1Q6R

Structure of 3-keto-L-gulonate 6-phosphate decarboxylase with bound L-xylulose 5-phosphate


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.76 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.190 
  • R-Value Observed: 0.192 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Structural Evidence for a 1,2-Enediolate Intermediate in the Reaction Catalyzed by 3-Keto-l-Gulonate 6-Phosphate Decarboxylase, a Member of the Orotidine 5'-Monophosphate Decarboxylase Suprafamily

Wise, E.L.Yew, W.S.Gerlt, J.A.Rayment, I.

(2003) Biochemistry 42: 12133-12142

  • DOI: 10.1021/bi0348819
  • Primary Citation of Related Structures:  
    1Q6L, 1Q6R, 1Q6Q, 1Q6O

  • PubMed Abstract: 
  • 3-Keto-L-gulonate 6-phosphate decarboxylase (KGPDC) and orotidine 5'-phosphate decarboxylase (OMPDC) are members of an enzyme suprafamily, the OMPDC suprafamily, because they are homologous enzymes that catalyze mechanistically distinct reactions using different substrates ...

    3-Keto-L-gulonate 6-phosphate decarboxylase (KGPDC) and orotidine 5'-phosphate decarboxylase (OMPDC) are members of an enzyme suprafamily, the OMPDC suprafamily, because they are homologous enzymes that catalyze mechanistically distinct reactions using different substrates. KGPDC catalyzes the Mg(2+) ion-dependent decarboxylation of 3-keto-L-gulonate 6-phosphate to yield L-xylulose 5-phosphate and CO(2); OMPDC catalyzes the metal ion-independent decarboxylation of OMP to UMP and CO(2). Structural studies have shown that KGPDC and OMPDC share several strictly conserved active site residues that are used differently by each enzyme to catalyze their mechanistically distinct reactions. Although the mechanism of the KGPDC-catalyzed reaction has yet to be elucidated, it is thought to proceed via a Mg(2+) ion-stabilized 1,2-enediolate intermediate. Here we report the crystal structures of KGPDC complexed with L-gulonate 6-phosphate, L-threonohydroxamate 4-phosphate, and L-xylitol 5-phosphate, analogues of the substrate, enediolate intermediate, and product, as well as with the product, L-xylulose 5-phosphate, at 1.2, 1.8, 1.7, and 1.8 A resolution, respectively. These structures support a mechanism that involves the formation of a cis-1,2-enediolate intermediate. Contrary to expectations, the geometry of the intermediate does not involve bidentate coordination of both enediolate oxygen atoms to the Mg(2+) ion but rather involves only the coordination of the oxygen on C2 to the Mg(2+) ion. The oxygen atom on C1 instead forms hydrogen bonds to both Lys64 and Asp67, two strictly conserved active site residues. Lys64 also interacts with the oxygen on C2 and may serve to stabilize a cis conformation of the 1,2-enediolate. These structures also implicate His136 to be the general acid that protonates the 1,2-enediolate intermediate. This study further demonstrates that multiple unrelated enzyme functions can evolve from a single active site architecture without regard for substrate binding affinity or mechanism.


    Organizational Affiliation

    Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
3-keto-L-gulonate 6-phosphate decarboxylaseA, B216Escherichia coliMutation(s): 0 
EC: 4.1.2 (PDB Primary Data), 4.1.1.85 (UniProt)
Find proteins for P39304 (Escherichia coli (strain K12))
Explore P39304 
Go to UniProtKB:  P39304
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
LX1
Query on LX1

Download Ideal Coordinates CCD File 
D [auth A], F [auth B]L-XYLULOSE 5-PHOSPHATE
C5 H13 O7 P
YPXGTKHZRCDZTL-WISUUJSJSA-N
 Ligand Interaction
MG
Query on MG

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

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.76 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.190 
  • R-Value Observed: 0.192 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 123.912α = 90
b = 41.58β = 96.41
c = 91.627γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
SCALEPACKdata scaling
CNSrefinement
HKL-2000data collection
HKL-2000data reduction
CNSphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-10-28
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2019-07-24
    Changes: Data collection, Refinement description