1EZL

CRYSTAL STRUCTURE OF THE DISULPHIDE BOND-DEFICIENT AZURIN MUTANT C3A/C26A: HOW IMPORTANT IS THE S-S BOND FOR FOLDING AND STABILITY?


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.189 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystal structure of the disulfide bond-deficient azurin mutant C3A/C26A: how important is the S-S bond for folding and stability?

Bonander, N.Leckner, J.Guo, H.Karlsson, B.G.Sjolin, L.

(2000) Eur.J.Biochem. 267: 4511-4519


  • PubMed Abstract: 
  • Azurin has a beta-barrel fold comprising eight beta-strands and one alpha helix. A disulfide bond between residues 3 and 26 connects the N-termini of beta strands beta1 and beta3. Three mutant proteins lacking the disulfide bond were constructed, C3A ...

    Azurin has a beta-barrel fold comprising eight beta-strands and one alpha helix. A disulfide bond between residues 3 and 26 connects the N-termini of beta strands beta1 and beta3. Three mutant proteins lacking the disulfide bond were constructed, C3A/C26A, C3A/C26I and a putative salt bridge (SB) in the C3A/S25R/C26A/K27R mutant. All three mutants exhibit spectroscopic properties similar to the wild-type protein. Furthermore, the crystal structure of the C3A/C26A mutant was determined at 2.0 A resolution and, in comparison to the wild-type protein, the only differences are found in the immediate proximity of the mutation. The mutants lose the 628 nm charge-transfer band at a temperature 10-22 degrees C lower than the wild-type protein. The folding of the zinc loaded C3A/C26A mutant was studied by guanidine hydrochloride (GdnHCl) induced denaturation monitored both by fluorescence and CD spectroscopy. The midpoint in the folding equilibrium, at 1.3 M GdnHCl, was observed using both CD and fluorescence spectroscopy. The free energy of folding determined from CD is -24.9 kJ.mol-1, a destabilization of approximately 20 kJ.mol-1 compared to the wild-type Zn2+-protein carrying an intact disulfide bond, indicating that the disulfide bond is important for giving azurin its stable structure. The C3A/C26I mutant is more stable and the SB mutant is less stable than C3A/C26A, both in terms of folding energy and thermal denaturation. The folding intermediate of the wild-type Zn2+-azurin is not observed for the disulfide-deficient C3A/C26A mutant. The rate of unfolding for the C3A/C26A mutant is similar to that of the wild-type protein, suggesting that the site of the mutation is not involved in an early unfolding reaction.


    Organizational Affiliation

    Department of Biochemistry and Biophysics, Lundberg Institute, Göteborg University and Chalmers University of Technology, Sweden.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
AZURIN
A, B, C, D
128Pseudomonas aeruginosa (strain ATCC 15692 / PAO1 / 1C / PRS 101 / LMG 12228)Gene Names: azu
Find proteins for P00282 (Pseudomonas aeruginosa (strain ATCC 15692 / PAO1 / 1C / PRS 101 / LMG 12228))
Go to UniProtKB:  P00282
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CU
Query on CU

Download SDF File 
Download CCD File 
A, B, C, D
COPPER (II) ION
Cu
JPVYNHNXODAKFH-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.189 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 57.400α = 90.00
b = 80.400β = 90.00
c = 110.300γ = 90.00
Software Package:
Software NamePurpose
X-PLORrefinement
X-PLORmodel building
SAINTdata scaling
X-PLORphasing
SMARTdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2000-08-09
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance