title: Characterization of an endo-processive-type xyloglucanase having a β-1,4-glucan-binding module and an endo-type xyloglucanase from Streptomyces avermitilis.
abstract: We cloned two glycoside hydrolase family 74 genes, the sav_1856 gene and the sav_2574 gene, from Streptomyces avermitilis NBRC14893 and characterized the resultant recombinant proteins. The sav_1856 gene product (SaGH74A) consisted of a catalytic domain and a family 2 carbohydrate-binding module at the C terminus, while the sav_2574 gene product (SaGH74B) consisted of only a catalytic domain. SaGH74A and SaGH74B were expressed successfully and had molecular masses of 92 and 78 kDa, respectively. Both recombinant proteins were xyloglucanases. SaGH74A had optimal activity at 60°C and pH 5.5, while SaGH74B had optimal activity at 55°C and pH 6.0. SaGH74A was stable over a broad pH range (pH 4.5 to 9.0), whereas SaGH74B was stable over a relatively narrow pH range (pH 6.0 to 6.5). Analysis of the hydrolysis products of tamarind xyloglucan and xyloglucan-derived oligosaccharides indicated that SaGH74A was endo-processive, while SaGH74B was a typical endo-enzyme. The C terminus of SaGH74A, which was annotated as a carbohydrate-binding module, bound to β-1,4-linked glucan-containing soluble polysaccharides such as hydroxyethyl cellulose, barley glucan, and xyloglucan.
authors.affiliation: Food Biotechnology Division, National Food Research Institute, Tsukuba, Ibaraki, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Ichinose
authors.forename: Yuko
authors.initials: Y
authors.lastname: Araki
authors.forename: Mari
authors.initials: M
authors.lastname: Michikawa
authors.forename: Koichi
authors.initials: K
authors.lastname: Harazono
authors.forename: Katsuro
authors.initials: K
authors.lastname: Yaoi
authors.forename: Shuichi
authors.initials: S
authors.lastname: Karita
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kaneko
mesh_terms: D020134:Catalytic Domain; D003001:Cloning, Molecular; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D009844:Oligosaccharides / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics; D029861:Tamarindus / Q000378:metabolism; D013696:Temperature
chemical_list: D009844:Oligosaccharides; D011994:Recombinant Proteins; D006026:Glycoside Hydrolases; C072818:xyloglucan endo(1-4)-beta-D-glucanase