1FIY

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

Summary for 1FIY

• Entry DOI: 10.2210/pdb1fiy/pdb
• Descriptor: PHOSPHOENOLPYRUVATE CARBOXYLASE, ASPARTIC ACID (3 entities in total)
• Functional Keywords: phosphoenolpyruvate, carboxylase, complex (lyase-inhibitor), complex (lyase-inhibitor) complex, complex (lyase/inhibitor)
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 99308.60

Authors

Kai, Y.,Matsumura, H.,Inoue, T.,Terada, K.,Nagara, Y.,Yoshinaga, T.,Kihara, A.,Izui, K. (deposition date: 1998-05-02, release date: 1999-02-09, Last modification date: 2024-02-07)

Primary citation

Kai, Y.,Matsumura, H.,Inoue, T.,Terada, K.,Nagara, Y.,Yoshinaga, T.,Kihara, A.,Tsumura, K.,Izui, K.
Three-dimensional structure of phosphoenolpyruvate carboxylase: a proposed mechanism for allosteric inhibition.
Proc.Natl.Acad.Sci.USA, 96:823-828, 1999

PubMed Abstract: 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.

PubMed: 9927652
DOI: 10.1073/pnas.96.3.823

Experimental method

X-RAY DIFFRACTION (2.8 Å)