RRC ID 19076
著者 Kiyohara M, Nakatomi T, Kurihara S, Fushinobu S, Suzuki H, Tanaka T, Shoda SI, Kitaoka M, Katayama T, Yamamoto K, Ashida H.
タイトル α-N-acetylgalactosaminidase from infant-associated bifidobacteria belonging to novel glycoside hydrolase family 129 is implicated in alternative mucin degradation pathway.
ジャーナル J Biol Chem
Abstract Bifidobacteria inhabit the lower intestine of mammals including humans where the mucin gel layer forms a space for commensal bacteria. We previously identified that infant-associated bifidobacteria possess an extracellular membrane-bound endo-α-N-acetylgalactosaminidase (EngBF) that may be involved in degradation and assimilation of mucin-type oligosaccharides. However, EngBF is highly specific for core-1-type O-glycan (Galβ1-3GalNAcα1-Ser/Thr), also called T antigen, which is mainly attached onto gastroduodenal mucins. By contrast, core-3-type O-glycans (GlcNAcβ1-3GalNAcα1-Ser/Thr) are predominantly found on the mucins in the intestines. Here, we identified a novel α-N-acetylgalactosaminidase (NagBb) from Bifidobacterium bifidum JCM 1254 that hydrolyzes the Tn antigen (GalNAcα1-Ser/Thr). Sialyl and galactosyl core-3 (Galβ1-3/4GlcNAcβ1-3(Neu5Acα2-6)GalNAcα1-Ser/Thr), a major tetrasaccharide structure on MUC2 mucin primarily secreted from goblet cells in human sigmoid colon, can be serially hydrolyzed into Tn antigen by previously identified bifidobacterial extracellular glycosidases such as α-sialidase (SiaBb2), lacto-N-biosidase (LnbB), β-galactosidase (BbgIII), and β-N-acetylhexosaminidases (BbhI and BbhII). Because NagBb is an intracellular enzyme without an N-terminal secretion signal sequence, it is likely involved in intracellular degradation and assimilation of Tn antigen-containing polypeptides, which might be incorporated through unknown transporters. Thus, bifidobacteria possess two distinct pathways for assimilation of O-glycans on gastroduodenal and intestinal mucins. NagBb homologs are conserved in infant-associated bifidobacteria, suggesting a significant role for their adaptation within the infant gut, and they were found to form a new glycoside hydrolase family 129.
巻・号 287(1)
ページ 693-700
公開日 2012-1-2
DOI 10.1074/jbc.M111.277384
PII S0021-9258(20)53551-5
PMID 22090027
PMC PMC3249124
MeSH Bifidobacterium / cytology Bifidobacterium / enzymology* Bifidobacterium / genetics Biocatalysis Carbohydrate Sequence Cloning, Molecular Humans Infant Intracellular Space / enzymology Molecular Sequence Data Mucins / metabolism* Phylogeny Proteolysis* alpha-N-Acetylgalactosaminidase / genetics alpha-N-Acetylgalactosaminidase / metabolism*
IF 4.238
引用数 55
WOS 分野 BIOCHEMISTRY & MOLECULAR BIOLOGY
リソース情報
一般微生物 JCM 1254