Crystal structure of a thermostable family-43 glycoside hydrolase

Experimental Data Snapshot

  • Resolution: 1.10 Å
  • R-Value Free: 0.145 
  • R-Value Work: 0.122 
  • R-Value Observed: 0.123 

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High-resolution crystal structure of a polyextreme GH43 glycosidase from Halothermothrix orenii with alpha-L-arabinofuranosidase activity.

Hassan, N.Kori, L.D.Gandini, R.Patel, B.K.Divne, C.Tan, T.C.

(2015) Acta Crystallogr Sect F Struct Biol Cryst Commun 71: 338-345

  • DOI: https://doi.org/10.1107/S2053230X15003337
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    A gene from the heterotrophic, halothermophilic marine bacterium Halothermothrix orenii has been cloned and overexpressed in Escherichia coli. This gene encodes the only glycoside hydrolase of family 43 (GH43) produced by H. orenii. The crystal structure of the H. orenii glycosidase was determined by molecular replacement and refined at 1.10 Å resolution. As for other GH43 members, the enzyme folds as a five-bladed β-propeller. The structure features a metal-binding site on the propeller axis, near the active site. Based on thermal denaturation data, the H. orenii glycosidase depends on divalent cations in combination with high salt for optimal thermal stability against unfolding. A maximum melting temperature of 76°C was observed in the presence of 4 M NaCl and Mn(2+) at pH 6.5. The gene encoding the H. orenii GH43 enzyme has previously been annotated as a putative α-L-arabinofuranosidase. Activity was detected with p-nitrophenyl-α-L-arabinofuranoside as a substrate, and therefore the name HoAraf43 was suggested for the enzyme. In agreement with the conditions for optimal thermal stability against unfolding, the highest arabinofuranosidase activity was obtained in the presence of 4 M NaCl and Mn(2+) at pH 6.5, giving a specific activity of 20-36 µmol min(-1) mg(-1). The active site is structurally distinct from those of other GH43 members, including arabinanases, arabinofuranosidases and xylanases. This probably reflects the special requirements for degrading the unique biomass available in highly saline aqueous ecosystems, such as halophilic algae and halophytes. The amino-acid distribution of HoAraf43 has similarities to those of mesophiles, thermophiles and halophiles, but also has unique features, for example more hydrophobic amino acids on the surface and fewer buried charged residues.

  • Organizational Affiliation

    School of Biotechnology, KTH Royal Institute of Technology, Stockholm, Sweden.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glycoside hydrolase family 43
A, B
315Halothermothrix orenii H 168Mutation(s): 0 
Gene Names: Hore_20580
Find proteins for B8CZV1 (Halothermothrix orenii (strain H 168 / OCM 544 / DSM 9562))
Explore B8CZV1 
Go to UniProtKB:  B8CZV1
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupB8CZV1
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.10 Å
  • R-Value Free: 0.145 
  • R-Value Work: 0.122 
  • R-Value Observed: 0.123 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 44.133α = 90
b = 73.882β = 94.27
c = 87.52γ = 90
Software Package:
Software NamePurpose
GDAdata collection
PHENIXmodel building
XDSdata reduction
XSCALEdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-03-11
    Type: Initial release
  • Version 1.1: 2015-03-25
    Changes: Database references
  • Version 1.2: 2023-09-20
    Changes: Data collection, Database references, Derived calculations, Refinement description