Kinetic coupling of the respiratory chain with ATP synthase, but not proton gradients, drives ATP production in cristae membranes
| Autor: | Christoph von Ballmoos, Axel Meyrat, Stefan Stoldt, Martin Ott, Alexandra Toth, Ricardo Santiago, Dirk Wenzel, Stefan Jakobs |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
Proteolipids Respiratory chain Oxidative phosphorylation Saccharomyces cerevisiae Mitochondrion 7. Clean energy Oxidative Phosphorylation Electron Transport 03 medical and health sciences 0302 clinical medicine Adenosine Triphosphate Cytochrome c oxidase Inner membrane Electrochemical gradient Multidisciplinary biology ATP synthase Chemistry Hydrogen-Ion Concentration Mitochondrial Proton-Translocating ATPases Proton Pumps Biological Sciences Mitochondria Kinetics 030104 developmental biology Mitochondrial Membranes Biophysics biology.protein Protons Cristae formation 030217 neurology & neurosurgery |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America Proc Natl Acad Sci U S A |
| Popis: | Mitochondria have a characteristic ultrastructure with invaginations of the inner membrane called cristae that contain the protein complexes of the oxidative phosphorylation system. How this particular morphology of the respiratory membrane impacts energy conversion is currently unknown. One proposed role of cristae formation is to facilitate the establishment of local proton gradients to fuel ATP synthesis. Here, we determined the local pH values at defined sublocations within mitochondria of respiring yeast cells by fusing a pH-sensitive GFP to proteins residing in different mitochondrial subcompartments. Only a small proton gradient was detected over the inner membrane in wild type or cristae-lacking cells. Conversely, the obtained pH values did barely permit ATP synthesis in a reconstituted system containing purified yeast F 1 F 0 ATP synthase, although, thermodynamically, a sufficiently high driving force was applied. At higher driving forces, where robust ATP synthesis was observed, a P -side pH value of 6 increased the ATP synthesis rate 3-fold compared to pH 7. In contrast, when ATP synthase was coreconstituted with an active proton-translocating cytochrome oxidase, ATP synthesis readily occurred at the measured, physiological pH values. Our study thus reveals that the morphology of the inner membrane does not influence the subcompartmental pH values and is not necessary for robust oxidative phosphorylation in mitochondria. Instead, it is likely that the dense packing of the oxidative phosphorylation complexes in the cristae membranes assists kinetic coupling between proton pumping and ATP synthesis. |
| Databáze: | OpenAIRE |
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