title: Sialidases from gut bacteria: a mini-review.
abstract: Sialidases are a large group of enzymes, the majority of which catalyses the cleavage of terminal sialic acids from complex carbohydrates on glycoproteins or glycolipids. In the gastrointestinal (GI) tract, sialic acid residues are mostly found in terminal location of mucins via α2-3/6 glycosidic linkages. Many enteric commensal and pathogenic bacteria can utilize sialic acids as a nutrient source, but not all express the sialidases that are required to release free sialic acid. Sialidases encoded by gut bacteria vary in terms of their substrate specificity and their enzymatic reaction. Most are hydrolytic sialidases, which release free sialic acid from sialylated substrates. However, there are also examples with transglycosylation activities. Recently, a third class of sialidases, intramolecular trans-sialidase (IT-sialidase), has been discovered in gut microbiota, releasing (2,7-anhydro-Neu5Ac) 2,7-anydro-N-acetylneuraminic acid instead of sialic acid. Reaction specificity varies, with hydrolytic sialidases demonstrating broad activity against α2,3-, α2,6- and α2,8-linked substrates, whereas IT-sialidases tend to be specific for α2,3-linked substrates. In this mini-review, we summarize the current knowledge on the structural and biochemical properties of sialidases involved in the interaction between gut bacteria and epithelial surfaces.
authors: Institute of Food Research, The Gut Health and Food Safety Institute Strategic Programme, Norwich Research Park, Norwich NR4 7UA, U.K. nathalie.juge@ifr.ac.uk.
authors: Nathalie
authors: N
authors: Juge
authors: Institute of Food Research, The Gut Health and Food Safety Institute Strategic Programme, Norwich Research Park, Norwich NR4 7UA, U.K.
authors: Louise
authors: L
authors: Tailford
authors: Biomolecular Sciences Building, University of St Andrews, St Andrews, Fife, KY16 9ST, UK.
authors: C David
authors: CD
authors: Owen
mesh_terms: D001419:Bacteria / Q000201:enzymology*; D041981:Gastrointestinal Tract / Q000382:microbiology*; D006023:Glycoproteins / Q000378:metabolism; D006868:Hydrolysis; D009439:Neuraminidase / Q000737:chemistry / Q000378:metabolism*; D012794:Sialic Acids / Q000737:chemistry / Q000378:metabolism
chemical_list: D006023:Glycoproteins; D012794:Sialic Acids; C069715:trans-sialidase; D009439:Neuraminidase
keywords: glycoside hydrolase; gut bacteria; gut microbiota; mucin degradation; sialic acid; sialidase