3OE1

Pyruvate decarboxylase variant Glu473Asp from Z. mobilis in complex with reaction intermediate 2-lactyl-ThDP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.99 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.197 

Starting Model: experimental
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Ligand Structure Quality Assessment 


This is version 1.3 of the entry. See complete history


Literature

Double duty for a conserved glutamate in pyruvate decarboxylase: evidence of the participation in stereoelectronically controlled decarboxylation and in protonation of the nascent carbanion/enamine intermediate .

Meyer, D.Neumann, P.Parthier, C.Friedemann, R.Nemeria, N.Jordan, F.Tittmann, K.

(2010) Biochemistry 49: 8197-8212

  • DOI: https://doi.org/10.1021/bi100828r
  • Primary Citation of Related Structures:  
    3OE1

  • PubMed Abstract: 

    Pyruvate decarboxylase (PDC) catalyzes the nonoxidative decarboxylation of pyruvate into acetaldehyde and carbon dioxide and requires thiamin diphosphate (ThDP) and a divalent cation as cofactors. Recent studies have permitted the assignment of functional roles of active site residues; however, the underlying reaction mechanisms of elementary steps have remained hypothetical. Here, a kinetic and thermodynamic single-step analysis in conjunction with X-ray crystallographic studies of PDC from Zymomonas mobilis implicates active site residue Glu473 (located on the re-face of the ThDP thiazolium nucleus) in facilitating both decarboxylation of 2-lactyl-ThDP and protonation of the 2-hydroxyethyl-ThDP carbanion/enamine intermediate. Variants carrying either an isofunctional (Glu473Asp) or isosteric (Glu473Gln) substitution exhibit a residual catalytic activity of less than 0.1% but accumulate different intermediates at the steady state. Whereas the predecarboxylation intermediate 2-lactyl-ThDP is accumulated in Glu473Asp because of a 3000-fold slower decarboxylation compared to that of the wild-type enzyme, Glu473Gln is not impaired in decarboxylation but generates a long-lived 2-hydroxyethyl-ThDP carbanion/enamine postdecarboxylation intermediate. CD spectroscopic analysis of the protonic and tautomeric equilibria of the cocatalytic aminopyrimidine part of ThDP indicates that an acidic residue is required at position 473 for proper substrate binding. Wild-type PDC and the Glu473Asp variant bind the substrate analogue acetylphosphinate with the same affinity, implying a similar stabilization of the predecarboxylation intermediate analogue on the enzyme, whereas Glu473Gln fails to bind the analogue. The X-ray crystallographic structure of 2-lactyl-ThDP trapped in the decarboxylation-deficient variant Glu473Asp reveals a common stereochemistry of the intermediate C2α stereocenter; however, the scissile C2α-C(carboxylate) bond deviates by ∼25-30° from the perpendicular "maximum overlap" orientation relative to the thiazolium ring plane as commonly observed in ThDP enzymes. Because a reactant-state stabilization of the predecarboxylation intermediate can be excluded to account for the slower decarboxylation, the data suggest a strong stereoelectronic effect for the transition state of decarboxylation as supported by additional DFT studies on models. To the best of our knowledge, this is a very rare example in which the magnitude of a stereoelectronic effect could be experimentally estimated for an enzymatic system. Given that variant Glu473Gln is not decarboxylation-deficient, electrostatic stress can be excluded as a driving force for decarboxylation. The apparent dual function of Glu473 further suggests that decarboxylation and protonation of the incipient carbanion are committed and presumably proceed in the same transition state.


  • Organizational Affiliation

    Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences, Georg-August-University Göttingen, Ernst-Caspari-Haus, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Pyruvate decarboxylase
A, B, C, D
568Zymomonas mobilisMutation(s): 1 
Gene Names: pdcZMO1360
EC: 4.1.1.1
UniProt
Find proteins for P06672 (Zymomonas mobilis subsp. mobilis (strain ATCC 31821 / ZM4 / CP4))
Explore P06672 
Go to UniProtKB:  P06672
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP06672
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
TDL
Query on TDL

Download Ideal Coordinates CCD File 
F [auth A],
H [auth B],
J [auth C],
L [auth D]
3-[(4-AMINO-2-METHYLPYRIMIDIN-5-YL)METHYL]-2-(1-CARBOXY-1-HYDROXYETHYL)-5-(2-{[HYDROXY(PHOSPHONOOXY)PHOSPHORYL]OXY}ETHYL)-4-METHYL-1,3-THIAZOL-3-IUM
C15 H23 N4 O10 P2 S
TVDSMGSBVYONNB-OAHLLOKOSA-O
GOL
Query on GOL

Download Ideal Coordinates CCD File 
M [auth D],
N [auth D]
GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
MG
Query on MG

Download Ideal Coordinates CCD File 
E [auth A],
G [auth B],
I [auth C],
K [auth D]
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.99 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.197 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 67.493α = 90
b = 165.356β = 108.93
c = 95.869γ = 90
Software Package:
Software NamePurpose
XSCALEdata scaling
PHASERphasing
PHENIXrefinement
PDB_EXTRACTdata extraction
MAR345dtbdata collection
XDSdata reduction

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-09-08
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-10-06
    Changes: Database references, Derived calculations
  • Version 1.3: 2023-09-06
    Changes: Data collection, Refinement description