2FM7

Evolution of Enzymatic Activity in the Tautomerase Superfamily: Mechanistic and Structural Consequences of the L8R Mutation in 4-Oxalocrotonate Tautomerase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.80 Å
  • R-Value Free: 0.301 
  • R-Value Work: 0.230 
  • R-Value Observed: 0.233 

Starting Model: experimental
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This is version 1.4 of the entry. See complete history


Literature

Evolution of enzymatic activity in the tautomerase superfamily: mechanistic and structural consequences of the L8R mutation in 4-oxalocrotonate tautomerase

Poelarends, G.J.Almrud, J.J.Serrano, H.Darty, J.E.Johnson, W.H.Hackert, M.L.Whitman, C.P.

(2006) Biochemistry 45: 7700-7708

  • DOI: https://doi.org/10.1021/bi0600603
  • Primary Citation of Related Structures:  
    2FM7

  • PubMed Abstract: 

    4-Oxalocrotonate tautomerase (4-OT) and trans-3-chloroacrylic acid dehalogenase (CaaD) are members of the tautomerase superfamily, a group of structurally homologous proteins that share a beta-alpha-beta fold and a catalytic amino-terminal proline. 4-OT, from Pseudomonas putida mt-2, catalyzes the conversion of 2-oxo-4-hexenedioate to 2-oxo-3-hexenedioate through the dienol intermediate 2-hydroxymuconate in a catabolic pathway for aromatic hydrocarbons. CaaD, from Pseudomonas pavonaceae 170, catalyzes the hydrolytic dehalogenation of trans-3-chloroacrylate in the trans-1,3-dichloropropene degradation pathway. Both reactions may involve an arginine-stabilized enediolate intermediate, a capability that may partially account for the low-level CaaD activity of 4-OT. Two active-site residues in 4-OT, Leu-8 and Ile-52, have now been mutated to the positionally conserved and catalytic ones in CaaD, alphaArg-8, and alphaGlu-52. The L8R and L8R/I52E mutants show improved CaaD activity (50- and 32-fold increases in k(cat)/K(m), respectively) and diminished 4-OT activity (5- and 1700-fold decreases in k(cat)/K(m), respectively). The increased efficiency of L8R-4-OT for the CaaD reaction stems primarily from an 8.8-fold increase in k(cat), whereas that of the L8R/I52E mutant is due largely to a 23-fold decrease in K(m). The presence of the additional arginine residue in the active site of L8R-4-OT does not alter the pK(a) of the Pro-1 amino group from that measured for the wild type (6.5 +/- 0.1 versus 6.4 +/- 0.2). Moreover, the crystal structure of L8R-4-OT is comparable to that of the wild type. Hence, the enhanced CaaD activity of L8R-4-OT is likely due to the additional arginine residue that can participate in substrate binding and/or stabilization of the putative enediolate intermediate. The results also suggest that the evolution of new functions within the tautomerase superfamily could be quite facile, requiring only a few strategically placed active-site mutations.


  • Organizational Affiliation

    Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, The University of Texas, Austin, Texas 78712-1074, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
4-Oxalocrotonate Tautomerase
A, B, C, D, E
A, B, C, D, E, F
62Pseudomonas putidaMutation(s): 1 
Gene Names: xylH
EC: 5.3.2
UniProt
Find proteins for Q01468 (Pseudomonas putida)
Explore Q01468 
Go to UniProtKB:  Q01468
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ01468
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
CL
Query on CL

Download Ideal Coordinates CCD File 
G [auth D]CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.80 Å
  • R-Value Free: 0.301 
  • R-Value Work: 0.230 
  • R-Value Observed: 0.233 
  • Space Group: P 63
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 80.863α = 90
b = 80.863β = 90
c = 117.038γ = 120
Software Package:
Software NamePurpose
HKL-2000data collection
SCALEPACKdata scaling
MOLREPphasing
REFMACrefinement
HKL-2000data reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-09-26
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2021-10-20
    Changes: Database references, Derived calculations
  • Version 1.4: 2023-08-30
    Changes: Data collection, Refinement description