Dataset Information

Tracking Gluten throughout Brewing Using N-Terminal Labeling Mass Spectrometry

ABSTRACT: Gluten-containing grains cause adverse health effects in individuals with celiac disease. Fermentation of these grains results in gluten-derived polypeptides with largely uncharacterized sizes and sequences, which may still trigger an immune response. This research used N-terminal labeling mass spectrometry to characterize protein hydrolysates during each stage of bench-scale brewing, including malting, mashing, boiling, fermentation, and aging. Gluten hydrolysates from each brewing step were tracked and the immunotoxic potential was evaluated in silico. The results indicate that proteolysis and precipitation of gliadins occurring during brewing differ by protein region and brewing stage. The termini of gliadins were hydrolyzed throughout the entire brewing process, but the central regions remained relatively stable. Most hydrolysis occurred during malting, and most precipitation occurred during boiling. The addition of yeast yielded new cleavage sites but did not result in complete hydrolysis. Consistent detection of peptides within the clinically important regions of gliadin corroborated the hydrolytic resistance of this region. N-terminal labeling mass spectrometry served as a novel approach to track the fate of gliadin/gluten throughout bench-scale brewing. Consistently identified fragments could serve as improved targets for detection of hydrolyzed gluten in fermented products.

INSTRUMENT(S): Q Exactive Plus

ORGANISM(S): Hordeum Vulgare (barley) Saccharomyces Cerevisiae (baker's Yeast) Triticum Aestivum (wheat)

TISSUE(S): Plant Cell, Germinated Grain, Seed

SUBMITTER: Melanie Downs

LAB HEAD: Melanie Downs

PROVIDER: PXD023482 | Pride | 2021-07-23

REPOSITORIES: Pride

ACCESS DATA

Similar Datasets

Project description:Within the complex wheat flour proteome, the gluten proteins have attracted most of the attention because of their importance in determining the functional properties of wheat flour doughs and their roles in human health conditions such as celiac disease and food allergies. However, certain non-gluten proteins also trigger immunological responses but may be present in flour in low amounts or obscured by the more abundant gluten proteins in two-dimensional gels of total protein preparations. Non-gluten proteins were preferentially extracted from the flour with a dilute salt solution and separated by two-dimensional gel electrophoresis. Proteins in 172 gel spots were identified by tandem mass spectrometry after cleavage with trypsin or chymotrypsin. Fifty-seven different types of non-gluten proteins were identified, including 14 types that are known or suspected immunogenic proteins. The predominant proteins in 18 gel spots were gluten proteins. Transgenic wheat lines in which specific groups of gluten proteins were suppressed by RNA interference were used to estimate the amount of carry-over of gluten proteins in the salt-soluble protein fraction. Analysis of salt-soluble proteins from a transgenic line missing omega-1,2 gliadins demonstrated that certain omega-1,2 gliadins were present in large amounts in the salt-soluble fraction and obscured relatively small amounts of beta-amylase and protein disulfide isomerase. In comparison, analysis of a transgenic line in which alpha gliadins were absent revealed that glyceraldehyde-3 phosphate dehydrogenase was a moderately abundant protein that co-migrated with several alpha gliadins. The proteomic map of the non-gluten protein fraction of wheat flour developed in this study complements a proteomic map of the total flour proteins developed previously for the same cultivar. Knowing the identities of low abundance proteins in the flour as well as proteins that are hidden by some of the major gluten proteins on two-dimensional gels is critical for studies aimed at assessing the immunogenic potential of wheat flour and determining how the growth conditions of the plants affect the levels of specific immunogenic proteins in the flour.

Project description:Celiac disease (CD) is a chronic inflammation of the small intestine triggered by the ingestion of gluten in genetically predisposed individuals. Tissue transglutaminase (TG2) is a key factor in the pathogenesis of CD, because it catalyzes both the deamidation of specific glutamine residues and the formation of covalent Nε-(γ-glutamyl)-lysine isopeptide crosslinks resulting in TG2-gluten peptide complexes. These complexes are thought to activate B cells causing the secretion of anti-TG2 autoantibodies that serve as diagnostic markers for CD, although their pathogenic role remains unclear. To gain more insight into the molecular structures of TG2-gluten peptide complexes, we developed a reciprocal proteomic analysis strategy, which facilitates the comprehensive identification of isopeptides in a complex protein hydrolysate. The workflow consists of four steps: (1) performance of the model reaction between TG2 and gluten peptide(s) followed by tryptic hydrolysis, clean-up and untargeted nLC-MS/MS analysis (2), prediction of tryptic TG2-derived lysine peptides that serve as potential isopeptide modifications (3) the search for isopeptides by configuring the TG2-modifications in MaxQuant and search against the α-gliadin fasta file and (4) the reciprocal search for isopeptides by configuring the gluten peptide(s) as modification in MaxQuant and search against the TG2 fasta file. After verification by manual data curation and visualization, this strategy enabled the identification of 26 different isopeptides involving 19 TG2 lysine residues, only six of which were known previously. Experiments with different TG2-gluten peptide molar ratios revealed that K-425, K-590, K-600 and K-649 were the most preferred lysine residues involved in isopeptide crosslinking. Further, expanding the model system to three gluten peptides allowed the localization of the preferred glutamine crosslinking sites. The described strategy is generally applicable to any hydrolysate containing isopeptides and these new insights into the structure of TG2-gluten peptide complexes may help clarify the role of extracellular TG2 in CD autoimmunity and in other inflammatory diseases.

Project description:Durum wheat requires high nitrogen inputs to obtain the high protein concentration necessary to satisfy pasta and semolina quality criteria. Optimizing plant nitrogen use efficiency is therefore of major importance for wheat grain quality. Here, we studied the impact on grain yield, protein concentration, and for the first time on protein composition of a marine (DPI4913) and a fungal (AF086) biostimulants applied to plant leaves. Plants were grown in a greenhouse and sampled at maturity for grain analysis. The protein concentration and quantity in grains per plant were determined, as well as water-use efficiency. A large-scale quantitative proteomics study of wheat flour samples was performed to determine the effect of biostimulant treatment on grain protein composition. Grain dry biomass and protein quantity were increased by 23.9% and 24.8% respectively with DPI4913, and by 27.4% and 25.9%, respectively, with AF086. A total of 1471 proteins were identified and 1391 were quantified. Quantitative proteomics analysis revealed 26 and 38 proteins with a significantly varying abundance after DPI4913 and AF086 treatment, respectively. Among these, 14 proteins were affected by both DPI4913 and AF086 treatments. The highest variations in proteins abundances were found for proteins involved in grain technological properties such as grain hardness, in storage functions with the substantial over-representation of the gluten protein gamma-gliadin, in regulation processes with the over-representation of proteins that play a transcription regulator role, and in stress responses with the over-representation of proteins implied in biotic and abiotic stress defense. The involvement of biostimulants in the abiotic stress response is suggested by the increase in water-use efficiency for DPI4913 treatment (15.4%) and for AF086 treatment (9.9%). In conclusion, our work, performed in greenhouse, has shown that DPI4913 and AF086 treatments promote grain yield while maintaining protein concentration in grains, and positively affect protein composition in term of grain quality. This study suggests that these biostimulants could be used to optimize durum wheat production and quality in field conditions.

Dataset Information

Tracking Gluten throughout Brewing Using N-Terminal Labeling Mass Spectrometry

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure