2OU4

Crystal structure of D-tagatose 3-epimerase from Pseudomonas cichorii


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.199 

Starting Model: experimental
View more details

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Crystal structures of D-tagatose 3-epimerase from Pseudomonas cichorii and its complexes with D-tagatose and D-fructose

Yoshida, H.Yamada, M.Nishitani, T.Takada, G.Izumori, K.Kamitori, S.

(2007) J Mol Biol 374: 443-453

  • DOI: https://doi.org/10.1016/j.jmb.2007.09.033
  • Primary Citation of Related Structures:  
    2OU4, 2QUL, 2QUM, 2QUN

  • PubMed Abstract: 

    Pseudomonas cichoriiid-tagatose 3-epimerase (P. cichoriid-TE) can efficiently catalyze the epimerization of not only d-tagatose to d-sorbose, but also d-fructose to d-psicose, and is used for the production of d-psicose from d-fructose. The crystal structures of P. cichoriid-TE alone and in complexes with d-tagatose and d-fructose were determined at resolutions of 1.79, 2.28, and 2.06 A, respectively. A subunit of P. cichoriid-TE adopts a (beta/alpha)(8) barrel structure, and a metal ion (Mn(2+)) found in the active site is coordinated by Glu152, Asp185, His211, and Glu246 at the end of the beta-barrel. P. cichoriid-TE forms a stable dimer to give a favorable accessible surface for substrate binding on the front side of the dimer. The simulated omit map indicates that O2 and O3 of d-tagatose and/or d-fructose coordinate Mn(2+), and that C3-O3 is located between carboxyl groups of Glu152 and Glu246, supporting the previously proposed mechanism of deprotonation/protonation at C3 by two Glu residues. Although the electron density is poor at the 4-, 5-, and 6-positions of the substrates, substrate-enzyme interactions can be deduced from the significant electron density at O6. The O6 possibly interacts with Cys66 via hydrogen bonding, whereas O4 and O5 in d-tagatose and O4 in d-fructose do not undergo hydrogen bonding to the enzyme and are in a hydrophobic environment created by Phe7, Trp15, Trp113, and Phe248. Due to the lack of specific interactions between the enzyme and its substrates at the 4- and 5-positions, P. cichoriid-TE loosely recognizes substrates in this region, allowing it to efficiently catalyze the epimerization of d-tagatose and d-fructose (C4 epimer of d-tagatose) as well. Furthermore, a C3-O3 proton-exchange mechanism for P. cichoriid-TE is suggested by X-ray structural analysis, providing a clear explanation for the regulation of the ionization state of Glu152 and Glu246.


  • Organizational Affiliation

    Life Science Research Center and Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
D-tagatose 3-epimerase
A, B, C, D
290Pseudomonas cichoriiMutation(s): 0 
EC: 5.3.1 (PDB Primary Data), 5.1.3.31 (UniProt)
UniProt
Find proteins for O50580 (Pseudomonas cichorii)
Explore O50580 
Go to UniProtKB:  O50580
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO50580
Sequence Annotations
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.199 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 76.797α = 90
b = 94.899β = 102.81
c = 91.732γ = 90
Software Package:
Software NamePurpose
CNSrefinement
ADSCdata collection
HKL-2000data reduction
HKL-2000data scaling
MOLREPphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-12-25
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2023-10-25
    Changes: Data collection, Database references, Derived calculations, Refinement description