PMID:15023367

Citation	Delbaere, LT, Sudom, AM, Prasad, L, Leduc, Y and Goldie, H (2004) Structure/function studies of phosphoryl transfer by phosphoenolpyruvate carboxykinase. Biochim. Biophys. Acta 1697:271-8
Abstract	Phosphoenolpyruvate carboxykinase (PCK) catalyzes the conversion of oxaloacetate (OAA) to PEP and carbon dioxide with the subsequent conversion of nucleoside triphosphate to nucleoside diphosphate (NDP). The 1.9 A resolution structure of Escherichia coli PCK consisted of a 275-residue N-terminal domain and a 265-residue C-terminal domain with the active site located in a cleft between these domains. Each domain has an alpha/beta topology and the overall structure represents a new protein fold. Furthermore, PCK has a unique mononucleotide-binding fold. The 1.8 A resolution structure of the complex of ATP/Mg(2+)/oxalate with PCK revealed a 20 degrees hinge-like rotation of the N- and C-terminal domains, which closed the active site cleft. The ATP was found in the unusual syn conformation as a result of binding to the enzyme. Along with the side chain of Lys254, Mg(2+) neutralizes charges on the P beta and P gamma oxygen atoms of ATP and stabilizes an extended, eclipsed conformation of the P beta and P gamma phosphoryl groups. The sterically strained high-energy conformation likely lowers the free energy of activation for phosphoryl transfer. Additionally, the gamma-phosphoryl group becomes oriented in-line with the appropriate enolate oxygen atom, which strongly supports a direct S(N)2-type displacement of this gamma-phosphoryl group by the enolate anion. In the 2.0 A resolution structure of the complex of PCK/ADP/Mg(2+)/AlF(3), the AlF(3) moiety represents the phosphoryl group being transferred during catalysis. There are three positively charged groups that interact with the fluorine atoms, which are complementary to the three negative charges that would occur for an associative transition state.
Links	PubMed Online version:10.1016/j.bbapap.2003.11.030
Keywords	Adenosine Diphosphate/metabolism; Adenosine Triphosphate/metabolism; Animals; Catalysis; Humans; Models, Molecular; Phosphoenolpyruvate Carboxykinase (ATP)/chemistry; Phosphoenolpyruvate Carboxykinase (ATP)/metabolism; Phosphoenolpyruvate Carboxykinase (GTP)/chemistry; Phosphoenolpyruvate Carboxykinase (GTP)/metabolism; Phosphoric Acid Esters/metabolism; Protein Conformation; Structure-Activity Relationship
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status

References

See Help:References for how to manage references in GONUTS.