GH124 cellulase from Ruminiclostridium thermocellum in complex with Mn and cellotriose

Experimental Data Snapshot

  • Resolution: 1.04 Å
  • R-Value Free: 0.137 
  • R-Value Work: 0.124 
  • R-Value Observed: 0.125 

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This is version 2.1 of the entry. See complete history


Structural studies of the unusual metal-ion site of the GH124 endoglucanase from Ruminiclostridium thermocellum.

Urresti, S.Cartmell, A.Liu, F.Walton, P.H.Davies, G.J.

(2018) Acta Crystallogr F Struct Biol Commun 74: 496-505

  • DOI: https://doi.org/10.1107/S2053230X18006842
  • Primary Citation of Related Structures:  
    6G1G, 6G1I

  • PubMed Abstract: 

    The recent discovery of `lytic' polysaccharide monooxygenases, copper-dependent enzymes for biomass degradation, has provided new impetus for the analysis of unusual metal-ion sites in carbohydrate-active enzymes. In this context, the CAZY family GH124 endoglucanase from Ruminiclostridium thermocellum contains an unusual metal-ion site, which was originally modelled as a Ca 2+ site but features aspartic acid, asparagine and two histidine imidazoles as coordinating residues, which are more consistent with a transition-metal binding environment. It was sought to analyse whether the GH124 metal-ion site might accommodate other metals. It is demonstrated through thermal unfolding experiments that this metal-ion site can accommodate a range of transition metals (Fe 2+ , Cu 2+ , Mn 2+ and Ni 2+ ), whilst the three-dimensional structure and mass spectrometry show that one of the histidines is partially covalently modified and is present as a 2-oxohistidine residue; a feature that is rarely observed but that is believed to be involved in an `off-switch' to transition-metal binding. Atomic resolution (<1.1 Å) complexes define the metal-ion site and also reveal the binding of an unusual fructosylated oligosaccharide, which was presumably present as a contaminant in the cellohexaose used for crystallization. Although it has not been possible to detect a biological role for the unusual metal-ion site, this work highlights the need to study some of the many metal-ion sites in carbohydrate-active enzymes that have long been overlooked or previously mis-assigned.

  • Organizational Affiliation

    Department of Chemistry, University of York, York YO10 5DD, England.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glycosyl Hydrolase223Acetivibrio thermocellus ATCC 27405Mutation(s): 0 
Gene Names: Cthe_0435
Find proteins for A3DCJ4 (Acetivibrio thermocellus (strain ATCC 27405 / DSM 1237 / JCM 9322 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372))
Explore A3DCJ4 
Go to UniProtKB:  A3DCJ4
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA3DCJ4
Sequence Annotations
  • Reference Sequence


Entity ID: 2
MoleculeChains Length2D Diagram Glycosylation3D Interactions
B, C
Glycosylation Resources
GlyTouCan:  G14338VK
GlyCosmos:  G14338VK
GlyGen:  G14338VK
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
MN (Subject of Investigation/LOI)
Query on MN

Download Ideal Coordinates CCD File 
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on OHI
Biologically Interesting Molecules (External Reference) 1 Unique
Experimental Data & Validation

Experimental Data

  • Resolution: 1.04 Å
  • R-Value Free: 0.137 
  • R-Value Work: 0.124 
  • R-Value Observed: 0.125 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 73.917α = 90
b = 73.917β = 90
c = 74.936γ = 120
Software Package:
Software NamePurpose
XDSdata reduction
Aimlessdata scaling

Structure Validation

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Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Biotechnology and Biological Sciences Research CouncilUnited KingdomBB/L021633/1

Revision History  (Full details and data files)

  • Version 1.0: 2018-08-15
    Type: Initial release
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Derived calculations, Structure summary
  • Version 2.1: 2024-01-17
    Changes: Data collection, Database references, Derived calculations, Refinement description, Structure summary