3K4Z

Crystal Structure of the Cellulosomal CBM4 from Clostridium thermocellum Cellulase CbhA


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.11 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.161 
  • R-Value Observed: 0.164 

wwPDB Validation   3D Report Full Report


Ligand Structure Quality Assessment 


This is version 2.1 of the entry. See complete history


Literature

The unique binding mode of cellulosomal CBM4 from Clostridium thermocellum cellobiohydrolase A.

Alahuhta, M.Xu, Q.Bomble, Y.J.Brunecky, R.Adney, W.S.Ding, S.Y.Himmel, M.E.Lunin, V.V.

(2010) J Mol Biol 402: 374-387

  • DOI: https://doi.org/10.1016/j.jmb.2010.07.028
  • Primary Citation of Related Structures:  
    3K4Z

  • PubMed Abstract: 

    The crystal structure of the carbohydrate-binding module (CBM) 4 Ig fused domain from the cellulosomal cellulase cellobiohydrolase A (CbhA) of Clostridium thermocellum was solved in complex with cellobiose at 2.11 A resolution. This is the first cellulosomal CBM4 crystal structure reported to date. It is similar to the previously solved noncellulosomal soluble oligosaccharide-binding CBM4 structures. However, this new structure possesses a significant feature-a binding site peptide loop with a tryptophan (Trp118) residing midway in the loop. Based on sequence alignment, this structural feature might be common to all cellulosomal clostridial CBM4 modules. Our results indicate that C. thermocellum CbhA CBM4 also has an extended binding pocket that can optimally bind to cellodextrins containing five or more sugar units. Molecular dynamics simulations and experimental binding studies with the Trp118Ala mutant suggest that Trp118 contributes to the binding and, possibly, the orientation of the module to soluble cellodextrins. Furthermore, the binding cleft aromatic residues Trp68 and Tyr110 play a crucial role in binding to bacterial microcrystalline cellulose (BMCC), amorphous cellulose, and soluble oligodextrins. Binding to BMCC is in disagreement with the structural features of the binding pocket, which does not support binding to the flat surface of crystalline cellulose, suggesting that CBM4 binds the amorphous part or the cellulose "whiskers" of BMCC. We propose that clostridial CBM4s have possibly evolved to bind the free-chain ends of crystalline cellulose in addition to their ability to bind soluble cellodextrins.


  • Organizational Affiliation

    National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glycoside hydrolase family 9289Acetivibrio thermocellus JW20Mutation(s): 0 
Gene Names: CtherDRAFT_1062
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
Expand
  • Reference Sequence
Oligosaccharides

Help

Entity ID: 2
MoleculeChains Length2D Diagram Glycosylation3D Interactions
beta-D-glucopyranose-(1-4)-beta-D-glucopyranose
B
2N/A
Glycosylation Resources
GlyTouCan:  G84824ZO
GlyCosmos:  G84824ZO
Biologically Interesting Molecules (External Reference) 1 Unique
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.11 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.161 
  • R-Value Observed: 0.164 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 60.578α = 90
b = 94.315β = 90
c = 113.487γ = 90
Software Package:
Software NamePurpose
MrBUMPphasing
REFMACrefinement

Structure Validation

View Full Validation Report



Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-07-28
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2017-11-01
    Changes: Refinement description
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Atomic model, Data collection, Database references, Derived calculations, Non-polymer description, Structure summary
  • Version 2.1: 2023-09-06
    Changes: Data collection, Database references, Refinement description, Structure summary