Bifunctional properties and characterization of a novel sialidase with esterase activity from Bifidobacterium bifidum |
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| Authors: | Hisashi Ashida Kana Tanigawa Masashi Kiyohara Toshihiko Katoh Takane Katayama |
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| Affiliation: | 1. Department of Applied Molecular Biology, Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, Japan;2. Department of Science and Technology on Food Safety, Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Wakayama, Japan;3. Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Ishikawa, Japan |
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| Abstract: | ABSTRACTSialidases catalyze the removal of terminal sialic acid from various complex carbohydrates. In the gastrointestinal tract, sialic acid is commonly found in the sugar chain of mucin, and many enteric commensals use mucin as a nutrient source. We previously identified two different sialidase genes in Bifidobacterium bifidum, and one was cloned and expressed as an extracellular protein designated as exo-α-sialidase SiaBb2. The other exo-α-sialidase gene (siabb1) from the same bifidobacterium encodes an extracellular protein (SiaBb1) consisting of 1795 amino acids with a molecular mass of 189 kDa. SiaBb1 possesses a catalytic domain that classifies this enzyme as a glycoside hydrolase family 33 member. SiaBb1 preferentially hydrolyzes α2,3-linked sialic acid over α2,6-linked sialic acid from sialoglycan, which is the same as SiaBb2. However, SiaBb1 has an SGNH hydrolase domain with sialate-O-acetylesterase activity and an N-terminal signal sequence and C-terminal transmembrane region. SiaBb1 is the first bifunctional sialidase identified with esterase activity.Abbreviations: GalNAc: N-acetyl-D-galactosamine; Fuc: L-fucose; Gal: D-galactose |
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| Keywords: | Sialidase Bifidobacterium bifidum bifunctional enzyme sialate-O-acetylesterase mucin |
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