title: Novel xylan-binding properties of an engineered family 4 carbohydrate-binding module.
abstract: Molecular engineering of ligand-binding proteins is commonly used for identification of variants that display novel specificities. Using this approach to introduce novel specificities into CBMs (carbohydrate-binding modules) has not been extensively explored. Here, we report the engineering of a CBM, CBM4-2 from the Rhodothermus marinus xylanase Xyn10A, and the identification of the X-2 variant. As compared with the wild-type protein, this engineered module displays higher specificity for the polysaccharide xylan, and a lower preference for binding xylo-oligomers rather than binding the natural decorated polysaccharide. The mode of binding of X-2 differs from other xylan-specific CBMs in that it only has one aromatic residue in the binding site that can make hydrophobic interactions with the sugar rings of the ligand. The evolution of CBM4-2 has thus generated a xylan-binding module with different binding properties to those displayed by CBMs available in Nature.
authors.affiliation: Department of Immunotechnology, Lund University, BMC D13, SE-221 84 Lund, Sweden.
authors.forename: Lavinia
authors.initials: L
authors.lastname: Cicortas Gunnarsson
authors.forename: Cedric
authors.initials: C
authors.lastname: Montanier
authors.forename: Richard B
authors.initials: RB
authors.lastname: Tunnicliffe
authors.forename: Mike P
authors.initials: MP
authors.lastname: Williamson
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Gilbert
authors.forename: Eva
authors.initials: E
authors.lastname: Nordberg Karlsson
authors.forename: Mats
authors.initials: M
authors.lastname: Ohlin
mesh_terms: D000577:Amides / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D045245:Rhodothermus / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012995:Solubility; D040681:Structural Homology, Protein; D013816:Thermodynamics; D014990:Xylans / Q000737:chemistry* / Q000378:metabolism*; D047071:beta-Glucans / Q000378:metabolism
chemical_list: D000577:Amides; D008024:Ligands; D014990:Xylans; D047071:beta-Glucans; D043364:Endo-1,4-beta Xylanases