1DYO

Xylan-Binding Domain from CBM 22, formally x6b domain


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.190 
  • R-Value Observed: 0.190 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

The X6 Thermostabilising Domains of Xylanases are Carbohydrate Binding Modules: Structure and Biochemistry of the Clostridium Thermocellum X6B Domain

Charnock, S.J.Bolam, D.N.Turkenburg, J.P.Gilbert, H.J.Ferreira, L.M.A.Davies, G.J.Fontes, C.M.G.A.

(2000) Biochemistry 39: 5013

  • DOI: 10.1021/bi992821q
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • Many polysaccharide-degrading enzymes display a modular structure in which a catalytic module is attached to one or more noncatalytic modules. Several xylanases contain a module of previously unknown function (termed "X6" modules) that had been impli ...

    Many polysaccharide-degrading enzymes display a modular structure in which a catalytic module is attached to one or more noncatalytic modules. Several xylanases contain a module of previously unknown function (termed "X6" modules) that had been implicated in thermostability. We have investigated the properties of two such "thermostabilizing" modules, X6a and X6b from the Clostridium thermocellumxylanase Xyn10B. These modules, expressed either as discrete entities or as their natural fusions with the catalytic module, were assayed, and their capacity to bind various carbohydrates and potentiate hydrolytic activity was determined. The data showed that X6b, but not X6a, increased the activity of the enzyme against insoluble xylan and bound specifically to xylooligosaccharides and various xylans. In contrast, X6a exhibited no affinity for soluble or insoluble forms of xylan. Isothermal titration calorimetry revealed that the ligand-binding site of X6b accommodates approximately four xylose residues. The protein exhibited K(d) values in the low micromolar range for xylotetraose, xylopentaose, and xylohexaose; 24 microM for xylotriose; and 50 microM for xylobiose. Negative DeltaH and DeltaS values indicate that the interaction of X6b with xylooligosaccharides and xylan is driven by enthalpic forces. The three-dimensional structure of X6b has been solved by X-ray crystallography to a resolution of 2.1 A. The protein is a beta-sandwich that presents a tryptophan and two tyrosine residues on the walls of a shallow cleft that is likely to be the xylan-binding site. In view of the structural and carbohydrate-binding properties of X6b, it is proposed that this and related modules be re-assigned as family 22 carbohydrate-binding modules.


    Organizational Affiliation

    Department of Chemistry, Structural Biology Laboratory, University of York, Heslington, York YO10 5DD, U.K.



Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
ENDO-1,4-BETA-XYLANASE Y
A, B
160Hungateiclostridium thermocellumMutation(s): 0 
Gene Names: xynY
EC: 3.2.1.8
Find proteins for P51584 (Hungateiclostridium thermocellum)
Go to UniProtKB:  P51584
Protein Feature View
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download CCD File 
A, B
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
MSE
Query on MSE
A,BL-PEPTIDE LINKINGC5 H11 N O2 SeMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.190 
  • R-Value Observed: 0.190 
  • Space Group: P 61 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 89.49α = 90
b = 89.49β = 90
c = 207.69γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2000-07-04
    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: 2019-07-24
    Changes: Data collection, Derived calculations