1ZKQ

Crystal structure of mouse thioredoxin reductase type 2


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.6 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.222 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystal structures of oxidized and reduced mitochondrial thioredoxin reductase provide molecular details of the reaction mechanism.

Biterova, E.I.Turanov, A.A.Gladyshev, V.N.Barycki, J.J.

(2005) Proc.Natl.Acad.Sci.Usa 102: 15018-15023

  • DOI: 10.1073/pnas.0504218102
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Thioredoxin reductase (TrxR) is an essential enzyme required for the efficient maintenance of the cellular redox homeostasis, particularly in cancer cells that are sensitive to reactive oxygen species. In mammals, distinct isozymes function in the cy ...

    Thioredoxin reductase (TrxR) is an essential enzyme required for the efficient maintenance of the cellular redox homeostasis, particularly in cancer cells that are sensitive to reactive oxygen species. In mammals, distinct isozymes function in the cytosol and mitochondria. Through an intricate mechanism, these enzymes transfer reducing equivalents from NADPH to bound FAD and subsequently to an active-site disulfide. In mammalian TrxRs, the dithiol then reduces a mobile C-terminal selenocysteine-containing tetrapeptide of the opposing subunit of the dimer. Once activated, the C-terminal redox center reduces a disulfide bond within thioredoxin. In this report, we present the structural data on a mitochondrial TrxR, TrxR2 (also known as TR3 and TxnRd2). Mouse TrxR2, in which the essential selenocysteine residue had been replaced with cysteine, was isolated as a FAD-containing holoenzyme and crystallized (2.6 A; R = 22.2%; R(free) = 27.6%). The addition of NADPH to the TrxR2 crystals resulted in a color change, indicating reduction of the active-site disulfide and formation of a species presumed to be the flavin-thiolate charge transfer complex. Examination of the NADP(H)-bound model (3.0 A; R = 24.1%; R(free) = 31.2%) indicates that an active-site tyrosine residue must rotate from its initial position to stack against the nicotinamide ring of NADPH, which is juxtaposed to the isoalloxazine ring of FAD to facilitate hydride transfer. Detailed analysis of the structural data in conjunction with a model of the unusual C-terminal selenenylsulfide suggests molecular details of the reaction mechanism and highlights evolutionary adaptations among reductases.


    Related Citations: 
    • Three-dimensional structure of a mammalian thioredoxin reductase: implications for mechanism and evolution of a selenocysteine-dependent enzyme.
      Sandalova, T.,Zhong, L.,Lindqvist, Y.,Holmgren, A.,Schneider, G.
      (2001) Proc.Natl.Acad.Sci.USA 98: 9533
    • Refined structure of glutathione reductase at 1.54 resolution
      Karplus, P.A.,Schulz, G.E.
      (1987) J.Mol.Biol. 195: 701


    Organizational Affiliation

    Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0664, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Thioredoxin reductase 2, mitochondrial
A
517Mus musculusMutation(s): 0 
Gene Names: Txnrd2 (Trxr2)
EC: 1.8.1.9
Find proteins for Q9JLT4 (Mus musculus)
Go to UniProtKB:  Q9JLT4
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
FAD
Query on FAD

Download SDF File 
Download CCD File 
A
FLAVIN-ADENINE DINUCLEOTIDE
C27 H33 N9 O15 P2
VWWQXMAJTJZDQX-UYBVJOGSSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.6 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.222 
  • Space Group: I 41 2 2
Unit Cell:
Length (Å)Angle (°)
a = 108.830α = 90.00
b = 108.830β = 90.00
c = 205.950γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
CNSphasing
d*TREKdata scaling
CrystalCleardata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-11-01
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Derived calculations, Version format compliance