Domain

Carbohydrate-binding type-2 domain (IPR001919)

Short name: CBD2

Overlapping homologous superfamilies

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.
SMART
Pfam
PROSITE profiles