2C24

FAMILY 30 CARBOHYDRATE-BINDING MODULE OF CELLULOSOMAL CELLULASE CEL9D- CEL44B OF CLOSTRIDIUM THERMOCELLUM


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.27 Å
  • R-Value Free: 0.265 
  • R-Value Work: 0.216 
  • R-Value Observed: 0.221 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Literature

Xyloglucan is Recognized by Carbohydrate-Binding Modules that Interact with Beta-Glucan Chains.

Najmudin, S.Guerreiro, C.I.P.D.Carvalho, A.L.Prates, J.A.M.Correia, M.A.S.Alves, V.D.Ferreira, L.M.A.Romao, M.J.Gilbert, H.J.Bolam, D.N.Fontes, C.M.G.A.

(2006) J Biol Chem 281: 8815

  • DOI: https://doi.org/10.1074/jbc.M510559200
  • Primary Citation of Related Structures:  
    2C24, 2C26, 2C4X

  • PubMed Abstract: 

    Enzyme systems that attack the plant cell wall contain noncatalytic carbohydrate-binding modules (CBMs) that mediate attachment to this composite structure and play a pivotal role in maximizing the hydrolytic process. Although xyloglucan, which includes a backbone of beta-1,4-glucan decorated primarily with xylose residues, is a key component of the plant cell wall, CBMs that bind to this polymer have not been identified. Here we showed that the C-terminal domain of the modular Clostridium thermocellum enzyme CtCel9D-Cel44A (formerly known as CelJ) comprises a novel CBM (designated CBM44) that binds with equal affinity to cellulose and xyloglucan. We also showed that accommodation of xyloglucan side chains is a general feature of CBMs that bind to single cellulose chains. The crystal structures of CBM44 and the other CBM (CBM30) in CtCel9D-Cel44A display a beta-sandwich fold. The concave face of both CBMs contains a hydrophobic platform comprising three tryptophan residues that can accommodate up to five glucose residues. The orientation of these aromatic residues is such that the bound ligand would adopt the twisted conformation displayed by cello-oligosaccharides in solution. Mutagenesis studies confirmed that the hydrophobic platform located on the concave face of both CBMs mediates ligand recognition. In contrast to other CBMs that bind to single polysaccharide chains, the polar residues in the binding cleft of CBM44 play only a minor role in ligand recognition. The mechanism by which these proteins are able to recognize linear and decorated beta-1,4-glucans is discussed based on the structures of CBM44 and the other CBMs that bind single cellulose chains.


  • Organizational Affiliation

    Requimte, Departamento de Química, FCT-UNL, 2829-516 Caparica, Portugal, CIISA-Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ENDOGLUCANASE
A, B
206Acetivibrio thermocellusMutation(s): 0 
UniProt
Find proteins for P71140 (Acetivibrio thermocellus)
Explore P71140 
Go to UniProtKB:  P71140
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP71140
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.27 Å
  • R-Value Free: 0.265 
  • R-Value Work: 0.216 
  • R-Value Observed: 0.221 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 66.579α = 90
b = 85.475β = 90
c = 88.926γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
MOLREPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-11-22
    Type: Initial release
  • Version 1.1: 2011-05-07
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2023-12-13
    Changes: Data collection, Database references, Other, Refinement description