1H6V

Mammalian thioredoxin reductase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.224 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Three-Dimensional Structure of a Mammalian Thioredoxin Reductase: Implication 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

  • DOI: 10.1073/pnas.171178698
  • Also Cited By: 1ZDL

  • PubMed Abstract: 
  • Thioredoxin reductases (TrxRs) from mammalian cells contain an essential selenocysteine residue in the conserved C-terminal sequence Gly-Cys-SeCys-Gly forming a selenenylsulfide in the oxidized enzyme. Reduction by NADPH generates a selenolthiol, whi ...

    Thioredoxin reductases (TrxRs) from mammalian cells contain an essential selenocysteine residue in the conserved C-terminal sequence Gly-Cys-SeCys-Gly forming a selenenylsulfide in the oxidized enzyme. Reduction by NADPH generates a selenolthiol, which is the active site in reduction of Trx. The three-dimensional structure of the SeCys498Cys mutant of rat TrxR in complex with NADP(+) has been determined to 3.0-A resolution by x-ray crystallography. The overall structure is similar to that of glutathione reductase (GR), including conserved amino acid residues binding the cofactors FAD and NADPH. Surprisingly, all residues directly interacting with the substrate glutathione disulfide in GR are conserved despite the failure of glutathione disulfide to act as a substrate for TrxR. The 16-residue C-terminal tail, which is unique to mammalian TrxR, folds in such a way that it can approach the active site disulfide of the other subunit in the dimer. A model of the complex of TrxR with Trx suggests that electron transfer from NADPH to the disulfide of the substrate is possible without large conformational changes. The C-terminal extension typical of mammalian TrxRs has two functions: (i) it extends the electron transport chain from the catalytic disulfide to the enzyme surface, where it can react with Trx, and (ii) it prevents the enzyme from acting as a GR by blocking the redox-active disulfide. Our results suggest that mammalian TrxR evolved from the GR scaffold rather than from its prokaryotic counterpart. This evolutionary switch renders cell growth dependent on selenium.


    Related Citations: 
    • Purification, Crystallization and Preliminarycrystallographic Data for Rat Cytosolic Selenocysteine 498 - Cysteine Mutant Thioredoxin Reductase
      Zhong, L.,Persson, K.,Sandalova, T.,Schneider, G.,Holmgren, A.
      (2000) Acta Crystallogr.,Sect.D 56: 1191


    Organizational Affiliation

    Division of Molecular Structural Biology and Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
THIOREDOXIN REDUCTASE
A, B, C, D, E, F
499Rattus norvegicusGene Names: Txnrd1 (Trxr1)
EC: 1.8.1.9
Find proteins for O89049 (Rattus norvegicus)
Go to UniProtKB:  O89049
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
FAD
Query on FAD

Download SDF File 
Download CCD File 
A, B, C, D, E, F
FLAVIN-ADENINE DINUCLEOTIDE
C27 H33 N9 O15 P2
VWWQXMAJTJZDQX-UYBVJOGSSA-N
 Ligand Interaction
NDP
Query on NDP

Download SDF File 
Download CCD File 
A, B, C, D, E, F
NADPH DIHYDRO-NICOTINAMIDE-ADENINE-DINUCLEOTIDE PHOSPHATE
C21 H30 N7 O17 P3
ACFIXJIJDZMPPO-NNYOXOHSSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.224 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 78.920α = 90.00
b = 140.464β = 94.64
c = 170.832γ = 90.00
Software Package:
Software NamePurpose
EPMRphasing
REFMACrefinement
SCALEPACKdata scaling
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-08-14
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2018-01-17
    Type: Data collection