--- _id: '8340' abstract: - lang: eng text: Mitochondria are sites of oxidative phosphorylation in eukaryotic cells. Oxidative phosphorylation operates by a chemiosmotic mechanism made possible by redox-driven proton pumping machines which establish a proton motive force across the inner mitochondrial membrane. This electrochemical proton gradient is used to drive ATP synthesis, which powers the majority of cellular processes such as protein synthesis, locomotion and signalling. In this thesis I investigate the structures and molecular mechanisms of two inner mitochondrial proton pumping enzymes, respiratory complex I and transhydrogenase. I present the first high-resolution structure of the full transhydrogenase from any species, and a significantly improved structure of complex I. Improving the resolution from 3.3 Å available previously to up to 2.3 Å in this thesis allowed us to model bound water molecules, crucial in the proton pumping mechanism. For both enzymes, up to five cryo-EM datasets with different substrates and inhibitors bound were solved to delineate the catalytic cycle and understand the proton pumping mechanism. In transhydrogenase, the proton channel is gated by reversible detachment of the NADP(H)-binding domain which opens the proton channel to the opposite sites of the membrane. In complex I, the proton channels are gated by reversible protonation of key glutamate and lysine residues and breaking of the water wire connecting the proton pumps with the quinone reduction site. The tight coupling between the redox and the proton pumping reactions in transhydrogenase is achieved by controlling the NADP(H) exchange which can only happen when the NADP(H)-binding domain interacts with the membrane domain. In complex I, coupling is achieved by cycling of the whole complex between the closed state, in which quinone can get reduced, and the open state, in which NADH can induce quinol ejection from the binding pocket. On the basis of these results I propose detailed mechanisms for catalytic cycles of transhydrogenase and complex I that are consistent with a large amount of previous work. In both enzymes, conformational and electrostatic mechanisms contribute to the overall catalytic process. Results presented here could be used for better understanding of the human pathologies arising from deficiencies of complex I or transhydrogenase and could be used to develop novel therapies. acknowledged_ssus: - _id: EM-Fac acknowledgement: 'I acknowledge the support of IST facilities, especially the Electron Miscroscopy facility for providing training and resources. Special thanks also go to cryo-EM specialists who helped me to collect the data present here: Dr Valentin Hodirnau (IST Austria), Dr Tom Heuser (IMBA, Vienna), Dr Rebecca Thompson (Uni. of Leeds) and Dr Jirka Nováček (CEITEC). This work has been supported by iNEXT, project number 653706, funded by the Horizon 2020 programme of the European Union. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No. 665385.' alternative_title: - ISTA Thesis article_processing_charge: No author: - first_name: Domen full_name: Kampjut, Domen id: 37233050-F248-11E8-B48F-1D18A9856A87 last_name: Kampjut citation: ama: Kampjut D. Molecular mechanisms of mitochondrial redox-coupled proton pumping enzymes. 2020. doi:10.15479/AT:ISTA:8340 apa: Kampjut, D. (2020). Molecular mechanisms of mitochondrial redox-coupled proton pumping enzymes. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:8340 chicago: Kampjut, Domen. “Molecular Mechanisms of Mitochondrial Redox-Coupled Proton Pumping Enzymes.” Institute of Science and Technology Austria, 2020. https://doi.org/10.15479/AT:ISTA:8340. ieee: D. Kampjut, “Molecular mechanisms of mitochondrial redox-coupled proton pumping enzymes,” Institute of Science and Technology Austria, 2020. ista: Kampjut D. 2020. Molecular mechanisms of mitochondrial redox-coupled proton pumping enzymes. Institute of Science and Technology Austria. mla: Kampjut, Domen. Molecular Mechanisms of Mitochondrial Redox-Coupled Proton Pumping Enzymes. Institute of Science and Technology Austria, 2020, doi:10.15479/AT:ISTA:8340. short: D. Kampjut, Molecular Mechanisms of Mitochondrial Redox-Coupled Proton Pumping Enzymes, Institute of Science and Technology Austria, 2020. date_created: 2020-09-07T18:42:23Z date_published: 2020-09-09T00:00:00Z date_updated: 2023-09-07T13:26:17Z day: '09' ddc: - '572' degree_awarded: PhD department: - _id: LeSa doi: 10.15479/AT:ISTA:8340 ec_funded: 1 file: - access_level: closed checksum: dd270baf82121eb4472ad19d77bf227c content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document creator: dkampjut date_created: 2020-09-08T13:32:06Z date_updated: 2021-09-11T22:30:04Z embargo_to: open_access file_id: '8345' file_name: ThesisFull20200908.docx file_size: 166146359 relation: source_file - access_level: open_access checksum: 82fce6f95ffa47ecc4ebca67ea2cc38c content_type: application/pdf creator: dernst date_created: 2020-09-14T15:02:20Z date_updated: 2021-09-11T22:30:04Z embargo: 2021-09-10 file_id: '8393' file_name: 2020_Thesis_Kampjut.pdf file_size: 13873769 relation: main_file file_date_updated: 2021-09-11T22:30:04Z has_accepted_license: '1' language: - iso: eng month: '09' oa: 1 oa_version: None page: '242' project: - _id: 2564DBCA-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '665385' name: International IST Doctoral Program publication_identifier: isbn: - 978-3-99078-008-4 issn: - 2663-337X publication_status: published publisher: Institute of Science and Technology Austria related_material: record: - id: '6848' relation: part_of_dissertation status: public status: public supervisor: - first_name: Leonid A full_name: Sazanov, Leonid A id: 338D39FE-F248-11E8-B48F-1D18A9856A87 last_name: Sazanov orcid: 0000-0002-0977-7989 title: Molecular mechanisms of mitochondrial redox-coupled proton pumping enzymes type: dissertation user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 year: '2020' ...