Crystal structure of Glycogen Debranching exzyme TreX from Sulfolobus solfatarius

Experimental Data Snapshot

  • Resolution: 3.00 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.206 

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Structural Insight Into the Bifunctional Mechanism of the Glycogen-Debranching Enzyme Trex from the Archaeon Sulfolobus Solfataricus.

Woo, E.Lee, S.Cha, H.Park, J.Yoon, S.Song, H.Park, K.

(2008) J Biol Chem 283: 28641

  • DOI: https://doi.org/10.1074/jbc.M802560200
  • Primary Citation of Related Structures:  
    2VNC, 2VR5, 2VUY

  • PubMed Abstract: 

    TreX is an archaeal glycogen-debranching enzyme that exists in two oligomeric states in solution, as a dimer and tetramer. Unlike its homologs, TreX from Sulfolobus solfataricus shows dual activities for alpha-1,4-transferase and alpha-1,6-glucosidase. To understand this bifunctional mechanism, we determined the crystal structure of TreX in complex with an acarbose ligand. The acarbose intermediate was covalently bound to Asp363, occupying subsites -1 to -3. Although generally similar to the monomeric structure of isoamylase, TreX exhibits two different active-site configurations depending on its oligomeric state. The N terminus of one subunit is located at the active site of the other molecule, resulting in a reshaping of the active site in the tetramer. This is accompanied by a large shift in the "flexible loop" (amino acids 399-416), creating connected holes inside the tetramer. Mutations in the N-terminal region result in a sharp increase in alpha-1,4-transferase activity and a reduced level of alpha-1,6-glucosidase activity. On the basis of geometrical analysis of the active site and mutational study, we suggest that the structural lid (acids 99-97) at the active site generated by the tetramerization is closely associated with the bifunctionality and in particular with the alpha-1,4-transferase activity. These results provide a structural basis for the modulation of activities upon TreX oligomerization that may represent a common mode of action for other glycogen-debranching enzymes in higher organisms.

  • Organizational Affiliation

    Translational Research Center, Korea Research Institute of Bioscience and Biotechnology, 111 Gwahangno, Yuseong-gu, Daejeon 305-806.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
718Saccharolobus solfataricusMutation(s): 0 
EC: 3.2.1
Find proteins for P95868 (Saccharolobus solfataricus)
Explore P95868 
Go to UniProtKB:  P95868
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP95868
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.00 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.206 
  • Space Group: P 3 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 203.633α = 90
b = 203.633β = 90
c = 89.428γ = 120
Software Package:
Software NamePurpose

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-07-29
    Type: Initial release
  • Version 1.1: 2012-08-29
    Changes: Advisory, Database references, Derived calculations, Other, Structure summary, Version format compliance
  • Version 1.2: 2015-04-01
    Changes: Database references
  • Version 1.3: 2023-12-13
    Changes: Data collection, Database references, Other, Refinement description