5A6L

High resolution structure of the thermostable glucuronoxylan endo-Beta-1, 4-xylanase, CtXyn30A, from Clostridium thermocellum with two xylobiose units bound


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.162 
  • R-Value Work: 0.136 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Conservation in the Mechanism of Glucuronoxylan Hydrolysis Revealed by the Structure of Glucuronoxylan Xylano-Hydrolase (Ctxyn30A) from Clostridium Thermocellum

Freire, F.Verma, A.K.Bule, P.Alves, V.D.Fontes, C.M.G.A.Goyal, A.Najmudin, S.

(2016) Acta Crystallogr.,Sect.D 72: 1162

  • DOI: 10.1107/S2059798316014376
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Glucuronoxylan endo-β-1,4-xylanases cleave the xylan chain specifically at sites containing 4-O-methylglucuronic acid substitutions. These enzymes have recently received considerable attention owing to their importance in the cooperative hydrolysis o ...

    Glucuronoxylan endo-β-1,4-xylanases cleave the xylan chain specifically at sites containing 4-O-methylglucuronic acid substitutions. These enzymes have recently received considerable attention owing to their importance in the cooperative hydrolysis of heteropolysaccharides. However, little is known about the hydrolysis of glucuronoxylans in extreme environments. Here, the structure of a thermostable family 30 glucuronoxylan endo-β-1,4-xylanase (CtXyn30A) from Clostridium thermocellum is reported. CtXyn30A is part of the cellulosome, a highly elaborate multi-enzyme complex secreted by the bacterium to efficiently deconstruct plant cell-wall carbohydrates. CtXyn30A preferably hydrolyses glucuronoxylans and displays maximum activity at pH 6.0 and 70°C. The structure of CtXyn30A displays a (β/α)8 TIM-barrel core with a side-associated β-sheet domain. Structural analysis of the CtXyn30A mutant E225A, solved in the presence of xylotetraose, revealed xylotetraose-cleavage oligosaccharides partially occupying subsites -3 to +2. The sugar ring at the +1 subsite is held in place by hydrophobic stacking interactions between Tyr139 and Tyr200 and hydrogen bonds to the OH group of Tyr227. Although family 30 glycoside hydrolases are retaining enzymes, the xylopyranosyl ring at the -1 subsite of CtXyn30A-E225A appears in the α-anomeric configuration. A set of residues were found to be strictly conserved in glucuronoxylan endo-β-1,4-xylanases and constitute the molecular determinants of the restricted specificity displayed by these enzymes. CtXyn30A is the first thermostable glucuronoxylan endo-β-1,4-xylanase described to date. This work reveals that substrate recognition by both thermophilic and mesophilic glucuronoxylan endo-β-1,4-xylanases is modulated by a conserved set of residues.


    Organizational Affiliation

    CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CARBOHYDRATE BINDING FAMILY 6
A
409Clostridium thermocellum (strain ATCC 27405 / DSM 1237 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372)Mutation(s): 3 
Find proteins for A3DJS9 (Clostridium thermocellum (strain ATCC 27405 / DSM 1237 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372))
Go to UniProtKB:  A3DJS9
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PO4
Query on PO4

Download SDF File 
Download CCD File 
A
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
PEG
Query on PEG

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Download CCD File 
A
DI(HYDROXYETHYL)ETHER
C4 H10 O3
MTHSVFCYNBDYFN-UHFFFAOYSA-N
 Ligand Interaction
XYP
Query on XYP

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

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.162 
  • R-Value Work: 0.136 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 50.133α = 90.00
b = 87.249β = 114.68
c = 60.027γ = 90.00
Software Package:
Software NamePurpose
XDSdata reduction
PHASERphasing
Aimlessdata scaling
REFMACrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2016-10-19
    Type: Initial release
  • Version 1.1: 2016-11-23
    Type: Database references
  • Version 1.2: 2017-08-23
    Type: Data collection