Studying Genomic Identification of Expressed Globulin Storage Proteins in Oats with MS/MS

A recent paper published in Frontiers in Plant Science (1) presented a complete set of expressed globulin genes, which code for the main storage protein in oats as well as their chromosomal positions. To access this information, tandem mass spectrometry (MS/MS) was utilized to analyze separate fractionated globulin proteins to confirm identity and expression in seed. The researchers identified 32 globulin gene sequences on the oat genome; out of these, the expression on RNA level could be confirmed and 27 were also detected as expressed proteins by MS. These results provide the most extensive set of salt-soluble oat globulin sequences to date, paving the way for further understanding their implications for human nutrition.

A highly nutritious cereal known for its health benefits, about 60% of oat grains are made up of starch, making it the most abundant carbohydrate (2). However, the protein content of oat kernels ranges, depending on the variety and cultivation conditions, from 12 to 20%, making it one of the food crops with the highest protein concentrations (3,4). Despite the substantial levels of protein and their importance in the dietary process, their presence in oats has not been extensively studied. The authors said that a better understanding of oat proteins abundance, expression, and potential properties in oat proteins in general, and globulins (the major protein component) in particular, will pave the way for future advancements in human nutrition has spurred the research that produced the resulting paper.

The research team retrieved and mapped the expressed globulins in oats to gain a comprehensive understanding of the most abundant protein family in this cereal. Their search for similarity of structure, was conducted by building on previously documented gene sequences, as well as by employing the recently developed Sang genome browser (5). These sequences were compared with the re-sequenced and reference-assembled Belinda oat genome. Oat globulin proteins were then fractionated according to solubility, separated by gel electrophoresis, and identified using MS/MS.

The authors state that their study presents the most comprehensive set of oat globulin genes, including their amino acid sequences, as well as expands the current knowledge on these proteins. Future research could explore the existence of additional globulin 12S proteins which are not salt-soluble, and that might not be as closely related to the discovered sequences in this article, which may result in the broadening of our understanding of the diversity within this protein family.

Oats. © luismolinero- stock.adobe.com

References

1. Gil-González, A. B.;Sjögren, L. L. E.; Bernfur, K.;Olsson, O.;Zambrano, J.A. Genomic Identification of Expressed Globulin Storage Proteins in Oat. Frontiers in Plant Science, 2024, 15. DOI: 10.3389/fpls.2024.1418658

2. Antonini, E.; Lombardi, F.; Alfieri, M.; Diamantini, G.; Redaelli, R.; Ninfali, P. Nutritional Characterization of Naked and Dehulled Oat Cultivar Samples at Harvest and After Storage. J. Cereal Sci. 2016, 72, 46–53. DOI: 10.1016/j.jcs.2016.09.016

3. Menon, R.; Gonzalez, T.; Ferruzzi, M.; Jackson, E.; Winderl, D.; Watson, J. Oats– From Farm to Fork. Adv. Food Nutr. Res. 2016, 77, 1–55. DOI: 10.1016/bs.afnr.2015.12.001

4. Poutanen, K. S., Kårlund, A. O., Gómez-Gallego, C., Johansson, D. P., Scheers, N. M., Marklinder, I. M., et al. (2022). Grains– A Major Source of Sustainable Protein for Health. Nutr. Rev. 2022, 80, 1648. DOI: 10.1093/nutrit/nuab084

5. Kamal, N.; Tsardakas Renhuldt, N.;Bentzer, J.; Gundlach, H.; Haberer, G.; Juhász, A., et al. The Mosaic Oat Genome Gives Insights into a Uniquely Healthy Cereal Crop. Nature 2022, 606 (7912), 113–119. DOI: 10.1038/s41586-022-04732-y