First characterisation of an enzyme that key gut bacteria use to feed on harder-to-unlock sugars in breastmilk
Microbiologists have found that an enzyme, not normally associated with microbial activities in the human gut, to have a role in how some bacteria access key nutrients in breast milk.
The findings, published in Nature Communications today (Monday 2 November), provides a new understanding about feeding preferences of bacteria that are important for a typical gut microbiota for infants.
The enzyme, a PNGaseA, is usually used in other processes in animals and plants, such as recycling of important cell components. However, in this instance, Dr Lucy Crouch from the University of Birmingham led a team that found that the enzyme has a key role for bacteria being able to feed on particular types of sugars in breast milk, which alongside other sugars is believed to stimulate the growth of infant-associated species of Bifidobacterium.
Some types of Bifidobacterium produce this enzyme to feed on these special nutrients, which are sugars found on short protein chains and need to be removed from the chain so that it can be available as food.
We were genuinely surprised to see that PNGaseA is used by gut bacteria to access nutrients and potentially contribute to the growth of a healthy community.
The characterisation of the PNGaseA enzyme has also helped the team of researchers to identify how important some understudied nutrients are to feed a healthy microbiome. The team found that the PNGaseA enzyme, produced by some species of Bifidobacterium, only accesses sugars found on short protein chains, which are in human breast milk but not found in formula feeding options.
Dr Lucy Crouch from the University of Birmingham and lead author of the study said: “This exciting finding shows just how complex the human milk-fed infant microbial community is. We were genuinely surprised to see that PNGaseA is used by gut bacteria to access nutrients and potentially contribute to the growth of a healthy community.
“We know there are some aspects of breast milk that can’t yet be truly synthetically replicated as ingredients for infant formula. Characterising all of the components that help ‘healthy’ bacteria to form can help to find solutions to making formula as much like human milk as possible and give the natural infant gut microbiomes everything they need to establish and thrive.”
Prof. Ramón Hurtado-Guerrero, from the University of Zaragoza and a co-author of the study, said: “This study also reveals the first structure of a PNGase enzyme bound to an N-glycopeptide, showing how it recognises both the sugar and the attached protein fragment. In addition, it offers clues to how other PNGases, including PNGaseF and other PNGaseA enzymes, might recognise their targets.”
This first characterisation of how a PNGaseA enzyme unlocks particular nutrients in breastmilk, and successive research, will help develop translational impacts for our overall knowledge of how breast milk drives the formation of a healthy infant microbial community. The resulting findings can help to engineer future formulas so that babies who don’t have access to human breast milk may benefit from the development prebiotics.
For media enquiries please contact Tim Mayo, Press Office, University of Birmingham, tel: +44 (0)7815 607 157.
Sir Henry Dale Fellow
Lucy Crouch is a glycobiologist and studies how gut microbes and pathogens use human-derived glycans as a nutrient source.
