'''PHOSPHOENOLPYRUVATE MUTASE FROM MOLLUSK IN WITH BOUND MG2-OXALATE'''
===PHOSPHOENOLPYRUVATE MUTASE FROM MOLLUSK IN WITH BOUND MG2-OXALATE===
==Overview==
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BACKGROUND: Phosphonate compounds are important secondary metabolites in nature and, when linked to macromolecules in eukaryotes, they might play a role in cell signaling. The first obligatory step in the biosynthesis of phosphonates is the formation of a carbon-phosphorus bond by converting phosphoenolpyruvate (PEP) to phosphonopyruvate (P-pyr), a reaction that is catalyzed by PEP mutase. The PEP mutase functions as a tetramer and requires magnesium ions (Mg2+). RESULTS: The crystal structure of PEP mutase from the mollusk Mytilus edulis, bound to the inhibitor Mg(2+)-oxalate, has been determined using multiwavelength anomalous diffraction, exploiting the selenium absorption edge of a selenomethionine-containing protein. The structure has been refined at 1.8 A resolution. PEP mutase adopts a modified alpha/beta barrel fold, in which the eighth alpha helix projects away from the alpha/beta barrel instead of packing against the beta sheet. A tightly associated dimer is formed, such that the two eighth helices are swapped, each packing against the beta sheet of the neighboring molecule. A dimer of dimers further associates into a tetramer. Mg(2+)-oxalate is buried close to the center of the barrel, at the C-terminal ends of the beta strands. CONCLUSIONS: The tetramer observed in the crystal is likely to be physiologically relevant. Because the Mg(2+)-oxalate is inaccessible to solvent, substrate binding and dissociation might be accompanied by conformational changes. A mechanism involving a phosphoenzyme intermediate is proposed, with Asp58 acting as the nucleophilic entity that accepts and delivers the phosphoryl group. The active-site architecture and the chemistry performed by PEP mutase are different from other alpha/beta-barrel proteins that bind pyruvate or PEP, thus the enzyme might represent a new family of alpha/beta-barrel proteins.
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==About this Structure==
==About this Structure==
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[[Category: Phosphomutase]]
[[Category: Phosphomutase]]
[[Category: Phosphotransferase]]
[[Category: Phosphotransferase]]
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Revision as of 06:35, 28 July 2008
This article has been automatically seeded. Changes to this page should pertain to the PDB entry only and not to the protein or biomolecule in general.
1PYM is a Single protein structure of sequence from Mytilus edulis. Full crystallographic information is available from OCA.
Reference
Helix swapping between two alpha/beta barrels: crystal structure of phosphoenolpyruvate mutase with bound Mg(2+)-oxalate., Huang K, Li Z, Jia Y, Dunaway-Mariano D, Herzberg O, Structure. 1999 May;7(5):539-48. PMID:10378273
