2RI6

Crystal Structure of S112A mutant of a C-C hydrolase, BphD from Burkholderia xenovorans LB400


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.68 Å
  • R-Value Free: 0.201 
  • R-Value Work: 0.175 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

The tautomeric half-reaction of BphD, a C-C bond hydrolase. Kinetic and structural evidence supporting a key role for histidine 265 of the catalytic triad.

Horsman, G.P.Bhowmik, S.Seah, S.Y.Kumar, P.Bolin, J.T.Eltis, L.D.

(2007) J.Biol.Chem. 282: 19894-19904

  • DOI: 10.1074/jbc.M702237200
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • BphD of Burkholderia xenovorans LB400 catalyzes an unusual C-C bond hydrolysis of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) to afford benzoic acid and 2-hydroxy-2,4-pentadienoic acid (HPD). An enol-keto tautomerization has been proposed t ...

    BphD of Burkholderia xenovorans LB400 catalyzes an unusual C-C bond hydrolysis of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) to afford benzoic acid and 2-hydroxy-2,4-pentadienoic acid (HPD). An enol-keto tautomerization has been proposed to precede hydrolysis via a gem-diol intermediate. The role of the canonical catalytic triad (Ser-112, His-265, Asp-237) in mediating these two half-reactions remains unclear. We previously reported that the BphD-catalyzed hydrolysis of HOPDA (lambda(max) is 434 nm for the free enolate) proceeds via an unidentified intermediate with a red-shifted absorption spectrum (lambda(max) is 492 nm) (Horsman, G. P., Ke, J., Dai, S., Seah, S. Y. K., Bolin, J. T., and Eltis, L. D. (2006) Biochemistry 45, 11071-11086). Here we demonstrate that the S112A variant generates and traps a similar intermediate (lambda(max) is 506 nm) with a similar rate, 1/tau approximately 500 s(-1). The crystal structure of the S112A:HOPDA complex at 1.8-A resolution identified this intermediate as the keto tautomer, (E)-2,6-dioxo-6-phenyl-hex-3-enoate. This keto tautomer did not accumulate in either the H265A or the S112A/H265A double variants, indicating that His-265 catalyzes tautomerization. Consistent with this role, the wild type and S112A enzymes catalyzed tautomerization of the product HPD, whereas H265A variants did not. This study thus identifies a keto intermediate, and demonstrates that the catalytic triad histidine catalyzes the tautomerization half-reaction, expanding the role of this residue from its purely hydrolytic function in other serine hydrolases. Finally, the S112A:HOPDA crystal structure is more consistent with hydrolysis occurring via an acyl-enzyme intermediate than a gem-diol intermediate as solvent molecules have poor access to C6, and the closest ordered water is 7 A away.


    Organizational Affiliation

    Department of Biochemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate hydrolase
A
283Paraburkholderia xenovorans (strain LB400)Mutation(s): 1 
Gene Names: bphD
EC: 3.7.1.8
Find proteins for P47229 (Paraburkholderia xenovorans (strain LB400))
Go to UniProtKB:  P47229
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA

Download SDF File 
Download CCD File 
A
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
MLI
Query on MLI

Download SDF File 
Download CCD File 
A
MALONATE ION
C3 H2 O4
OFOBLEOULBTSOW-UHFFFAOYSA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.68 Å
  • R-Value Free: 0.201 
  • R-Value Work: 0.175 
  • Space Group: I 41 2 2
Unit Cell:
Length (Å)Angle (°)
a = 117.293α = 90.00
b = 117.293β = 90.00
c = 87.306γ = 90.00
Software Package:
Software NamePurpose
MOLREPphasing
REFMACrefinement
HKL-2000data scaling
PDB_EXTRACTdata extraction
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2007-10-10 
  • Released Date: 2007-11-06 
  • Deposition Author(s): Bhowmik, S., Bolin, J.T.
  • This entry supersedes: 2PU6

Revision History 

  • Version 1.0: 2007-11-06
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Source and taxonomy, Version format compliance
  • Version 1.2: 2017-10-25
    Type: Refinement description