PROSITE documentation PDOC51759 [for PROSITE entry PS51759]

Carbohydrate-binding module 15 (CBM15) domain profile

Microbial plant cell wall hydrolases are often modular proteins comprising a catalytic module linked via a highly flexible sequence to one or more carbohydrate-binding modules (CBMs). CBMs bind to a range of plant structural polysaccharides that include both crystalline cellulose and noncrystalline β-1,4-glucan, xylan, mannan, β-1,3-glucan, and glucomannan. Their primary function is to increase the catalytic efficiency of these enzymes against their soluble substrates by bringing the catalytic module into prolonged and intimate contact with its substrate. CBMs have been grouped into approximately 30 families based on amino acid sequence similarities.

The family 15 CBM (CBM15) binds both soluble xylan and xylooligosaccharides. The structure of the CBM15 domain forms a classic β-jelly roll fold, predominantly consisting of five major anti-parallel β-strands on the two faces (see <PDB:1GNY>). The CBM15 domain displays a single disulfide bond linking the two β-sheets that form the jelly roll. The CBM15 domain contains a deep cleft that runs along the concave face of the β-sheet which forms the binding site for the target ligands [1,2,E1].

Protein known to contain a CBM15 domain:

• Pseudomonas cellulosa xylanase Xyn10C, comprised of a C-terminal xylanase GH10 catalytic module with an N-terminal carbohydrate-binding module that belongs to family 15 (CBM15).

The profile we developed covers the entire CBM15 domain.