3MOS

The structure of human Transketolase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.206 
  • R-Value Work: 0.162 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

The crystal structure of human transketolase and new insights into its mode of action.

Mitschke, L.Parthier, C.Schroder-Tittmann, K.Coy, J.Ludtke, S.Tittmann, K.

(2010) J.Biol.Chem. 285: 31559-31570

  • DOI: 10.1074/jbc.M110.149955

  • PubMed Abstract: 
  • The crystal structure of human transketolase (TKT), a thiamine diphosphate (ThDP) and Ca(2+)-dependent enzyme that catalyzes the interketol transfer between ketoses and aldoses as part of the pentose phosphate pathway, has been determined to 1.75 Å r ...

    The crystal structure of human transketolase (TKT), a thiamine diphosphate (ThDP) and Ca(2+)-dependent enzyme that catalyzes the interketol transfer between ketoses and aldoses as part of the pentose phosphate pathway, has been determined to 1.75 Å resolution. The recombinantly produced protein crystallized in space group C2 containing one monomer in the asymmetric unit. Two monomers form the homodimeric biological assembly with two identical active sites at the dimer interface. Although the protomer exhibits the typical three (α/β)-domain structure and topology reported for TKTs from other species, structural differences are observed for several loop regions and the linker that connects the PP and Pyr domain. The cofactor and substrate binding sites of human TKT bear high resemblance to those of other TKTs but also feature unique properties, including two lysines and a serine that interact with the β-phosphate of ThDP. Furthermore, Gln(189) spans over the thiazolium moiety of ThDP and replaces an isoleucine found in most non-mammalian TKTs. The side chain of Gln(428) forms a hydrogen bond with the 4'-amino group of ThDP and replaces a histidine that is invariant in all non-mammalian TKTs. All other amino acids involved in substrate binding and catalysis are strictly conserved. Besides a steady-state kinetic analysis, microscopic equilibria of the donor half-reaction were characterized by an NMR-based intermediate analysis. These studies reveal that formation of the central 1,2-dihydroxyethyl-ThDP carbanion-enamine intermediate is thermodynamically favored with increasing carbon chain length of the donor ketose substrate. Based on the structure of human transketolase and sequence alignments, putative functional properties of the related transketolase-like proteins TKTL1 and -2 are discussed in light of recent findings suggesting that TKTL1 plays a role in cancerogenesis.


    Organizational Affiliation

    Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, 06120 Halle, Germany.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Transketolase
A
616Homo sapiensMutation(s): 0 
Gene Names: TKT
EC: 2.2.1.1
Find proteins for P29401 (Homo sapiens)
Go to Gene View: TKT
Go to UniProtKB:  P29401
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
TPP
Query on TPP

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Download CCD File 
A
THIAMINE DIPHOSPHATE
C12 H19 N4 O7 P2 S
AYEKOFBPNLCAJY-UHFFFAOYSA-O
 Ligand Interaction
NA
Query on NA

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A
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
CA
Query on CA

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Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
EDO
Query on EDO

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Download CCD File 
A
1,2-ETHANEDIOL
ETHYLENE GLYCOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.206 
  • R-Value Work: 0.162 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 113.630α = 90.00
b = 85.330β = 125.69
c = 72.740γ = 90.00
Software Package:
Software NamePurpose
CrystalCleardata collection
PDB_EXTRACTdata extraction
XSCALEdata scaling
PHASERphasing
REFMACrefinement
XDSdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-07-28
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance