Authors
Junya Kawasaki, Jintaro Sugahara, Hisashi Ashida
Published in
Carbohydrate research. Volume 568. Pages 110048. Jul 16, 2026. Epub Jul 16, 2026.
Abstract
Bifidobacteria are a group of commensal microorganisms in human gut and are closely associated with host health. Previous studies have revealed that bifidobacteria employ diverse survival strategies to persist within the human gut, one of which involves the utilization of mucin glycans secreted by the intestinal epithelial mucosa as a primary energy source. Previously, we have cloned and characterized exo-α-N-acetylgalactosaminidase (NagBb) from Bifidobacterium bifidum, which hydrolyzes the Tn antigen (GalNAcα1-Ser/Thr) of mucin core structure, thereby leading to establishment of the glycoside hydrolase family 129 (GH129) in the CAZy database. In this study, we found that NagBL from B. longum subsp. longum, an ortholog of NagBb, exhibits strong activity not only toward GalNAcα1-R but also the Core1 (Galβ1-3GalNAcα1-R) as well as the Core3 (GlcNAcβ1-3GalNAcα1-R) structures. To elucidate why NagBL exhibits broader substrate specificity compared to NagBb, we generated site-directed mutant enzymes of NagBL and compared their enzymatic activities with those of the wild type and NagBb. The results revealed that amino acid residues A151, R394, I555 and V557 located surrounding the active site of NagBL are critical for disaccharide-releasing activity. To the best of our knowledge, glycosidases capable of releasing both monosaccharides and disaccharides are extremely rare.
PMID:
42468075
Bibliographic data and abstract were imported from PubMed on 18 Jul 2026.
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