Quantitative Phosphoproteome of Infant Formula: New Insights into the Difference of Phosphorylation in Milk Proteins between Bovine and Goat Species

Abstract

Phosphorylation is a broad post-translational protein modification, and the level of phosphorylation of milk proteins is associated with lactation, coagulation properties, and digestibility. However, phosphoproteins in bovine milk-based and goat milk-based infant formula have not been systematically explored. Here, we have analyzed six bovine and six goat milk-based infant formula using a quantitative phosphoproteomics approach, from which we identified 200 phosphoproteins with 276 phosphorylation sites and 156 phosphorylation sites from 75 phosphoproteins, respectively. Of these, 99 phosphorylation sites from 26 shared phosphoproteins were differentially expressed between bovine and goat milk-based infant formula. Especially, CSN1S1 was the most phosphoprotein with 25 quantified phosphorylation sites. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that the identified phosphoproteins not only provide nutrition to the infant but also have anti-inflammatory, antipathogenic, and other biological functions. Our results shed light on the composition, phosphorylation sites, and biological functions of phosphoproteins in bovine milk and goat milk-based infant formula, which provide new insights into the key role of protein modifications during infant development. It also helps us to better understand the differences in digestibility of infant formula from different animal milk sources and thus guides the choice of milk source for infant formula.

Phosphoproteomics Revealed Differentially Expressed Sites and Function of the Bovine Milk Fat Globule Membrane in Colostrum and Mature Milk

“…SxE motif is common in milk protein phosphorylation, for example, bovine whey protein, 40 human milk fat globule membrane protein, 32 and formula milk powder. 41 This seems to indicate that this motif is conserved in milk proteins. The extent of phosphorylation can be influenced by residues next to phosphorylation sites as protein kinases primarily identify short linear motifs surrounding the specific residue being targeted.…”

“…Motif analysis by the Motif-x algorithm showed that both the matching motif in BC and BM was SxE (Figure G,H). SxE motif is common in milk protein phosphorylation, for example, bovine whey protein, human milk fat globule membrane protein, and formula milk powder . This seems to indicate that this motif is conserved in milk proteins.…”

Lactobacillus casei-Derived Postbiotics Elevate the Bioaccessibility of Proteins via Allosteric Regulation of Pepsin and Trypsin and Introduction of Endopeptidases

“…Animal-sourced milk is the primary nutritional source for the development of infants after weaning, and the recommended age for neonates to consume animal-derived milk is typically 12 months to prevent iron-deficiency anemia . Increasing evidence in literature indicate that goat milk can be considered as a high-quality ingredient for infant complementary foods and follow-on formula due to its potential health benefits, specifically including improvements in gastrointestinal disorders, hypo allergenicity, promoting the absorption of iron and copper ions, and elevating the levels of vitamin A, thiamine, Ca, niacin, cholesterol and riboflavin. , In addition, goat milk proteins are a vital source of bioactive peptides and provide essential amino acids for the growth and development of infants. , A small number of peptides can be naturally present in goat milk, while the majority of them are generated during gastrointestinal digestion. , It had been reported that foods with different physicochemical properties such as viscosity, microstructure, and various enzymatic hydrolysis conditions lead to the differences in the digestion; however, the relevance of active peptides to infant health depends on whether they are released during gastrointestinal digestion and whether they survive to reach their sites of activity . Elevating the digestibility of protein in the gastrointestinal tract is the crux to promote the release of bioactive peptides and improve the bioaccessibility and bioavailability of goat milk, which warrants further investigation on its potential functions in the health and development of infants and young children.…”

“…Current research focuses on the identification of the peptides in goat milk and the improvement of the immune effect of postbiotic supplementation on organisms, − while the effect of postbiotics on bioactive peptide release in goat milk during gastrointestinal digestion is still not clear . In this study, ultra-high performance liquid chromatography-quadrupole-Orbitrap (UHPLC-Q-Orbitrap)-based spatial omics combined with vDIA acquisition model and the unsupervised variational autoencoders is applied to profile the molecular mechanism of postbiotic supplementation- induced release of bioactive peptides in goat milk during gastrointestinal digestion, which establishes a critical groundwork and provides evidence for the clinical application of postbiotics in infant complementary foods (Figure ).…”

“…2,3 In addition, goat milk proteins are a vital source of bioactive peptides and provide essential amino acids for the growth and development of infants. 4,5 A small number of peptides can be naturally present in goat milk, while the majority of them are generated during gastrointestinal digestion. 6,7 It had been reported that foods with different physicochemical properties such as viscosity, microstructure, and various enzymatic hydrolysis conditions lead to the differences in the digestion; however, the relevance of active peptides to infant health depends on whether they are released during gastrointestinal digestion and whether they survive to reach their sites of activity.…”