5LA2

The mechanism by which arabinoxylanases can recognise highly decorated xylans


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.65 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.146 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

The Mechanism by Which Arabinoxylanases Can Recognize Highly Decorated Xylans.

Labourel, A.Crouch, L.I.Bras, J.L.Jackson, A.Rogowski, A.Gray, J.Yadav, M.P.Henrissat, B.Fontes, C.M.Gilbert, H.J.Najmudin, S.Basle, A.Cuskin, F.

(2016) J.Biol.Chem. 291: 22149-22159

  • DOI: 10.1074/jbc.M116.743948
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The enzymatic degradation of plant cell walls is an important biological process of increasing environmental and industrial significance. Xylan, a major component of the plant cell wall, consists of a backbone of β-1,4-xylose (Xylp) units that are of ...

    The enzymatic degradation of plant cell walls is an important biological process of increasing environmental and industrial significance. Xylan, a major component of the plant cell wall, consists of a backbone of β-1,4-xylose (Xylp) units that are often decorated with arabinofuranose (Araf) side chains. A large penta-modular enzyme, CtXyl5A, was shown previously to specifically target arabinoxylans. The mechanism of substrate recognition displayed by the enzyme, however, remains unclear. Here we report the crystal structure of the arabinoxylanase and the enzyme in complex with ligands. The data showed that four of the protein modules adopt a rigid structure, which stabilizes the catalytic domain. The C-terminal non-catalytic carbohydrate binding module could not be observed in the crystal structure, suggesting positional flexibility. The structure of the enzyme in complex with Xylp-β-1,4-Xylp-β-1,4-Xylp-[α-1,3-Araf]-β-1,4-Xylp showed that the Araf decoration linked O3 to the xylose in the active site is located in the pocket (-2* subsite) that abuts onto the catalytic center. The -2* subsite can also bind to Xylp and Arap, explaining why the enzyme can utilize xylose and arabinose as specificity determinants. Alanine substitution of Glu68, Tyr92, or Asn139, which interact with arabinose and xylose side chains at the -2* subsite, abrogates catalytic activity. Distal to the active site, the xylan backbone makes limited apolar contacts with the enzyme, and the hydroxyls are solvent-exposed. This explains why CtXyl5A is capable of hydrolyzing xylans that are extensively decorated and that are recalcitrant to classic endo-xylanase attack.


    Organizational Affiliation

    From the Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Carbohydrate binding family 6
A, B
491Clostridium thermocellum (strain ATCC 27405 / DSM 1237 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372)Mutation(s): 0 
Find proteins for A3DHG6 (Clostridium thermocellum (strain ATCC 27405 / DSM 1237 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372))
Go to UniProtKB:  A3DHG6
Small Molecules
Ligands 5 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ARB
Query on ARB

Download SDF File 
Download CCD File 
A, B
BETA-L-ARABINOSE
C5 H10 O5
SRBFZHDQGSBBOR-KLVWXMOXSA-N
 Ligand Interaction
AHR
Query on AHR

Download SDF File 
Download CCD File 
A, B
ALPHA-L-ARABINOFURANOSE
C5 H10 O5
HMFHBZSHGGEWLO-QMKXCQHVSA-N
 Ligand Interaction
CA
Query on CA

Download SDF File 
Download CCD File 
A, B
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
XYS
Query on XYS

Download SDF File 
Download CCD File 
A, B
XYLOPYRANOSE
C5 H10 O5
SRBFZHDQGSBBOR-LECHCGJUSA-N
 Ligand Interaction
XYP
Query on XYP

Download SDF File 
Download CCD File 
A, B
BETA-D-XYLOPYRANOSE
C5 H10 O5
SRBFZHDQGSBBOR-KKQCNMDGSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.65 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.146 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 76.273α = 90.00
b = 123.176β = 90.00
c = 125.380γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
Aimlessdata scaling
XDSdata scaling
MOLREPphasing
XDSdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Biotechnology and Biological Sciences Research CouncilUnited KingdomBB/K020358/1

Revision History 

  • Version 1.0: 2016-08-31
    Type: Initial release
  • Version 1.1: 2016-10-26
    Type: Database references
  • Version 1.2: 2017-08-30
    Type: Author supporting evidence