scholarly journals Superoxide production by NADH:ubiquinone oxidoreductase (complex I) depends on the pH gradient across the mitochondrial inner membrane

2004 ◽  
Vol 382 (2) ◽  
pp. 511-517 ◽  
Author(s):  
Adrian J. LAMBERT ◽  
Martin D. BRAND
Keyword(s):  
Membrane Potential ◽  
Electron Transport ◽  
Complex I ◽  
Superoxide Production ◽  
Ph Gradient ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Protonmotive Force ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Reverse Electron Transport

The relationship between protonmotive force and superoxide production by mitochondria is poorly understood. To address this issue, the rate of superoxide production from complex I of rat skeletal muscle mitochondria incubated under a variety of conditions was assessed. By far, the largest rate of superoxide production was from mitochondria respiring on succinate; this rate was almost abolished by rotenone or piericidin, indicating that superoxide production from complex I is large under conditions of reverse electron transport. The high rate of superoxide production by complex I could also be abolished by uncoupler, confirming that superoxide production is sensitive to protonmotive force. It was inhibited by nigericin, suggesting that it is more dependent on the pH gradient across the mitochondrial inner membrane than on the membrane potential. These effects were examined in detail, leading to the conclusions that the effect of protonmotive force was mostly direct, and not indirect through changes in the redox state of the ubiquinone pool, and that the production of superoxide by complex I during reverse electron transport was at least 3-fold more sensitive to the pH gradient than to the membrane potential.

External alternative NADH:ubiquinone oxidoreductase redirected to the internal face of the mitochondrial inner membrane rescues complex I deficiency in Yarrowia lipolytica

2001 ◽  
Vol 114 (21) ◽  
pp. 3915-3921 ◽  
Author(s):  
Stefan J. Kerscher ◽  
Andrea Eschemann ◽  
Pamela M. Okun ◽  
Ulrich Brandt
Keyword(s):  
Yarrowia Lipolytica ◽  
Complex I ◽  
Functional Expression ◽  
Proton Pumping ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
The Matrix ◽  
Cytosolic Side ◽  
Respiratory Membrane

Alternative NADH:ubiquinone oxidoreductases are single subunit enzymes capable of transferring electrons from NADH to ubiquinone without contributing to the proton gradient across the respiratory membrane. The obligately aerobic yeast Yarrowia lipolytica has only one such enzyme, encoded by the NDH2 gene and located on the external face of the mitochondrial inner membrane. In sharp contrast to ndh2 deletions, deficiencies in nuclear genes for central subunits of proton pumping NADH:ubiquinone oxidoreductases (complex I) are lethal. We have redirected NDH2 to the internal face of the mitochondrial inner membrane by N-terminally attaching the mitochondrial targeting sequence of NUAM, the largest subunit of complex I. Lethality of complex I mutations was rescued by the internal, but not the external version of alternative NADH:ubiquinone oxidoreductase. Internal NDH2 also permitted growth in the presence of complex I inhibitors such as 2-decyl-4-quinazolinyl amine (DQA). Functional expression of NDH2 on both sides of the mitochondrial inner membrane indicates that alternative NADH:ubiquinone oxidoreductase requires no additional components for catalytic activity. Our findings also demonstrate that shuttle mechanisms for the transfer of redox equivalents from the matrix to the cytosolic side of the mitochondrial inner membrane are insufficient in Y. lipolytica.

scholarly journals Correction: Control of mitochondrial superoxide production by reverse electron transport at complex I.

2019 ◽  
Vol 294 (19) ◽  
pp. 7966-7966
Author(s):  
Ellen L. Robb ◽  
Andrew R. Hall ◽  
Tracy A. Prime ◽  
Simon Eaton ◽  
Marten Szibor ◽  
...  
Keyword(s):  
Electron Transport ◽  
Complex I ◽  
Superoxide Production ◽  
Mitochondrial Superoxide ◽  
Reverse Electron Transport

scholarly journals Control of mitochondrial superoxide production by reverse electron transport at complex I

2018 ◽  
Vol 293 (25) ◽  
pp. 9869-9879 ◽  
Author(s):  
Ellen L. Robb ◽  
Andrew R. Hall ◽  
Tracy A. Prime ◽  
Simon Eaton ◽  
Marten Szibor ◽  
...  
Keyword(s):  
Electron Transport ◽  
Complex I ◽  
Superoxide Production ◽  
Mitochondrial Superoxide ◽  
Reverse Electron Transport

Targeting Dinitrophenol to Mitochondria: Limitations to the Development of a Self-limiting Mitochondrial Protonophore

2006 ◽  
Vol 26 (3) ◽  
pp. 231-243 ◽  
Author(s):  
Frances H. Blaikie ◽  
Stephanie E. Brown ◽  
Linda M. Samuelsson ◽  
Martin D. Brand ◽  
Robin A. J. Smith ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Membrane Potential ◽  
Oxidative Phosphorylation ◽  
Atp Synthesis ◽  
Proton Leak ◽  
Protonmotive Force ◽  
Inner Membrane ◽  
Atp Production ◽  
Mitochondrial Inner Membrane ◽  
Predominant Component

The protonmotive force (Δp) across the mitochondrial inner membrane drives ATP synthesis. In addition, the energy stored in Δp can be dissipated by proton leak through the inner membrane, contributing to basal metabolic rate and thermogenesis. Increasing mitochondrial proton leak pharmacologically should decrease the efficiency of oxidative phosphorylation and counteract obesity by enabling fatty acids to be oxidised with decreased ATP production. While protonophores such as 2,4-dinitrophenol (DNP) increase mitochondrial proton leak and have been used to treat obesity, a slight increase in DNP concentration above the therapeutically effective dose disrupts mitochondrial function and leads to toxicity. Therefore we set out to develop a less toxic protonophore that would increase proton leak significantly at high Δp but not at low Δp. Our design concept for a potential self-limiting protonophore was to couple the DNP moiety to the lipophilic triphenylphosphonium (TPP) cation and this was achieved by the preparation of 3-(3,5-dinitro-4-hydroxyphenyl)propyltriphenylphosphonium methanesulfonate (MitoDNP). TPP cations accumulate within mitochondria driven by the membrane potential (Δψ), the predominant component of Δp. Our hypothesis was that MitoDNP would accumulate in mitochondria at high Δψ where it would act as a protonophore, but that at lower Δψ the accumulation and uncoupling would be far less. We found that MitoDNP was extensively taken into mitochondria driven by Δψ. However MitoDNP did not uncouple mitochondria as judged by its inability to either increase respiration rate or decrease Δψ. Therefore MitoDNP did not act as a protonophore, probably because the efflux of deprotonated MitoDNP was inhibited.

scholarly journals Cardiolipin promotes electron transport between ubiquinone and complex I to rescue PINK1 deficiency

2017 ◽  
Vol 216 (3) ◽  
pp. 695-708 ◽  
Author(s):  
Melissa Vos ◽  
Ann Geens ◽  
Claudia Böhm ◽  
Liesbeth Deaulmerie ◽  
Jef Swerts ◽  
...  
Keyword(s):  
Electron Transport ◽  
Complex I ◽  
Fatty Acid Synthase ◽  
Induced Pluripotent Stem Cell ◽  
Mitochondrial Inner Membrane ◽  
Mitochondrial Defects ◽  
Mouse Cells ◽  
Induced Pluripotent ◽  
Specific Lipid ◽  
Pharmacologic Inhibition

PINK1 is mutated in Parkinson’s disease (PD), and mutations cause mitochondrial defects that include inefficient electron transport between complex I and ubiquinone. Neurodegeneration is also connected to changes in lipid homeostasis, but how these are related to PINK1-induced mitochondrial dysfunction is unknown. Based on an unbiased genetic screen, we found that partial genetic and pharmacological inhibition of fatty acid synthase (FASN) suppresses toxicity induced by PINK1 deficiency in flies, mouse cells, patient-derived fibroblasts, and induced pluripotent stem cell–derived dopaminergic neurons. Lower FASN activity in PINK1 mutants decreases palmitate levels and increases the levels of cardiolipin (CL), a mitochondrial inner membrane–specific lipid. Direct supplementation of CL to isolated mitochondria not only rescues the PINK1-induced complex I defects but also rescues the inefficient electron transfer between complex I and ubiquinone in specific mutants. Our data indicate that genetic or pharmacologic inhibition of FASN to increase CL levels bypasses the enzymatic defects at complex I in a PD model.

scholarly journals Membrane potential of mitochondria in intact lymphocytes during early mitogenic stimulation

1984 ◽  
Vol 217 (2) ◽  
pp. 453-459 ◽  
Author(s):  
M D Brand ◽  
S M Felber
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Concanavalin A ◽  
Mitochondrial Membrane ◽  
Ph Gradient ◽  
Electrochemical Gradient ◽  
Inner Membrane ◽  
Mitogenic Stimulation ◽  
Ion Movements

The mitochondrial membrane potential (delta psi m) in intact lymphocytes was calculated by measuring the distribution of radiolabelled methyltriphenylphosphonium cation. The value obtained was 120 mV. The pH gradient across the mitochondrial membrane in situ (delta pH m) was estimated to be 73 mV (1.2 pH units). Thus the electrochemical gradient of protons was about 190 mV. Addition of the mitogen concanavalin A did not alter delta psi m, showing that, if movement of Ca2+ across the inner membrane of lymphocyte mitochondria occurs when concanavalin A is added, it is accompanied by charge-compensating ion movements.

Abstract 332: Mitochondrial Inner-Membrane Potential Instability Promotes Sarcolemmal Electrical Instability after Ischemia-Reperfusion in Monolayers of Cardiac Myocytes

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Soroosh Solhjoo ◽  
Brian O’Rourke
Keyword(s):  
Membrane Potential ◽  
Cardiac Myocytes ◽  
Mitochondrial Function ◽  
Ischemia Reperfusion ◽  
Neonatal Rat ◽  
Partial Recovery ◽  
Mitochondrial Network ◽  
Electrical Excitability ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane

Mitochondrial uncoupling due to oxidative stress can, through opening of sarcolemmal KATP channels, alter cellular electrical excitability, and it has been proposed that mitochondrial function is a major factor in arrhythmogenesis during ischemia-reperfusion. Here, we examine the effects of ischemia-reperfusion on mitochondrial inner membrane potential (ΔΨm) and corresponding changes in electrical excitability and wave propagation in monolayer cultures of neonatal rat ventricular myocytes. Changes in ΔΨm were observed using TMRM and changes in the sarcolemmal voltage were recorded with a 464-element photodiode array using di-4-ANEPPS. Ischemia was induced by covering the center part of the monolayer (D = 22 mm) with a coverslip (D = 15 mm). Cell contractions ceased after approximately 6 min of ischemia; however, electrical activity continued for 11.3 ± 4.2 min (N = 5). Amplitude and conduction velocity of the action potentials in the ischemic region decreased over the same time period. ΔΨm was lost in two phases: a reversible phase of partial depolarization, after 11.2 ± 1.3 min of ischemia, and a nonreversible phase, which happened after 30 ± 6 min of ischemia, during which the whole mitochondrial network of the myocyte became depolarized and the cells underwent contracture (N = 4). Reperfusion after the long ischemia resulted in only partial recovery and the observance of oscillations of ΔΨm in the mitochondrial network or rapid flickering of individual mitochondrial clusters and was associated with heterogeneous electrical recovery, and formation of wavelets and reentry (4/5 monolayers). In contrast, mitochondria fully recovered and reentry was rare (1/5 monolayers) for reperfusion after the short ischemia (10-12 min). 4’-chlorodiazepam, an inhibitor of inner membrane anion channels, stabilized mitochondrial function after the long ischemia, and prevented wavelets (5/5 monolayers) and reentry (4/5 monolayers). In conclusion, incomplete or unstable recovery of mitochondrial function after ischemia correlates with reentrant arrhythmias in monolayers of cardiac myocytes. Our findings suggest that stabilization of mitochondrial network dynamics is an important strategy for preventing ischemia/reperfusion-related arrhythmias.

scholarly journals Blockade of Electron Transport at the Onset of Reperfusion Decreases Cardiac Injury in Aged Hearts by Protecting the Inner Mitochondrial Membrane

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Qun Chen ◽  
Thomas Ross ◽  
Ying Hu ◽  
Edward J. Lesnefsky
Keyword(s):  
Membrane Potential ◽  
Electron Transport ◽  
Cell Injury ◽  
Ischemia Reperfusion ◽  
Cardiac Injury ◽  
Membrane Integrity ◽  
Reversible Inhibitor ◽  
Inner Mitochondrial Membrane ◽  
Inner Membrane ◽  
Fischer 344

Myocardial injury is increased in the aged heart following ischemia-reperfusion (ISC-REP) compared to adult hearts. Intervention at REP with ischemic postconditioning decreases injury in the adult heart by attenuating mitochondrial driven cell injury. Unfortunately, postconditioning is ineffective in aged hearts. Blockade of electron transport at the onset of REP with the reversible inhibitor amobarbital (AMO) decreases injury in adult hearts. We tested if AMO treatment at REP protects the aged heart via preservation of mitochondrial integrity. Buffer-perfused elderly Fischer 344 24 mo. rat hearts underwent 25 min global ISC and 30 min REP. AMO (2.5 mM) or vehicle was given for 3 min at the onset of REP. Subsarcolemmal (SSM) and interfibrillar (IFM) mitochondria were isolated after REP. Oxidative phosphorylation (OXPHOS) and mitochondrial inner membrane potential were measured. AMO treatment at REP decreased cardiac injury. Compared to untreated ISC-REP, AMO improved inner membrane potential in SSM and IFM during REP, indicating preserved inner membrane integrity. Thus, direct pharmacologic modulation of electron transport at REP protects mitochondria and decreases cardiac injury in the aged heart, even when signaling-induced pathways of postconditioning that are upstream of mitochondria are ineffective.

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