JBIC Journal of Biological Inorganic Chemistry

, Volume 17, Issue 6, pp 939–949

1-Aminocyclopropane-1-carboxylic acid oxidase: insight into cofactor binding from experimental and theoretical studies

  • Lydie Brisson
  • Nadia El Bakkali-Taheri
  • Michel Giorgi
  • Antoine Fadel
  • József Kaizer
  • Marius Réglier
  • Thierry Tron
  • El Hassan Ajandouz
  • A. Jalila Simaan
Original Paper

DOI: 10.1007/s00775-012-0910-3

Cite this article as:
Brisson, L., El Bakkali-Taheri, N., Giorgi, M. et al. J Biol Inorg Chem (2012) 17: 939. doi:10.1007/s00775-012-0910-3

Abstract

1-Aminocyclopropane-1-carboxylic acid oxidase (ACCO) is a nonheme Fe(II)-containing enzyme that is related to the 2-oxoglutarate-dependent dioxygenase family. The binding of substrates/cofactors to tomato ACCO was investigated through kinetics, tryptophan fluorescence quenching, and modeling studies. α-Aminophosphonate analogs of the substrate (1-aminocyclopropane-1-carboxylic acid, ACC), 1-aminocyclopropane-1-phosphonic acid (ACP) and (1-amino-1-methyl)ethylphosphonic acid (AMEP), were found to be competitive inhibitors versus both ACC and bicarbonate (HCO3) ions. The measured dissociation constants for Fe(II) and ACC clearly indicate that bicarbonate ions improve both Fe(II) and ACC binding, strongly suggesting a stabilization role for this cofactor. A structural model of tomato ACCO was constructed and used for docking experiments, providing a model of possible interactions of ACC, HCO3, and ascorbate at the active site. In this model, the ACC and bicarbonate binding sites are located close together in the active pocket. HCO3 is found at hydrogen-bond distance from ACC and interacts (hydrogen bonds or electrostatic interactions) with residues K158, R244, Y162, S246, and R300 of the enzyme. The position of ascorbate is also predicted away from ACC. Individually docked at the active site, the inhibitors ACP and AMEP were found coordinating the metal ion in place of ACC with the phosphonate groups interacting with K158 and R300, thus interlocking with both ACC and bicarbonate binding sites. In conclusion, HCO3 and ACC together occupy positions similar to the position of 2-oxoglutarate in related enzymes, and through a hydrogen bond HCO3 likely plays a major role in the stabilization of the substrate in the active pocket.

Keywords

Enzyme kinetics Fluorescence Docking 1-Aminocyclopropane-1-carboxylic acid oxidase Nonheme iron 

Supplementary material

775_2012_910_MOESM1_ESM.pdf (267 kb)
Supplementary material 1 (PDF 266 kb)

Copyright information

© SBIC 2012

Authors and Affiliations

  • Lydie Brisson
    • 1
  • Nadia El Bakkali-Taheri
    • 1
  • Michel Giorgi
    • 2
  • Antoine Fadel
    • 3
  • József Kaizer
    • 4
  • Marius Réglier
    • 1
  • Thierry Tron
    • 1
  • El Hassan Ajandouz
    • 1
  • A. Jalila Simaan
    • 1
  1. 1.Aix-Marseille Université and CNRS, Institut des Sciences Moléculaires de Marseille, UMR 7313Marseille Cedex 20France
  2. 2.SpectropoleAix-Marseille UniversitéMarseille Cedex 20France
  3. 3.Laboratoire de Synthèse Organique et Méthodologie, ICMMO, UMR 8182, Bât. 420Université Paris-SudOrsay CedexFrance
  4. 4.Department of ChemistryUniversity of PannoniaVeszprémHungary

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