Identification of yeast-derived emulsification proteins through analyses of proteins distributed into the emulsified phase. (March 2021)

• Record Type: Journal Article
• Authors: Onishi, Masaya; Ueda, Mana; Saito, Daiki; Takata, Mao; Ojima, Yoshihiro; Azuma, Masayuki
• Is Part Of: Food hydrocolloids. Volume 112(2021)
• Publication Date: 2021-03
• Subjects: Emulsify -- Emulsion -- Yeast -- Cell wall -- Gas proteins -- GPI; Hydrocolloids -- Periodicals; Food additives -- Periodicals; Colloïdes -- Périodiques; Aliments -- Additifs -- Périodiques; Colloids; Food additives; Periodicals; Electronic journals; 664.06
• DOI: 10.1016/j.foodhyd.2020.106321
• Languages: English
• ISSNs: 0268-005X

Abstract

Abstract: Emulsifiers are widely used in food manufacturing, and cell wall mannoproteins from Saccharomyces cerevisiae, a representative food yeast, have been proposed as potential new emulsifiers. However, their use has not become widespread. One reason is that the protein responsible for emulsification has not been identified so no efficient preparation method has been established. In this study, the emulsification substances were identified. Many mannoproteins are fixed to the cell wall via a glycosylphosphatidylinositol (GPI) anchor. Because emulsifying activity was found in the culture supernatant (CS) in gup1 Δ with a mutation of GPI anchor synthesis, a protein distributed from the CS into the emulsified phase by emulsification treatment was analyzed. Using mass spectrometry, it was identified to be Gas1, a mannoprotein localized to the cell wall via a GPI anchor. Further, recombinant Gas1 without a C-terminal GPI anchor binding signal was purified, and it showed activity similar to bovine serum albumin, a well-known protein emulsifier. Gas1 also retained its activity under a wide range of pH and high salt conditions. Saccharomyces cerevisiae has Gas3 and Gas5, proteins homologous to Gas1, and recombinant Gas3 and Gas5 without the C-terminal signal were also purified and found to have emulsifying activity similar to that of recombinant Gas1. These results strongly suggest that Gas proteins take part in the emulsifying activity of yeast mannoproteins. It was also demonstrated that emulsification proteins could be identified by analyzing proteins distributed in an emulsified phase, so this method will be effective in finding new emulsification proteins. Graphical abstract: Image 1 Highlights: Proteins distributed into an emulsified phase were analyzed by mass spectrometry. Gas1, Gas3, and Gas5 among yeast mannoproteins were selected as the candidates. The emulsifying activities were confirmed using recombinant Gas1, Gas3, and Gas5. These components take part in emulsification by mannoproteins extracted from yeast. Analysis of distributed proteins will contribute to finding new protein emulsifiers.