1
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Čunátová K, Fernández-Vizarra E. Pathological variants in nuclear genes causing mitochondrial complex III deficiency: An update. J Inherit Metab Dis 2024. [PMID: 39053894 DOI: 10.1002/jimd.12751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 04/24/2024] [Accepted: 05/02/2024] [Indexed: 07/27/2024]
Abstract
Mitochondrial disorders are a group of clinically and biochemically heterogeneous genetic diseases within the group of inborn errors of metabolism. Primary mitochondrial diseases are mainly caused by defects in one or several components of the oxidative phosphorylation system (complexes I-V). Within these disorders, those associated with complex III deficiencies are the least common. However, thanks to a deeper knowledge about complex III biogenesis, improved clinical diagnosis and the implementation of next-generation sequencing techniques, the number of pathological variants identified in nuclear genes causing complex III deficiency has expanded significantly. This updated review summarizes the current knowledge concerning the genetic basis of complex III deficiency, and the main clinical features associated with these conditions.
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Affiliation(s)
- Kristýna Čunátová
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, Padova, Italy
| | - Erika Fernández-Vizarra
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, Padova, Italy
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2
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Zhan J, Zeher A, Huang R, Tang WK, Jenkins LM, Xia D. Conformations of Bcs1L undergoing ATP hydrolysis suggest a concerted translocation mechanism for folded iron-sulfur protein substrate. Nat Commun 2024; 15:4655. [PMID: 38821922 PMCID: PMC11143374 DOI: 10.1038/s41467-024-49029-y] [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: 10/10/2023] [Accepted: 05/20/2024] [Indexed: 06/02/2024] Open
Abstract
The human AAA-ATPase Bcs1L translocates the fully assembled Rieske iron-sulfur protein (ISP) precursor across the mitochondrial inner membrane, enabling respiratory Complex III assembly. Exactly how the folded substrate is bound to and released from Bcs1L has been unclear, and there has been ongoing debate as to whether subunits of Bcs1L act in sequence or in unison hydrolyzing ATP when moving the protein cargo. Here, we captured Bcs1L conformations by cryo-EM during active ATP hydrolysis in the presence or absence of ISP substrate. In contrast to the threading mechanism widely employed by AAA proteins in substrate translocation, subunits of Bcs1L alternate uniformly between ATP and ADP conformations without detectable intermediates that have different, co-existing nucleotide states, indicating that the subunits act in concert. We further show that the ISP can be trapped by Bcs1 when its subunits are all in the ADP-bound state, which we propose to be released in the apo form.
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Affiliation(s)
- Jingyu Zhan
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Allison Zeher
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- NIH Intramural Cryo-EM Consortium (NICE), Bethesda, MD, USA
| | - Rick Huang
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- NIH Intramural Cryo-EM Consortium (NICE), Bethesda, MD, USA
| | - Wai Kwan Tang
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Lisa M Jenkins
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Di Xia
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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3
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Klugherz I, Basch M, Ng N, Zhu Z, Wagener N, Wagener J. Only One of Three Bcs1 Homologs in Aspergillus fumigatus Confers Respiratory Growth. J Fungi (Basel) 2023; 9:1074. [PMID: 37998879 PMCID: PMC10672213 DOI: 10.3390/jof9111074] [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: 10/04/2023] [Revised: 10/23/2023] [Accepted: 10/25/2023] [Indexed: 11/25/2023] Open
Abstract
The mitochondrial translocase Bcs1 is required for the correct assembly of complex III of the mitochondrial respiratory chain. Because of its importance, Bcs1 was recently proposed as a target for antifungal agents. The function of this AAA (ATPase Associated with diverse cellular Activities) protein has been extensively characterized in Saccharomyces cerevisiae. This yeast as well as previously studied mammals each encode only one homolog. In contrast, the pathogenic mold Aspergillus fumigatus encodes three putative Bcs1 homologs, none of which have been characterized to date. To study the role of these three homologs in A. fumigatus, conditional and deletion mutants of the respective genes AFUA_3G13000 (bcs1A), AFUA_4G01260 (bcs1B), and AFUA_2G14760 (bcs1C) were generated. A deletion or downregulation of bcs1A resulted in drastically reduced growth and sporulation rates and in a significantly altered susceptibility to azole antifungals. In contrast, mutants lacking Bcs1B or Bcs1C did not show any phenotypes differing from the wild type. Salicylhydroxamic acid-an inhibitor of the alternative oxidase that allows the respiratory chain to bypass complex III in some species-caused a complete growth arrest of the bcs1A deletion mutant. In a Galleria mellonella infection model, the deletion of bcs1A resulted in significantly decreased virulence. Only Bcs1A was able to partially complement a deletion of BCS1 in S. cerevisiae. The subcellular localization of Bcs1B and Bcs1C outside of mitochondria suggests that these Bcs1 homologs exert cellular functions different from that of Bcs1. Our data demonstrate that Bcs1A is the sole Bcs1 ortholog in A. fumigatus.
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Affiliation(s)
- Isabel Klugherz
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Medizinische Fakultät, Ludwig-Maximilians-Universität München, 80336 Munich, Germany; (I.K.)
- Diagnostic and Research Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Marion Basch
- Zell- und Entwicklungsbiologie, Department Biologie II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, 82152 Munich, Germany
| | - Natanya Ng
- Department of Clinical Microbiology, School of Medicine, Trinity College Dublin, The University of Dublin, St James’s Hospital Campus, D08 RX0X Dublin, Ireland
| | - Zhaojun Zhu
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Medizinische Fakultät, Ludwig-Maximilians-Universität München, 80336 Munich, Germany; (I.K.)
| | - Nikola Wagener
- Zell- und Entwicklungsbiologie, Department Biologie II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, 82152 Munich, Germany
| | - Johannes Wagener
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Medizinische Fakultät, Ludwig-Maximilians-Universität München, 80336 Munich, Germany; (I.K.)
- Department of Clinical Microbiology, School of Medicine, Trinity College Dublin, The University of Dublin, St James’s Hospital Campus, D08 RX0X Dublin, Ireland
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4
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Pan Y, Zhan J, Jiang Y, Xia D, Scheuring S. A concerted ATPase cycle of the protein transporter AAA-ATPase Bcs1. Nat Commun 2023; 14:6369. [PMID: 37821516 PMCID: PMC10567702 DOI: 10.1038/s41467-023-41806-5] [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: 03/16/2023] [Accepted: 09/18/2023] [Indexed: 10/13/2023] Open
Abstract
Bcs1, a homo-heptameric transmembrane AAA-ATPase, facilitates folded Rieske iron-sulfur protein translocation across the inner mitochondrial membrane. Structures in different nucleotide states (ATPγS, ADP, apo) provided conformational snapshots, but the kinetics and structural transitions of the ATPase cycle remain elusive. Here, using high-speed atomic force microscopy (HS-AFM) and line scanning (HS-AFM-LS), we characterized single-molecule Bcs1 ATPase cycling. While the ATP conformation had ~5600 ms lifetime, independent of the ATP-concentration, the ADP/apo conformation lifetime was ATP-concentration dependent and reached ~320 ms at saturating ATP-concentration, giving a maximum turnover rate of 0.17 s-1. Importantly, Bcs1 ATPase cycle conformational changes occurred in concert. Furthermore, we propose that the transport mechanism involves opening the IMS gate through energetically costly straightening of the transmembrane helices, potentially driving rapid gate resealing. Overall, our results establish a concerted ATPase cycle mechanism in Bcs1, distinct from other AAA-ATPases that use a hand-over-hand mechanism.
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Affiliation(s)
- Yangang Pan
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Jingyu Zhan
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yining Jiang
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
- Biochemistry & Structural Biology, Cell & Developmental Biology, and Molecular Biology (BCMB) Program, Weill Cornell Graduate School of Biomedical Sciences, New York, USA
| | - Di Xia
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Simon Scheuring
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA.
- Department of Physiology & Biophysics, Weill Cornell Medical College, New York, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA.
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5
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Busch JD, Fielden LF, Pfanner N, Wiedemann N. Mitochondrial protein transport: Versatility of translocases and mechanisms. Mol Cell 2023; 83:890-910. [PMID: 36931257 DOI: 10.1016/j.molcel.2023.02.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 03/17/2023]
Abstract
Biogenesis of mitochondria requires the import of approximately 1,000 different precursor proteins into and across the mitochondrial membranes. Mitochondria exhibit a wide variety of mechanisms and machineries for the translocation and sorting of precursor proteins. Five major import pathways that transport proteins to their functional intramitochondrial destination have been elucidated; these pathways range from the classical amino-terminal presequence-directed pathway to pathways using internal or even carboxy-terminal targeting signals in the precursors. Recent studies have provided important insights into the structural organization of membrane-embedded preprotein translocases of mitochondria. A comparison of the different translocases reveals the existence of at least three fundamentally different mechanisms: two-pore-translocase, β-barrel switching, and transport cavities open to the lipid bilayer. In addition, translocases are physically engaged in dynamic interactions with respiratory chain complexes, metabolite transporters, quality control factors, and machineries controlling membrane morphology. Thus, mitochondrial preprotein translocases are integrated into multi-functional networks of mitochondrial and cellular machineries.
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Affiliation(s)
- Jakob D Busch
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Laura F Fielden
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
| | - Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
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6
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Zhan J, Xia D. Bcs1, a novel target for fungicide. Front Chem 2023; 11:1146753. [PMID: 36993815 PMCID: PMC10040684 DOI: 10.3389/fchem.2023.1146753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/03/2023] [Indexed: 03/14/2023] Open
Abstract
The mitochondrial respiratory chain has long been a primary target for the development of fungicides for its indispensable role in various cellular functions including energy metabolism. Over the years, a wide range of natural and synthetic fungicides and pesticides targeting the respiratory chain complexes have been discovered or developed and used in agriculture and in medicine, which brought considerable economic gains but was also accompanied by the emergence of resistance to these compounds. To delay and overcome the onset of resistance, novel targets for fungicides development are actively being pursued. Mitochondrial AAA protein Bcs1 is necessary for the biogenesis of respiratory chain Complex III, also known as cyt bc1 complex, by delivering the last essential iron-sulfur protein subunit in its folded form to the cyt bc1 precomplex. Although no report on the phenotypes of knock-out Bcs1 has been reported in animals, pathogenic Bcs1 mutations cause Complex III deficiency and respiratory growth defects, which makes it a promising new target for the development of fungicides. Recent Cryo-EM and X-ray structures of mouse and yeast Bcs1 revealed the basic oligomeric states of Bcs1, shed light on the translocation mechanism of its substrate ISP, and provided the basis for structure-based drug design. This review summarizes the recent progress made on understanding the structure and function of Bcs1, proposes the use of Bcs1 as an antifungal target, and provides novel prospects for fungicides design by targeting Bcs1.
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7
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Wu D, Liu Y, Dai Y, Wang G, Lu G, Chen Y, Li N, Lin J, Gao N. Comprehensive structural characterization of the human AAA+ disaggregase CLPB in the apo- and substrate-bound states reveals a unique mode of action driven by oligomerization. PLoS Biol 2023; 21:e3001987. [PMID: 36745679 PMCID: PMC9934407 DOI: 10.1371/journal.pbio.3001987] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 02/16/2023] [Accepted: 01/04/2023] [Indexed: 02/07/2023] Open
Abstract
The human AAA+ ATPase CLPB (SKD3) is a protein disaggregase in the mitochondrial intermembrane space (IMS) and functions to promote the solubilization of various mitochondrial proteins. Loss-of-function CLPB mutations are associated with a few human diseases with neutropenia and neurological disorders. Unlike canonical AAA+ proteins, CLPB contains a unique ankyrin repeat domain (ANK) at its N-terminus. How CLPB functions as a disaggregase and the role of its ANK domain are currently unclear. Herein, we report a comprehensive structural characterization of human CLPB in both the apo- and substrate-bound states. CLPB assembles into homo-tetradecamers in apo-state and is remodeled into homo-dodecamers upon substrate binding. Conserved pore-loops (PLs) on the ATPase domains form a spiral staircase to grip and translocate the substrate in a step-size of 2 amino acid residues. The ANK domain is not only responsible for maintaining the higher-order assembly but also essential for the disaggregase activity. Interactome analysis suggests that the ANK domain may directly interact with a variety of mitochondrial substrates. These results reveal unique properties of CLPB as a general disaggregase in mitochondria and highlight its potential as a target for the treatment of various mitochondria-related diseases.
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Affiliation(s)
- Damu Wu
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Yan Liu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yuhao Dai
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
- Academy of Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Guopeng Wang
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Guoliang Lu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yan Chen
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Ningning Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
- Changping Laboratory, Beijing, China
| | - Jinzhong Lin
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai, China
- * E-mail: (JL); (NG)
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
- Changping Laboratory, Beijing, China
- National Biomedical Imaging Center, Peking University, Beijing, China
- * E-mail: (JL); (NG)
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8
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Banerjee R, Purhonen J, Kallijärvi J. The mitochondrial coenzyme Q junction and complex III: biochemistry and pathophysiology. FEBS J 2022; 289:6936-6958. [PMID: 34428349 DOI: 10.1111/febs.16164] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/13/2021] [Accepted: 08/23/2021] [Indexed: 01/13/2023]
Abstract
Coenzyme Q (CoQ, ubiquinone) is the electron-carrying lipid in the mitochondrial electron transport system (ETS). In mammals, it serves as the electron acceptor for nine mitochondrial inner membrane dehydrogenases. These include the NADH dehydrogenase (complex I, CI) and succinate dehydrogenase (complex II, CII) but also several others that are often omitted in the context of respiratory enzymes: dihydroorotate dehydrogenase, choline dehydrogenase, electron-transferring flavoprotein dehydrogenase, mitochondrial glycerol-3-phosphate dehydrogenase, proline dehydrogenases 1 and 2, and sulfide:quinone oxidoreductase. The metabolic pathways these enzymes are involved in range from amino acid and fatty acid oxidation to nucleotide biosynthesis, methylation, and hydrogen sulfide detoxification, among many others. The CoQ-linked metabolism depends on CoQ reoxidation by the mitochondrial complex III (cytochrome bc1 complex, CIII). However, the literature is surprisingly limited as for the role of the CoQ-linked metabolism in the pathogenesis of human diseases of oxidative phosphorylation (OXPHOS), in which the CoQ homeostasis is directly or indirectly affected. In this review, we give an introduction to CIII function, and an overview of the pathological consequences of CIII dysfunction in humans and mice and of the CoQ-dependent metabolic processes potentially affected in these pathological states. Finally, we discuss some experimental tools to dissect the various aspects of compromised CoQ oxidation.
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Affiliation(s)
- Rishi Banerjee
- Folkhälsan Research Center, Helsinki, Finland.,Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Janne Purhonen
- Folkhälsan Research Center, Helsinki, Finland.,Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Jukka Kallijärvi
- Folkhälsan Research Center, Helsinki, Finland.,Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
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9
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Crystal structure and biochemical analysis suggest that YjoB ATPase is a putative substrate-specific molecular chaperone. Proc Natl Acad Sci U S A 2022; 119:e2207856119. [PMID: 36191235 PMCID: PMC9565160 DOI: 10.1073/pnas.2207856119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
AAA+ ATPases are ubiquitous proteins associated with most cellular processes, including DNA unwinding and protein unfolding. Their functional and structural properties are typically determined by domains and motifs added to the conserved ATPases domain. Currently, the molecular function and structure of many ATPases remain elusive. Here, we report the crystal structure and biochemical analyses of YjoB, a Bacillus subtilis AAA+ protein. The crystal structure revealed that the YjoB hexamer forms a bucket hat-shaped structure with a porous chamber. Biochemical analyses showed that YjoB prevents the aggregation of vegetative catalase KatA and gluconeogenesis-specific glyceraldehyde-3 phosphate dehydrogenase GapB but not citrate synthase, a conventional substrate. Structural and biochemical analyses further showed that the internal chamber of YjoB is necessary for inhibition of substrate aggregation. Our results suggest that YjoB, conserved in the class Bacilli, is a potential molecular chaperone acting in the starvation/stationary phases of B. subtilis growth.
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Uusimaa J, Kettunen J, Varilo T, Järvelä I, Kallijärvi J, Kääriäinen H, Laine M, Lapatto R, Myllynen P, Niinikoski H, Rahikkala E, Suomalainen A, Tikkanen R, Tyynismaa H, Vieira P, Zarybnicky T, Sipilä P, Kuure S, Hinttala R. The Finnish genetic heritage in 2022 – from diagnosis to translational research. Dis Model Mech 2022; 15:278566. [PMID: 36285626 PMCID: PMC9637267 DOI: 10.1242/dmm.049490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Isolated populations have been valuable for the discovery of rare monogenic diseases and their causative genetic variants. Finnish disease heritage (FDH) is an example of a group of hereditary monogenic disorders caused by single major, usually autosomal-recessive, variants enriched in the population due to several past genetic drift events. Interestingly, distinct subpopulations have remained in Finland and have maintained their unique genetic repertoire. Thus, FDH diseases have persisted, facilitating vigorous research on the underlying molecular mechanisms and development of treatment options. This Review summarizes the current status of FDH, including the most recently discovered FDH disorders, and introduces a set of other recently identified diseases that share common features with the traditional FDH diseases. The Review also discusses a new era for population-based studies, which combine various forms of big data to identify novel genotype–phenotype associations behind more complex conditions, as exemplified here by the FinnGen project. In addition to the pathogenic variants with an unequivocal causative role in the disease phenotype, several risk alleles that correlate with certain phenotypic features have been identified among the Finns, further emphasizing the broad value of studying genetically isolated populations.
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Affiliation(s)
- Johanna Uusimaa
- Children and Adolescents, Oulu University Hospital 1 , 90029 Oulu , Finland
- Research Unit of Clinical Medicine and Medical Research Center, Oulu University Hospital and University of Oulu 2 , 90014 Oulu , Finland
| | - Johannes Kettunen
- Computational Medicine, Center for Life Course Health Research, University of Oulu 3 , 90014 Oulu , Finland
- Department of Public Health and Welfare, Finnish Institute for Health and Welfare 4 , 00271 Helsinki
- Finland 4 , 00271 Helsinki
- Biocenter Oulu, University of Oulu 5 , 90014 Oulu , Finland
| | - Teppo Varilo
- Department of Public Health and Welfare, Finnish Institute for Health and Welfare 4 , 00271 Helsinki
- Finland 4 , 00271 Helsinki
- Department of Medical Genetics, University of Helsinki 6 , 00251 Helsinki , Finland
| | - Irma Järvelä
- Department of Medical Genetics, University of Helsinki 6 , 00251 Helsinki , Finland
| | - Jukka Kallijärvi
- Folkhälsan Institute of Genetics, Folkhälsan Research Center 7 , 00014 Helsinki , Finland
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki 8 , 00014 Helsinki , Finland
| | - Helena Kääriäinen
- Department of Public Health and Welfare, Finnish Institute for Health and Welfare 4 , 00271 Helsinki
- Finland 4 , 00271 Helsinki
| | - Minna Laine
- Department of Pediatric Neurology, Helsinki University Hospital and University of Helsinki 9 , 00029 Helsinki , Finland
| | - Risto Lapatto
- Children's Hospital, University of Helsinki and Helsinki University Central Hospital 10 , 00029 Helsinki , Finland
| | - Päivi Myllynen
- Department of Clinical Chemistry, Cancer and Translational Medicine Research Unit, Medical Research Center, University of Oulu and Northern Finland Laboratory Centre NordLab, Oulu University Hospital 11 , 90029 Oulu , Finland
| | - Harri Niinikoski
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku 12 , 20014 Turku , Finland
- Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku 13 , 20014 Turku , Finland
- Centre for Population Health Research, University of Turku and Turku University Hospital 14 , 20014 Turku , Finland
- Department of Pediatrics, Turku University Hospital 15 , 20014 Turku , Finland
| | - Elisa Rahikkala
- Research Unit of Clinical Medicine and Medical Research Center, Oulu University Hospital and University of Oulu 2 , 90014 Oulu , Finland
- Department of Clinical Genetics, Oulu University Hospital 16 , 90029 Oulu , Finland
| | - Anu Suomalainen
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki 8 , 00014 Helsinki , Finland
- HUS Diagnostics, Helsinki University Hospital 17 , 00014 Helsinki , Finland
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen 18 , D-35392 Giessen , Germany
| | - Henna Tyynismaa
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki 8 , 00014 Helsinki , Finland
- Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki 19 , 00014 Helsinki , Finland
| | - Päivi Vieira
- Children and Adolescents, Oulu University Hospital 1 , 90029 Oulu , Finland
- Research Unit of Clinical Medicine and Medical Research Center, Oulu University Hospital and University of Oulu 2 , 90014 Oulu , Finland
| | - Tomas Zarybnicky
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki 8 , 00014 Helsinki , Finland
- Helsinki Institute of Life Science, University of Helsinki 20 , 00014 Helsinki , Finland
| | - Petra Sipilä
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku 12 , 20014 Turku , Finland
- Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku 21 , 20014 Turku , Finland
| | - Satu Kuure
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki 8 , 00014 Helsinki , Finland
- GM-Unit, Laboratory Animal Center, Helsinki Institute of Life Science, University of Helsinki 22 , 00014 Helsinki , Finland
| | - Reetta Hinttala
- Research Unit of Clinical Medicine and Medical Research Center, Oulu University Hospital and University of Oulu 2 , 90014 Oulu , Finland
- Biocenter Oulu, University of Oulu 5 , 90014 Oulu , Finland
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11
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Pei D, Dalbey RE. Membrane Translocation of Folded Proteins. J Biol Chem 2022; 298:102107. [PMID: 35671825 PMCID: PMC9251779 DOI: 10.1016/j.jbc.2022.102107] [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: 02/05/2022] [Revised: 05/31/2022] [Accepted: 06/01/2022] [Indexed: 12/01/2022] Open
Abstract
An ever-increasing number of proteins have been shown to translocate across various membranes of bacterial as well as eukaryotic cells in their folded states as a part of physiological and/or pathophysiological processes. Herein we provide an overview of the systems/processes that are established or likely to involve the membrane translocation of folded proteins, such as protein export by the twin-arginine translocation (TAT) system in bacteria and chloroplasts, unconventional protein secretion (UPS) and protein import into the peroxisome in eukaryotes, and the cytosolic entry of proteins (e.g., bacterial toxins) and viruses into eukaryotes. We also discuss the various mechanistic models that have previously been proposed for the membrane translocation of folded proteins including pore/channel formation, local membrane disruption, membrane thinning, and transport by membrane vesicles. Finally, we introduce a newly discovered vesicular transport mechanism, vesicle budding and collapse (VBC), and present evidence that VBC may represent a unifying mechanism that drives some (and potentially all) of folded protein translocation processes.
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Affiliation(s)
- Dehua Pei
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210.
| | - Ross E Dalbey
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210.
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12
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Wang Z, Li S, Xu F, Fu J, Sun J, Gan X, Yang C, Mao Z. ncRNAs-mediated high expression of TIMM8A correlates with poor prognosis and act as an oncogene in breast cancer. Cancer Cell Int 2022; 22:177. [PMID: 35501914 PMCID: PMC9063222 DOI: 10.1186/s12935-022-02595-x] [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: 11/14/2021] [Accepted: 04/18/2022] [Indexed: 11/17/2022] Open
Abstract
Background Breast cancer is notorious for its increasing incidence for decades. Ascending evidence has demonstrated that translocase of inner mitochondrial membrane (TIMM) proteins play vital roles in progression of several types of human cancer. However, the biological behaviors and molecular mechanisms of TIMM8A in breast cancer remain not fully illustrated. Methods Pan-cancer analysis was firstly performed for TIMM8A’s expression and prognosis by Oncomine database. Subsequently, TIMM8A-related noncoding RNAs (ncRNAs) were identified by a series of bioinformatics analyses and dual-luciferase reporter assay, including expression analysis, correlation analysis, and survival analysis. Moreover, the effect of TIMM8A on breast cancer proliferation and apoptosis was evaluated in vitro by CCK-8 assays, EdU cell proliferation assays, JC-1 mitochondrial membrane potential detection assays and Western blot assays and the in vivo effect was revealed through a patient-derived xenograft mouse model. Results We found that TIMM8A showed higher expression level in breast cancer and the higher TIMM8A mRNA expression group had a poorer prognosis than the lower TIMM8A group. hsa-circ-0107314/hsa-circ-0021867/hsa-circ-0122013 might be the three most potential upstream circRNAs of hsa-miR-34c-5p/hsa-miR-449a-TIMM8A axis in breast cancer. TIMM8A promotes proliferation of breast cancer cells in vitro and tumor growth in vivo. Conclusion Our results confirmed that ncRNAs-mediated upregulation of TIMM8A correlated with poor prognosis and act as an oncogene in breast cancer. Supplementary Information The online version contains supplementary material available at 10.1186/s12935-022-02595-x.
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Affiliation(s)
- Zhonglin Wang
- Department of General Surgery, The First Affiliated Hospital of Soochow University, Soochow, 215006, China.,Department of Breast Surgery, The Second People's Hospital of Lianyungang, Lianyungang, 222006, China
| | - Shuqin Li
- Department of Breast Surgery, The Affiliated Lianyungang Hospital of Xuzhou Medical University, Lianyungang, 222006, China
| | - Feng Xu
- Jiangsu Breast Disease Center, The First Affiliated Hospital With Nanjing Medical University, Nanjing, 210029, China
| | - Jingyue Fu
- Jiangsu Breast Disease Center, The First Affiliated Hospital With Nanjing Medical University, Nanjing, 210029, China
| | - Jie Sun
- Department of General Surgery, The First Affiliated Hospital of Soochow University, Soochow, 215006, China
| | - XinLi Gan
- Department of General Surgery, The First Affiliated Hospital of Soochow University, Soochow, 215006, China
| | - Chuang Yang
- Jiangsu Breast Disease Center, The First Affiliated Hospital With Nanjing Medical University, Nanjing, 210029, China.
| | - Zhongqi Mao
- Department of General Surgery, The First Affiliated Hospital of Soochow University, Soochow, 215006, China.
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13
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AAA+ proteins: one motor, multiple ways to work. Biochem Soc Trans 2022; 50:895-906. [PMID: 35356966 DOI: 10.1042/bst20200350] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/14/2022] [Accepted: 03/15/2022] [Indexed: 12/15/2022]
Abstract
Numerous ATPases associated with diverse cellular activities (AAA+) proteins form hexameric, ring-shaped complexes that function via ATPase-coupled translocation of substrates across the central channel. Cryo-electron microscopy of AAA+ proteins processing substrate has revealed non-symmetric, staircase-like hexameric structures that indicate a sequential clockwise/2-residue step translocation model for these motors. However, for many of the AAA+ proteins that share similar structural features, their translocation properties have not yet been experimentally determined. In the cases where translocation mechanisms have been determined, a two-residue translocation step-size has not been resolved. In this review, we explore Hsp104, ClpB, ClpA and ClpX as examples to review the experimental methods that have been used to examine, in solution, the translocation mechanisms employed by AAA+ motor proteins. We then ask whether AAA+ motors sharing similar structural features can have different translocation mechanisms. Finally, we discuss whether a single AAA+ motor can adopt multiple translocation mechanisms that are responsive to different challenges imposed by the substrate or the environment. We suggest that AAA+ motors adopt more than one translocation mechanism and are tuned to switch to the most energetically efficient mechanism when constraints are applied.
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14
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Cryo-EM structure of transmembrane AAA+ protease FtsH in the ADP state. Commun Biol 2022; 5:257. [PMID: 35322207 PMCID: PMC8943139 DOI: 10.1038/s42003-022-03213-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 03/01/2022] [Indexed: 11/08/2022] Open
Abstract
AAA+ proteases regulate numerous physiological and cellular processes through tightly regulated proteolytic cleavage of protein substrates driven by ATP hydrolysis. FtsH is the only known family of membrane-anchored AAA+ proteases essential for membrane protein quality control. Although a spiral staircase rotation mechanism for substrate translocation across the FtsH pore has been proposed, the detailed conformational changes among various states have not been clear due to absence of FtsH structures in these states. We report here the cryo-EM structure for Thermotoga maritima FtsH (TmFtsH) in a fully ADP-bound symmetric state. Comparisons of the ADP-state structure with its apo-state and a substrate-engaged yeast YME1 structure show conformational changes in the ATPase domains, rather than the protease domains. A reconstruction of the full-length TmFtsH provides structural insights for the dynamic transmembrane and the periplasmic domains. Our structural analyses expand the understanding of conformational switches between different nucleotide states in ATP hydrolysis by FtsH.
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15
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Vercellino I, Sazanov LA. The assembly, regulation and function of the mitochondrial respiratory chain. Nat Rev Mol Cell Biol 2022; 23:141-161. [PMID: 34621061 DOI: 10.1038/s41580-021-00415-0] [Citation(s) in RCA: 276] [Impact Index Per Article: 138.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2021] [Indexed: 02/08/2023]
Abstract
The mitochondrial oxidative phosphorylation system is central to cellular metabolism. It comprises five enzymatic complexes and two mobile electron carriers that work in a mitochondrial respiratory chain. By coupling the oxidation of reducing equivalents coming into mitochondria to the generation and subsequent dissipation of a proton gradient across the inner mitochondrial membrane, this electron transport chain drives the production of ATP, which is then used as a primary energy carrier in virtually all cellular processes. Minimal perturbations of the respiratory chain activity are linked to diseases; therefore, it is necessary to understand how these complexes are assembled and regulated and how they function. In this Review, we outline the latest assembly models for each individual complex, and we also highlight the recent discoveries indicating that the formation of larger assemblies, known as respiratory supercomplexes, originates from the association of the intermediates of individual complexes. We then discuss how recent cryo-electron microscopy structures have been key to answering open questions on the function of the electron transport chain in mitochondrial respiration and how supercomplexes and other factors, including metabolites, can regulate the activity of the single complexes. When relevant, we discuss how these mechanisms contribute to physiology and outline their deregulation in human diseases.
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Affiliation(s)
- Irene Vercellino
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Klosterneuburg, Austria.
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16
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Chojnacka KJ, Elancheliyan P, Mussulini BHM, Mohanraj K, Callegari S, Gosk A, Banach T, Góral T, Szczepanowska K, Rehling P, Serwa RA, Chacińska A. Ovarian carcinoma immunoreactive antigen-like protein 2 (OCIAD2) is a novel complex III specific assembly factor in mitochondria. Mol Biol Cell 2022; 33:ar29. [PMID: 35080992 PMCID: PMC9250361 DOI: 10.1091/mbc.e21-03-0143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Assembly of the dimeric complex III (CIII2) in the mitochondrial inner membrane is an intricate process in which several accessory proteins are involved as assembly factors. Despite numerous studies, this process has yet to be fully understood. Here we report the identification of human OCIAD2 (ovarian carcinoma immunoreactive antigen–like protein 2) as an assembly factor for CIII2. OCIAD2 was found to be deregulated in several carcinomas and also in some neurogenerative disorders; however, its nonpathological role had not been elucidated. We have shown that OCIAD2 localizes to mitochondria and interacts with electron transport chain (ETC) proteins. Complete loss of OCIAD2 using gene editing in HEK293 cells resulted in abnormal mitochondrial morphology, a substantial decrease of both CIII2 and supercomplex III2+IV, and a reduction in CIII enzymatic activity. Identification of OCIAD2 as a protein required for assembly of functional CIII2 provides a new insight into the biogenesis and architecture of the ETC. Elucidating the mechanism of OCIAD2 action is important both for the understanding of cellular metabolism and for an understanding of its role in malignant transformation.
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Affiliation(s)
| | | | | | - Karthik Mohanraj
- ReMedy International Research Agenda Unit, IMol Polish Academy of Sciences, Warsaw, Poland
| | - Sylvie Callegari
- Ubiquitin Signalling Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Cellular Biochemistry, University Medical Center Göttingen, 37073, Göttingen, Germany
| | - Aleksandra Gosk
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Tomasz Banach
- ReMedy International Research Agenda Unit, IMol Polish Academy of Sciences, Warsaw, Poland
| | - Tomasz Góral
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Karolina Szczepanowska
- ReMedy International Research Agenda Unit, IMol Polish Academy of Sciences, Warsaw, Poland
| | - Peter Rehling
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Goettingen, Germany.,Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Remigiusz Adam Serwa
- ReMedy International Research Agenda Unit, IMol Polish Academy of Sciences, Warsaw, Poland
| | - Agnieszka Chacińska
- ReMedy International Research Agenda Unit, IMol Polish Academy of Sciences, Warsaw, Poland
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17
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Hikmat O, Isohanni P, Keshavan N, Ferla MP, Fassone E, Abbott MA, Bellusci M, Darin N, Dimmock D, Ghezzi D, Houlden H, Invernizzi F, Kamarus Jaman NB, Kurian MA, Morava E, Naess K, Ortigoza-Escobar JD, Parikh S, Pennisi A, Barcia G, Tylleskär KB, Brackman D, Wortmann SB, Taylor JC, Bindoff LA, Fellman V, Rahman S. Expanding the phenotypic spectrum of BCS1L-related mitochondrial disease. Ann Clin Transl Neurol 2021; 8:2155-2165. [PMID: 34662929 PMCID: PMC8607453 DOI: 10.1002/acn3.51470] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 09/29/2021] [Indexed: 01/09/2023] Open
Abstract
Objective To delineate the full phenotypic spectrum of BCS1L‐related disease, provide better understanding of the genotype–phenotype correlations and identify reliable prognostic disease markers. Methods We performed a retrospective multinational cohort study of previously unpublished patients followed in 15 centres from 10 countries. Patients with confirmed biallelic pathogenic BCS1L variants were considered eligible. Clinical, laboratory, neuroimaging and genetic data were analysed. Patients were stratified into different groups based on the age of disease onset, whether homozygous or compound heterozygous for the c.232A>G (p.Ser78Gly) variant, and those with other pathogenic BCS1L variants. Results Thirty‐three patients were included. We found that growth failure, lactic acidosis, tubulopathy, hepatopathy and early death were more frequent in those with disease onset within the first month of life. In those with onset after 1 month, neurological features including movement disorders and seizures were more frequent. Novel phenotypes, particularly involving movement disorder, were identified in this group. The presence of the c.232A>G (p.Ser78Gly) variant was associated with significantly worse survival and exclusively found in those with disease onset within the first month of life, whilst other pathogenic BCS1L variants were more frequent in those with later symptom onset. Interpretation The phenotypic spectrum of BCS1L‐related disease comprises a continuum of clinical features rather than a set of separate syndromic clinical identities. Age of onset defines BCS1L‐related disease clinically and early presentation is associated with poor prognosis. Genotype correlates with phenotype in the presence of the c.232A>G (p.Ser78Gly) variant.
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Affiliation(s)
- Omar Hikmat
- Department of Paediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, 5021, Norway.,Department of Clinical Medicine (K1), University of Bergen, Norway
| | - Pirjo Isohanni
- Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.,Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Nandaki Keshavan
- Mitochondrial Research Group, UCL Great Ormond Street Institute of Child Health, London, UK.,Metabolic Unit, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Matteo P Ferla
- NIHR Oxford Biomedical Research Centre, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Elisa Fassone
- Mitochondrial Research Group, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Mary-Alice Abbott
- Medical Genetics, Department of Pediatrics, UMass Chan Medical School, Baystate, USA
| | - Marcello Bellusci
- Reference Center for Hereditary Metabolic Disorders - MetabERN, '12 de Octubre' University Hospital, Madrid, Spain.,Instituto de Investigación Hospital 12 de Octubre (imas12), Madrid, Spain
| | - Niklas Darin
- Department of Pediatrics, University of Gothenburg, The Queen Silvia Children's Hospital, Gothenburg, Sweden
| | - David Dimmock
- Rady Children's Institute for Genomic Medicine, San Diego, California, USA
| | - Daniele Ghezzi
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, 20126, Italy.,Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Henry Houlden
- Department of Molecular Neuroscience, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - Federica Invernizzi
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, 20126, Italy
| | | | - Manju A Kurian
- Neurogenetics Group, Developmental Neurosciences, Zayed Centre for Research into Rare Diseases in Children, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Eva Morava
- Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota, USA.,Metabolic Center, University Hospitals Leuven, Leuven, 3000, Belgium
| | - Karin Naess
- Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden.,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Juan Darío Ortigoza-Escobar
- Movement Disorders Unit, Institut de Recerca Sant Joan de Déu, CIBERER-ISCIII, Barcelona, Spain.,European Reference Network for Rare Neurological Diseases (ERN-RND), Barcelona, Spain
| | - Sumit Parikh
- Neuroscience Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Alessandra Pennisi
- Federation of Medical Genetics and Reference Center for Mitochondrial Diseases (CARAMMEL), Necker - Enfants Malades Hospital, Paris, France
| | - Giulia Barcia
- Federation of Medical Genetics and Reference Center for Mitochondrial Diseases (CARAMMEL), Necker - Enfants Malades Hospital, Paris, France
| | - Karin B Tylleskär
- Department of Paediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, 5021, Norway
| | - Damien Brackman
- Department of Paediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, 5021, Norway
| | - Saskia B Wortmann
- University Children's Hospital, Paracelsus Medical University, Salzburg, Austria.,Radboud Center for Mitochondrial Medicine (RCMM), Amalia Children's Hospital, Radboudumc, Nijmegen, The Netherlands
| | - Jenny C Taylor
- NIHR Oxford Biomedical Research Centre, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Laurence A Bindoff
- Department of Clinical Medicine (K1), University of Bergen, Norway.,Neuro-SysMed Center of Excellence for Clinical Research in Neurological Diseases, Department of Neurology, Haukeland University Hospital, Bergen, 5021, Norway
| | - Vineta Fellman
- Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.,Folkhälsan Research Center, Helsinki, Finland.,Department of Clinical Sciences, Lund University, Paediatrics, Sweden
| | - Shamima Rahman
- Mitochondrial Research Group, UCL Great Ormond Street Institute of Child Health, London, UK.,Metabolic Unit, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
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18
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Khan YA, White KI, Brunger AT. The AAA+ superfamily: a review of the structural and mechanistic principles of these molecular machines. Crit Rev Biochem Mol Biol 2021; 57:156-187. [PMID: 34632886 DOI: 10.1080/10409238.2021.1979460] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
ATPases associated with diverse cellular activities (AAA+ proteins) are a superfamily of proteins found throughout all domains of life. The hallmark of this family is a conserved AAA+ domain responsible for a diverse range of cellular activities. Typically, AAA+ proteins transduce chemical energy from the hydrolysis of ATP into mechanical energy through conformational change, which can drive a variety of biological processes. AAA+ proteins operate in a variety of cellular contexts with diverse functions including disassembly of SNARE proteins, protein quality control, DNA replication, ribosome assembly, and viral replication. This breadth of function illustrates both the importance of AAA+ proteins in health and disease and emphasizes the importance of understanding conserved mechanisms of chemo-mechanical energy transduction. This review is divided into three major portions. First, the core AAA+ fold is presented. Next, the seven different clades of AAA+ proteins and structural details and reclassification pertaining to proteins in each clade are described. Finally, two well-known AAA+ proteins, NSF and its close relative p97, are reviewed in detail.
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Affiliation(s)
- Yousuf A Khan
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Center for Biomedical Informatics Research, Stanford University, Stanford, CA, USA
| | - K Ian White
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Axel T Brunger
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
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19
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Zanfardino P, Doccini S, Santorelli FM, Petruzzella V. Tackling Dysfunction of Mitochondrial Bioenergetics in the Brain. Int J Mol Sci 2021; 22:8325. [PMID: 34361091 PMCID: PMC8348117 DOI: 10.3390/ijms22158325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/29/2021] [Accepted: 07/30/2021] [Indexed: 12/15/2022] Open
Abstract
Oxidative phosphorylation (OxPhos) is the basic function of mitochondria, although the landscape of mitochondrial functions is continuously growing to include more aspects of cellular homeostasis. Thanks to the application of -omics technologies to the study of the OxPhos system, novel features emerge from the cataloging of novel proteins as mitochondrial thus adding details to the mitochondrial proteome and defining novel metabolic cellular interrelations, especially in the human brain. We focussed on the diversity of bioenergetics demand and different aspects of mitochondrial structure, functions, and dysfunction in the brain. Definition such as 'mitoexome', 'mitoproteome' and 'mitointeractome' have entered the field of 'mitochondrial medicine'. In this context, we reviewed several genetic defects that hamper the last step of aerobic metabolism, mostly involving the nervous tissue as one of the most prominent energy-dependent tissues and, as consequence, as a primary target of mitochondrial dysfunction. The dual genetic origin of the OxPhos complexes is one of the reasons for the complexity of the genotype-phenotype correlation when facing human diseases associated with mitochondrial defects. Such complexity clinically manifests with extremely heterogeneous symptoms, ranging from organ-specific to multisystemic dysfunction with different clinical courses. Finally, we briefly discuss the future directions of the multi-omics study of human brain disorders.
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Affiliation(s)
- Paola Zanfardino
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy;
| | - Stefano Doccini
- IRCCS Fondazione Stella Maris, Calambrone, 56128 Pisa, Italy;
| | | | - Vittoria Petruzzella
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy;
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20
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Brischigliaro M, Frigo E, Corrà S, De Pittà C, Szabò I, Zeviani M, Costa R. Modelling of BCS1L-related human mitochondrial disease in Drosophila melanogaster. J Mol Med (Berl) 2021; 99:1471-1485. [PMID: 34274978 PMCID: PMC8455400 DOI: 10.1007/s00109-021-02110-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 06/04/2021] [Accepted: 06/29/2021] [Indexed: 11/09/2022]
Abstract
Mutations in BCS1L are the most frequent cause of human mitochondrial disease linked to complex III deficiency. Different forms of BCS1L-related diseases and more than 20 pathogenic alleles have been reported to date. Clinical symptoms are highly heterogenous, and multisystem involvement is often present, with liver and brain being the most frequently affected organs. BCS1L encodes a mitochondrial AAA + -family member with essential roles in the latest steps in the biogenesis of mitochondrial respiratory chain complex III. Since Bcs1 has been investigated mostly in yeast and mammals, its function in invertebrates remains largely unknown. Here, we describe the phenotypical, biochemical and metabolic consequences of Bcs1 genetic manipulation in Drosophila melanogaster. Our data demonstrate the fundamental role of Bcs1 in complex III biogenesis in invertebrates and provide novel, reliable models for BCS1L-related human mitochondrial diseases. These models recapitulate several features of the human disorders, collectively pointing to a crucial role of Bcs1 and, in turn, of complex III, in development, organismal fitness and physiology of several tissues.
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Affiliation(s)
| | - Elena Frigo
- Department of Biology, University of Padova, Padova, Italy
| | - Samantha Corrà
- Department of Biology, University of Padova, Padova, Italy
| | | | - Ildikò Szabò
- Department of Biology, University of Padova, Padova, Italy
| | - Massimo Zeviani
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Rodolfo Costa
- Department of Biology, University of Padova, Padova, Italy. .,Italian National Research Council (CNR) Institute of Neuroscience, Padova, Italy.
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21
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Needs HI, Protasoni M, Henley JM, Prudent J, Collinson I, Pereira GC. Interplay between Mitochondrial Protein Import and Respiratory Complexes Assembly in Neuronal Health and Degeneration. Life (Basel) 2021; 11:432. [PMID: 34064758 PMCID: PMC8151517 DOI: 10.3390/life11050432] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/27/2021] [Accepted: 05/02/2021] [Indexed: 12/14/2022] Open
Abstract
The fact that >99% of mitochondrial proteins are encoded by the nuclear genome and synthesised in the cytosol renders the process of mitochondrial protein import fundamental for normal organelle physiology. In addition to this, the nuclear genome comprises most of the proteins required for respiratory complex assembly and function. This means that without fully functional protein import, mitochondrial respiration will be defective, and the major cellular ATP source depleted. When mitochondrial protein import is impaired, a number of stress response pathways are activated in order to overcome the dysfunction and restore mitochondrial and cellular proteostasis. However, prolonged impaired mitochondrial protein import and subsequent defective respiratory chain function contributes to a number of diseases including primary mitochondrial diseases and neurodegeneration. This review focuses on how the processes of mitochondrial protein translocation and respiratory complex assembly and function are interlinked, how they are regulated, and their importance in health and disease.
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Affiliation(s)
- Hope I. Needs
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
| | - Margherita Protasoni
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
| | - Jeremy M. Henley
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
- Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Julien Prudent
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
| | - Gonçalo C. Pereira
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
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22
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The Pseudomonas aeruginosa substrate-binding protein Ttg2D functions as a general glycerophospholipid transporter across the periplasm. Commun Biol 2021; 4:448. [PMID: 33837253 PMCID: PMC8035174 DOI: 10.1038/s42003-021-01968-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 03/04/2021] [Indexed: 11/19/2022] Open
Abstract
In Pseudomonas aeruginosa, Ttg2D is the soluble periplasmic phospholipid-binding component of an ABC transport system thought to be involved in maintaining the asymmetry of the outer membrane. Here we use the crystallographic structure of Ttg2D at 2.5 Å resolution to reveal that this protein can accommodate four acyl chains. Analysis of the available structures of Ttg2D orthologs shows that they conform a new substrate-binding-protein structural cluster. Native and denaturing mass spectrometry experiments confirm that Ttg2D, produced both heterologously and homologously and isolated from the periplasm, can carry two diacyl glycerophospholipids as well as one cardiolipin. Binding is notably promiscuous, allowing the transport of various molecular species. In vitro binding assays coupled to native mass spectrometry show that binding of cardiolipin is spontaneous. Gene knockout experiments in P. aeruginosa multidrug-resistant strains reveal that the Ttg2 system is involved in low-level intrinsic resistance against certain antibiotics that use a lipid-mediated pathway to permeate through membranes. Yero et al. elucidate the function of Ttg2D, a Pseudomonas aeruginosa periplasmic protein, in maintaining phospholipid asymmetry between the outer and inner membrane. Gram negative bacteria have inner and outer membranes that differ in phospholipd composition. Using X-ray crystallography and mass spectrometry, the authors show that Ttg2D can carry two diacyl glycerophospholipids or a cardiolipin. The authors also identify a role for Ttg2D in resistance against antibiotics that use a lipid-mediated pathway into the cell.
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23
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Blackout in the powerhouse: clinical phenotypes associated with defects in the assembly of OXPHOS complexes and the mitoribosome. Biochem J 2021; 477:4085-4132. [PMID: 33151299 PMCID: PMC7657662 DOI: 10.1042/bcj20190767] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 09/29/2020] [Accepted: 10/05/2020] [Indexed: 12/26/2022]
Abstract
Mitochondria produce the bulk of the energy used by almost all eukaryotic cells through oxidative phosphorylation (OXPHOS) which occurs on the four complexes of the respiratory chain and the F1–F0 ATPase. Mitochondrial diseases are a heterogenous group of conditions affecting OXPHOS, either directly through mutation of genes encoding subunits of OXPHOS complexes, or indirectly through mutations in genes encoding proteins supporting this process. These include proteins that promote assembly of the OXPHOS complexes, the post-translational modification of subunits, insertion of cofactors or indeed subunit synthesis. The latter is important for all 13 of the proteins encoded by human mitochondrial DNA, which are synthesised on mitochondrial ribosomes. Together the five OXPHOS complexes and the mitochondrial ribosome are comprised of more than 160 subunits and many more proteins support their biogenesis. Mutations in both nuclear and mitochondrial genes encoding these proteins have been reported to cause mitochondrial disease, many leading to defective complex assembly with the severity of the assembly defect reflecting the severity of the disease. This review aims to act as an interface between the clinical and basic research underpinning our knowledge of OXPHOS complex and ribosome assembly, and the dysfunction of this process in mitochondrial disease.
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Tifoun N, De las Heras JM, Guillaume A, Bouleau S, Mignotte B, Le Floch N. Insights into the Roles of the Sideroflexins/SLC56 Family in Iron Homeostasis and Iron-Sulfur Biogenesis. Biomedicines 2021; 9:103. [PMID: 33494450 PMCID: PMC7911444 DOI: 10.3390/biomedicines9020103] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 01/25/2023] Open
Abstract
Sideroflexins (SLC56 family) are highly conserved multi-spanning transmembrane proteins inserted in the inner mitochondrial membrane in eukaryotes. Few data are available on their molecular function, but since their first description, they were thought to be metabolite transporters probably required for iron utilization inside the mitochondrion. Such as numerous mitochondrial transporters, sideroflexins remain poorly characterized. The prototypic member SFXN1 has been recently identified as the previously unknown mitochondrial transporter of serine. Nevertheless, pending questions on the molecular function of sideroflexins remain unsolved, especially their link with iron metabolism. Here, we review the current knowledge on sideroflexins, their presumed mitochondrial functions and the sparse-but growing-evidence linking sideroflexins to iron homeostasis and iron-sulfur cluster biogenesis. Since an imbalance in iron homeostasis can be detrimental at the cellular and organismal levels, we also investigate the relationship between sideroflexins, iron and physiological disorders. Investigating Sideroflexins' functions constitutes an emerging research field of great interest and will certainly lead to the main discoveries of mitochondrial physio-pathology.
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Affiliation(s)
- Nesrine Tifoun
- LGBC, UVSQ, Université Paris-Saclay, 78000 Versailles, France; (N.T.); (J.M.D.l.H.); (A.G.); (S.B.); (B.M.)
| | - José M. De las Heras
- LGBC, UVSQ, Université Paris-Saclay, 78000 Versailles, France; (N.T.); (J.M.D.l.H.); (A.G.); (S.B.); (B.M.)
| | - Arnaud Guillaume
- LGBC, UVSQ, Université Paris-Saclay, 78000 Versailles, France; (N.T.); (J.M.D.l.H.); (A.G.); (S.B.); (B.M.)
| | - Sylvina Bouleau
- LGBC, UVSQ, Université Paris-Saclay, 78000 Versailles, France; (N.T.); (J.M.D.l.H.); (A.G.); (S.B.); (B.M.)
| | - Bernard Mignotte
- LGBC, UVSQ, Université Paris-Saclay, 78000 Versailles, France; (N.T.); (J.M.D.l.H.); (A.G.); (S.B.); (B.M.)
- École Pratique des Hautes Études, PSL University, 75014 Paris, France
| | - Nathalie Le Floch
- LGBC, UVSQ, Université Paris-Saclay, 78000 Versailles, France; (N.T.); (J.M.D.l.H.); (A.G.); (S.B.); (B.M.)
- GCGP Department, IUT de Vélizy/Rambouillet, UVSQ, Université Paris-Saclay, 78120 Rambouillet, France
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Mitochondrial Structure and Bioenergetics in Normal and Disease Conditions. Int J Mol Sci 2021; 22:ijms22020586. [PMID: 33435522 PMCID: PMC7827222 DOI: 10.3390/ijms22020586] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/03/2021] [Accepted: 01/04/2021] [Indexed: 02/06/2023] Open
Abstract
Mitochondria are ubiquitous intracellular organelles found in almost all eukaryotes and involved in various aspects of cellular life, with a primary role in energy production. The interest in this organelle has grown stronger with the discovery of their link to various pathologies, including cancer, aging and neurodegenerative diseases. Indeed, dysfunctional mitochondria cannot provide the required energy to tissues with a high-energy demand, such as heart, brain and muscles, leading to a large spectrum of clinical phenotypes. Mitochondrial defects are at the origin of a group of clinically heterogeneous pathologies, called mitochondrial diseases, with an incidence of 1 in 5000 live births. Primary mitochondrial diseases are associated with genetic mutations both in nuclear and mitochondrial DNA (mtDNA), affecting genes involved in every aspect of the organelle function. As a consequence, it is difficult to find a common cause for mitochondrial diseases and, subsequently, to offer a precise clinical definition of the pathology. Moreover, the complexity of this condition makes it challenging to identify possible therapies or drug targets.
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M. Iyer L, Anantharaman V, Krishnan A, Burroughs AM, Aravind L. Jumbo Phages: A Comparative Genomic Overview of Core Functions and Adaptions for Biological Conflicts. Viruses 2021; 13:v13010063. [PMID: 33466489 PMCID: PMC7824862 DOI: 10.3390/v13010063] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/31/2020] [Accepted: 12/31/2020] [Indexed: 02/07/2023] Open
Abstract
Jumbo phages have attracted much attention by virtue of their extraordinary genome size and unusual aspects of biology. By performing a comparative genomics analysis of 224 jumbo phages, we suggest an objective inclusion criterion based on genome size distributions and present a synthetic overview of their manifold adaptations across major biological systems. By means of clustering and principal component analysis of the phyletic patterns of conserved genes, all known jumbo phages can be classified into three higher-order groups, which include both myoviral and siphoviral morphologies indicating multiple independent origins from smaller predecessors. Our study uncovers several under-appreciated or unreported aspects of the DNA replication, recombination, transcription and virion maturation systems. Leveraging sensitive sequence analysis methods, we identify novel protein-modifying enzymes that might help hijack the host-machinery. Focusing on host–virus conflicts, we detect strategies used to counter different wings of the bacterial immune system, such as cyclic nucleotide- and NAD+-dependent effector-activation, and prevention of superinfection during pseudolysogeny. We reconstruct the RNA-repair systems of jumbo phages that counter the consequences of RNA-targeting host effectors. These findings also suggest that several jumbo phage proteins provide a snapshot of the systems found in ancient replicons preceding the last universal ancestor of cellular life.
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Affiliation(s)
- Lakshminarayan M. Iyer
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA; (L.M.I.); (V.A.); (A.M.B.)
| | - Vivek Anantharaman
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA; (L.M.I.); (V.A.); (A.M.B.)
| | - Arunkumar Krishnan
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Berhampur, Odisha 760010, India;
| | - A. Maxwell Burroughs
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA; (L.M.I.); (V.A.); (A.M.B.)
| | - L. Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA; (L.M.I.); (V.A.); (A.M.B.)
- Correspondence:
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Fernandez-Vizarra E, Zeviani M. Mitochondrial disorders of the OXPHOS system. FEBS Lett 2020; 595:1062-1106. [PMID: 33159691 DOI: 10.1002/1873-3468.13995] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/21/2020] [Accepted: 11/01/2020] [Indexed: 12/13/2022]
Abstract
Mitochondrial disorders are among the most frequent inborn errors of metabolism, their primary cause being the dysfunction of the oxidative phosphorylation system (OXPHOS). OXPHOS is composed of the electron transport chain (ETC), formed by four multimeric enzymes and two mobile electron carriers, plus an ATP synthase [also called complex V (cV)]. The ETC performs the redox reactions involved in cellular respiration while generating the proton motive force used by cV to synthesize ATP. OXPHOS biogenesis involves multiple steps, starting from the expression of genes encoded in physically separated genomes, namely the mitochondrial and nuclear DNA, to the coordinated assembly of components and cofactors building each individual complex and eventually the supercomplexes. The genetic cause underlying around half of the diagnosed mitochondrial disease cases is currently known. Many of these cases result from pathogenic variants in genes encoding structural subunits or additional factors directly involved in the assembly of the ETC complexes. Here, we review the historical and most recent findings concerning the clinical phenotypes and the molecular pathological mechanisms underlying this particular group of disorders.
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Affiliation(s)
- Erika Fernandez-Vizarra
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, UK
| | - Massimo Zeviani
- Venetian Institute of Molecular Medicine, Padova, Italy.,Department of Neurosciences, University of Padova, Italy
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Xia D. Structural snapshots of the cellular folded protein translocation machinery Bcs1. FEBS J 2020; 288:2870-2883. [PMID: 32979284 PMCID: PMC7994207 DOI: 10.1111/febs.15576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/05/2020] [Accepted: 09/22/2020] [Indexed: 11/29/2022]
Abstract
Proteins destined to various intra‐ and extra‐cellular locations must traverse membranes most frequently in an unfolded form. When the proteins being translocated need to remain in a folded state, specialized cellular transport machinery is used. One such machine is the membrane‐bound AAA protein Bcs1 (Bcs1), which assists the iron‐sulfur protein, an essential subunit of the respiratory Complex III, across the mitochondrial inner membrane. Recent structure determinations of mouse and yeast Bcs1 in three different nucleotide states reveal its homo‐heptameric association and at least two dramatically different conformations. The apo and ADP‐bound structures are similar, both containing a large substrate‐binding cavity accessible to the mitochondrial matrix space, which contracts by concerted motion of the ATPase domains upon ATP binding, suggesting that bound substrate could then be pushed across the membrane. ATP hydrolysis drives substrate release and resets Bcs1 conformation back to the apo/ADP form. These structures shed new light on the mechanism of folded protein translocation across a membrane, provide better understanding on the assembly process of the respiratory Complex III, and correlate clinical presentations of disease‐associated mutations with their locations in the 3D structure.
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Affiliation(s)
- Di Xia
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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