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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Crop Improvement and Genetics Research » Research » Publications at this Location » Publication #344944
Title: Proteomic profiling and epitope analysis of the complex alpha, gamma- and omega-gliadin families in a commercial bread wheat

Author
item CHO, KYOUNGWAN - National Institute For Agricultural Science & Technology
item BEOM, HYE-RANG - National Institute For Agricultural Science & Technology
item JANG, YOU-RAN - National Institute For Agricultural Science & Technology
item Altenbach, Susan
item Vensel, William
item Simon-Buss, Annamaria
item LIM, SUN-HYUNG - National Institute For Agricultural Science & Technology
item KIM, MIN - Gyeongsang National University
item LEE, JONG-YEOL - National Institute For Agricultural Science & Technology

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2018
Publication Date: 6/15/2018
Citation: Cho, K., Beom, H., Jang, Y., Altenbach, S.B., Vensel, W.H., Simon-Buss, A., Lim, S., Kim, M.G., Lee, J. 2018. Proteomic profiling and epitope analysis of the complex alpha, gamma- and omega-gliadin families in a commercial bread wheat. Frontiers in Plant Science. 9:818. https://doi.org/10.3389/fpls.2018.00818.
DOI: https://doi.org/10.3389/fpls.2018.00818

Interpretive Summary: The gliadins are a major group of proteins in wheat flour that are important for bread making quality, but also present significant health problems for consumers with celiac disease or wheat allergies. There are three groups of gliadins in wheat flour, referred to as alpha-, gamma- and omega-gliadins. Each group consists of many similar proteins. In this study, we carried out a detailed analysis of gliadins in a commercial bread wheat cultivar. Gliadins were preferentially extracted from wheat flour and separated on the basis of both charge and size using two-dimensional gel electrophoresis. Individual proteins were then cleaved into smaller peptides and the sequences of the peptides were determined by tandem mass spectrometry. In this way, 23 alpha-gliadins, 11 gamma-gliadins and five omega-gliadins were identified in 66 individual protein spots. Protein sequences were analyzed for specific peptides (epitopes) that trigger celiac disease and food allergy. This study contributes to a better understanding of how the composition of gliadins among wheat cultivars influences the immunogenic potential of the flour. The study provides critical background information that will make it possible to identify and/or produce hypoallergenic wheat lines with reduced levels of harmful gliadin proteins using either breeding or biotechnology approaches.

Technical Abstract: Wheat gliadins contribute to the functional properties of wheat flour doughs and contain epitopes that are relevant for celiac disease (CD) and wheat-dependent exercise-induced anaphylaxis (WDEIA). The gliadins include three types of proteins, alpha-, gamma- and omega-gliadins that are encoded at Gli-1, Gli-2 and Gli-3 loci on homoeologous group 1 and 6 chromosomes in hexaploid wheat cultivars. The large sizes of their gene families containing many similar sequences coupled with the high proportion of pseudogenes make it difficult to study the composition of gliadin in hexaploid wheat varieties. In this study, we extracted ethanol-soluble gliadin fractions from flour of the Korean bread wheat cultivar Keumkang (Triticum aestivum L. cv. Keumkang). Proteins were separated by 2-dimensional gel electrophoresis (2-DGE) and individual spots were excised from gels, digested with chymotrypsin and subjected to tandem mass spectrometry (MS/MS). Alpha-, gamma- and omega-gliadins were identified as the predominant proteins in 31, 28 and one of 96 spots, respectively. Eleven spots in this fraction were identified as LMW-GS and seven were identified as non-gluten proteins. An additional six omega gliadins were identified in a separate experiment. The composition and number of CD- and WDEIA-relevant epitopes in the gliadin sequences indicate the potential immunogenicity of Keumkang flour and provide the background necessary to devise strategies to improve functional properties and reduce the adverse health effects of the flour.