Carbohydrate Binding Module 6 (CBM6) and CBM35_like superfamily. Carbohydrate binding module family 6 (CBM6, family 6 CBM), also known as cellulose binding domain family VI (CBD VI), and related CBMs (CBM35 and CBM36). These are non-catalytic carbohydrate binding domains found in a range of enzymes that display activities against a diverse range of carbohydrate targets, including mannan, xylan, beta-glucans, cellulose, agarose, and arabinans. These domains facilitate the strong binding of the appended catalytic modules to their dedicated, insoluble substrates. Many of these CBMs are associated with glycoside hydrolase (GH) domains. CBM6 is an unusual CBM as it represents a chimera of two distinct binding sites with different modes of binding: binding site I within the loop regions and binding site II on the concave face of the beta-sandwich fold. CBM36s are calcium-dependent xylan binding domains. CBM35s display conserved specificity through extensive sequence similarity, but divergent function through their appended catalytic modules. This alignment model also contains the C-terminal domains of bacterial insecticidal toxins, where they may be involved in determining insect specificity through carbohydrate binding functionality.
Carbohydrate Binding Module 35 (CBM35); appended to several carbohydrate binding enzymes, including several glycoside hydrolase (GH) family 26 mannanase domains. This family includes carbohydrate binding module 35 (CBM35) domains that are appended to several carbohydrate binding enzymes, including periplasmic component of ABC-type sugar transport system involved in carbohydrate transport and metabolism, and several glycoside hydrolase (GH) domains, including GH26. These CBM6s are non-catalytic carbohydrate binding domains that facilitate the strong binding of the GH catalytic modules with their dedicated, insoluble substrates. Examples of proteins having CMB35s belonging to this family are mannanase A from Clostridium thermocellum (GH26), Man26B from Paenibacillus sp. BME-14 (GH26), and the multifunctional Cel44C-Man26A from Paenibacillus polymyxa GS01 (which has two GH domains, GH44 and GH26). GH26 mainly includes mannan endo-1,4-beta-mannosidase which hydrolyzes 1,4-beta-D-linkages in mannans, galacto-mannans, glucomannans, and galactoglucomannans, but displays little activity towards other plant cell wall polysaccharides. A few proteins belonging to this family have additional CBM3 domains; these CBM3s are not found in the CBM6-CBM35-CBM36_like superfamily.