Xylanases module

The Type C CBMs were first discovered as lectins with small-sugar-binding activity and have only subsequently been included as CBMs due to their discovery in a number of glycoside hydrolases. This family of CBMs is found exclusively in xylanases. Differences between Type B and Type C CBMs can be small, but the hydrogen-bonding network between protein and ligand is more extensive in Type C CBMs than in Type B modules. 

All Type B function is associated with a p-sandwich fold, but not all p-sandwich folds are associated with Type B function. The p-sandwich fold is adopted by CAZy sequence Families 2, 3,4, 6, 9,11,15,17,22,27,28,29, 32, 34 and 36, but some CAZy Family 2 members (CBM 2a) and all CBM Family 3 members have Type A function. In CBM 2a and CBM 3, three aromatic residues are again disposed to make a planar hydrophobic face sheet, as with CBM 1, even though the overall fold is a p-sandwich. The multiplicity of binding functions that can be supported by the p-sandwich is emphasised from the structure of a CBM6 attached to a Clostridium thermocellum xylanase, which had two binding clefts, only one of which appeared to be used in xylan binding the apparently unused cleft in this structure was, however, the main binding site for a Family 22 and a Family 4 module. ... 

Enhancing the Catafytic Activity of Xylanase by Fusing the Carbohydrate Binding Module... 

CBMs anchor ceUulases and hemicellulases to their target substrates, therefore eliciting efficient hydrolysis of recalcitrant polysaccharides. Recombinant derivatives of a xylanase from C. thermocellim, containing a CBM6, were used to supplement poultry cereal-based diets. The data obtained showed that birds fed on a wheat-based diet supplemented with CBM-xylanase display an increased final body weight, when compared with birds receiving the xylanase catalytic module only [163]. 

Boraston, AB Tomme, P Amandoron, EA Kilburn, DG. A novel mechanism of xylan binding by a lectin-like module from Streptomyces lividans xylanase 10A. Biochem J, 2000, 350, 933-41. 

Hachem, MA Karlsson, EN Bartonek-Roxa, E Raghothama, S Simpson, PJ Gilbert, HJ et al. Carbohydrate-binding modules from a thermostable Rhodothermus marinus xylanase cloning, expression and binding studies. Biochem J., 2000, 345(Pt 1), 53-60. 

Notenboom, V Boraston, AB Kilburn, DG Rose, DR. Crystal structures of the family 9 carbohydrate-binding module from Thermotoga maritima xylanase lOA in native and ligand-bound forms. Biochemistry, 2001, 40, 6248-56. 

Boraston, AB McLean, BW Chen, G Li, A Warren, RAJ Kilbum, DG. Co-operative binding of triplicate carbohydrate-binding modules from a thermophilic xylanase. Molecular Microbiology, 2002, 43(1), 187-94. 

Charnock, SJ Bolam, DN Turkenburg, JP Gilbert, HJ Ferreira, LMA Davies, GJ et al. The X6 Thermostabilizing Domains of Xylanases Are Carbohydrate-Binding Modules Structure and Biochemistry of the Clostridium thermocellum X6b Domain. Biochemistry, 2000, 39(17), 5013-21. 

Zhao, G Ali, E Araki, R Sakka, M Kimura, T Sakka, K. Function of the Family-9 and Family-22 Carbohydrate-Binding Modules in a Modular (3-1,3-1,4-Glucanase/Xylanase Derived from Clostridium stercorarium XynlOB. Bioscience, Biotechnology, and Biochemistry, 2005, 69(8), 1562-7. 

Fontes, CM Ponte, PI Reis, TC Soares, MC Gama, LT Dias, FM et al. A family 6 carbohydrate-binding module potentiates the efficiency of a recombinant xylanase used to supplement cereal-based diets for poultry. Br Poult Sci., 2004, 45(5), 648-56. 

Kavoosi, M Meijer, J Kwan, E Creagh, AL Kilburn, DG Haynes, CA. Inexpensive one-step purification of polypeptides expressed in Escherichia coli as fusions with the family 9 carbohydrate-binding module of xylanase lOA from T. maritima. J Chromatogr B Analyt Technol BiomedLife ScL, 2004, 807(1), 87-94. 

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