Distelmaier 2009 Brain

From Bioblast
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Distelmaier F, Koopman WJ, van den Heuvel LP, Rodenburg RJ, Mayatepek E, Willems PH, Smeitink JA (2009) Mitochondrial Complex I deficiency: from organelle dysfunction to clinical disease. Brain 132:833-42.

Β» PMID: 19336460 Open Access

Distelmaier F, Koopman WJ, van den Heuvel LP, Rodenburg RJ, Mayatepek E, Willems PH, Smeitink JA (2009) Brain

Abstract: Mitochondria are essential for cellular bioenergetics by way of energy production in the form of ATP through the process of oxidative phosphorylation. This crucial task is executed by five multi-protein Complexes of which mitochondrial NADH:ubiquinone oxidoreductase or Complex I is the largest and most complicated one. During recent years, mutations in nuclear genes encoding structural subunits of Complex I have been identified as a cause of devastating neurodegenerative disorders with onset in early childhood. Here, we present a comprehensive overview of clinical, biochemical and cell physiological information of 15 children with isolated, nuclear-encoded Complex I deficiency, which was generated in a joint effort of clinical and fundamental research. Our findings point to a rather homogeneous clinical picture in these children and drastically illustrate the severity of the disease. In extensive live cell studies with patient-derived skin fibroblasts we uncovered important cell physiological aspects of Complex I deficiency, which point to a central regulatory role of cellular reactive oxygen species production and altered mitochondrial membrane potential in the pathogenesis of the disorder. Moreover, we critically discuss possible interconnections between clinical signs and cellular pathology. Finally, our results indicate apparent differences to drug therapy on the cellular level, depending on the severity of the catalytic defect and identify modulators of cellular Ca(2+) homeostasis as new candidates in the therapy of Complex I deficiency.

β€’ O2k-Network Lab: NL Nijmegen Koopman WJ, NL Nijmegen Rodenburg R

Distelmaier 2009 Brain 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. https://doi.org/10.1016/j.jbc.2023.105470 - Β»Bioblast linkΒ«

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+ β†’ 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 β†’ 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.


Enzyme: Complex I, Complex II;succinate dehydrogenase 

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