Cooperativity of two active sites in bacterial homodimeric aconitases

Daisuke Tsuchiya, Nobutaka Shimizu, Masaru Tomita

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Aconitase catalyzes a reversible isomerization of citrate into isocitrate in the Krebs cycle. Escherichia coli possesses two kinds of aconitases, aconitase A (AcnA) and B (AcnB), whose structural organizations are different. We analyzed the structural state of AcnA by the chemical crosslinking and small-angle X-ray scattering. The protein adopts a homodimer in solution, as AcnB does. The catalytic assay of the two aconitases revealed that the isomerization of isocitrate displayed a negative cooperativity of the two active sites within each homodimer. On the other hand, insignificant cooperativity was observed in the reverse reaction. Therefore, the homodimerization of AcnAB yields a substrate-dependent cooperative effect. In conjunction with the dissociable homodimer of AcnB, the catalytic property could affect the intracellular metabolic process involving the Krebs cycle.

Original languageEnglish
Pages (from-to)485-488
Number of pages4
JournalBiochemical and Biophysical Research Communications
Volume379
Issue number2
DOIs
Publication statusPublished - 2009 Feb 6

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Keywords

  • Enzyme catalysis
  • Negative cooperativity
  • Quaternary structure of protein
  • Small-angle X-ray scattering
  • Structural modeling

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Molecular Biology

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