1ZCP

Crystal Structure of a catalytic site mutant E. coli TrxA (CACA)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Free: 0.281 
  • R-Value Work: 0.229 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

The crystal structure of TrxA(CACA): Insights into the formation of a [2Fe-2S] iron-sulfur cluster in an Escherichia coli thioredoxin mutant

Collet, J.-F.Peisach, D.Bardwell, J.C.Xu, Z.

(2005) Protein Sci. 14: 1863-1869

  • DOI: 10.1110/ps.051464705

  • PubMed Abstract: 
  • Escherichia coli thioredoxin is a small monomeric protein that reduces disulfide bonds in cytoplasmic proteins. Two cysteine residues present in a conserved CGPC motif are essential for this activity. Recently, we identified mutations of this motif t ...

    Escherichia coli thioredoxin is a small monomeric protein that reduces disulfide bonds in cytoplasmic proteins. Two cysteine residues present in a conserved CGPC motif are essential for this activity. Recently, we identified mutations of this motif that changed thioredoxin into a homodimer bridged by a [2Fe-2S] iron-sulfur cluster. When exported to the periplasm, these thioredoxin mutants could restore disulfide bond formation in strains lacking the entire periplasmic oxidative pathway. Essential for the assembly of the iron-sulfur was an additional cysteine that replaced the proline at position three of the CGPC motif. We solved the crystalline structure at 2.3 Angstroms for one of these variants, TrxA(CACA). The mutant protein crystallized as a dimer in which the iron-sulfur cluster is replaced by two intermolecular disulfide bonds. The catalytic site, which forms the dimer interface, crystallized in two different conformations. In one of them, the replacement of the CGPC motif by CACA has a dramatic effect on the structure and causes the unraveling of an extended alpha-helix. In both conformations, the second cysteine residue of the CACA motif is surface-exposed, which contrasts with wildtype thioredoxin where the second cysteine of the CXXC motif is buried. This exposure of a pair of vicinal cysteine residues apparently allows thioredoxin to acquire an iron-sulfur cofactor at its active site, and thus a new activity and mechanism of action.


    Related Citations: 
    • An engineered pathway for the formation of protein disulfide bonds
      Masip, L.,Pan, J.L.,Haldar, S.,Penner-Hahn, J.E.,DeLisa, M.P.,Georgiou, G.,Bardwell, J.C.A.,Collet, J.-F.
      (2004) Science 303: 1185


    Organizational Affiliation

    Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, 48109, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Thioredoxin 1
A, B, C, D
108Escherichia coli (strain K12)Mutation(s): 3 
Gene Names: trxA (fipA, tsnC)
Find proteins for P0AA25 (Escherichia coli (strain K12))
Go to UniProtKB:  P0AA25
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Free: 0.281 
  • R-Value Work: 0.229 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 34.720α = 90.00
b = 46.250β = 93.13
c = 126.000γ = 90.00
Software Package:
Software NamePurpose
MAR345data collection
CNSrefinement
MOLREPphasing
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-08-09
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-10-11
    Type: Refinement description