2QEW

Rat cytosolic PEPCK, in complex with manganese ion.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.213 
  • R-Value Work: 0.178 
  • R-Value Observed: 0.180 

Starting Model: experimental
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wwPDB Validation   3D Report Full Report


This is version 1.4 of the entry. See complete history


Literature

Structures of rat cytosolic PEPCK: insight into the mechanism of phosphorylation and decarboxylation of oxaloacetic acid.

Sullivan, S.M.Holyoak, T.

(2007) Biochemistry 46: 10078-10088

  • DOI: https://doi.org/10.1021/bi701038x
  • Primary Citation of Related Structures:  
    2QEW, 2QEY, 2QF1, 2QF2

  • PubMed Abstract: 

    The structures of the rat cytosolic isoform of phosphoenolpyruvate carboxykinase (PEPCK) reported in the PEPCK-Mn2+, -Mn2+-oxaloacetic acid (OAA), -Mn2+-OAA-Mn2+-guanosine-5'-diphosphate (GDP), and -Mn2+-Mn2+-guanosine-5'-tri-phosphate (GTP) complexes provide insight into the mechanism of phosphoryl transfer and decarboxylation mediated by this enzyme. OAA is observed to bind in a number of different orientations coordinating directly to the active site metal. The Mn2+-OAA and Mn2+-OAA-Mn2+GDP structures illustrate inner-sphere coordination of OAA to the manganese ion through the displacement of two of the three water molecules coordinated to the metal in the holo-enzyme by the C3 and C4 carbonyl oxygens. In the PEPCK-Mn2+-OAA complex, an alternate bound conformation of OAA is present. In this conformation, in addition to the previous interactions, the C1 carboxylate is directly coordinated to the active site Mn2+, displacing all of the waters coordinated to the metal in the holo-enzyme. In the PEPCK-Mn2+-GTP structure, the same water molecule displaced by the C1 carboxylate of OAA is displaced by one of the gamma-phosphate oxygens of the triphosphate nucleotide. The structures are consistent with a mechanism of direct in-line phosphoryl transfer, supported by the observed stereochemistry of the reaction. In the catalytically competent binding mode, the C1 carboxylate of OAA is sandwiched between R87 and R405 in an environment that would serve to facilitate decarboxylation. In the reverse reaction, these two arginines would form the CO2 binding site. Comparison of the Mn2+-OAA-Mn2+GDP and Mn2+-Mn2+GTP structures illustrates a marked difference in the bound conformations of the nucleotide substrates in which the GTP nucleotide is bound in a high-energy state resulting from the eclipsing of all three of the phosphoryl groups along the triphosphate chain. This contrasts a previously determined structure of PEPCK in complex with a triphosphate nucleotide analogue in which the analogue mirrors the conformation of GDP as opposed to GTP. Last, the structures illustrate a correlation between conformational changes in the P-loop, the nucleotide binding site, and the active site lid that are important for catalysis.


  • Organizational Affiliation

    Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas 66160, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Phosphoenolpyruvate carboxykinase, cytosolic [GTP]624Rattus norvegicusMutation(s): 0 
Gene Names: Pck1
EC: 4.1.1.32 (PDB Primary Data), 2.7.11 (UniProt)
UniProt
Find proteins for P07379 (Rattus norvegicus)
Explore P07379 
Go to UniProtKB:  P07379
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP07379
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.213 
  • R-Value Work: 0.178 
  • R-Value Observed: 0.180 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 44.448α = 90
b = 119.046β = 109.59
c = 60.599γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
REFMACrefinement
PDB_EXTRACTdata extraction
CrystalCleardata collection
HKL-2000data reduction
HKL-2000data scaling
MOLREPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-08-21
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Version format compliance
  • Version 1.2: 2017-10-18
    Changes: Refinement description
  • Version 1.3: 2018-01-24
    Changes: Structure summary
  • Version 1.4: 2023-08-30
    Changes: Data collection, Database references, Derived calculations, Refinement description