2Y8K

Structure of CtGH5-CBM6, an arabinoxylan-specific xylanase.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.47 Å
  • R-Value Free: 0.166 
  • R-Value Work: 0.146 
  • R-Value Observed: 0.147 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Structure and Function of an Arabinoxylan-Specific Xylanase.

Correia, M.A.Mazumder, K.Bras, J.L.Firbank, S.J.Zhu, Y.Lewis, R.J.York, W.S.Fontes, C.M.Gilbert, H.J.

(2011) J Biol Chem 286: 22510

  • DOI: https://doi.org/10.1074/jbc.M110.217315
  • Primary Citation of Related Structures:  
    2Y8K

  • PubMed Abstract: 

    The enzymatic degradation of plant cell walls plays a central role in the carbon cycle and is of increasing environmental and industrial significance. The enzymes that catalyze this process include xylanases that degrade xylan, a β-1,4-xylose polymer that is decorated with various sugars. Although xylanases efficiently hydrolyze unsubstituted xylans, these enzymes are unable to access highly decorated forms of the polysaccharide, such as arabinoxylans that contain arabinofuranose decorations. Here, we show that a Clostridium thermocellum enzyme, designated CtXyl5A, hydrolyzes arabinoxylans but does not attack unsubstituted xylans. Analysis of the reaction products generated by CtXyl5A showed that all the oligosaccharides contain an O3 arabinose linked to the reducing end xylose. The crystal structure of the catalytic module (CtGH5) of CtXyl5A, appended to a family 6 noncatalytic carbohydrate-binding module (CtCBM6), showed that CtGH5 displays a canonical (α/β)(8)-barrel fold with the substrate binding cleft running along the surface of the protein. The catalytic apparatus is housed in the center of the cleft. Adjacent to the -1 subsite is a pocket that could accommodate an l-arabinofuranose-linked α-1,3 to the active site xylose, which is likely to function as a key specificity determinant. CtCBM6, which adopts a β-sandwich fold, recognizes the termini of xylo- and gluco-configured oligosaccharides, consistent with the pocket topology displayed by the ligand-binding site. In contrast to typical modular glycoside hydrolases, there is an extensive hydrophobic interface between CtGH5 and CtCBM6, and thus the two modules cannot function as independent entities.


  • Organizational Affiliation

    Centro de Investigação Interdisciplinar em Sanidade Animal, 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
CARBOHYDRATE BINDING FAMILY 6491Acetivibrio thermocellusMutation(s): 0 
UniProt
Find proteins for A3DHG6 (Acetivibrio thermocellus (strain ATCC 27405 / DSM 1237 / JCM 9322 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372))
Explore A3DHG6 
Go to UniProtKB:  A3DHG6
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA3DHG6
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
GOL
Query on GOL

Download Ideal Coordinates CCD File 
B [auth A]
C [auth A]
D [auth A]
E [auth A]
F [auth A]
B [auth A],
C [auth A],
D [auth A],
E [auth A],
F [auth A],
G [auth A],
H [auth A],
I [auth A]
GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
CA
Query on CA

Download Ideal Coordinates CCD File 
J [auth A]CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
NA
Query on NA

Download Ideal Coordinates CCD File 
K [auth A],
L [auth A],
M [auth A],
N [auth A]
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.47 Å
  • R-Value Free: 0.166 
  • R-Value Work: 0.146 
  • R-Value Observed: 0.147 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 69.12α = 90
b = 75.55β = 90
c = 105.97γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
SHELXCDEphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2011-02-16
    Type: Initial release
  • Version 1.1: 2011-06-23
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-05-08
    Changes: Data collection, Database references, Derived calculations, Other