1BQ7

DSBA MUTANT P151A, ROLE OF THE CIS-PROLINE IN THE ACTIVE SITE OF DSBA


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.289 
  • R-Value Work: 0.218 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

On the role of the cis-proline residue in the active site of DsbA.

Charbonnier, J.B.Belin, P.Moutiez, M.Stura, E.A.Quemeneur, E.

(1999) Protein Sci. 8: 96-105

  • DOI: 10.1110/ps.8.1.96

  • PubMed Abstract: 
  • In addition to the Cys-Xaa-Xaa-Cys motif at position 30-33, DsbA, the essential catalyst for disulfide bond formation in the bacterial periplasm shares with other oxidoreductases of the thioredoxin family a cis-proline in proximity of the active site ...

    In addition to the Cys-Xaa-Xaa-Cys motif at position 30-33, DsbA, the essential catalyst for disulfide bond formation in the bacterial periplasm shares with other oxidoreductases of the thioredoxin family a cis-proline in proximity of the active site residues. In the variant DsbA(P151A), this residue has been changed to an alanine, an almost isosteric residue which is not disposed to adopt the cis conformation. The substitution strongly destabilized the structure of DsbA, as determined by the decrease in the free energy of folding. The pKa of the thiol of Cys30 was only marginally decreased. Although in vivo the variant appeared to be correctly oxidized, it exhibited an activity less than half that of the wild-type enzyme with respect to the folding of alkaline phosphatase, used as a reporter of the disulfide bond formation in the periplasm. DsbA(P151A) crystallized in a different crystal form from the wild-type protein, in space group P2(1) with six molecules in the asymmetric unit. Its X-ray structure was determined to 2.8 A resolution. The most significant conformational changes occurred at the active site. The loop 149-152 adopted a new backbone conformation with Ala151 in a trans conformation. This rearrangement resulted in the loss of van der Waals interactions between this loop and the disulfide bond. His32 from the Cys-Xaa-Xaa-Cys sequence presented in four out of six molecules in the asymmetric unit a gauche conformation not observed in the wild-type protein. The X-ray structure and folding studies on DsbA(P151A) were consistent with the cis-proline playing a major role in the stabilization of the protein. A role for the positioning of the substrate is discussed. These important properties for the enzyme function might explain the conservation of this residue in DsbA and related proteins possessing the thioredoxin fold.


    Related Citations: 
    • Thioredoxin-A Fold for All Reasons
      Martin, J.L.
      (1995) Structure 3: 245
    • Structural Analysis of Three His32 Mutants of DsbA: Support for an Electrostatic Role of His32 in DsbA Stability
      Guddat, L.,Bardwell, J.C.,Glockshuber, R.,Huber-Wunderlich, M.,Zander, T.,Martin, J.L.
      (1997) Protein Sci. 6: 1893


    Organizational Affiliation

    CEA, Département d'Ingénierie et d'Etudes des Protéines, Gif-sur-Yvette, France.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
PROTEIN (DISULFIDE OXIDOREDUCTASE)
A, B, C, D, E, F
189Escherichia coli (strain K12)Gene Names: dsbA (dsf, ppfA)
Find proteins for P0AEG4 (Escherichia coli (strain K12))
Go to UniProtKB:  P0AEG4
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.289 
  • R-Value Work: 0.218 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 64.900α = 90.00
b = 190.700β = 111.90
c = 67.100γ = 90.00
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
AMoREphasing
X-PLORphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1999-08-20
    Type: Initial release
  • Version 1.1: 2007-10-16
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance