The American Society for Biochemistry and Molecular Biology highlighted a recently published paper in Molecular and Cellular Proteomics by Daniel Garrido, a Ph.D. student in Dr. David Mills’ Lab. The paper, “Endo-β-N-acetylglucosaminidases from infant-gut associated bifidobacteria release complex N-glycans from human milk glycoproteins,” was co-authored by Charles Nwosu, Santiago Ruiz-Moyano, Danielle Aldredge, J. Bruce German, Carlito B. Lebrilla and David A. Mills. In addition to the press release, the American Society for Biochemistry and Molecular Biology will also feature the research on their website, ASBMB Today.
Breast milk contains complex sugars (glycans) that infants cannot break down, however, breast milk also promotes the growth of protective bacteria, called bifidobacteria, that are able to process these glycans. Through their work, researchers in Dr. Mills’ Lab have shown that babies can obtain nourishment from a previously unknown source, the glycoproteins that are abundant in breast milk. Glycoproteins are proteins that have been decorated with glycans in a process called post-translational modification. These protein-bound glycans are important for a number of biological functions including protein folding and cellular communication. Importantly, in the digestive tract, glycans affect the ability of digestive enzymes to break down the protein, thus making it more difficult for the protein to be digested and absorbed.
Garrido and others found that certain intestinal bifidobacteria contain enzymes capable of removing complex sugars from glycoproteins to use as a food source. Dr. Mills explains that the ability of one specific enzyme, EndBI-1, to remove a variety of complex N-linked glycans combined with its unusual heat stability make “this potentially a very useful tool in both food processing and proteomics/pharmaceutical research.” The ability of these enzymes to break down glycoproteins means they can be used to make certain proteins more digestible, which is especially important for at-risk populations such as premature infants, whose ability to digest and absorb proteins is limited because of the immaturity of their digestive tracts.
However, Dr. Mills envisions that an obvious goal of this research is to “find ways to translate the benefits provided by milk and bifidobacteria to at risk populations such as premature infants and malnourished children, among many others.” Breast milk is an incredibly complex and beneficial food source for infants in a myriad of ways. The work of Daniel Garrido, and other doctoral and postdoctoral students in the Mills’ Lab, furthers our understanding of the intricate processes within the infant gut, and how protective bacteria can improve the nutrition and overall health of children.
As the primary researcher in this article, Daniel Garrido was supported by the University of California Discovery Grant Program, the California Dairy Research Foundation, and the National Institute of Health. Garrido was sponsored in part through a Fulbright-CONICYT Chile scholarship and was also the 2011 recipient of the National Milk Producer Federation Scholarship award. The article contributes to ongoing work within the Milk Bioactives group at the Foods for Health Institute that explains the way that protective bacteria in the infant gut can help babies break down breast milk.