1IRB

CARBOXYLIC ESTER HYDROLASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Work: 0.192 
  • R-Value Observed: 0.192 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Phospholipase A2 engineering. Deletion of the C-terminus segment changes substrate specificity and uncouples calcium and substrate binding at the zwitterionic interface.

Huang, B.Yu, B.Z.Rogers, J.Byeon, I.J.Sekar, K.Chen, X.Sundaralingam, M.Tsai, M.D.Jain, M.K.

(1996) Biochemistry 35: 12164-12174

  • DOI: 10.1021/bi960234o
  • Primary Citation of Related Structures:  
    1IRB

  • PubMed Abstract: 
  • It has been suggested [Dijkstra, B. W., Drenth, J., & Kalk, K. H. (1981) Nature 289, 604-606] that the interfacial binding site of phospholipase A2 (PLA2) involves a large number of residues, including a cluster at the N-terminus and another cluster at the C-terminus ...

    It has been suggested [Dijkstra, B. W., Drenth, J., & Kalk, K. H. (1981) Nature 289, 604-606] that the interfacial binding site of phospholipase A2 (PLA2) involves a large number of residues, including a cluster at the N-terminus and another cluster at the C-terminus. The approaches of multiple mutation and deletion were used to test the roles of the C-terminal residues of bovine pancreatic PLA2 overexpressed in Escherichia coli. A double mutant K120A/K121A and a deletion mutant delta 115-123/ C27A were constructed, and structural and functional analyses were performed on both mutants. The double mutant showed little perturbation in the global structure on the basis of proton NMR and X-ray crystallographic analyses. The proton NMR analysis of the deletion mutant suggested that a few residues at the active site, the hydrophobic channel, and the calcium binding loop are perturbed, but the global conformation is not changed. The mutants were then characterized for catalytic and binding properties by use of various kinetic and spectroscopic methods. The double mutant behaved in a manner similar to that of the wild type (WT) PLA2 in every property examined. The deletion mutant was found to show an interesting change of substrate specificity. The kcat,app of the zwitterionic DC8PC micelles but not the anionic DC8PM micelles decreased by a factor of > 100; however, the activity of DC8PC was restored upon addition of 4 M NaCl. The results of fluorescence spectroscopic studies indicate that the deletion mutant behaves in a manner similar to that of WT in the binding to anionic vesicles and to zwitterionic neutral diluent. Thus, the binding affinity of the enzyme to the interface (the E to E* step) should not be the main cause for the change in substrate specificity. The cause lies at least partially in the binding of substrate or inhibitor to the active site of the enzyme at the interface, i.e., the E* to E*L step, as revealed by the results of equilibrium binding studies. The equilibrium dissociation constants of ligands are generally higher for the deletion mutant (relative to WT) at the zwitterionic interface but not at the anionic interface. The cause for the low affinity of an active site-directed ligand to the active site at the zwitterionic interface could be related to the inability of Ca2+ to enhance ligand binding for the deletion mutant. This is in contrast to the WT PLA2 for which Ca2+ binding enhances binding of the substrate to the active site. Overall, the structural and functional perturbations caused by deleting the C-terminal segment are modest, but the changes in substrate specificity and the uncoupling between substrate and calcium binding are interesting and significant.


    Related Citations: 
    • Phospholipase A2 Engineering. X-Ray Structural and Functional Evidence for the Interaction of Lysine-56 with Substrates
      Noel, J.P., Bingman, C.A., Deng, T.L., Dupureur, C.M., Hamilton, K.J., Jiang, R.T., Kwak, J.G., Sekharudu, C., Sundaralingam, M., Tsai, M.D.
      (1991) Biochemistry 30: 11801

    Organizational Affiliation

    Department of Chemistry, Ohio State University, Columbus 43210, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
PHOSPHOLIPASE A2A123Bos taurusMutation(s): 2 
Gene Names: MATURE PLA2PLA2G1B
EC: 3.1.1.4
UniProt
Find proteins for P00593 (Bos taurus)
Explore P00593 
Go to UniProtKB:  P00593
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download Ideal Coordinates CCD File 
B [auth A]CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Work: 0.192 
  • R-Value Observed: 0.192 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 46.81α = 90
b = 46.81β = 90
c = 102.89γ = 120
Software Package:
Software NamePurpose
R-AXISdata collection
R-AXISdata reduction
X-PLORmodel building
X-PLORrefinement
R-AXISdata scaling
X-PLORphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

  • Deposited Date: 1997-08-13 
  • Released Date: 1997-12-24 
  • Deposition Author(s): Sundaralingam, M.

Revision History  (Full details and data files)

  • Version 1.0: 1997-12-24
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance