Anaerobiospirillum succiniciproducens Phosphoenolpyruvate Carboxykinase: Mutagenesis at Metal Site 2

Ana María Jabalquinto, Maris Laivenieks, Fernando D. González-Nilo, María Victoria Encinas, Gregory Zeikus, Emilio Cardemil

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Phosphoenolpyruvate (PEP) carboxykinases harbor two divalent metal-binding sites. One cation interacts with the enzyme (metal binding site 1) to elicit activation, while a second cation (metal binding site 2) interacts with the nucleotide to serve as the metal nucleotide substrate. Mutants of Anaerobiospirillum succiniciproducens PEP carboxykinase have been constructed where Thr249 and Asp262, two residues of metal binding site 2 of the enzyme, were altered. Binding of the 3′(2′ )-O-(N-methylantraniloyl) derivative of ADP provides a test of the structural integrity of these mutants. The conservative mutation (Asp262Glu) retains a significant proportion of the wild type enzymatic activity. Meanwhile, removal of the OH group of Thr249 in the Thr249Ala mutant causes a decrease in Vmax by a factor of 1.1 × 104. Molecular modeling of wild type and mutant enzymes suggests that the lower catalytic efficiency of the Thr249Ala enzyme could be explained by a movement of the lateral chain of Lys248, a critical catalytic residue, away from the reaction center.

Original languageEnglish
Pages (from-to)515-519
Number of pages5
JournalJournal of Protein Chemistry
Volume22
Issue number6
DOIs
Publication statusPublished - Aug 2003

Keywords

  • Anaerobiospirillum succiniciproducens
  • Phosphoenolpyruvate carboxykinase
  • Site-directed mutagenesis

ASJC Scopus subject areas

  • Biochemistry

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