3HGX

Crystal Structure of Pseudomonas aeruginosa Isochorismate-Pyruvate Lyase K42A mutant in complex with salicylate and pyruvate


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.216 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structure-function analyses of isochorismate-pyruvate lyase from Pseudomonas aeruginosa suggest differing catalytic mechanisms for the two pericyclic reactions of this bifunctional enzyme.

Luo, Q.Olucha, J.Lamb, A.L.

(2009) Biochemistry 48: 5239-5245

  • DOI: 10.1021/bi900456e
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The isochorismate-pyruvate lyase from Pseudomonas aeruginosa (PchB) catalyzes two pericyclic reactions in a single active site. PchB physiologically produces salicylate and pyruvate from isochorismate for ultimate incorporation of the salicylate into ...

    The isochorismate-pyruvate lyase from Pseudomonas aeruginosa (PchB) catalyzes two pericyclic reactions in a single active site. PchB physiologically produces salicylate and pyruvate from isochorismate for ultimate incorporation of the salicylate into the siderophore pyochelin. PchB also produces prephenate from chorismate, most likely due to structural homology to the Escherchia coli chorismate mutase. The molecular basis of catalysis among enzymatic pericyclic reactions is a matter of debate, one view holding that catalysis may be derived from electrostatic transition state stabilization and the opposing view that catalysis is derived from the generation of a reactive substrate conformation. Mutant forms of PchB were generated by site-directed mutagenesis at the site (K42) hypothesized to be key for electrostatic transition state stabilization (K42A, K42Q, K42E, and K42H). The loop containing K42 is mobile, and a mutant to slow loop dynamics was also designed (A43P). Finally, a previously characterized mutation (I87T) was also produced. Circular dichroism was used to assess the overall effect on secondary structure as a result of the mutations, and X-ray crystallographic structures are reported for K42A with salicylate and pyruvate bound and for apo-I87T. The data illustrate that the active site architecture is maintained in K42A-PchB, which indicates that differences in activity are not caused by secondary structural changes or by differences in active site loop conformation but rather by the chemical nature of this key residue. In contrast, the I87T structure demonstrates considerable mobility, suggesting that loop dynamics and conformational plasticity may be important for efficient catalysis. Finally, the mutational effects on k(cat) provide evidence that the two activities of PchB are not covariant and that a single hypothesis may not provide a sufficient explanation for catalysis.


    Organizational Affiliation

    Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Salicylate biosynthesis protein pchB
A, B
101Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)Mutation(s): 1 
Gene Names: pchB
EC: 4.2.99.21
Find proteins for Q51507 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Go to UniProtKB:  Q51507
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PYR
Query on PYR

Download SDF File 
Download CCD File 
A, B
PYRUVIC ACID
C3 H4 O3
LCTONWCANYUPML-UHFFFAOYSA-N
 Ligand Interaction
SAL
Query on SAL

Download SDF File 
Download CCD File 
A, B
2-HYDROXYBENZOIC ACID
SALICYLIC ACID
C7 H6 O3
YGSDEFSMJLZEOE-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.216 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 48.015α = 90.00
b = 53.150β = 90.00
c = 82.336γ = 90.00
Software Package:
Software NamePurpose
DENZOdata reduction
REFMACrefinement
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
PHASERphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2009-05-14 
  • Released Date: 2009-06-30 
  • Deposition Author(s): Luo, Q., Lamb, A.L.

Revision History 

  • Version 1.0: 2009-06-30
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2017-11-01
    Type: Advisory, Refinement description