Forward operation of adenine nucleotide translocase during F 0F1-ATPase reversal: Critical role of matrix substrate-level phosphorylation

Christos Chinopoulos, Akos A. Gerencser, Miklos Mandi, Katalin Mathe, Beata Töröcsik, Judit Doczi, Lilla Turiak, Gergely Kiss, Csaba Konràd, Szilvia Vajda, Viktoria Vereczki, Richard J. Oh, Vera Adam-Vizi

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

In pathological conditions, F0F1-ATPase hydrolyzes ATP in an attempt to maintain mitochondrial membrane potential. Using thermodynamic assumptions and computer modeling, we established that mitochondrial membrane potential can be more negative than the reversal potential of the adenine nucleotide translocase (ANT) but more positive than that of the F0F1-ATPase. Experiments on isolated mitochondria demonstrated that, when the electron transport chain is compromised, the F0F1-ATPase reverses, and the membrane potential is maintained as long as matrix substrate-level phosphorylation is functional, without a concomitant reversal of the ANT. Consistently, no cytosolic ATP consumption was observed using plasmalemmal KATP channels as cytosolic ATP biosensors in cultured neurons, in which their in situ mitochondria were compromised by respiratory chain inhibitors. This finding was further corroborated by quantitative measurements of mitochondrial membrane potential, oxygen consumption, and extracellular acidification rates, indicating nonreversal of ANT of compromised in situ neuronal and astrocytic mitochondria; and by bioluminescence ATP measurements in COS-7 cells transfected with cytosolicor nuclear-targeted luciferases and treated with mitochondrial respiratory chain inhibitors in the presence of glycolytic plus mitochondrial vs. only mitochondrial substrates. Our findings imply the possibility of a rescue mechanism that is protecting against cytosolic/nuclear ATP depletion under pathological conditions involving impaired respiration. This mechanism comes into play when mitochondria respire on substrates that support matrix substrate-level phosphorylation.

Original languageEnglish
Pages (from-to)2405-2416
Number of pages12
JournalFASEB Journal
Volume24
Issue number7
DOIs
Publication statusPublished - Jul 1 2010

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Keywords

  • ATP synthasome
  • Adenine nucleotide carrier
  • Bioenergetics
  • SUCLA2
  • Systems biology of mitochondria

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics

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