Document Detail

α-N-acetylgalactosaminidase from infant-associated bifidobacteria belonging to novel glycoside hydrolase family 129 is implicated in alternative mucin degradation pathway.
MedLine Citation:
PMID:  22090027     Owner:  NLM     Status:  MEDLINE    
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.
Masashi Kiyohara; Takashi Nakatomi; Shin Kurihara; Shinya Fushinobu; Hideyuki Suzuki; Tomonari Tanaka; Shin-Ichiro Shoda; Motomitsu Kitaoka; Takane Katayama; Kenji Yamamoto; Hisashi Ashida
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-11-16
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  287     ISSN:  1083-351X     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-01-02     Completed Date:  2012-05-08     Revised Date:  2013-06-27    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  693-700     Citation Subset:  IM    
Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
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MeSH Terms
Bifidobacterium / cytology,  enzymology*,  genetics
Carbohydrate Sequence
Cloning, Molecular
Intracellular Space / enzymology
Molecular Sequence Data
Mucins / metabolism*
alpha-N-Acetylgalactosaminidase / genetics,  metabolism*
Reg. No./Substance:
0/Mucins; EC

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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