α-Galactosidase and Sucrose-Kinase Relationships in a Bi-functional AgaSK Enzyme Produced by the Human Gut Symbiont E1.

Plant α-galactosides belonging to the raffinose family oligosaccharides (RFOs) and considered as prebiotics, are commonly degraded by α-galactosidases produced by the human gut microbiome. In this environment, the E1 symbiont-well-known for various benefit-is able to produce an original AgaSK bifunctional enzyme. This enzyme contains an hydrolytic α-galactosidase domain linked to an ATP dependent extra-domain, specifically involved in the α-galactoside hydrolysis and the phosphorylation of the glucose, respectively.

Sucrose 6-phosphate phosphorylase: a novel insight in the human gut microbiome.

The human gut microbiome plays an essential role in maintaining human health including in degradation of dietary fibres and carbohydrates further used as nutrients by both the host and the gut bacteria. Previously, we identified a polysaccharide utilization loci (PUL) involved in sucrose and raffinose family oligosaccharide (RFO) metabolism from one of the most common Firmicutes present in individuals, Ruminococcus gnavus E1. One of the enzymes encoded by this PUL was annotated as a putative sucrose phosphate phosphorylase (RgSPP).

α-Galactosidase/sucrose kinase (AgaSK), a novel bifunctional enzyme from the human microbiome coupling galactosidase and kinase activities.

α-Galactosides are non-digestible carbohydrates widely distributed in plants. They are a potential source of energy in our daily food, and their assimilation by microbiota may play a role in obesity. In the intestinal tract, they are degraded by microbial glycosidases, which are often modular enzymes with catalytic domains linked to carbohydrate-binding modules.