2BV9

HOW FAMILY 26 GLYCOSIDE HYDROLASES ORCHESTRATE CATALYSIS ON DIFFERENT POLYSACCHARIDES. STRUCTURE AND ACTIVITY OF A CLOSTRIDIUM THERMOCELLUM LICHENASE, CtLIC26A


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.5 Å
  • R-Value Free: 0.157 
  • R-Value Work: 0.131 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

How Family 26 Glycoside Hydrolases Orchestrate Catalysis on Different Polysaccharides: Structure and Activity of a Clostridium Thermocellum Lichenase, Ctlic26A.

Taylor, E.J.Goyal, A.Guerreiro, C.I.P.D.Prates, J.A.M.Money, V.A.Ferry, N.Morland, C.Planas, A.Macdonald, J.A.Stick, R.V.Gilbert, H.J.Fontes, C.M.G.A.Davies, G.J.

(2005) J.Biol.Chem. 280: 32761

  • DOI: 10.1074/jbc.M506580200
  • Primary Citation of Related Structures:  
  • Also Cited By: 2VI0

  • PubMed Abstract: 
  • One of the most intriguing features of the 90 glycoside hydrolase families (GHs) is the range of specificities displayed by different members of the same family, whereas the catalytic apparatus and mechanism are often invariant. Family GH26 predomina ...

    One of the most intriguing features of the 90 glycoside hydrolase families (GHs) is the range of specificities displayed by different members of the same family, whereas the catalytic apparatus and mechanism are often invariant. Family GH26 predominantly comprises beta-1,4 mannanases; however, a bifunctional Clostridium thermocellum GH26 member (hereafter CtLic26A) displays a markedly different specificity. We show that CtLic26A is a lichenase, specific for mixed (Glcbeta1,4Glcbeta1,4Glcbeta1,3)n oligo- and polysaccharides, and displays no activity on manno-configured substrates or beta-1,4-linked homopolymers of glucose or xylose. The three-dimensional structure of the native form of CtLic26A has been solved at 1.50-A resolution, revealing a characteristic (beta/alpha)8 barrel with Glu-109 and Glu-222 acting as the catalytic acid/base and nucleophile in a double-displacement mechanism. The complex with the competitive inhibitor, Glc-beta-1,3-isofagomine (Ki 1 microm), at 1.60 A sheds light on substrate recognition in the -2 and -1 subsites and illuminates why the enzyme is specific for lichenan-based substrates. Hydrolysis of beta-mannosides by GH26 members is thought to proceed through transition states in the B2,5 (boat) conformation in which structural distinction of glucosides versus mannosides reflects not the configuration at C2 but the recognition of the pseudoaxial O3 of the B2,5 conformation. We suggest a different conformational itinerary for the GH26 enzymes active on gluco-configured substrates.


    Organizational Affiliation

    York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5YW, United Kingdom.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
ENDOGLUCANASE H
A
290Clostridium thermocellum (strain ATCC 27405 / DSM 1237 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372)Mutation(s): 0 
Gene Names: celH
EC: 3.2.1.4
Find proteins for P16218 (Clostridium thermocellum (strain ATCC 27405 / DSM 1237 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372))
Go to UniProtKB:  P16218
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.5 Å
  • R-Value Free: 0.157 
  • R-Value Work: 0.131 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 49.828α = 90.00
b = 63.646β = 90.00
c = 100.021γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
SHELXDphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-06-30
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Atomic model, Version format compliance