Topography of tyrosine residues and their involvement in peroxidation of polyunsaturated cardiolipin in cytochrome c/cardiolipin peroxidase complexes

Alexandr A. Kapralov, Naveena Yanamala, Yulia Y. Tyurina, Laura Castro, Alejandro Samhan-Arias, Yuri A. Vladimirov, Akihiro Maeda, Andrew A. Weitz, Jim Peterson, Danila Mylnikov, Verónica Demicheli, Verónica Tortora, Judith Klein-Seetharaman, Rafael Radi, Valerian E. Kagan

Research output: Contribution to journalArticlepeer-review

61 Scopus citations

Abstract

Formation of cytochrome c (cyt c)/cardiolipin (CL) peroxidase complex selective toward peroxidation of polyunsaturated CLs is a pre-requisite for mitochondrial membrane permeabilization. Tyrosine residues - via the generation of tyrosyl radicals (Tyr) - are likely reactive intermediates of the peroxidase cycle leading to CL peroxidation. We used mutants of horse heart cyt c in which each of the four Tyr residues was substituted for Phe and assessed their contribution to the peroxidase catalysis. Tyr67Phe mutation was associated with a partial loss of the oxygenase function of the cyt c/CL complex and the lowest concentration of H2O2-induced Tyr radicals in electron paramagnetic resonance (EPR) spectra. Our MS experiments directly demonstrated decreased production of CL-hydroperoxides (CL-OOH) by Tyr67Phe mutant. Similarly, oxidation of a phenolic substrate, Amplex Red, was affected to a greater extent in Tyr67Phe than in three other mutants. Tyr67Phe mutant exerted high resistance to H2O2-induced oligomerization. Measurements of Tyr fluorescence, hetero-nuclear magnetic resonance (NMR) and computer simulations position Tyr67 in close proximity to the porphyrin ring heme iron and one of the two axial heme-iron ligand residues, Met80. Thus, the highly conserved Tyr67 is a likely electron-donor (radical acceptor) in the oxygenase half-reaction of the cyt c/CL peroxidase complex.

Original languageEnglish (US)
Pages (from-to)2147-2155
Number of pages9
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1808
Issue number9
DOIs
StatePublished - Sep 2011
Externally publishedYes

Keywords

  • Cardiolipin
  • Cardiolipin hydroperoxide
  • Cytochrome c
  • Peroxidase
  • Tyrosine

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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