1fiy
From Proteopedia
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'''THREE-DIMENSIONAL STRUCTURE OF PHOSPHOENOLPYRUVATE CARBOXYLASE FROM ESCHERICHIA COLI AT 2.8 A RESOLUTION''' | '''THREE-DIMENSIONAL STRUCTURE OF PHOSPHOENOLPYRUVATE CARBOXYLASE FROM ESCHERICHIA COLI AT 2.8 A RESOLUTION''' | ||
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[[Category: Terada, K.]] | [[Category: Terada, K.]] | ||
[[Category: Yoshinaga, T.]] | [[Category: Yoshinaga, T.]] | ||
| - | [[Category: | + | [[Category: Carboxylase]] |
| - | [[Category: | + | [[Category: Phosphoenolpyruvate]] |
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Revision as of 13:22, 2 May 2008
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. 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 Page seeded by OCA on Fri May 2 16:22:55 2008
