Increased sulfur-containing amino acid content and altered conformational characteristics of soybean proteins by rebalancing 11S and 7S compositions

Abstract

Soybean proteins are limited by their low contents of methionine and cysteine. Herein, 7S globulin accumulation was reduced using RNA interference to silence CG-β-1 expression, and the content of the A2B1a subunit was largely increased under the soybean seed-specific oleosin8 promoter. The results showed that the sulfur-containing amino acid content in soybean seeds drastically improved, reaching 79.194 nmol/mg, and the 11S/7S ratio had a 1.89-fold increase compared to the wild-type acceptor. The secondary structures of 11S globulin were also altered, and the β-sheet content increased with decreasing β-turn content, which was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy and circular dichroism analysis. Our findings suggested that raising the accumulation of 11S glycinin at the expense of reducing the content of 7S globulin is an attractive and precise engineering strategy to increase the amount of sulfur-containing amino acids, and soybean proteins with A2B1a subunits of 11S isolates improved, and β-subunits of 7S fractions reduced simultaneously might be an effective new material for food production.

Effects of Germination on the Structure, Functional Properties, and In Vitro Digestibility of a Black Bean (Glycine max (L.) Merr.) Protein Isolate

“…According to previous studies, 11S globulin has been found to be rich in sulfur-containing amino acids, with a content that is five to six times higher than that of 7S globulin. This indicates that 11S globulin has higher protein quality and can provide greater nutritional value [57].…”

Bibliometric Analysis of Functional Crops and Nutritional Quality: Identification of Gene Resources to Improve Crop Nutritional Quality through Gene Editing Technology

“…Soybean is an indispensable raw material in animal feed due to its high protein content, high protein digestibility, balanced amino acid composition, availability, and relatively fair production cost. Generally speaking, soybean seeds contain 35–40% protein [ 88 ], with the storage proteins 11S globulin and 7S globulin accounting for 70–80% of the total protein [ 89 ]. The total protein content of rice seeds is only about 8%, which is one of the crops with the lowest protein content.…”

Recent advances in plant protein modification: spotlight on hemp protein

“…Reports indicate that a deficiency in these amino acids can negatively impact animal growth and development. 23 Plant proteins, such as pea, 24 soybean, 23,25 almond 26 and chickpea protein 27 are particularly deficient in these amino acids. Hemp protein is of interest as it is rich in cysteine and methionine.…”