Bifidobacterium longum subsp. infantis ABC transporter substrate-binding protein for human milk oligosaccharides (B. infantis HMO SBP)

Bifidobacterium longum subsp. infantis ABC transporter substrate-binding proteins (SBPs) are specialized proteins located in the periplasm or anchored to the cell membrane of the probiotic bacterium B. infantis. These proteins play a critical role in the selective uptake of human milk oligosaccharides (HMOs), which are complex carbohydrates found in breast milk that are indigestible by the human host (Sela et al., 2008, PNAS). By binding specifically to various HMO structures—such as 2'-fucosyllactose and lacto-N-tetraose—these SBPs facilitate the transport of these nutrients into the bacterial cell for fermentation (Garrido et al., 2011, PLoS ONE). This process provides B. infantis with a competitive advantage in the infant gut, promoting a healthy microbiome dominated by beneficial bacteria and lowering gut pH through the production of organic acids. Therapeutically, these proteins are targeted through the administration of specific prebiotics (HMOs) or synbiotics to prevent dysbiosis, necrotizing enterocolitis, and other inflammatory conditions in neonates (Underwood et al., 2013, Pediatric Research). The high affinity and specificity of these SBPs, such as Blon_2177, ensure that B. infantis can efficiently capture even low concentrations of complex glycans in the competitive gut environment (UniProt, B7GPL1).

Other names

HMO-binding proteinSolute-binding proteinBlon_2177Blon_0191Blon_2344Blon_2347Extracellular solute-binding protein family 1

Substrate sequestration and delivery to the transmembrane permease of the ABC transporter system for intracellular translocation.