1GWK

Carbohydrate binding module family29

Summary for 1GWK

• Entry DOI: 10.2210/pdb1gwk/pdb
• Related: 1GWL 1GWM
• Descriptor: NON-CATALYTIC PROTEIN 1 (2 entities in total)
• Functional Keywords: carbohydrate binding domain, glucomannan, cellohexaose, mannohexaose, cellulosome
• Biological source: PIROMYCES EQUI
• Total number of polymer chains: 2
• Total formula weight: 34807.48

Authors

Charnock, S.J.,Nurizzo, D.,Davies, G.J. (deposition date: 2002-03-19, release date: 2003-03-20, Last modification date: 2024-11-06)

Primary citation

Charnock, S.J.,Bolam, D.,Nurizzo, D.,Szabo, L.,Mckie, V.,Gilbert, H.,Davies, G.J.
Promiscuity in Ligand-Binding: The Three-Dimensional Structure of a Piromyces Carbohydrate-Binding Module,Cbm29-2,in Complex with Cello- and Mannohexaose
Proc.Natl.Acad.Sci.USA, 99:14077-, 2002

PubMed 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.

PubMed: 12391332
DOI: 10.1073/PNAS.212516199

Experimental method

X-RAY DIFFRACTION (2.34 Å)