title: Key amino acid residues for the endo-processive activity of GH74 xyloglucanase.
abstract: Unlike endo-dissociative-xyloglucanases, Paenibacillus XEG74 is an endo-processive xyloglucanase that contains four unique tryptophan residues in the negative subsites (W61 and W64) and the positive subsites (W318 and W319), as indicated by three-dimensional homology modelling. Selective replacement of the positive subsite residues with alanine mutations reduced the degree of processive activity and resulted in the more endo-dissociative-activity. The results showed that W318 and W319, which are found in the positive subsites, are essential for processive degradation and are responsible for maintaining binding interactions with xyloglucan polysaccharide through a stacking effect.
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tukuba Central 6, 1-1-1 Higashi, Tukuba, Ibaraki 305-8566, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Matsuzawa
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Saito
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tukuba Central 6, 1-1-1 Higashi, Tukuba, Ibaraki 305-8566, Japan. Electronic address: k-yaoi@aist.go.jp.
authors.forename: Katsuro
authors.initials: K
authors.lastname: Yaoi
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry*; D020134:Catalytic Domain; D005936:Glucans / Q000737:chemistry; D006026:Glycoside Hydrolases / Q000737:chemistry*; D006868:Hydrolysis; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D056507:Paenibacillus / Q000201:enzymology*; D040681:Structural Homology, Protein; D013379:Substrate Specificity; D014783:Viscosity; D014990:Xylans / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D005936:Glucans; D014990:Xylans; C029353:xyloglucan; D006026:Glycoside Hydrolases; C072818:xyloglucan endo(1-4)-beta-D-glucanase
keywords: Endo-processive; Glucanase; Hemicellulose; Xyloglucan; Xyloglucanase