Beta-galactosidase (BbrY_0422) (BbrY_0422)

BbrY_0422 is a specialized beta-galactosidase belonging to the Glycoside Hydrolase Family 42 (GH42), primarily identified in Bifidobacterium breve strain Yakult (YIT 4064). Unlike many generalist beta-galactosidases, BbrY_0422 exhibits high substrate specificity for 4'-galactosyllactose (4'-GL) and 4-galactobiose (4-GB), which are major components of prebiotic galacto-oligosaccharides (GOS). It notably lacks activity against lactose and other GOS isomers such as 3'-GL and 6'-GL, highlighting its role in a niche metabolic pathway. The enzyme is part of a genetic locus co-induced with an ABC transporter system (including the solute-binding protein BbrY_0420) that facilitates the uptake and intracellular breakdown of specific prebiotics. This metabolic capability is essential for the competitive colonization and persistence of B. breve in the human gut, particularly in infants. While not a traditional drug target, BbrY_0422 is a key focus in the development of targeted prebiotic therapies and the optimization of probiotic efficacy for improving gut health and preventing infections.

Other names

GH42 beta-galactosidaseBbrY_0422 glycoside hydrolase4'-galactosyllactose-specific beta-galactosidase

Hydrolysis of terminal non-reducing beta-D-galactose residues in beta-D-galactosides, specifically targeting the beta-1,4-glycosidic bond in 4'-galactosyllactose and 4-galactobiose.