Robb 2018 J Biol Chem
|Robb EL, Hall AR, Prime TA, Eaton S, Szibor M, Viscomi C, James AM, Murphy MP (2018) Control of mitochondrial superoxide production by reverse electron transport at complex I. J Biol Chem 293:9869-79. https://doi.org/10.1074/jbc.RA118.003647|
Abstract: The generation of mitochondrial superoxide (O2̇•-)) by reverse electron transport (RET) at complex I causes oxidative damage in pathologies such as ischemia reperfusion injury, but also provides the precursor to H2O2 production in physiological mitochondrial redox signaling. Here, we quantified the factors that determine mitochondrial O2̇•- production by RET in isolated heart mitochondria. Measuring mitochondrial H2O2 production at a range of proton-motive force (Δp) values and for several coenzyme Q (CoQ) and NADH pool redox states obtained with the uncoupler p-trifluoromethoxyphenylhydrazone, we show that O2̇•- production by RET responds to changes in O2̇•- concentration, the magnitude of Δp, and the redox states of the CoQ and NADH pools. Moreover, we determined how expressing the alternative oxidase from the tunicate Ciona intestinalis to oxidize the CoQ pool affected RET-mediated O2̇•- production at complex I, underscoring the importance of the CoQ pool for mitochondrial O2̇•- production by RET. An analysis of O2̇•- production at complex I as a function of the thermodynamic forces driving RET at complex I revealed that many molecules that affect mitochondrial reactive oxygen species production do so by altering the overall thermodynamic driving forces of RET, rather than by directly acting on complex I. These findings clarify the factors controlling RET-mediated mitochondrial O2̇•- production in both pathological and physiological conditions. We conclude that O2̇•- production by RET is highly responsive to small changes in Δp and the CoQ redox state, indicating that complex I RET represents a major mode of mitochondrial redox signaling. • Keywords: RET, Coenzyme Q, Complex I, Mitochondria, Mitochondrial membrane potential, Reactive oxygen species (ROS), Redox signaling, Respiration, Reverse electron transport, Superoxide • Bioblast editor: Kandolf G • O2k-Network Lab: FI Helsinki Jacobs HT, IT Padova Viscomi C, DE Jena Szibor M
- Komlódi T, Sobotka O, Gnaiger E (2021) Facts and artefacts on the oxygen dependence of hydrogen peroxide production using Amplex UltraRed. Bioenerg Commun 2021.4. https://doi:10.26124/BEC:2021-0004
- Komlódi T, Schmitt S, Zdrazilova L, Donnelly C, Zischka H, Gnaiger E (2022) Oxygen dependence of hydrogen peroxide production in isolated mitochondria and permeabilized cells. MitoFit Preprints 2022 (in prep).
- Komlodi et al (2022) Hydrogen peroxide production, mitochondrial membrane potential and the coenzyme Q redox state measured at tissue normoxia and experimental hyperoxia in heart mitochondria. MitoFit Preprints 2021 (in prep)
- Komlódi T, Gnaiger E (2022) Discrepancy on oxygen dependence of mitochondrial ROS production - review. MitoFit Preprints 2022 (in prep).
Labels: MiParea: Respiration, nDNA;cell genetics
Stress:Oxidative stress;RONS Organism: Rat Tissue;cell: Heart Preparation: Isolated mitochondria
Coupling state: ET Pathway: N, S, ROX HRR: Oxygraph-2k, O2k-Fluorometer
2018-07, AmR, MitoFit 2021 AmR, MitoFit 2021 Tissue normoxia, MitoFit 2021 AmR-O2, MitoFit 2022 ROS review