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Benard 2011 Springer

From Bioblast
Publications in the MiPMap
Benard G, Bellance N, Jose C, Rossignol R (2011) Relationships between mitochondrial dynamics and bioenergetics. In: Lu Bingwei (ed) Mitochondrial dynamics and neurodegeneration. Springer ISBN 978-94-007-1290-4:47-68.

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Benard G, Bellance N, Jose C, Rossignol R (2011) Springer

Abstract: In this chapter we describe the fundamental mechanisms by which mammalian cells regulate energy production, and we put emphasis on the importance of mitochondrial dynamics for the regulation of bioenergetics. We discuss both the impact of shape changes of the mitochondrion on organellar energy production, and the existence of reverse mechanisms of regulation of mitochondrial fusion and fission by the cellular energy state. Hence, in complement to pioneering concepts of metabolic control which only considered the key controlling steps of energy fluxes at the level of the respiratory chain, the recent study of mitochondrial dynamics highlights new possibilities for OXPHOS control. The implications of such a regulatory loop between mitochondrial dynamics and bioenergetics impacts several fields of human biology, as diverse as embryonic development, energy storage, cell motility, lipid and membrane biogenesis, intracellular trafficking and cell death. In addition, most neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and Hereditary Spastic Paraplegia are associated with defects in mitochondrial dynamics and bioenergetics. Therefore, to unravel the fundamental mechanisms by which mitochondrial form interacts with mitochondrial function could permit to increase our basic knowledge on the regulation of energy metabolism and to decipher the pathophysiology of a group of rare neuronal diseases.

Bioblast editor: Gnaiger E

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Hydrogen ion ambiguities in the electron transfer system

Communicated by Gnaiger E (2023-10-08) last update 2023-11-10
Electron (e-) transfer linked to hydrogen ion (hydron; H+) transfer is a fundamental concept in the field of bioenergetics, critical for understanding redox-coupled energy transformations.
Ambiguity alert H+.png
However, the current literature contains inconsistencies regarding H+ formation on the negative side of bioenergetic membranes, such as the matrix side of the mitochondrial inner membrane, when NADH is oxidized during oxidative phosphorylation (OXPHOS). Ambiguities arise when examining the oxidation of NADH by respiratory Complex I or succinate by Complex II.
Ambiguity alert e-.png
Oxidation of NADH or succinate involves a two-electron transfer of 2{H++e-} to FMN or FAD, respectively. Figures indicating a single electron e- transferred from NADH or succinate lack accuracy.
Ambiguity alert NAD.png
The oxidized NAD+ is distinguished from NAD indicating nicotinamide adenine dinucleotide independent of oxidation state.
NADH + H+ → NAD+ +2{H++e-} is the oxidation half-reaction in this H+-linked electron transfer represented as 2{H++e-} (Gnaiger 2023). Putative H+ formation shown as NADH → NAD+ + H+ conflicts with chemiosmotic coupling stoichiometries between H+ translocation across the coupling membrane and electron transfer to oxygen. Ensuring clarity in this complex field is imperative to tackle the apparent ambiguity crisis and prevent confusion, particularly in light of the increasing number of interdisciplinary publications on bioenergetics concerning diagnostic and clinical applications of OXPHOS analysis.
Benard 2011 Springer 2.4 CORRECTION.png

Correction: FADH2 and Complex II

Ambiguity alert.png
FADH2 is shown as the substrate feeding electrons into Complex II (CII). This is wrong and requires correction - for details see Gnaiger (2024).
Gnaiger E (2024) Complex II ambiguities ― FADH2 in the electron transfer system. J Biol Chem 300:105470. - »Bioblast link«

Labels: MiParea: mt-Structure;fission;fusion  Pathology: Neurodegenerative