2VOC

THIOREDOXIN A ACTIVE SITE MUTANTS FORM MIXED DISULFIDE DIMERS THAT RESEMBLE ENZYME-SUBSTRATE REACTION INTERMEDIATE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.5 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.185 

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This is version 1.1 of the entry. See complete history

Literature

Thioredoxin a Active-Site Mutants Form Mixed Disulfide Dimers that Resemble Enzyme-Substrate Reaction Intermediates.

Kouwen, T.R.H.M.Andrell, J.Schrijver, R.Dubois, J.Y.F.Maher, M.J.Iwata, S.Carpenter, E.P.Van Dijl, J.M.

(2008) J.Mol.Biol. 379: 520

  • DOI: 10.1016/j.jmb.2008.03.077

  • PubMed Abstract: 
  • Thioredoxin functions in nearly all organisms as the major thiol-disulfide oxidoreductase within the cytosol. Its prime purpose is to maintain cysteine-containing proteins in the reduced state by converting intramolecular disulfide bonds into dithiol ...

    Thioredoxin functions in nearly all organisms as the major thiol-disulfide oxidoreductase within the cytosol. Its prime purpose is to maintain cysteine-containing proteins in the reduced state by converting intramolecular disulfide bonds into dithiols in a disulfide exchange reaction. Thioredoxin has been reported to contribute to a wide variety of physiological functions by interacting with specific sets of substrates in different cell types. To investigate the function of the essential thioredoxin A (TrxA) in the low-GC Gram-positive bacterium Bacillus subtilis, we purified wild-type TrxA and three mutant TrxA proteins that lack either one or both of the two cysteine residues in the CxxC active site. The pure proteins were used for substrate-binding studies known as "mixed disulfide fishing" in which covalent disulfide-bonded reaction intermediates can be visualized. An unprecedented finding is that both active-site cysteine residues can form mixed disulfides with substrate proteins when the other active-site cysteine is absent, but only the N-terminal active-site cysteine forms stable interactions. A second novelty is that both single-cysteine mutant TrxA proteins form stable homodimers due to thiol oxidation of the remaining active-site cysteine residue. To investigate whether these dimers resemble mixed enzyme-substrate disulfides, the structure of the most abundant dimer, C32S, was characterized by X-ray crystallography. This yielded a high-resolution (1.5A) X-ray crystallographic structure of a thioredoxin homodimer from a low-GC Gram-positive bacterium. The C32S TrxA dimer can be regarded as a mixed disulfide reaction intermediate of thioredoxin, which reveals the diversity of thioredoxin/substrate-binding modes.


    Organizational Affiliation

    Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, Hanzeplein 1, PO Box 30001, 9700 RB Groningen, The Netherlands.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
THIOREDOXIN
A, B
112Bacillus subtilis (strain 168)Gene Names: trxA (trx)
Find proteins for P14949 (Bacillus subtilis (strain 168))
Go to UniProtKB:  P14949
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PEG
Query on PEG

Download SDF File 
Download CCD File 
A
DI(HYDROXYETHYL)ETHER
C4 H10 O3
MTHSVFCYNBDYFN-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.5 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.185 
  • Space Group: P 1
Unit Cell:
Length (Å)Angle (°)
a = 36.765α = 83.33
b = 38.395β = 66.62
c = 41.878γ = 78.08
Software Package:
Software NamePurpose
SCALEPACKdata scaling
DENZOdata reduction
PHASERphasing
REFMACrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-03-10
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Advisory, Version format compliance