1
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Maldonado M. Plant supercomplex I + III2 structure and function: implications for the growing field. Biochem Soc Trans 2024; 52:1647-1659. [PMID: 39177070 DOI: 10.1042/bst20230947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 08/01/2024] [Accepted: 08/07/2024] [Indexed: 08/24/2024]
Abstract
Mitochondrial respiration is major source of chemical energy for all free-living eukaryotes. Nevertheless, the mechanisms of the respiratory complexes and supercomplexes remain poorly understood. Here, I review recent structural and functional investigations of plant supercomplex I + III2 from Arabidopsis thaliana and Vigna radiata. I discuss commonalities, open questions and implications for complex I, complex III2 and supercomplexes in plants and non-plants. Studies across further clades will enhance our understanding of respiration and the potential universal mechanisms of its complexes and supercomplexes.
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Affiliation(s)
- Maria Maldonado
- Department of Plant Biology, University of California, Davis, Davis, CA, U.S.A
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2
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Laube E, Schiller J, Zickermann V, Vonck J. Using cryo-EM to understand the assembly pathway of respiratory complex I. Acta Crystallogr D Struct Biol 2024; 80:159-173. [PMID: 38372588 PMCID: PMC10910544 DOI: 10.1107/s205979832400086x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 01/23/2024] [Indexed: 02/20/2024] Open
Abstract
Complex I (proton-pumping NADH:ubiquinone oxidoreductase) is the first component of the mitochondrial respiratory chain. In recent years, high-resolution cryo-EM studies of complex I from various species have greatly enhanced the understanding of the structure and function of this important membrane-protein complex. Less well studied is the structural basis of complex I biogenesis. The assembly of this complex of more than 40 subunits, encoded by nuclear or mitochondrial DNA, is an intricate process that requires at least 20 different assembly factors in humans. These are proteins that are transiently associated with building blocks of the complex and are involved in the assembly process, but are not part of mature complex I. Although the assembly pathways have been studied extensively, there is limited information on the structure and molecular function of the assembly factors. Here, the insights that have been gained into the assembly process using cryo-EM are reviewed.
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Affiliation(s)
- Eike Laube
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Jonathan Schiller
- Institute of Biochemistry II, University Hospital, Goethe University, 60590 Frankfurt am Main, Germany
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, 60438 Frankfurt am Main, Germany
| | - Volker Zickermann
- Institute of Biochemistry II, University Hospital, Goethe University, 60590 Frankfurt am Main, Germany
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, 60438 Frankfurt am Main, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
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3
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Braun HP, Klusch N. Promotion of oxidative phosphorylation by complex I-anchored carbonic anhydrases? TRENDS IN PLANT SCIENCE 2024; 29:64-71. [PMID: 37599162 DOI: 10.1016/j.tplants.2023.07.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/12/2023] [Accepted: 07/19/2023] [Indexed: 08/22/2023]
Abstract
The mitochondrial NADH-dehydrogenase complex of the respiratory chain, known as complex I, includes a carbonic anhydrase (CA) module attached to its membrane arm on the matrix side in protozoans, algae, and plants. Its physiological role is so far unclear. Recent electron cryo-microscopy (cryo-EM) structures show that the CA module may directly provide protons for translocation across the inner mitochondrial membrane at complex I. CAs can have a central role in adjusting the proton concentration in the mitochondrial matrix. We suggest that CA anchoring in complex I represents the original configuration to secure oxidative phosphorylation (OXPHOS) in the context of early endosymbiosis. After development of 'modern mitochondria' with pronounced cristae structures, this anchoring became dispensable, but has been retained in protozoans, algae, and plants.
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Affiliation(s)
- Hans-Peter Braun
- Institute of Plant Genetics, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany.
| | - Niklas Klusch
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt, Germany.
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4
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Prokopchuk G, Butenko A, Dacks JB, Speijer D, Field MC, Lukeš J. Lessons from the deep: mechanisms behind diversification of eukaryotic protein complexes. Biol Rev Camb Philos Soc 2023; 98:1910-1927. [PMID: 37336550 PMCID: PMC10952624 DOI: 10.1111/brv.12988] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 05/30/2023] [Accepted: 06/05/2023] [Indexed: 06/21/2023]
Abstract
Genetic variation is the major mechanism behind adaptation and evolutionary change. As most proteins operate through interactions with other proteins, changes in protein complex composition and subunit sequence provide potentially new functions. Comparative genomics can reveal expansions, losses and sequence divergence within protein-coding genes, but in silico analysis cannot detect subunit substitutions or replacements of entire protein complexes. Insights into these fundamental evolutionary processes require broad and extensive comparative analyses, from both in silico and experimental evidence. Here, we combine data from both approaches and consider the gamut of possible protein complex compositional changes that arise during evolution, citing examples of complete conservation to partial and total replacement by functional analogues. We focus in part on complexes in trypanosomes as they represent one of the better studied non-animal/non-fungal lineages, but extend insights across the eukaryotes by extensive comparative genomic analysis. We argue that gene loss plays an important role in diversification of protein complexes and hence enhancement of eukaryotic diversity.
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Affiliation(s)
- Galina Prokopchuk
- Institute of Parasitology, Biology Centre, Czech Academy of SciencesBranišovská 1160/31České Budějovice37005Czech Republic
- Faculty of ScienceUniversity of South BohemiaBranišovská 1160/31České Budějovice37005Czech Republic
| | - Anzhelika Butenko
- Institute of Parasitology, Biology Centre, Czech Academy of SciencesBranišovská 1160/31České Budějovice37005Czech Republic
- Faculty of ScienceUniversity of South BohemiaBranišovská 1160/31České Budějovice37005Czech Republic
- Life Science Research Centre, Faculty of ScienceUniversity of OstravaChittussiho 983/10Ostrava71000Czech Republic
| | - Joel B. Dacks
- Institute of Parasitology, Biology Centre, Czech Academy of SciencesBranišovská 1160/31České Budějovice37005Czech Republic
- Division of Infectious Diseases, Department of MedicineUniversity of Alberta1‐124 Clinical Sciences Building, 11350‐83 AvenueEdmontonT6G 2R3AlbertaCanada
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and the EnvironmentUniversity College LondonDarwin Building, Gower StreetLondonWC1E 6BTUK
| | - Dave Speijer
- Medical Biochemistry, Amsterdam UMCUniversity of AmsterdamMeibergdreef 15Amsterdam1105 AZThe Netherlands
| | - Mark C. Field
- Institute of Parasitology, Biology Centre, Czech Academy of SciencesBranišovská 1160/31České Budějovice37005Czech Republic
- School of Life SciencesUniversity of DundeeDow StreetDundeeDD1 5EHScotlandUK
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of SciencesBranišovská 1160/31České Budějovice37005Czech Republic
- Faculty of ScienceUniversity of South BohemiaBranišovská 1160/31České Budějovice37005Czech Republic
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5
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Gahan JM, Cartwright P, Nicotra ML, Schnitzler CE, Steinmetz PRH, Juliano CE. Cnidofest 2022: hot topics in cnidarian research. EvoDevo 2023; 14:13. [PMID: 37620964 PMCID: PMC10463417 DOI: 10.1186/s13227-023-00217-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 08/08/2023] [Indexed: 08/26/2023] Open
Abstract
The second annual Cnidarian Model Systems Meeting, aka "Cnidofest", took place in Davis, California from 7 to 10th of September, 2022. The meeting brought together scientists using cnidarians to study molecular and cellular biology, development and regeneration, evo-devo, neurobiology, symbiosis, physiology, and comparative genomics. The diversity of topics and species represented in presentations highlighted the importance and versatility of cnidarians in addressing a wide variety of biological questions. In keeping with the spirit of the first meeting (and its predecessor, Hydroidfest), almost 75% of oral presentations were given by early career researchers (i.e., graduate students and postdocs). In this review, we present research highlights from the meeting.
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Affiliation(s)
- James M Gahan
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- Michael Sars Centre, University of Bergen, Thormøhlensgt. 55, 5008, Bergen, Norway
| | - Paulyn Cartwright
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66045, USA
| | - Matthew L Nicotra
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, 15261, USA
- Center for Evolutionary Biology and Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Christine E Schnitzler
- Whitney Laboratory for Marine Bioscience and Department of Biology, University of Florida, St. Augustine, FL, 32080, USA
| | | | - Celina E Juliano
- Department of Molecular and Cellular Biology, University of California, Davis, CA, 95616, USA.
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6
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Ghifari AS, Saha S, Murcha MW. The biogenesis and regulation of the plant oxidative phosphorylation system. PLANT PHYSIOLOGY 2023; 192:728-747. [PMID: 36806687 DOI: 10.1093/plphys/kiad108] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/19/2023] [Accepted: 01/22/2023] [Indexed: 06/01/2023]
Abstract
Mitochondria are central organelles for respiration in plants. At the heart of this process is oxidative phosphorylation (OXPHOS) system, which generates ATP required for cellular energetic needs. OXPHOS complexes comprise of multiple subunits that originated from both mitochondrial and nuclear genome, which requires careful orchestration of expression, translation, import, and assembly. Constant exposure to reactive oxygen species due to redox activity also renders OXPHOS subunits to be more prone to oxidative damage, which requires coordination of disassembly and degradation. In this review, we highlight the composition, assembly, and activity of OXPHOS complexes in plants based on recent biochemical and structural studies. We also discuss how plants regulate the biogenesis and turnover of OXPHOS subunits and the importance of OXPHOS in overall plant respiration. Further studies in determining the regulation of biogenesis and activity of OXPHOS will advances the field, especially in understanding plant respiration and its role to plant growth and development.
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Affiliation(s)
- Abi S Ghifari
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia
| | - Saurabh Saha
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia
| | - Monika W Murcha
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia
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7
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Han F, Hu Y, Wu M, He Z, Tian H, Zhou L. Structures of Tetrahymena thermophila respiratory megacomplexes on the tubular mitochondrial cristae. Nat Commun 2023; 14:2542. [PMID: 37248254 DOI: 10.1038/s41467-023-38158-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 04/19/2023] [Indexed: 05/31/2023] Open
Abstract
Tetrahymena thermophila, a classic ciliate model organism, has been shown to possess tubular mitochondrial cristae and highly divergent electron transport chain involving four transmembrane protein complexes (I-IV). Here we report cryo-EM structures of its ~8 MDa megacomplex IV2 + (I + III2 + II)2, as well as a ~ 10.6 MDa megacomplex (IV2 + I + III2 + II)2 at lower resolution. In megacomplex IV2 + (I + III2 + II)2, each CIV2 protomer associates one copy of supercomplex I + III2 and one copy of CII, forming a half ring-shaped architecture that adapts to the membrane curvature of mitochondrial cristae. Megacomplex (IV2 + I + III2 + II)2 defines the relative position between neighbouring half rings and maintains the proximity between CIV2 and CIII2 cytochrome c binding sites. Our findings expand the current understanding of divergence in eukaryotic electron transport chain organization and how it is related to mitochondrial morphology.
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Affiliation(s)
- Fangzhu Han
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
| | - Yiqi Hu
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
| | - Mengchen Wu
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
| | - Zhaoxiang He
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
| | - Hongtao Tian
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China
| | - Long Zhou
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China.
- Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, 310058, China.
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8
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Röhricht H, Przybyla-Toscano J, Forner J, Boussardon C, Keech O, Rouhier N, Meyer EH. Mitochondrial ferredoxin-like is essential for forming complex I-containing supercomplexes in Arabidopsis. PLANT PHYSIOLOGY 2023; 191:2170-2184. [PMID: 36695030 PMCID: PMC10069907 DOI: 10.1093/plphys/kiad040] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 01/11/2023] [Indexed: 06/02/2023]
Abstract
In eukaryotes, mitochondrial ATP is mainly produced by the oxidative phosphorylation (OXPHOS) system, which is composed of 5 multiprotein complexes (complexes I-V). Analyses of the OXPHOS system by native gel electrophoresis have revealed an organization of OXPHOS complexes into supercomplexes, but their roles and assembly pathways remain unclear. In this study, we characterized an atypical mitochondrial ferredoxin (mitochondrial ferredoxin-like, mFDX-like). This protein was previously found to be part of the bridge domain linking the matrix and membrane arms of the complex I. Phylogenetic analysis suggested that the Arabidopsis (Arabidopsis thaliana) mFDX-like evolved from classical mitochondrial ferredoxins (mFDXs) but lost one of the cysteines required for the coordination of the iron-sulfur (Fe-S) cluster, supposedly essential for the electron transfer function of FDXs. Accordingly, our biochemical study showed that AtmFDX-like does not bind an Fe-S cluster and is therefore unlikely to be involved in electron transfer reactions. To study the function of mFDX-like, we created deletion lines in Arabidopsis using a CRISPR/Cas9-based strategy. These lines did not show any abnormal phenotype under standard growth conditions. However, the characterization of the OXPHOS system demonstrated that mFDX-like is important for the assembly of complex I and essential for the formation of complex I-containing supercomplexes. We propose that mFDX-like and the bridge domain are required for the correct conformation of the membrane arm of complex I that is essential for the association of complex I with complex III2 to form supercomplexes.
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Affiliation(s)
| | - Jonathan Przybyla-Toscano
- Present address: Laboratoire Physiologie Cellulaire & Végétale, Institut de Recherche Interdisciplinaire de Grenoble, Université Grenoble Alpes, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Commissariat à l’Energie Atomique et aux Energie Alternatives, Centre National de la Recherche Scientifique, F-38000 Grenoble, France
| | - Joachim Forner
- Department of Organelle Biology, Biotechnology and Molecular Ecophysiology, Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany
| | - Clément Boussardon
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, S-90187 Umeå, Sweden
| | - Olivier Keech
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, S-90187 Umeå, Sweden
| | - Nicolas Rouhier
- Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Interactions Arbres-Microorganismes (IAM), Université de Lorraine, F-54000 Nancy, France
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9
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Maldonado M, Fan Z, Abe KM, Letts JA. Plant-specific features of respiratory supercomplex I + III 2 from Vigna radiata. NATURE PLANTS 2023; 9:157-168. [PMID: 36581760 PMCID: PMC9873571 DOI: 10.1038/s41477-022-01306-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 11/08/2022] [Indexed: 05/07/2023]
Abstract
The last steps of cellular respiration-an essential metabolic process in plants-are carried out by mitochondrial oxidative phosphorylation. This process involves a chain of multi-subunit membrane protein complexes (complexes I-V) that form higher-order assemblies called supercomplexes. Although supercomplexes are the most physiologically relevant form of the oxidative phosphorylation complexes, their functions and structures remain mostly unknown. Here we present the cryogenic electron microscopy structure of the supercomplex I + III2 from Vigna radiata (mung bean). The structure contains the full subunit complement of complex I, including a newly assigned, plant-specific subunit. It also shows differences in the mitochondrial processing peptidase domain of complex III2 relative to a previously determined supercomplex with complex IV. The supercomplex interface, while reminiscent of that in other organisms, is plant specific, with a major interface involving complex III2's mitochondrial processing peptidase domain and no participation of complex I's bridge domain. The complex I structure suggests that the bridge domain sets the angle between the enzyme's two arms, limiting large-scale conformational changes. Moreover, complex I's catalytic loops and its response in active-to-deactive assays suggest that, in V. radiata, the resting complex adopts a non-canonical state and can sample deactive- or open-like conformations even in the presence of substrate. This study widens our understanding of the possible conformations and behaviour of complex I and supercomplex I + III2. Further studies of complex I and its supercomplexes in diverse organisms are needed to determine the universal and clade-specific mechanisms of respiration.
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Affiliation(s)
- M Maldonado
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA.
- Department of Plant Biology, University of California, Davis, CA, USA.
| | - Z Fan
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA
| | - K M Abe
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA
| | - J A Letts
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA.
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10
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Klusch N, Dreimann M, Senkler J, Rugen N, Kühlbrandt W, Braun HP. Cryo-EM structure of the respiratory I + III 2 supercomplex from Arabidopsis thaliana at 2 Å resolution. NATURE PLANTS 2023; 9:142-156. [PMID: 36585502 PMCID: PMC9873573 DOI: 10.1038/s41477-022-01308-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 11/08/2022] [Indexed: 05/15/2023]
Abstract
Protein complexes of the mitochondrial respiratory chain assemble into respiratory supercomplexes. Here we present the high-resolution electron cryo-microscopy structure of the Arabidopsis respiratory supercomplex consisting of complex I and a complex III dimer, with a total of 68 protein subunits and numerous bound cofactors. A complex I-ferredoxin, subunit B14.7 and P9, a newly defined subunit of plant complex I, mediate supercomplex formation. The component complexes stabilize one another, enabling new detailed insights into their structure. We describe (1) an interrupted aqueous passage for proton translocation in the membrane arm of complex I; (2) a new coenzyme A within the carbonic anhydrase module of plant complex I defining a second catalytic centre; and (3) the water structure at the proton exit pathway of complex III2 with a co-purified ubiquinone in the QO site. We propose that the main role of the plant supercomplex is to stabilize its components in the membrane.
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Affiliation(s)
- Niklas Klusch
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt, Germany.
| | - Maximilian Dreimann
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt, Germany
| | - Jennifer Senkler
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, Germany
| | - Nils Rugen
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt, Germany
| | - Hans-Peter Braun
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, Germany.
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11
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Wang G, Wang Y, Ni J, Li R, Zhu F, Wang R, Tian Q, Shen Q, Yang Q, Tang J, Murcha MW, Wang G. An MCIA-like complex is required for mitochondrial complex I assembly and seed development in maize. MOLECULAR PLANT 2022; 15:1470-1487. [PMID: 35957532 DOI: 10.1016/j.molp.2022.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 05/13/2022] [Accepted: 08/08/2022] [Indexed: 06/15/2023]
Abstract
During adaptive radiation, mitochondria have co-evolved with their hosts, leading to gain or loss of subunits and assembly factors of respiratory complexes. Plant mitochondrial complex I harbors ∼40 nuclear- and 9 mitochondrial-encoded subunits, and is formed by stepwise assembly during which different intermediates are integrated via various assembly factors. In mammals, the mitochondrial complex I intermediate assembly (MCIA) complex is required for building the membrane arm module. However, plants have lost almost all of the MCIA complex components, giving rise to the hypothesis that plants follow an ancestral pathway to assemble the membrane arm subunits. Here, we characterize a maize crumpled seed mutant, crk1, and reveal by map-based cloning that CRK1 encodes an ortholog of human complex I assembly factor 1, zNDUFAF1, the only evolutionarily conserved MCIA subunit in plants. zNDUFAF1 is localized in the mitochondria and accumulates in two intermediate complexes that contain complex I membrane arm subunits. Disruption of zNDUFAF1 results in severe defects in complex I assembly and activity, a cellular bioenergetic shift to aerobic glycolysis, and mitochondrial vacuolation. Moreover, we found that zNDUFAF1, the putative mitochondrial import inner membrane translocase ZmTIM17-1, and the isovaleryl-coenzyme A dehydrogenase ZmIVD1 interact each other, and could be co-precipitated from the mitochondria and co-migrate in the same assembly intermediates. Knockout of either ZmTIM17-1 or ZmIVD1 could lead to the significantly reduced complex I stability and activity as well as defective seeds. These results suggest that zNDUFAF1, ZmTIM17-1 and ZmIVD1 probably form an MCIA-like complex that is essential for the biogenesis of mitochondrial complex I and seed development in maize. Our findings also imply that plants and mammals recruit MCIA subunits independently for mitochondrial complex I assembly, highlighting the importance of parallel evolution in mitochondria adaptation to their hosts.
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Affiliation(s)
- Gang Wang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yongyan Wang
- National Key Laboratory of Wheat and Maize Crops Science, CIMMYT--China Joint Center of Wheat and Maize, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China
| | - Jiacheng Ni
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Rongrong Li
- National Key Laboratory of Wheat and Maize Crops Science, CIMMYT--China Joint Center of Wheat and Maize, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China
| | - Fengling Zhu
- National Key Laboratory of Wheat and Maize Crops Science, CIMMYT--China Joint Center of Wheat and Maize, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China
| | - Ruyin Wang
- National Key Laboratory of Wheat and Maize Crops Science, CIMMYT--China Joint Center of Wheat and Maize, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China
| | - Qiuzhen Tian
- National Key Laboratory of Wheat and Maize Crops Science, CIMMYT--China Joint Center of Wheat and Maize, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China
| | - Qingwen Shen
- National Key Laboratory of Wheat and Maize Crops Science, CIMMYT--China Joint Center of Wheat and Maize, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China
| | - Qinghua Yang
- National Key Laboratory of Wheat and Maize Crops Science, CIMMYT--China Joint Center of Wheat and Maize, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China
| | - Jihua Tang
- National Key Laboratory of Wheat and Maize Crops Science, CIMMYT--China Joint Center of Wheat and Maize, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China; The Shennong Laboratory, Zhengzhou, Henan 450002, China
| | - Monika W Murcha
- School of Molecular Sciences & The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia
| | - Guifeng Wang
- National Key Laboratory of Wheat and Maize Crops Science, CIMMYT--China Joint Center of Wheat and Maize, Center for Crop Genome Engineering, College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China.
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12
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Meyer EH, Letts JA, Maldonado M. Structural insights into the assembly and the function of the plant oxidative phosphorylation system. THE NEW PHYTOLOGIST 2022; 235:1315-1329. [PMID: 35588181 DOI: 10.1111/nph.18259] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 05/05/2022] [Indexed: 05/23/2023]
Abstract
One of the key functions of mitochondria is the production of ATP to support cellular metabolism and growth. The last step of mitochondrial ATP synthesis is performed by the oxidative phosphorylation (OXPHOS) system, an ensemble of protein complexes embedded in the inner mitochondrial membrane. In the last 25 yr, many structures of OXPHOS complexes and supercomplexes have been resolved in yeast, mammals, and bacteria. However, structures of plant OXPHOS enzymes only became available very recently. In this review, we highlight the plant-specific features revealed by the recent structures and discuss how they advance our understanding of the function and assembly of plant OXPHOS complexes. We also propose new hypotheses to be tested and discuss older findings to be re-evaluated. Further biochemical and structural work on the plant OXPHOS system will lead to a deeper understanding of plant respiration and its regulation, with significant agricultural, environmental, and societal implications.
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Affiliation(s)
- Etienne H Meyer
- Institute of Plant Physiology, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, 06120, Halle (Saale), Germany
| | - James A Letts
- Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Maria Maldonado
- Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue, Davis, CA, 95616, USA
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13
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Kampjut D, Sazanov LA. Structure of respiratory complex I – An emerging blueprint for the mechanism. Curr Opin Struct Biol 2022; 74:102350. [PMID: 35316665 PMCID: PMC7613608 DOI: 10.1016/j.sbi.2022.102350] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/25/2022] [Accepted: 02/08/2022] [Indexed: 11/26/2022]
Abstract
Complex I is one of the major respiratory complexes, conserved from bacteria to mammals. It oxidises NADH, reduces quinone and pumps protons across the membrane, thus playing a central role in the oxidative energy metabolism. In this review we discuss our current state of understanding the structure of complex I from various species of mammals, plants, fungi, and bacteria, as well as of several complex I-related proteins. By comparing the structural evidence from these systems in different redox states and data from mutagenesis and molecular simulations, we formulate the mechanisms of electron transfer and proton pumping and explain how they are conformationally and electrostatically coupled. Finally, we discuss the structural basis of the deactivation phenomenon in mammalian complex I.
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14
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Zhou L, Maldonado M, Padavannil A, Guo F, Letts JA. Structures of Tetrahymena's respiratory chain reveal the diversity of eukaryotic core metabolism. Science 2022; 376:831-839. [PMID: 35357889 PMCID: PMC9169680 DOI: 10.1126/science.abn7747] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Respiration is a core biological energy-converting process whose last steps are carried out by a chain of multisubunit complexes in the inner mitochondrial membrane. To probe the functional and structural diversity of eukaryotic respiration, we examined the respiratory chain of the ciliate Tetrahymena thermophila (Tt). Using cryo-electron microscopy on a mixed sample, we solved structures of a supercomplex between Tt complex I (Tt-CI) and Tt-CIII2 (Tt-SC I+III2) and a structure of Tt-CIV2. Tt-SC I+III2 (~2.3 megadaltons) is a curved assembly with structural and functional symmetry breaking. Tt-CIV2 is a ~2.7-megadalton dimer with more than 50 subunits per protomer, including mitochondrial carriers and a TIM83-TIM133-like domain. Our structural and functional study of the T. thermophila respiratory chain reveals divergence in key components of eukaryotic respiration, thereby expanding our understanding of core metabolism.
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Affiliation(s)
- Long Zhou
- Department of Biophysics and Department of Critical Care Medicine of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - María Maldonado
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Abhilash Padavannil
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Fei Guo
- BIOEM Facility, University of California, Davis, CA 95616, USA
| | - James A. Letts
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
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15
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Proteolytic regulation of mitochondrial oxidative phosphorylation components in plants. Biochem Soc Trans 2022; 50:1119-1132. [PMID: 35587610 PMCID: PMC9246333 DOI: 10.1042/bst20220195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/07/2022] [Accepted: 05/03/2022] [Indexed: 11/28/2022]
Abstract
Mitochondrial function relies on the homeostasis and quality control of their proteome, including components of the oxidative phosphorylation (OXPHOS) pathway that generates energy in form of ATP. OXPHOS subunits are under constant exposure to reactive oxygen species due to their oxidation-reduction activities, which consequently make them prone to oxidative damage, misfolding, and aggregation. As a result, quality control mechanisms through turnover and degradation are required for maintaining mitochondrial activity. Degradation of OXPHOS subunits can be achieved through proteomic turnover or modular degradation. In this review, we present multiple protein degradation pathways in plant mitochondria. Specifically, we focus on the intricate turnover of OXPHOS subunits, prior to protein import via cytosolic proteasomal degradation and post import and assembly via intra-mitochondrial proteolysis involving multiple AAA+ proteases. Together, these proteolytic pathways maintain the activity and homeostasis of OXPHOS components.
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16
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Cloning and Organelle Expression of Bamboo Mitochondrial Complex I Subunits Nad1, Nad2, Nad4, and Nad5 in the Yeast Saccharomyces cerevisiae. Int J Mol Sci 2022; 23:ijms23074054. [PMID: 35409414 PMCID: PMC8999482 DOI: 10.3390/ijms23074054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/02/2022] [Accepted: 04/04/2022] [Indexed: 02/04/2023] Open
Abstract
Mitochondrial respiratory complex I catalyzes electron transfer from NADH to ubiquinone and pumps protons from the matrix into the intermembrane space. In particular, the complex I subunits Nad1, Nad2, Nad4, and Nad5, which are encoded by the nad1, nad2, nad4, and nad5 genes, reside at the mitochondrial inner membrane and possibly function as proton (H+) and ion translocators. To understand the individual functional roles of the Nad1, Nad2, Nad4, and Nad5 subunits in bamboo, each cDNA of these four genes was cloned into the pYES2 vector and expressed in the mitochondria of the yeast Saccharomyces cerevisiae. The mitochondrial targeting peptide mt gene (encoding MT) and the egfp marker gene (encoding enhanced green fluorescent protein, EGFP) were fused at the 5'-terminal and 3'-terminal ends, respectively. The constructed plasmids were then transformed into yeast. RNA transcripts and fusion protein expression were observed in the yeast transformants. Mitochondrial localizations of the MT-Nad1-EGFP, MT-Nad2-EGFP, MT-Nad4-EGFP, and MT-Nad5-EGFP fusion proteins were confirmed by fluorescence microscopy. The ectopically expressed bamboo subunits Nad1, Nad2, Nad4, and Nad5 may function in ion translocation, which was confirmed by growth phenotype assays with the addition of different concentrations of K+, Na+, or H+.
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17
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Grba DN, Blaza JN, Bridges HR, Agip ANA, Yin Z, Murai M, Miyoshi H, Hirst J. Cryo-electron microscopy reveals how acetogenins inhibit mitochondrial respiratory complex I. J Biol Chem 2022; 298:101602. [PMID: 35063503 PMCID: PMC8861642 DOI: 10.1016/j.jbc.2022.101602] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 12/22/2022] Open
Abstract
Mitochondrial complex I (NADH:ubiquinone oxidoreductase), a crucial enzyme in energy metabolism, captures the redox potential energy from NADH oxidation/ubiquinone reduction to create the proton motive force used to drive ATP synthesis in oxidative phosphorylation. High-resolution single-particle electron cryo-EM analyses have provided detailed structural knowledge of the catalytic machinery of complex I, but not of the molecular principles of its energy transduction mechanism. Although ubiquinone is considered to bind in a long channel at the interface of the membrane-embedded and hydrophilic domains, with channel residues likely involved in coupling substrate reduction to proton translocation, no structures with the channel fully occupied have yet been described. Here, we report the structure (determined by cryo-EM) of mouse complex I with a tight-binding natural product acetogenin inhibitor, which resembles the native substrate, bound along the full length of the expected ubiquinone-binding channel. Our structure reveals the mode of acetogenin binding and the molecular basis for structure-activity relationships within the acetogenin family. It also shows that acetogenins are such potent inhibitors because they are highly hydrophobic molecules that contain two specific hydrophilic moieties spaced to lock into two hydrophilic regions of the otherwise hydrophobic channel. The central hydrophilic section of the channel does not favor binding of the isoprenoid chain when the native substrate is fully bound but stabilizes the ubiquinone/ubiquinol headgroup as it transits to/from the active site. Therefore, the amphipathic nature of the channel supports both tight binding of the amphipathic inhibitor and rapid exchange of the ubiquinone/ubiquinol substrate and product.
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Affiliation(s)
- Daniel N Grba
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - James N Blaza
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Hannah R Bridges
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Ahmed-Noor A Agip
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Zhan Yin
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Judy Hirst
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
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18
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MISF2 Encodes an Essential Mitochondrial Splicing Cofactor Required for nad2 mRNA Processing and Embryo Development in Arabidopsis thaliana. Int J Mol Sci 2022; 23:ijms23052670. [PMID: 35269810 PMCID: PMC8910670 DOI: 10.3390/ijms23052670] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 12/20/2022] Open
Abstract
Mitochondria play key roles in cellular energy metabolism in eukaryotes. Mitochondria of most organisms contain their own genome and specific transcription and translation machineries. The expression of angiosperm mtDNA involves extensive RNA-processing steps, such as RNA trimming, editing, and the splicing of numerous group II-type introns. Pentatricopeptide repeat (PPR) proteins are key players in plant organelle gene expression and RNA metabolism. In the present analysis, we reveal the function of the MITOCHONDRIAL SPLICING FACTOR 2 gene (MISF2, AT3G22670) and show that it encodes a mitochondria-localized PPR protein that is crucial for early embryo development in Arabidopsis. Molecular characterization of embryo-rescued misf2 plantlets indicates that the splicing of nad2 intron 1, and thus respiratory complex I biogenesis, are strongly compromised. Moreover, the molecular function seems conserved between MISF2 protein in Arabidopsis and its orthologous gene (EMP10) in maize, suggesting that the ancestor of MISF2/EMP10 was recruited to function in nad2 processing before the monocot-dicot divergence ~200 million years ago. These data provide new insights into the function of nuclear-encoded factors in mitochondrial gene expression and respiratory chain biogenesis during plant embryo development.
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19
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Padavannil A, Ayala-Hernandez MG, Castellanos-Silva EA, Letts JA. The Mysterious Multitude: Structural Perspective on the Accessory Subunits of Respiratory Complex I. Front Mol Biosci 2022; 8:798353. [PMID: 35047558 PMCID: PMC8762328 DOI: 10.3389/fmolb.2021.798353] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 11/25/2021] [Indexed: 01/10/2023] Open
Abstract
Complex I (CI) is the largest protein complex in the mitochondrial oxidative phosphorylation electron transport chain of the inner mitochondrial membrane and plays a key role in the transport of electrons from reduced substrates to molecular oxygen. CI is composed of 14 core subunits that are conserved across species and an increasing number of accessory subunits from bacteria to mammals. The fact that adding accessory subunits incurs costs of protein production and import suggests that these subunits play important physiological roles. Accordingly, knockout studies have demonstrated that accessory subunits are essential for CI assembly and function. Furthermore, clinical studies have shown that amino acid substitutions in accessory subunits lead to several debilitating and fatal CI deficiencies. Nevertheless, the specific roles of CI’s accessory subunits have remained mysterious. In this review, we explore the possible roles of each of mammalian CI’s 31 accessory subunits by integrating recent high-resolution CI structures with knockout, assembly, and clinical studies. Thus, we develop a framework of experimentally testable hypotheses for the function of the accessory subunits. We believe that this framework will provide inroads towards the complete understanding of mitochondrial CI physiology and help to develop strategies for the treatment of CI deficiencies.
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Affiliation(s)
- Abhilash Padavannil
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
| | - Maria G Ayala-Hernandez
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
| | - Eimy A Castellanos-Silva
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
| | - James A Letts
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
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20
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A Structural Perspective on the RNA Editing of Plant Respiratory Complexes. Int J Mol Sci 2022; 23:ijms23020684. [PMID: 35054870 PMCID: PMC8775464 DOI: 10.3390/ijms23020684] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 12/31/2021] [Accepted: 01/05/2022] [Indexed: 02/07/2023] Open
Abstract
The last steps of respiration, a core energy-harvesting process, are carried out by a chain of multi-subunit complexes in the inner mitochondrial membrane. Several essential subunits of the respiratory complexes are RNA-edited in plants, frequently leading to changes in the encoded amino acids. While the impact of RNA editing is clear at the sequence and phenotypic levels, the underlying biochemical explanations for these effects have remained obscure. Here, we used the structures of plant respiratory complex I, complex III2 and complex IV to analyze the impact of the amino acid changes of RNA editing in terms of their location and biochemical features. Through specific examples, we demonstrate how the structural information can explain the phenotypes of RNA-editing mutants. This work shows how the structural perspective can bridge the gap between sequence and phenotype and provides a framework for the continued analysis of RNA-editing mutants in plant mitochondria and, by extension, in chloroplasts.
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21
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López-López A, Keech O, Rouhier N. Maturation and Assembly of Iron-Sulfur Cluster-Containing Subunits in the Mitochondrial Complex I From Plants. FRONTIERS IN PLANT SCIENCE 2022; 13:916948. [PMID: 35677241 PMCID: PMC9168917 DOI: 10.3389/fpls.2022.916948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 05/04/2022] [Indexed: 05/13/2023]
Abstract
In plants, the mitochondrial complex I is the protein complex encompassing the largest number of iron-sulfur (Fe-S) clusters. The whole, membrane-embedded, holo-complex is assembled stepwise from assembly intermediates. The Q and N modules are combined to form a peripheral arm in the matrix, whereas the so-called membrane arm is formed after merging a carbonic anhydrase (CA) module with so-called Pp (proximal) and the Pd (distal) domains. A ferredoxin bridge connects both arms. The eight Fe-S clusters present in the peripheral arm for electron transfer reactions are synthesized via a dedicated protein machinery referred to as the iron-sulfur cluster (ISC) machinery. The de novo assembly occurs on ISCU scaffold proteins from iron, sulfur and electron delivery proteins. In a second step, the preformed Fe-S clusters are transferred, eventually converted and inserted in recipient apo-proteins. Diverse molecular actors, including a chaperone-cochaperone system, assembly factors among which proteins with LYR motifs, and Fe-S cluster carrier/transfer proteins, have been identified as contributors to the second step. This mini-review highlights the recent progresses in our understanding of how specificity is achieved during the delivery of preformed Fe-S clusters to complex I subunits.
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Affiliation(s)
- Alicia López-López
- INRAE, IAM, Université de Lorraine, Nancy, France
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, Umeå, Sweden
| | - Olivier Keech
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, Umeå, Sweden
| | - Nicolas Rouhier
- INRAE, IAM, Université de Lorraine, Nancy, France
- *Correspondence: Nicolas Rouhier,
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22
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The Assembly of Super-Complexes in the Plant Chloroplast. Biomolecules 2021; 11:biom11121839. [PMID: 34944483 PMCID: PMC8699064 DOI: 10.3390/biom11121839] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/02/2021] [Accepted: 12/02/2021] [Indexed: 11/17/2022] Open
Abstract
Increasing evidence has revealed that the enzymes of several biological pathways assemble into larger supramolecular structures called super-complexes. Indeed, those such as association of the mitochondrial respiratory chain complexes play an essential role in respiratory activity and promote metabolic fitness. Dynamically assembled super-complexes are able to alternate between participating in large complexes and existing in a free state. However, the functional significance of the super-complexes is not entirely clear. It has been proposed that the organization of respiratory enzymes into super-complexes could reduce oxidative damage and increase metabolism efficiency. There are several protein complexes that have been revealed in the plant chloroplast, yet little research has been focused on the formation of super-complexes in this organelle. The photosystem I and light-harvesting complex I super-complex’s structure suggests that energy absorbed by light-harvesting complex I could be efficiently transferred to the PSI core by avoiding concentration quenching. Here, we will discuss in detail core complexes of photosystem I and II, the chloroplast ATPase the chloroplast electron transport chain, the Calvin–Benson cycle and a plastid localized purinosome. In addition, we will also describe the methods to identify these complexes.
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23
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Petersen G, Shyama Prasad Rao R, Anderson B, Zervas A, Seberg O, Rasmusson AG, Max Møller I. Genes from oxidative phosphorylation complexes II-V and two dual-function subunits of complex I are transcribed in Viscum album despite absence of the entire mitochondrial holo-complex I. Mitochondrion 2021; 62:1-12. [PMID: 34740863 DOI: 10.1016/j.mito.2021.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 10/09/2021] [Accepted: 10/28/2021] [Indexed: 11/30/2022]
Abstract
Mistletoes (Viscum) and close relatives are unique among flowering plants in having a drastically altered electron transport chain. Lack of complex I genes has previously been reported for the mitochondrial genome, and here we report an almost complete absence of nuclear-encoded complex I genes in the transcriptome of Viscum album. Compared to Arabidopsis with approximately 40 nuclear complex I genes, we recover only transcripts of two dual-function genes: gamma carbonic anhydrase and L-galactono-1,4-lactone dehydrogenase. The complement of genes belonging to complexes II-V of the oxidative phosphorylation pathway appears to be in accordance with other vascular plants. Additionally, transcripts encoding alternative NAD(P)H dehydrogenases and alternative oxidase were found. Despite sequence divergence, structural modeling suggests that the encoded proteins are structurally conserved. Complex I loss is a special feature in Viscum species and relatives, as all other parasitic flowering plants investigated to date seem to have a complete OXPHOS system. Hence, Viscum offers a unique system for specifically investigating molecular consequences of complex I absence, such as the role of complex I subunits involved in secondary functions.
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Affiliation(s)
- Gitte Petersen
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
| | - R Shyama Prasad Rao
- Biostatistics and Bioinformatics Division, Yenepoya Research Center, Yenepoya University, Mangaluru 575018, Karnataka, India
| | - Benjamin Anderson
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Athanasios Zervas
- Department of Environmental Science, Aarhus University, DK-4000 Roskilde, Denmark
| | - Ole Seberg
- Natural History Museum of Denmark, University of Copenhagen, DK-1353 Copenhagen, Denmark
| | | | - Ian Max Møller
- Department of Molecular Biology and Genetics, Aarhus University, DK-4200 Slagelse, Denmark
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24
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Møller IM, Rasmusson AG, Van Aken O. Plant mitochondria - past, present and future. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:912-959. [PMID: 34528296 DOI: 10.1111/tpj.15495] [Citation(s) in RCA: 113] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 09/02/2021] [Accepted: 09/06/2021] [Indexed: 06/13/2023]
Abstract
The study of plant mitochondria started in earnest around 1950 with the first isolations of mitochondria from animal and plant tissues. The first 35 years were spent establishing the basic properties of plant mitochondria and plant respiration using biochemical and physiological approaches. A number of unique properties (compared to mammalian mitochondria) were observed: (i) the ability to oxidize malate, glycine and cytosolic NAD(P)H at high rates; (ii) the partial insensitivity to rotenone, which turned out to be due to the presence of a second NADH dehydrogenase on the inner surface of the inner mitochondrial membrane in addition to the classical Complex I NADH dehydrogenase; and (iii) the partial insensitivity to cyanide, which turned out to be due to an alternative oxidase, which is also located on the inner surface of the inner mitochondrial membrane, in addition to the classical Complex IV, cytochrome oxidase. With the appearance of molecular biology methods around 1985, followed by genomics, further unique properties were discovered: (iv) plant mitochondrial DNA (mtDNA) is 10-600 times larger than the mammalian mtDNA, yet it only contains approximately 50% more genes; (v) plant mtDNA has kept the standard genetic code, and it has a low divergence rate with respect to point mutations, but a high recombinatorial activity; (vi) mitochondrial mRNA maturation includes a uniquely complex set of activities for processing, splicing and editing (at hundreds of sites); (vii) recombination in mtDNA creates novel reading frames that can produce male sterility; and (viii) plant mitochondria have a large proteome with 2000-3000 different proteins containing many unique proteins such as 200-300 pentatricopeptide repeat proteins. We describe the present and fairly detailed picture of the structure and function of plant mitochondria and how the unique properties make their metabolism more flexible allowing them to be involved in many diverse processes in the plant cell, such as photosynthesis, photorespiration, CAM and C4 metabolism, heat production, temperature control, stress resistance mechanisms, programmed cell death and genomic evolution. However, it is still a challenge to understand how the regulation of metabolism and mtDNA expression works at the cellular level and how retrograde signaling from the mitochondria coordinates all those processes.
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Affiliation(s)
- Ian Max Møller
- Department of Molecular Biology and Genetics, Aarhus University, Forsøgsvej 1, DK-4200, Slagelse, Denmark
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25
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Ansari F, Yoval-Sánchez B, Niatsetskaya Z, Sosunov S, Stepanova A, Garcia C, Owusu-Ansah E, Ten V, Wittig I, Galkin A. Quantification of NADH:ubiquinone oxidoreductase (complex I) content in biological samples. J Biol Chem 2021; 297:101204. [PMID: 34543622 PMCID: PMC8503622 DOI: 10.1016/j.jbc.2021.101204] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/26/2021] [Accepted: 08/31/2021] [Indexed: 12/14/2022] Open
Abstract
Impairments in mitochondrial energy metabolism have been implicated in human genetic diseases associated with mitochondrial and nuclear DNA mutations, neurodegenerative and cardiovascular disorders, diabetes, and aging. Alteration in mitochondrial complex I structure and activity has been shown to play a key role in Parkinson's disease and ischemia/reperfusion tissue injury, but significant difficulty remains in assessing the content of this enzyme complex in a given sample. The present study introduces a new method utilizing native polyacrylamide gel electrophoresis in combination with flavin fluorescence scanning to measure the absolute content of complex I, as well as α-ketoglutarate dehydrogenase complex, in any preparation. We show that complex I content is 19 ± 1 pmol/mg of protein in the brain mitochondria, whereas varies up to 10-fold in different mouse tissues. Together with the measurements of NADH-dependent specific activity, our method also allows accurate determination of complex I catalytic turnover, which was calculated as 104 min-1 for NADH:ubiquinone reductase in mouse brain mitochondrial preparations. α-ketoglutarate dehydrogenase complex content was determined to be 65 ± 5 and 123 ± 9 pmol/mg protein for mouse brain and bovine heart mitochondria, respectively. Our approach can also be extended to cultured cells, and we demonstrated that about 90 × 103 complex I molecules are present in a single human embryonic kidney 293 cell. The ability to determine complex I content should provide a valuable tool to investigate the enzyme status in samples after in vivo treatment in mutant organisms, cells in culture, or human biopsies.
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Affiliation(s)
- Fariha Ansari
- Division of Neonatology, Department of Pediatrics, Columbia University Medical Center, New York, New York, USA
| | - Belem Yoval-Sánchez
- Division of Neonatology, Department of Pediatrics, Columbia University Medical Center, New York, New York, USA
| | - Zoya Niatsetskaya
- Division of Neonatology, Department of Pediatrics, Columbia University Medical Center, New York, New York, USA
| | - Sergey Sosunov
- Division of Neonatology, Department of Pediatrics, Columbia University Medical Center, New York, New York, USA
| | - Anna Stepanova
- Division of Neonatology, Department of Pediatrics, Columbia University Medical Center, New York, New York, USA
| | - Christian Garcia
- Department of Physiology & Cellular Biophysics, Columbia University, New York, New York, USA
| | - Edward Owusu-Ansah
- Department of Physiology & Cellular Biophysics, Columbia University, New York, New York, USA
| | - Vadim Ten
- Division of Neonatology, Department of Pediatrics, Columbia University Medical Center, New York, New York, USA
| | - Ilka Wittig
- Functional Proteomics, Institute of Cardiovascular Physiology, Goethe University, Frankfurt am Main, Germany; German Center for Cardiovascular Research (DZHK), Partner site RheinMain, Frankfurt am Main, Germany
| | - Alexander Galkin
- Division of Neonatology, Department of Pediatrics, Columbia University Medical Center, New York, New York, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York, USA.
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26
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Deyssenroth MA, Rosa MJ, Eliot MN, Kelsey KT, Kloog I, Schwartz JD, Wellenius GA, Peng S, Hao K, Marsit CJ, Chen J. Placental gene networks at the interface between maternal PM 2.5 exposure early in gestation and reduced infant birthweight. ENVIRONMENTAL RESEARCH 2021; 199:111342. [PMID: 34015297 PMCID: PMC8195860 DOI: 10.1016/j.envres.2021.111342] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 05/31/2023]
Abstract
BACKGROUND A growing body of evidence links maternal exposure to particulate matter <2.5 μM in diameter (PM2.5) and deviations in fetal growth. Several studies suggest that the placenta plays a critical role in conveying the effects of maternal PM2.5 exposure to the developing fetus. These include observed associations between air pollutants and candidate placental features, such as mitochondrial DNA content, DNA methylation and telomere length. However, gaps remain in delineating the pathways linking the placenta to air pollution-related health effects, including a comprehensive profiling of placental processes impacted by maternal PM2.5 exposure. In this study, we examined alterations in a placental transcriptome-wide network in relation to maternal PM2.5 exposure prior to and during pregnancy and infant birthweight. METHODS We evaluated PM2.5 exposure and placental RNA-sequencing data among study participants enrolled in the Rhode Island Child Health Study (RICHS). Daily residential PM2.5 levels were estimated using a hybrid model incorporating land-use regression and satellite remote sensing data. Distributed lag models were implemented to assess the impact on infant birthweight due to PM2.5 weekly averages ranging from 12 weeks prior to gestation until birth. Correlations were assessed between PM2.5 levels averaged across the identified window of susceptibility and a placental transcriptome-wide gene coexpression network previously generated using the WGCNA R package. RESULTS We identified a sensitive window spanning 12 weeks prior to and 13 weeks into gestation during which maternal PM2.5 exposure is significantly associated with reduced infant birthweight. Two placental coexpression modules enriched for genes involved in amino acid transport and cellular respiration were correlated with infant birthweight as well as maternal PM2.5 exposure levels averaged across the identified growth restriction window. CONCLUSION Our findings suggest that maternal PM2.5 exposure may alter placental programming of fetal growth, with potential implications for downstream health effects, including susceptibility to cardiometabolic health outcomes and viral infections.
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Affiliation(s)
- Maya A Deyssenroth
- Department of Environmental Health Sciences, Columbia University Mailman School of Public Health, New York, NY, 10032, USA.
| | - Maria José Rosa
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Melissa N Eliot
- Department of Epidemiology, Brown University School of Public Health, Providence, RI, 02903, USA
| | - Karl T Kelsey
- Department of Epidemiology, Brown University School of Public Health, Providence, RI, 02903, USA; Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, 02903, USA
| | - Itai Kloog
- Department of Geography and Environmental Development, Faculty of Humanities and Social Sciences, Ben Gurion University, Beersheba, 8410501, Israel
| | - Joel D Schwartz
- Department of Environmental Health, Harvard TH Chan School of Public Health, Boston, MA, 02215, USA; Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, 02215, USA
| | - Gregory A Wellenius
- Boston University School of Public Health, Boston University, Boston, MA, 02215, USA
| | - Shouneng Peng
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Ke Hao
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Carmen J Marsit
- Environmental Health, Rollins School of Public Health of Emory University, Atlanta, GA, 30322, USA
| | - Jia Chen
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
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Klusch N, Senkler J, Yildiz Ö, Kühlbrandt W, Braun HP. A ferredoxin bridge connects the two arms of plant mitochondrial complex I. THE PLANT CELL 2021; 33:2072-2091. [PMID: 33768254 PMCID: PMC8290278 DOI: 10.1093/plcell/koab092] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 03/19/2021] [Indexed: 05/23/2023]
Abstract
Mitochondrial complex I is the main site for electron transfer to the respiratory chain and generates much of the proton gradient across the inner mitochondrial membrane. Complex I is composed of two arms, which form a conserved L-shape. We report the structures of the intact, 47-subunit mitochondrial complex I from Arabidopsis thaliana and the 51-subunit complex I from the green alga Polytomella sp., both at around 2.9 Å resolution. In both complexes, a heterotrimeric γ-carbonic anhydrase domain is attached to the membrane arm on the matrix side. Two states are resolved in A. thaliana complex I, with different angles between the two arms and different conformations of the ND1 (NADH dehydrogenase subunit 1) loop near the quinol binding site. The angle appears to depend on a bridge domain, which links the peripheral arm to the membrane arm and includes an unusual ferredoxin. We propose that the bridge domain participates in regulating the activity of plant complex I.
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Affiliation(s)
- Niklas Klusch
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt 60438, Germany
| | - Jennifer Senkler
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover 30419, Germany
| | - Özkan Yildiz
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt 60438, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt 60438, Germany
| | - Hans-Peter Braun
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover 30419, Germany
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28
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Ivanova A, Ghifari AS, Berkowitz O, Whelan J, Murcha MW. The mitochondrial AAA protease FTSH3 regulates Complex I abundance by promoting its disassembly. PLANT PHYSIOLOGY 2021; 186:599-610. [PMID: 33616659 PMCID: PMC8154063 DOI: 10.1093/plphys/kiab074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 01/28/2021] [Indexed: 06/02/2023]
Abstract
ATP is generated in mitochondria by oxidative phosphorylation. Complex I (NADH:ubiquinone oxidoreductase or NADH dehydrogenase) is the first multisubunit protein complex of this pathway, oxidizing NADH and transferring electrons to the ubiquinone pool. Typically, Complex I mutants display a slow growth rate compared to wild-type plants. Here, using a forward genetic screen approach for restored growth of a Complex I mutant, we have identified the mitochondrial ATP-dependent metalloprotease, Filamentous Temperature Sensitive H 3 (FTSH3), as a factor that is required for the disassembly of Complex I. An ethyl methanesulfonate-induced mutation in FTSH3, named as rmb1 (restoration of mitochondrial biogenesis 1), restored Complex I abundance and plant growth. Complementation could be achieved with FTSH3 lacking proteolytic activity, suggesting the unfoldase function of FTSH3 has a role in Complex I disassembly. The introduction of the rmb1 to an additional, independent, and extensively characterized Complex I mutant, ndufs4, resulted in similar increases to Complex I abundance and a partial restoration of growth. These results show that disassembly or degradation of Complex I plays a role in determining its steady-state abundance and thus turnover may vary under different conditions.
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Affiliation(s)
- Aneta Ivanova
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth 6009, Australia
- The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth 6009, Australia
| | - Abi S Ghifari
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth 6009, Australia
- The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth 6009, Australia
| | - Oliver Berkowitz
- Department of Animal, Plant and Soil Science, School of Life Science, The ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora 3086, Vic, Australia
| | - James Whelan
- Department of Animal, Plant and Soil Science, School of Life Science, The ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora 3086, Vic, Australia
| | - Monika W Murcha
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth 6009, Australia
- The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth 6009, Australia
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29
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Protein interaction patterns in Arabidopsis thaliana leaf mitochondria change in dependence to light. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148443. [PMID: 33965424 DOI: 10.1016/j.bbabio.2021.148443] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 04/20/2021] [Accepted: 04/23/2021] [Indexed: 02/08/2023]
Abstract
Mitochondrial biology is underpinned by the presence and activity of large protein assemblies participating in the organelle-located steps of respiration, TCA-cycle, glycine oxidation, and oxidative phosphorylation. While the enzymatic roles of these complexes are undisputed, little is known about the interactions of the subunits beyond their presence in these protein complexes and their functions in regulating mitochondrial metabolism. By applying one of the most important regulatory cues for plant metabolism, the presence or absence of light, we here assess changes in the composition and molecular mass of protein assemblies involved in NADH-production in the mitochondrial matrix and in oxidative phosphorylation by employing a differential complexome profiling strategy. Covering a mass up to 25 MDa, we demonstrate dynamic associations of matrix enzymes and of components involved in oxidative phosphorylation. The data presented here form the basis for future studies aiming to advance our understanding of the role of protein:protein interactions in regulating plant mitochondrial functions.
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30
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Kell DB. A protet-based, protonic charge transfer model of energy coupling in oxidative and photosynthetic phosphorylation. Adv Microb Physiol 2021; 78:1-177. [PMID: 34147184 DOI: 10.1016/bs.ampbs.2021.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Textbooks of biochemistry will explain that the otherwise endergonic reactions of ATP synthesis can be driven by the exergonic reactions of respiratory electron transport, and that these two half-reactions are catalyzed by protein complexes embedded in the same, closed membrane. These views are correct. The textbooks also state that, according to the chemiosmotic coupling hypothesis, a (or the) kinetically and thermodynamically competent intermediate linking the two half-reactions is the electrochemical difference of protons that is in equilibrium with that between the two bulk phases that the coupling membrane serves to separate. This gradient consists of a membrane potential term Δψ and a pH gradient term ΔpH, and is known colloquially as the protonmotive force or pmf. Artificial imposition of a pmf can drive phosphorylation, but only if the pmf exceeds some 150-170mV; to achieve in vivo rates the imposed pmf must reach 200mV. The key question then is 'does the pmf generated by electron transport exceed 200mV, or even 170mV?' The possibly surprising answer, from a great many kinds of experiment and sources of evidence, including direct measurements with microelectrodes, indicates it that it does not. Observable pH changes driven by electron transport are real, and they control various processes; however, compensating ion movements restrict the Δψ component to low values. A protet-based model, that I outline here, can account for all the necessary observations, including all of those inconsistent with chemiosmotic coupling, and provides for a variety of testable hypotheses by which it might be refined.
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Affiliation(s)
- Douglas B Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative, Biology, University of Liverpool, Liverpool, United Kingdom; The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark.
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31
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Amphipathic environments for determining the structure of membrane proteins by single-particle electron cryo-microscopy. Q Rev Biophys 2021; 54:e6. [PMID: 33785082 DOI: 10.1017/s0033583521000044] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Over the past decade, the structural biology of membrane proteins (MPs) has taken a new turn thanks to epoch-making technical progress in single-particle electron cryo-microscopy (cryo-EM) as well as to improvements in sample preparation. The present analysis provides an overview of the extent and modes of usage of the various types of surfactants for cryo-EM studies. Digitonin, dodecylmaltoside, protein-based nanodiscs, lauryl maltoside-neopentyl glycol, glyco-diosgenin, and amphipols (APols) are the most popular surfactants at the vitrification step. Surfactant exchange is frequently used between MP purification and grid preparation, requiring extensive optimization each time the study of a new MP is undertaken. The variety of both the surfactants and experimental approaches used over the past few years bears witness to the need to continue developing innovative surfactants and optimizing conditions for sample preparation. The possibilities offered by novel APols for EM applications are discussed.
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32
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Przybyla-Toscano J, Christ L, Keech O, Rouhier N. Iron-sulfur proteins in plant mitochondria: roles and maturation. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:2014-2044. [PMID: 33301571 DOI: 10.1093/jxb/eraa578] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 12/05/2020] [Indexed: 05/22/2023]
Abstract
Iron-sulfur (Fe-S) clusters are prosthetic groups ensuring electron transfer reactions, activating substrates for catalytic reactions, providing sulfur atoms for the biosynthesis of vitamins or other cofactors, or having protein-stabilizing effects. Hence, metalloproteins containing these cofactors are essential for numerous and diverse metabolic pathways and cellular processes occurring in the cytoplasm. Mitochondria are organelles where the Fe-S cluster demand is high, notably because the activity of the respiratory chain complexes I, II, and III relies on the correct assembly and functioning of Fe-S proteins. Several other proteins or complexes present in the matrix require Fe-S clusters as well, or depend either on Fe-S proteins such as ferredoxins or on cofactors such as lipoic acid or biotin whose synthesis relies on Fe-S proteins. In this review, we have listed and discussed the Fe-S-dependent enzymes or pathways in plant mitochondria including some potentially novel Fe-S proteins identified based on in silico analysis or on recent evidence obtained in non-plant organisms. We also provide information about recent developments concerning the molecular mechanisms involved in Fe-S cluster synthesis and trafficking steps of these cofactors from maturation factors to client apoproteins.
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Affiliation(s)
- Jonathan Przybyla-Toscano
- Université de Lorraine, INRAE, IAM, Nancy, France
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, Umeå, Sweden
| | - Loïck Christ
- Université de Lorraine, INRAE, IAM, Nancy, France
| | - Olivier Keech
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, Umeå, Sweden
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33
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Abstract
Atomic structures of mitochondrial enzyme complexes in plants are shedding light on their multiple functions.
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Affiliation(s)
- Hans-Peter Braun
- Institut für Pflanzengenetik, Leibniz Universität HannoverHannoverGermany
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34
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Maldonado M, Guo F, Letts JA. Atomic structures of respiratory complex III 2, complex IV, and supercomplex III 2-IV from vascular plants. eLife 2021; 10:e62047. [PMID: 33463523 PMCID: PMC7815315 DOI: 10.7554/elife.62047] [Citation(s) in RCA: 144] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 11/25/2020] [Indexed: 12/11/2022] Open
Abstract
Mitochondrial complex III (CIII2) and complex IV (CIV), which can associate into a higher-order supercomplex (SC III2+IV), play key roles in respiration. However, structures of these plant complexes remain unknown. We present atomic models of CIII2, CIV, and SC III2+IV from Vigna radiata determined by single-particle cryoEM. The structures reveal plant-specific differences in the MPP domain of CIII2 and define the subunit composition of CIV. Conformational heterogeneity analysis of CIII2 revealed long-range, coordinated movements across the complex, as well as the motion of CIII2's iron-sulfur head domain. The CIV structure suggests that, in plants, proton translocation does not occur via the H channel. The supercomplex interface differs significantly from that in yeast and bacteria in its interacting subunits, angle of approach and limited interactions in the mitochondrial matrix. These structures challenge long-standing assumptions about the plant complexes and generate new mechanistic hypotheses.
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Affiliation(s)
- Maria Maldonado
- Department of Molecular and Cellular Biology, University of California DavisDavisUnited States
| | - Fei Guo
- Department of Molecular and Cellular Biology, University of California DavisDavisUnited States
- BIOEM Facility, University of California DavisDavisUnited States
| | - James A Letts
- Department of Molecular and Cellular Biology, University of California DavisDavisUnited States
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