1LWJ

CRYSTAL STRUCTURE OF T. MARITIMA 4-ALPHA-GLUCANOTRANSFERASE/ACARBOSE COMPLEX


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.302 
  • R-Value Work: 0.225 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

CRYSTAL STRUCTURE OF THERMOTOGA MARITIMA 4-ALPHA-GLUCANOTRANSFERASE AND ITS ACARBOSE COMPLEX: IMPLICATIONS FOR SUBSTRATE SPECIFICITY AND CATALYSIS

Roujeinikova, A.Raasch, C.Sedelnikova, S.Liebl, W.Rice, D.W.

(2002) J.Mol.Biol. 321: 149-162

  • Primary Citation of Related Structures:  1LWH

  • PubMed Abstract: 
  • 4-alpha-Glucanotransferase (GTase) is an essential enzyme in alpha-1,4-glucan metabolism in bacteria and plants. It catalyses the transfer of maltooligosaccharides from an 1,4-alpha-D-glucan molecule to the 4-hydroxyl group of an acceptor sugar molec ...

    4-alpha-Glucanotransferase (GTase) is an essential enzyme in alpha-1,4-glucan metabolism in bacteria and plants. It catalyses the transfer of maltooligosaccharides from an 1,4-alpha-D-glucan molecule to the 4-hydroxyl group of an acceptor sugar molecule. The crystal structures of Thermotoga maritima GTase and its complex with the inhibitor acarbose have been determined at 2.6A and 2.5A resolution, respectively. The GTase structure consists of three domains, an N-terminal domain with the (beta/alpha)(8) barrel topology (domain A), a 65 residue domain, domain B, inserted between strand beta3 and helix alpha6 of the barrel, and a C-terminal domain, domain C, which forms an antiparallel beta-structure. Analysis of the complex of GTase with acarbose has revealed the locations of five sugar-binding subsites (-2 to +3) in the active-site cleft lying between domain B and the C-terminal end of the (beta/alpha)(8) barrel. The structure of GTase closely resembles the family 13 glycoside hydrolases and conservation of key catalytic residues previously identified for this family is consistent with a double-displacement catalytic mechanism for this enzyme. A distinguishing feature of GTase is a pair of tryptophan residues, W131 and W218, which, upon the carbohydrate inhibitor binding, form a remarkable aromatic "clamp" that captures the sugar rings at the acceptor-binding sites +1 and +2. Analysis of the structure of the complex shows that sugar residues occupying subsites from -2 to +2 engage in extensive interactions with the protein, whereas the +3 glucosyl residue makes relatively few contacts with the enzyme. Thus, the structure suggests that four subsites, from -2 to +2, play the dominant role in enzyme-substrate recognition, consistent with the observation that the smallest donor for T.maritima GTase is maltotetraose, the smallest chain transferred is a maltosyl unit and that the smallest residual fragment after transfer is maltose. A close similarity between the structures of GTase and oligo-1,6-glucosidase has allowed the structural features that determine differences in substrate specificity of these two enzymes to be analysed.


    Related Citations: 
    • CRYSTALLIZATION AND PRELIMINARY X-RAY CRYSTALLOGRAPHIC STUDIES ON 4-ALPHA-GLUCANOTRANSFERASE FROM THERMOTOGA MARITIMA
      Roujeinikova, A.,Raasch, C.,Sedelnikova, S.,Liebl, W.,Rice, D.W.
      (2001) Acta Crystallogr.,Sect.D 57: 1046


    Organizational Affiliation

    Department of Molecular Biology and Biotechnology, Krebs Institute for Biomolecular Research, The University of Sheffield, England, UK.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
4-ALPHA-GLUCANOTRANSFERASE
A, B
441Thermotoga maritima (strain ATCC 43589 / MSB8 / DSM 3109 / JCM 10099)Gene Names: mgtA
EC: 2.4.1.25
Find proteins for P80099 (Thermotoga maritima (strain ATCC 43589 / MSB8 / DSM 3109 / JCM 10099))
Go to UniProtKB:  P80099
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download SDF File 
Download CCD File 
A, B
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
ACG
Query on ACG

Download SDF File 
Download CCD File 
A, B
MODIFIED ACARBOSE PENTASACCHARIDE
C31 H53 N O22
QWNATFSCUHKKDP-WYKVUHPSSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.302 
  • R-Value Work: 0.225 
  • Space Group: I 2 2 2
Unit Cell:
Length (Å)Angle (°)
a = 94.542α = 90.00
b = 181.354β = 90.00
c = 197.317γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data reduction
DENZOdata reduction
SCALEPACKdata scaling
CNSrefinement
AMoREphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2002-08-14
    Type: Initial release
  • Version 1.1: 2008-04-28
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance