1ZCP

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


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.281 
  • R-Value Work: 0.229 
  • R-Value Observed: 0.229 

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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
  • Primary Citation of Related Structures:  
    1ZCP

  • 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 that changed thioredoxin into a homodimer bridged by a [2Fe-2S] iron-sulfur cluster ...

    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:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Thioredoxin 1A, B, C, D108Escherichia coliMutation(s): 3 
Gene Names: trxAfipAtsnC
UniProt
Find proteins for P0AA25 (Escherichia coli (strain K12))
Explore P0AA25 
Go to UniProtKB:  P0AA25
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.281 
  • R-Value Work: 0.229 
  • R-Value Observed: 0.229 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 34.72α = 90
b = 46.25β = 93.13
c = 126γ = 90
Software Package:
Software NamePurpose
CNSrefinement
MAR345data collection
SCALEPACKdata scaling
MOLREPphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

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