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Structure of mitochondrial OXPHOS system and cristae membrane illustrating a proton transfer pathway. (A) The cluster of OXPHOS at the bend of crista of heart mitochondria (Nesterov et al. 2021a). Yellow -ATP synthase dimers, blue -complex I, purple -complex III dimers, green -complex IV, grey -lipid membrane. (B) A dedicated direction of proton transfer between rows of proton pumps (proton sources) and ATP synthases (proton sinks). (C) Schematic reconstruction of the OXPHOS cluster on the membrane fold and a pathway of the
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The results of many experimental and theoretical works indicate that after transport of protons across the mitochondrial inner membrane (MIM) in oxidative phosphorylation system (OXPHOS), they are retained on the membrane-water interface in non-equilibrium state with free energy excess due to low proton surface-to-bulk release. This well-establishe...
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... of the dynamic model of proton transport in OXPHOS should reflect the real structure of that system. In our model, we used the new data on the macromolecular organization of OXPHOS and the complex cristae ultra-structure obtained by cryo-electron tomography (cryo-ET) ( Davies et al. 2011;Nesterov et al. 2021a) (Fig. 1A). The most ordered known forms of OXPHOS are located on the cristae folds and consist of clustered oligomeric structures of parallel rows of respirasomes and rows of ATP synthase dimers. Even in less compressed and ordered structures, in any case, ATP synthase dimers form rows at the edges of the cristae ( Strauss et al. 2008). This ...
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... structures of parallel rows of respirasomes and rows of ATP synthase dimers. Even in less compressed and ordered structures, in any case, ATP synthase dimers form rows at the edges of the cristae ( Strauss et al. 2008). This makes possible to consider proton transport as an unidirectional motion from the pump row to the ATP synthase row (Fig. 1B). The short distance of less than 80 nm between the observed rows of proton pumps and ATP synthase dimers provides the direct and fast transfer of proton to ATP synthases along the cristae membrane avoiding proton surface-to-bulk release ( Sjöholm et al. 2017). The fact that hydrogen ions move laterally in a thin near-membrane layer of ...
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... the cristae membrane avoiding proton surface-to-bulk release ( Sjöholm et al. 2017). The fact that hydrogen ions move laterally in a thin near-membrane layer of water ( Weichselbaum et al. 2017) is also taken into account in our model. Schematic representation of proton transfer along the membrane from the respirasome to ATP synthase is shown on Fig. 1C. It should be mentioned that apart from charge carrier transport, pumping protons can also transfer the excess free energy due to their nonequilibrium hydration shell formed on the membrane-water interface ( Nesterov et al. 2022). The excess free energy of the energized proton may cause local membrane deformation and induce collective ...
Context 4
... of the dynamic model of proton transport in OXPHOS should reflect the real structure of that system. In our model, we used the new data on the macromolecular organization of OXPHOS and the complex cristae ultra-structure obtained by cryo-electron tomography (cryo-ET) ( Davies et al. 2011;Nesterov et al. 2021a) (Fig. 1A). The most ordered known forms of OXPHOS are located on the cristae folds and consist of clustered oligomeric structures of parallel rows of respirasomes and rows of ATP synthase dimers. Even in less compressed and ordered structures, in any case, ATP synthase dimers form rows at the edges of the cristae ( Strauss et al. 2008). This ...
Context 5
... structures of parallel rows of respirasomes and rows of ATP synthase dimers. Even in less compressed and ordered structures, in any case, ATP synthase dimers form rows at the edges of the cristae ( Strauss et al. 2008). This makes possible to consider proton transport as an unidirectional motion from the pump row to the ATP synthase row (Fig. 1B). The short distance of less than 80 nm between the observed rows of proton pumps and ATP synthase dimers provides the direct and fast transfer of proton to ATP synthases along the cristae membrane avoiding proton surface-to-bulk release ( Sjöholm et al. 2017). The fact that hydrogen ions move laterally in a thin near-membrane layer of ...
Context 6
... the cristae membrane avoiding proton surface-to-bulk release ( Sjöholm et al. 2017). The fact that hydrogen ions move laterally in a thin near-membrane layer of water ( Weichselbaum et al. 2017) is also taken into account in our model. Schematic representation of proton transfer along the membrane from the respirasome to ATP synthase is shown on Fig. 1C. It should be mentioned that apart from charge carrier transport, pumping protons can also transfer the excess free energy due to their nonequilibrium hydration shell formed on the membrane-water interface ( Nesterov et al. 2022). The excess free energy of the energized proton may cause local membrane deformation and induce collective ...
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Citations
It is well known that in the heart and kidney mitochondria, more than 95% of ATP production is supported by the β-oxidation of long-chain fatty acids. However, the β-oxidation of fatty acids by mitochondria has been studied much less than the substrates formed during the catabolism of carbohydrates and amino acids. In the last few decades, several discoveries have been made that are directly related to fatty acid oxidation. In this review, we made an attempt to re-evaluate the β-oxidation of long-chain fatty acids from the perspectives of new discoveries. The single set of electron transporters of the cardiac mitochondrial respiratory chain is organized into three supercomplexes. Two of them contain complex I, a dimer of complex III, and two dimers of complex IV. The third, smaller supercomplex contains a dimer of complex III and two dimers of complex IV. We also considered other important discoveries. First, the enzymes of the β-oxidation of fatty acids are physically associated with the respirasome. Second, the β-oxidation of fatty acids creates the highest level of QH 2 and reverses the flow of electrons from QH 2 through complex II, reducing fumarate to succinate. Third, β-oxidation is greatly stimulated in the presence of succinate. We argue that the respirasome is uniquely adapted for the β-oxidation of fatty acids. The acyl-CoA dehydrogenase complex reduces the membrane's pool of ubiquinone to QH 2 , which is instantly oxidized by the smaller supercomplex, generating a high energization of mitochondria and reversing the electron flow through complex II, which reverses the electron flow through complex I, increasing the NADH/NAD + ratio in the matrix. The mitochondrial nicotinamide nucleotide transhydrogenase catalyzes a hydride (H-, a proton plus two electrons) transfer across the inner mitochondrial membrane, reducing the cytosolic pool of NADP(H), thus providing the heart with ATP for muscle contraction and energy and reducing equivalents for the housekeeping processes.