title: Endo-beta-1,3-galactanase from winter mushroom Flammulina velutipes.
abstract: Arabinogalactan proteins are proteoglycans found on the cell surface and in the cell walls of higher plants. The carbohydrate moieties of most arabinogalactan proteins are composed of β-1,3-galactan main chains and β-1,6-galactan side chains, to which other auxiliary sugars are attached. For the present study, an endo-β-1,3-galactanase, designated FvEn3GAL, was first purified and cloned from winter mushroom Flammulina velutipes. The enzyme specifically hydrolyzed β-1,3-galactan, but did not act on β-1,3-glucan, β-1,3:1,4-glucan, xyloglucan, and agarose. It released various β-1,3-galactooligosaccharides together with Gal from β-1,3-galactohexaose in the early phase of the reaction, demonstrating that it acts on β-1,3-galactan in an endo-fashion. Phylogenetic analysis revealed that FvEn3GAL is member of a novel subgroup distinct from known glycoside hydrolases such as endo-β-1,3-glucanase and endo-β-1,3:1,4-glucanase in glycoside hydrolase family 16. Point mutations replacing the putative catalytic Glu residues conserved for enzymes in this family with Asp abolished activity. These results indicate that FvEn3GAL is a highly specific glycoside hydrolase 16 endo-β-1,3-galactanase.
authors.affiliation: Division of Life Science, Graduate School of Science and Engineering, Faculty of Science, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan. kotake@molbiol.saitama-u.ac.jp
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Kotake
authors.forename: Naohiro
authors.initials: N
authors.lastname: Hirata
authors.forename: Yuta
authors.initials: Y
authors.lastname: Degi
authors.forename: Maki
authors.initials: M
authors.lastname: Ishiguro
authors.forename: Kiminari
authors.initials: K
authors.lastname: Kitazawa
authors.forename: Ryohei
authors.initials: R
authors.lastname: Takata
authors.forename: Hitomi
authors.initials: H
authors.lastname: Ichinose
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kaneko
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Igarashi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Samejima
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Tsumuraya
mesh_terms: D000363:Agaricales / Q000201:enzymology*; D001483:Base Sequence; D003001:Cloning, Molecular; D003470:Culture Media; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010802:Phylogeny; D001616:beta-Galactosidase / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D003470:Culture Media; D017931:DNA Primers; D001616:beta-Galactosidase