Crystal Structures of C4 Form Maize and Quaternary Complex of E. Coli Phosphoenolpyruvate Carboxylases

Structure. 2002 Dec;10(12):1721-30. doi: 10.1016/s0969-2126(02)00913-9.

Abstract

Phosphoenolpyruvate carboxylase (PEPC) catalyzes the first step in the fixation of atmospheric CO(2) during C(4) photosynthesis. The crystal structure of C(4) form maize PEPC (ZmPEPC), the first structure of the plant PEPCs, has been determined at 3.0 A resolution. The structure includes a sulfate ion at the plausible binding site of an allosteric activator, glucose 6-phosphate. The crystal structure of E. coli PEPC (EcPEPC) complexed with Mn(2+), phosphoenolpyruvate analog (3,3-dichloro-2-dihydroxyphosphinoylmethyl-2-propenoate), and an allosteric inhibitor, aspartate, has also been determined at 2.35 A resolution. Dynamic movements were found in the ZmPEPC structure, compared with the EcPEPC structure, around two loops near the active site. On the basis of these molecular structures, the mechanisms for the carboxylation reaction and for the allosteric regulation of PEPC are proposed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allosteric Regulation
  • Amino Acid Sequence
  • Binding Sites
  • Crystallography, X-Ray
  • Escherichia coli / enzymology*
  • Models, Molecular
  • Molecular Sequence Data
  • Phosphoenolpyruvate Carboxylase / chemistry*
  • Phosphoenolpyruvate Carboxylase / metabolism
  • Protein Conformation
  • Sequence Homology, Amino Acid
  • Zea mays / enzymology*

Substances

  • Phosphoenolpyruvate Carboxylase

Associated data

  • PDB/1JQN
  • PDB/1JQO