Mitochondrial diaphorases as NAD+ donors to segments of the citric acid cycle that support substrate-level phosphorylation yielding ATP during respiratory inhibition

Gergely Kiss, Csaba Konrad, Issa Pour-Ghaz, Josef J. Mansour, Beáta Németh, Anatoly A. Starkov, V. Ádám-Vizi, C. Chinopoulos

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Substrate-level phosphorylation mediated by succinyl-CoA ligase in the mitochondrial matrix produces high-energy phosphates in the absence of oxidative phosphorylation. Furthermore, when the electron transport chain is dysfunctional, provision of succinyl-CoA by the ±-ketoglutarate dehydrogenase complex (KGDHC) is crucial for maintaining the function of succinyl-CoA ligase yielding ATP, preventing the adenine nucleotide translocase from reversing. We addressed the source of the NAD+ supply for KGDHC under anoxic conditions and inhibition of complex I. Using pharmacologic tools and specific substrates and by examining tissues from pigeon liver exhibiting no diaphorase activity, we showed that mitochondrial diaphorases in the mouse liver contribute up to 81% to the NAD+ pool during respiratory inhibition. Under these conditions, KGDHC's function, essential for the provision of succinyl-CoA to succinyl-CoA ligase, is supported by NAD + derived from diaphorases. Through this process, diaphorases contribute to the maintenance of substrate-level phosphorylation during respiratory inhibition, which is manifested in the forward operation of adenine nucleotide translocase. Finally, we show that reoxidation of the reducible substrates for the diaphorases is mediated by complex III of the respiratory chain.

Original languageEnglish
Pages (from-to)1682-1697
Number of pages16
JournalFASEB Journal
Volume28
Issue number4
DOIs
Publication statusPublished - 2014

Fingerprint

Dihydrolipoamide Dehydrogenase
Phosphorylation
Citric Acid Cycle
NAD
Adenosine Triphosphate
Ligases
ATP Translocases Mitochondrial ADP
Ketoglutarate Dehydrogenase Complex
Substrates
Electron Transport
Liver
Electron Transport Complex III
Oxidative Phosphorylation
Columbidae
Phosphates
Maintenance
succinyl-coenzyme A
Tissue

Keywords

  • Adenine nucleotide translocase
  • DT-diaphorase
  • Reducing equivalent
  • Succinyl-CoA ligase

ASJC Scopus subject areas

  • Biochemistry
  • Biotechnology
  • Genetics
  • Molecular Biology

Cite this

Mitochondrial diaphorases as NAD+ donors to segments of the citric acid cycle that support substrate-level phosphorylation yielding ATP during respiratory inhibition. / Kiss, Gergely; Konrad, Csaba; Pour-Ghaz, Issa; Mansour, Josef J.; Németh, Beáta; Starkov, Anatoly A.; Ádám-Vizi, V.; Chinopoulos, C.

In: FASEB Journal, Vol. 28, No. 4, 2014, p. 1682-1697.

Research output: Contribution to journalArticle

Kiss, Gergely ; Konrad, Csaba ; Pour-Ghaz, Issa ; Mansour, Josef J. ; Németh, Beáta ; Starkov, Anatoly A. ; Ádám-Vizi, V. ; Chinopoulos, C. / Mitochondrial diaphorases as NAD+ donors to segments of the citric acid cycle that support substrate-level phosphorylation yielding ATP during respiratory inhibition. In: FASEB Journal. 2014 ; Vol. 28, No. 4. pp. 1682-1697.
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