Domain

Carbohydrate-binding type-2 domain (IPR001919)

Short name: CBD2

Domain relationships

None.

Description

The microbial degradation of cellulose and xylans requires several types of enzyme such as endoglucanases (EC 3.2.1.4), cellobiohydrolases (EC 3.2.1.91) (exoglucanases), or xylanases (EC 3.2.1.8) [PMID: 1886523]. Structurally, cellulases and xylanases generally consist of a catalytic domain and a conserved region of ~100 amino acid residues, the carbohydrate-binding module 2 (CBM2) [PMID: 1812490]. It is found either at the N-terminal or at the C-terminal extremity of these enzymes.

CBM2 can be classified in 2 subfamilies according to substrate specificities: CBM2a which binds cellulose and CBM2b which interacts specifically with xylan. Like other CBM domains CBM2 is a beta-sheet domain containing a planar face which interacts with its ligand via a hydrophobic strip of aromatic residues [PMID: 7766609]. In family 2a this hydrophobic surface consists of three tryptophan residues, which are all required for binding soluble and insoluble forms of cellulose [PMID: 9662439]. In family 2b only 2 surface-exposed tryptophans are conserved and the first one is oriented differently. It is therefore not well oriented to interact with cellulose but is ideal for binding xylan [PMID: 10425686].

This domain recognises both CBM2 subfamilies.

GO terms

Biological Process

GO:0005975 carbohydrate metabolic process

Molecular Function

GO:0030246 carbohydrate binding
GO:0004553 hydrolase activity, hydrolyzing O-glycosyl compounds

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE profiles
Pfam
SMART