Unique bifunctional α-sialidase/β-N-acetylgalactosaminidase from Bifidobacterium bifidum acting on the Sd^a antigen.

ABSTRACT: Sd^a antigens [GalNAcβ1-4(Neu5Acα2-3)Galβ1-O-R] are present at the nonreducing termini of O-glycans of colonic mucins of humans. Previously, we reported characterization of two glycoside hydrolase (GH) family 33 α-sialidases, SiaBb1 and SiaBb2, from a symbiotic Bifidobacterium bifidum dwelling in the human intestines. In this study, we identified a third α-sialidase, SiaBb3 from B. bifidum, that is distinguished from the aforementioned two sialidases by its possession of an additional GH123 β-N-acetylgalactosaminidase domain within the same polypeptide. The purified recombinant SiaBb3 efficiently converted GM2 ganglioside [GalNAcβ1-4(Neu5Acα2-3)Galβ1-4Glcβ1-ceramide], sharing the same terminal trisaccharide structure with the Sd^a antigen, to lactosylceramide by releasi

SUBMITTER: Katoh T 

PROVIDER: S-EPMC12856340 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature