), chloroplasts (chaperonin), cytoplasm (actin, profilin), and vacuole (V-type ATPase) were identified on purified raphides.
- Actin is suggested to play a role in raphide needle formation.
- Specific taro profilin genes exhibited unique inserts (17-amino acid and 2-amino acid) correlating with increased antigenic epitope prediction.
- Taro profilins showed high similarity (83-92%) to known profilins, which are recognized allergens.
Conclusions:
- Taro raphides are formed through a complex biocrystallization process involving various cellular proteins.
- Profilins associated with taro raphides possess characteristics suggesting allergenic potential, contributing to acridity.
- Commercial allergen test strips for profilins (e.g., from hazelnuts) could be adapted for screening taro germplasm to reduce acridity and for quality control in food processing.
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