1fiy

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spinqualitylabelsall models 1fiy, resolution 2.8Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

THREE-DIMENSIONAL STRUCTURE OF PHOSPHOENOLPYRUVATE CARBOXYLASE FROM ESCHERICHIA COLI AT 2.8 A RESOLUTION

Overview

The crystal structure of phosphoenolpyruvate carboxylase (PEPC; EC 4., 1.1.31) has been determined by x-ray diffraction methods at 2.8-A, resolution by using Escherichia coli PEPC complexed with L-aspartate, an, allosteric inhibitor of all known PEPCs. The four subunits are arranged in, a "dimer-of-dimers" form with respect to subunit contact, resulting in an, overall square arrangement. The contents of alpha-helices and beta-strands, are 65% and 5%, respectively. All of the eight beta-strands, which are, widely dispersed in the primary structure, participate in the formation of, a single beta-barrel. Replacement of a conserved Arg residue (Arg-438) in, this linkage with Cys increased the tendency of the enzyme to dissociate, into dimers. The location of the catalytic site is likely to be near the, C-terminal side of the beta-barrel. The binding site for L-aspartate is, located about 20 A away from the catalytic site, and four residues, (Lys-773, Arg-832, Arg-587, and Asn-881) are involved in effector binding., The participation of Arg-587 is unexpected, because it is known to be, catalytically essential. Because this residue is in a highly conserved, glycine-rich loop, which is characteristic of PEPC, L-aspartate seemingly, causes inhibition by removing this glycine-rich loop from the catalytic, site. There is another mobile loop from Lys-702 to Gly-708 that is missing, in the crystal structure. The importance of this loop in catalytic, activity was also shown. Thus, the crystal-structure determination of PEPC, revealed two mobile loops bearing the enzymatic functions and accompanying, allosteric inhibition by L-aspartate.

About this Structure

1FIY is a Single protein structure of sequence from Escherichia coli with ASP as ligand. Active as Phosphoenolpyruvate carboxylase, with EC number 4.1.1.31 Full crystallographic information is available from OCA.

Reference

Three-dimensional structure of phosphoenolpyruvate carboxylase: a proposed mechanism for allosteric inhibition., Kai Y, Matsumura H, Inoue T, Terada K, Nagara Y, Yoshinaga T, Kihara A, Tsumura K, Izui K, Proc Natl Acad Sci U S A. 1999 Feb 2;96(3):823-8. PMID:9927652

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