2olr
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Crystal structure of Escherichia coli phosphoenolpyruvate carboxykinase complexed with carbon dioxide, Mg2+, ATP
OverviewOverview
Phosphoenolpyruvate carboxykinase (PCK) reversibly catalyzes the, carboxylation of phosphoenolpyruvate to oxaloacetate. Carbon dioxide, and, not bicarbonate ion, is the substrate utilized. Assays of the, carboxylation reaction show that initial velocities are 7.6-fold higher, when CO(2) is used instead of HCO(3)(-). Two Escherichia coli PCK-CO(2), crystal structures are presented here. The location of CO(2) is the same, for both structures; however the orientation of CO(2) is significantly, different, likely from the presence of a manganese ion in one of the, structures. PCK and the other three known protein-CO(2) crystal structure, complexes have been compared; all have CO(2) hydrogen bonding with a basic, amino acid side chain (Arg65 or Lys213 in PCK), likely to polarize CO(2), to make the central carbon atom more electrophilic and thus more reactive., Kinetic studies found that the PCK mutant Arg65Gln increased the K(M) for, substrates PEP and oxaloacetate but not for CO(2). The unchanged K(M) for, CO(2) can be explained since the Arg65Gln mutant likely maintains a, hydrogen bond to one of the oxygen atoms of carbon dioxide.
About this StructureAbout this Structure
2OLR is a Single protein structure of sequence from Escherichia coli with MG, CL, CO2 and ATP as ligands. Active as Phosphoenolpyruvate carboxykinase (ATP), with EC number 4.1.1.49 Full crystallographic information is available from OCA.
ReferenceReference
How does an enzyme recognize CO(2)?, Cotelesage JJ, Puttick J, Goldie H, Rajabi B, Novakovski B, Delbaere LT, Int J Biochem Cell Biol. 2007;39(6):1204-10. Epub 2007 Mar 30. PMID:17475535
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