1K41

Crystal structure of KSI Y57S mutant


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.315 
  • R-Value Work: 0.235 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Maintenance of alpha-helical structures by phenyl rings in the active-site tyrosine triad contributes to catalysis and stability of ketosteroid isomerase from Pseudomonas putida biotype B

Nam, G.H.Jang, D.S.Cha, S.S.Lee, T.H.Kim, D.H.Hong, B.H.Yun, Y.S.Oh, B.H.Choi, K.Y.

(2001) Biochemistry 40: 13529-13537


  • PubMed Abstract: 
  • Ketosteroid isomerase (KSI) from Pseudomonas putida biotype B is a homodimeric enzyme catalyzing an allylic rearrangement of Delta5-3-ketosteroids at rates comparable with the diffusion-controlled limit. The tyrosine triad (Tyr14.Tyr55.Tyr30) forming ...

    Ketosteroid isomerase (KSI) from Pseudomonas putida biotype B is a homodimeric enzyme catalyzing an allylic rearrangement of Delta5-3-ketosteroids at rates comparable with the diffusion-controlled limit. The tyrosine triad (Tyr14.Tyr55.Tyr30) forming a hydrogen-bond network in the apolar active site of KSI has been characterized in an effort to identify the roles of the phenyl rings in catalysis, stability, and unfolding of the enzyme. The replacement of Tyr14, a catalytic residue, with serine resulted in a 33-fold decrease of kcat, while the replacements of Tyr30 and Tyr55 with serine decreased kcat by 4- and 51-fold, respectively. The large decrease of kcat for Y55S could be due to the structural perturbation of alpha-helix A3, which results in the reorientation of the active-site residues as judged by the crystal structure of Y55S determined at 2.2 A resolution. Consistent with the analysis of the Y55S crystal structure, the far-UV circular dichroism spectra of Y14S, Y30S, and Y55S indicated that the elimination of the phenyl ring of the tyrosine reduced significantly the content of alpha-helices. Urea-induced equilibrium unfolding experiments revealed that the DeltaG(U)H2O values of Y14S, Y30S, and Y55S were significantly decreased by 11.9, 13.7, and 9.5 kcal/mol, respectively, as compared with that of the wild type. A characterization of the unfolding kinetics based on PhiU-value analysis indicates that the interactions mediated by the tyrosine triad in the native state are very resistant to unfolding. Taken together, our results demonstrate that the internal packing by the phenyl rings in the active-site tyrosine triad contributes to the conformational stability and catalytic activity of KSI by maintaining the structural integrity of the alpha-helices.


    Organizational Affiliation

    Division of Molecular and Life Sciences National Research Laboratory of Protein Engineering, and National CRI Center for Biomolecular Recognition, Pohang University of Science and Technology, Pohang, 790-784, South Korea.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Ketosteroid Isomerase
A, B
131Pseudomonas putidaGene Names: ksi
EC: 5.3.3.1
Find proteins for P07445 (Pseudomonas putida)
Go to UniProtKB:  P07445
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.315 
  • R-Value Work: 0.235 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 88.889α = 90.00
b = 73.135β = 89.85
c = 51.156γ = 90.00
Software Package:
Software NamePurpose
X-PLORrefinement
DENZOdata reduction
AMoREphasing
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2002-10-16
    Type: Initial release
  • Version 1.1: 2008-05-05
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance