title: Characterization of an exo-beta-1,3-D-galactanase from Streptomyces avermitilis NBRC14893 acting on arabinogalactan-proteins.
abstract: A gene belonging to glycoside hydrolase family 43 (GH43) was isolated from Streptomyces avermitilis NBRC14893. The gene encodes a modular protein consisting of N-terminal GH43 module and a family 13 carbohydrate-binding module at the C-terminus. The gene corresponding to the GH43 module was expressed in Escherichia coli, and the gene product was characterized. The recombinant enzyme specifically hydrolyzed only beta-1,3-linkage of two D-galactosyl residues at non-reducing ends of the substrates. The analysis of the hydrolysis products indicated that the enzyme produced galactose from beta-1,3-D-galactan in an exo-acting manner. When the enzyme catalyze hydrolysis of the arabinogalactan-protein, the enzyme produced oligosaccharides together with galactose, suggesting that the enzyme is able to accommodate beta-1,6-linked D-galactosyl side chains. These properties are the same as the other previously reported exo-beta-1,3-D-galactanases. Therefore, we concluded the isolated gene certainly encodes an exo-beta-1,3-D-galactanase. This is the first report of exo-beta-1,3-D-galactanase from actinomycetes.
authors.affiliation: Food Biotechnology Division, National Food Research Institute, Kannondai, Tsujkuba, Ibaraki, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Ichinose
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Kotake
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Tsumuraya
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kaneko
mesh_terms: D005690:Galactose / Q000378:metabolism; D015870:Gene Expression; D006026:Glycoside Hydrolases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006868:Hydrolysis; D009088:Mucoproteins / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D009088:Mucoproteins; D010940:Plant Proteins; D011994:Recombinant Proteins; C006619:arabinogalactan proteins; D006026:Glycoside Hydrolases; C063901:exo-beta-(1--3)-D-galactanase; D005690:Galactose