1GWK: Carbohydrate Binding Module Family29

Citation:
Abstract
Carbohydrate-protein recognition is central to many biological processes. Enzymes that act on polysaccharide substrates frequently contain noncatalytic domains, "carbohydrate-binding modules" (CBMs), that target the enzyme to the appropriate substrate. CBMs that recognize specific plant structural polysaccharides are often able to accommodate both the variable backbone and the side-chain decorations of heterogeneous ligands. "CBM29" modules, derived from a noncatalytic component of the Piromyces equi cellulase/hemicellulase complex, provide an example of this selective yet flexible recognition. They discriminate strongly against some polysaccharides while remaining relatively promiscuous toward both beta-1,4-linked manno- and cello-oligosaccharides. This feature may reflect preferential, but flexible, targeting toward glucomannans in the plant cell wall. The three-dimensional structure of CBM29-2 and its complexes with cello- and mannohexaose reveal a beta-jelly-roll topology, with an extended binding groove on the concave surface. The orientation of the aromatic residues complements the conformation of the target sugar polymer while accommodation of both manno- and gluco-configured oligo- and polysaccharides is conferred by virtue of the plasticity of the direct interactions from their axial and equatorial 2-hydroxyls, respectively. Such flexible ligand recognition targets the anaerobic fungal complex to a range of different components in the plant cell wall and thus plays a pivotal role in the highly efficient degradation of this composite structure by the microbial eukaryote.
PDB ID: 1GWKDownload
MMDB ID: 22243
PDB Deposition Date: 2002/3/19
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.34  Å
Source Organism:
Similar Structures:
Biological Unit for 1GWK: monomeric; determined by author and by software (PQS)
Molecular Components in 1GWK
Label Count Molecule
Protein (1 molecule)
1
Non-catalytic Protein 1
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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