Carbohydrate Binding Module 6 (CBM6); appended mainly to glycoside hydrolase (GH) family 16 alpha- and beta agarases
This family includes carbohydrate binding module 6 (CBM6) domains that are appended mainly to glycoside hydrolase (GH) family 16 agarases. These CBM6s are non-catalytic carbohydrate binding domains that facilitate the activity of alpha- and beta-agarase catalytic modules which are involved in the hydrolysis of 1,4-beta-D-galactosidic linkages. These CBM6s bind specifically to the non-reducing end of agarose chains, recognizing only the first repeat of the disaccharide, and directing the appended catalytic modules to areas of the plant cell wall attacked by beta-agarases. 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. This family includes three tandem CBM6s from the Saccharophagus degradans agarase Aga86E, and three tandem CBM6s from Vibrio sp. strain PO-303 AgaA; in both these proteins these are appended to a GH16 domain. Vibrio AgaA also contains a Big-2-like protein-protein interaction domain. This family also includes two tandem CBM6s from an endo-type beta-agarase from a deep-sea Microbulbifer-like isolate, which are appended to a GH16 domain, and two of three CBM6s of Alteromonas agarilytica AgaA alpha-agarase, which are appended to a GH96 domain.
Feature 1:ligand binding site [chemical binding site]
Evidence:
Comment:CBM6 module in beta-agarase binds specifically to the non-reducing terminus of the agarose chain, recognizing only the first repeat of the disaccharide
Structure:2CDP: Saccharophagus degradans CBM6 binds neoagarohexoase, contacts at 4A
Jiyao W et al.(2023). "The conserved domain database in 2023.",