Kinetic coupling of the respiratory chain with ATP synthase, but not proton gradients, drives ATP production in cristae membranes.

Toth, Alexandra; Meyrat, Axel; Stoldt, Stefan; Santiago, Ricardo; Wenzel, Dirk; Jakobs, Stefan; von Ballmoos, Christoph; Ott, Martin (2020). Kinetic coupling of the respiratory chain with ATP synthase, but not proton gradients, drives ATP production in cristae membranes. Proceedings of the National Academy of Sciences of the United States of America - PNAS, 117(5), pp. 2412-2421. National Academy of Sciences NAS 10.1073/pnas.1917968117

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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 F1F0 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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)

UniBE Contributor:

Meyrat, Axel Alexandre and von Ballmoos, Christoph

Subjects:

500 Science > 540 Chemistry

ISSN:

0027-8424

Publisher:

National Academy of Sciences NAS

Language:

English

Submitter:

Christoph von Ballmoos

Date Deposited:

28 Oct 2020 14:16

Last Modified:

28 Oct 2020 14:16

Publisher DOI:

10.1073/pnas.1917968117

PubMed ID:

31964824

Uncontrolled Keywords:

ATP synthesis cristae energy conversion kinetic coupling mitochondria

BORIS DOI:

10.7892/boris.147126

URI:

https://boris.unibe.ch/id/eprint/147126

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