4HHO

Serum paraoxonase-1 by directed evolution with the H115W mutation

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.184 

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Literature

Catalytic metal ion rearrangements underline promiscuity and evolvability of a metalloenzyme.

Ben-David, M., Wieczorek, G., Elias, M., Silman, I., Sussman, J.L., Tawfik, D.S.

(2013) J Mol Biol 425: 1028-1038

  • DOI: 10.1016/j.jmb.2013.01.009
  • Primary Citation of Related Structures:  
    4HHO, 4HHQ

  • PubMed Abstract: 

    • Although largely deemed as structurally conserved, catalytic metal ion sites can rearrange, thereby contributing to enzyme evolvability. Here, we show that in paraoxonase-1, a lipo-lactonase, catalytic promiscuity and divergence into an organophosphate hydrolase are correlated with an alternative mode of the catalytic Ca(2+) ...

    Although largely deemed as structurally conserved, catalytic metal ion sites can rearrange, thereby contributing to enzyme evolvability. Here, we show that in paraoxonase-1, a lipo-lactonase, catalytic promiscuity and divergence into an organophosphate hydrolase are correlated with an alternative mode of the catalytic Ca(2+). We describe the crystal structures of active-site mutants bearing mutations at position 115. The histidine at this position acts as a base to activate the lactone-hydrolyzing water molecule. Mutations to Trp or Gln indeed diminish paraoxonase-1's lactonase activity; however, the promiscuous organophosphate hydrolase activity is enhanced. The structures reveal a 1.8-Å upward displacement towards the enzyme's surface of the catalytic Ca(2+) in the His115 mutants and configurational changes in the ligating side chains and water molecules, relative to the wild-type enzyme. Biochemical analysis and molecular dynamics simulations suggest that this alternative, upward metal mode mediates the promiscuous hydrolysis of organophosphates. The upward Ca(2+) mode observed in the His115 mutants also appears to mediate the wild type's paraoxonase activity. However, whereas the upward mode dominates in the Trp115 mutant, it is scarcely populated in wild type. Thus, the plasticity of active-site metal ions may permit alternative, latent, promiscuous activities and also provide the basis for the divergence of new enzymatic functions.

    Organizational Affiliation: 

    Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
SERUM PARAOXONASE BY DIRECTED EVOLUTIONA355synthetic constructMutation(s): 0 
Gene Names: Homo sapiens, oryctolagus cuniculus, mus musculus, rattus rattus
EC: 3.1.1.2 (PDB Primary Data), 3.1.8.1 (PDB Primary Data), 3.1.1.25 (PDB Primary Data)
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
LMT
Query on LMT
Download Ideal Coordinates CCD File 
D [auth A]DODECYL-BETA-D-MALTOSIDE
C24 H46 O11
NLEBIOOXCVAHBD-QKMCSOCLSA-N		 Ligand Interaction
BR
Query on BR
Download Ideal Coordinates CCD File 
E [auth A],
F [auth A]		BROMIDE ION
Br
CPELXLSAUQHCOX-UHFFFAOYSA-M		 Ligand Interaction
CA
Query on CA
Download Ideal Coordinates CCD File 
B [auth A],
C [auth A]		CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.184 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 93.782α = 90
b = 93.782β = 90
c = 145.158γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
PHASERphasing
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-03-27
    Type: Initial release