title: Extra tyrosine in the carbohydrate-binding module of Irpex lacteus Xyn10B enhances its cellulose-binding ability.
abstract: The xylanase (Xyn10B) that strongly adsorbs on microcrystalline cellulose was isolated from Driselase. The Xyn10B contains a Carbohydrate-binding module family 1 (CBM1) (IrpCBMXyn10B) at N-terminus. The canonical essential aromatic residues required for cellulose binding were conserved in IrpCBMXyn10B; however, its adsorption ability was markedly higher than that typically observed for the CBM1 of an endoglucanase from Trametes hirsuta (ThCBMEG1). An analysis of the CBM-GFP fusion proteins revealed that the binding capacity to cellulose (7.8 μmol/g) and distribution coefficient (2.0 L/μmol) of IrpCBMXyn10B-GFP were twofold higher than those of ThCBMEG1-GFP (3.4 μmol/g and 1.2 L/μmol, respectively), used as a reference structure. Besides the canonical aromatic residues (W24-Y50-Y51) of typical CBM1-containing proteins, IrpCBMXyn10B had an additional aromatic residue (Y52). The mutation of Y52 to Ser (IrpCBMY52S-GFP) reduced these adsorption parameters to 4.4 μmol/g and 1.5 L/μmol, which were similar to those of ThCBMEG1-GFP. These results indicate that Y52 plays a crucial role in strong cellulose binding.
authors.affiliation: a Department of Bioscience & Textile Technology, Interdisciplinary Graduate School of Science and Technology , Shinshu University , Nagano , Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Nishijima
authors.forename: Kouichi
authors.initials: K
authors.lastname: Nozaki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Mizuno
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Arai
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Amano
mesh_terms: D000595:Amino Acid Sequence; D001487:Basidiomycota / Q000201:enzymology*; D001665:Binding Sites; D002482:Cellulose / Q000737:chemistry / Q000378:metabolism; D005591:Chemical Fractionation; D032561:Cotton Fiber; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D014443:Tyrosine; D002482:Cellulose; D006026:Glycoside Hydrolases; C035212:driselase; D043364:Endo-1,4-beta Xylanases
keywords: Irpex lacteus; carbohydrate-binding module family 1; glycoside hydrolase family 10 xylanase