3odm | pdb_00003odm
Archaeal-type phosphoenolpyruvate carboxylase
Structural highlights
Function[CAPPA_CLOPE] Catalyzes the irreversible beta-carboxylation of phosphoenolpyruvate (PEP) to form oxaloacetate (OAA), a four-carbon dicarboxylic acid source for the tricarboxylic acid cycle.[1] Publication Abstract from PubMedThe crystal structure of an archaeal-type phosphoenolpyruvate carboxylase from Clostridium perfringens has been determined based on X-ray data extending to 3 A. The asymmetric unit of the structure includes two tetramers (each a dimer-of-dimers) of the enzyme. The precipitant, malonate, employed for the crystallization is itself a weak inhibitor of phosphoenolpyruvate carboxylase and a malonate molecule is seen in the active-site in the crystal structure. The allosteric binding sites for aspartate (an inhibitor) and glucose-6-phosphate (an activator) observed in the Escherichia coli and Zea mays phosphoenolpyruvate carboxylase structures, respectively, are not conserved in the C. perfringens structure. Aspartate inhibits the C. perfringens enzyme competitively with respect to the substrate, Mg(++.) phosphoenolpyruvate. A mechanism for inhibition is proposed based on the structure and sequence comparisons with other archaeal-type phosphoenolpyruvate carboxylases with differing sensitivity to inhibition by aspartate. Proteins 2011; (c) 2011 Wiley-Liss, Inc. Structure of an archaeal-type phosphoenolpyruvate carboxylase sensitive to inhibition by aspartate.,Dharmarajan L, Kraszewski JL, Mukhopadhyay B, Dunten PW Proteins. 2011 Feb 3. doi: 10.1002/prot.23006. PMID:21491491[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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