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Nussberger S, Ghosh R, Wang S. New insights into the structure and dynamics of the TOM complex in mitochondria. Biochem Soc Trans 2024; 52:911-922. [PMID: 38629718 PMCID: PMC11088910 DOI: 10.1042/bst20231236] [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: 02/13/2024] [Revised: 03/21/2024] [Accepted: 04/03/2024] [Indexed: 04/25/2024]
Abstract
To date, there is no general physical model of the mechanism by which unfolded polypeptide chains with different properties are imported into the mitochondria. At the molecular level, it is still unclear how transit polypeptides approach, are captured by the protein translocation machinery in the outer mitochondrial membrane, and how they subsequently cross the entropic barrier of a protein translocation pore to enter the intermembrane space. This deficiency has been due to the lack of detailed structural and dynamic information about the membrane pores. In this review, we focus on the recently determined sub-nanometer cryo-EM structures and our current knowledge of the dynamics of the mitochondrial two-pore outer membrane protein translocation machinery (TOM core complex), which provide a starting point for addressing the above questions. Of particular interest are recent discoveries showing that the TOM core complex can act as a mechanosensor, where the pores close as a result of interaction with membrane-proximal structures. We highlight unusual and new correlations between the structural elements of the TOM complexes and their dynamic behavior in the membrane environment.
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Affiliation(s)
- Stephan Nussberger
- Department of Biophysics, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Stuttgart, Germany
| | - Robin Ghosh
- Department of Bioenergetics, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Stuttgart, Germany
| | - Shuo Wang
- Department of Biophysics, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Stuttgart, Germany
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2
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Busto JV, Ganesan I, Mathar H, Steiert C, Schneider EF, Straub SP, Ellenrieder L, Song J, Stiller SB, Lübbert P, Chatterjee R, Elsaesser J, Melchionda L, Schug C, den Brave F, Schulte U, Klecker T, Kraft C, Fakler B, Becker T, Wiedemann N. Role of the small protein Mco6 in the mitochondrial sorting and assembly machinery. Cell Rep 2024; 43:113805. [PMID: 38377000 DOI: 10.1016/j.celrep.2024.113805] [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: 08/24/2023] [Revised: 12/22/2023] [Accepted: 01/31/2024] [Indexed: 02/22/2024] Open
Abstract
The majority of mitochondrial precursor proteins are imported through the Tom40 β-barrel channel of the translocase of the outer membrane (TOM). The sorting and assembly machinery (SAM) is essential for β-barrel membrane protein insertion into the outer membrane and thus required for the assembly of the TOM complex. Here, we demonstrate that the α-helical outer membrane protein Mco6 co-assembles with the mitochondrial distribution and morphology protein Mdm10 as part of the SAM machinery. MCO6 and MDM10 display a negative genetic interaction, and a mco6-mdm10 yeast double mutant displays reduced levels of the TOM complex. Cells lacking Mco6 affect the levels of Mdm10 and show assembly defects of the TOM complex. Thus, this work uncovers a role of the SAMMco6 complex for the biogenesis of the mitochondrial outer membrane.
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Affiliation(s)
- Jon V Busto
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Iniyan Ganesan
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Hannah Mathar
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Conny Steiert
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Eva F Schneider
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sebastian P Straub
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Lars Ellenrieder
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jiyao Song
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Sebastian B Stiller
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Philipp Lübbert
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ritwika Chatterjee
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Jana Elsaesser
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Laura Melchionda
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christina Schug
- Institute of Cell Biology, University of Bayreuth, Bayreuth, Germany
| | - Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Uwe Schulte
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Till Klecker
- Institute of Cell Biology, University of Bayreuth, Bayreuth, Germany
| | - Claudine Kraft
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany; Center for Basics in NeuroModulation, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany.
| | - Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany.
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3
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Guo L, Liu JJ, Long SY, Wang PY, Li S, Wang JL, Wei XF, Li J, Lei L, Huang AL, Hu JL. TIM22 and TIM29 inhibit HBV replication by up-regulating SRSF1 expression. J Med Virol 2024; 96:e29439. [PMID: 38294104 DOI: 10.1002/jmv.29439] [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: 09/13/2023] [Revised: 01/10/2024] [Accepted: 01/19/2024] [Indexed: 02/01/2024]
Abstract
Hepatitis B virus (HBV) infection is a serious global health problem. After the viruses infect the human body, the host can respond to the virus infection by coordinating various cellular responses, in which mitochondria play an important role. Evidence has shown that mitochondrial proteins are involved in host antiviral responses. In this study, we found that the overexpression of TIM22 and TIM29, the members of the inner membrane translocase TIM22 complex, significantly reduced the level of intracellular HBV DNA and RNA and secreted HBV surface antigens and E antigen. The effects of TIM22 and TIM29 on HBV replication and transcription is attributed to the reduction of core promoter activity mediated by the increased expression of SRSF1 which acts as a suppressor of HBV replication. This study provides new evidence for the critical role of mitochondria in the resistance of HBV infection and new targets for the development of treatment against HBV infection.
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Affiliation(s)
- Lin Guo
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Chongqing, China
- Department of Clinical Laboratory, Chengdu Seventh People's Hospital (Affiliated Cancer Hospital of Chengdu Medical College), Chengdu, China
| | - Jia-Jun Liu
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Chongqing, China
| | - Shao-Yuan Long
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Chongqing, China
| | - Pei-Yun Wang
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Chongqing, China
| | - Shan Li
- Department of Clinical Laboratory, the Sixth Hospital of Chengdu, Chengdu, China
| | - Jin-Lan Wang
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Chongqing, China
| | - Xia-Fei Wei
- Institute for Hepatology, National Clinical Research Center for Infectious Disease, Shenzhen Third People's Hospital, Southern University of Science and Technology, Shenzhen, China
| | - Jie Li
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Chongqing, China
| | - Ling Lei
- Chongqing Health Center for Women and Children, Women and Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Ai-Long Huang
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Chongqing, China
| | - Jie-Li Hu
- Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Chongqing, China
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4
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Lionaki E, Gkikas I, Tavernarakis N. Mitochondrial protein import machinery conveys stress signals to the cytosol and beyond. Bioessays 2023; 45:e2200160. [PMID: 36709422 DOI: 10.1002/bies.202200160] [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: 08/16/2022] [Revised: 12/14/2022] [Accepted: 01/02/2023] [Indexed: 01/30/2023]
Abstract
Mitochondria hold diverse and pivotal roles in fundamental processes that govern cell survival, differentiation, and death, in addition to organismal growth, maintenance, and aging. The mitochondrial protein import system is a major contributor to mitochondrial biogenesis and lies at the crossroads between mitochondrial and cellular homeostasis. Recent findings highlight the mitochondrial protein import system as a signaling hub, receiving inputs from other cellular compartments and adjusting its function accordingly. Impairment of protein import, in a physiological, or disease context, elicits adaptive responses inside and outside mitochondria. In this review, we discuss recent developments, relevant to the mechanisms of mitochondrial protein import regulation, with a particular focus on quality control, proteostatic and metabolic cellular responses, triggered upon impairment of mitochondrial protein import.
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Affiliation(s)
- Eirini Lionaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Crete, Greece
| | - Ilias Gkikas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Crete, Greece
- Department of Biology, School of Sciences and Engineering, University of Crete, Heraklion, Crete, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Crete, Greece
- Department of Basic Sciences, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece
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5
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Guna A, Stevens TA, Inglis AJ, Replogle JM, Esantsi TK, Muthukumar G, Shaffer KCL, Wang ML, Pogson AN, Jones JJ, Lomenick B, Chou TF, Weissman JS, Voorhees RM. MTCH2 is a mitochondrial outer membrane protein insertase. Science 2022; 378:317-322. [PMID: 36264797 PMCID: PMC9674023 DOI: 10.1126/science.add1856] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In the mitochondrial outer membrane, α-helical transmembrane proteins play critical roles in cytoplasmic-mitochondrial communication. Using genome-wide CRISPR screens, we identified MTCH2, and its paralog MTCH1, and showed that it is required for insertion of biophysically diverse tail-anchored (TA), signal-anchored, and multipass proteins, but not outer membrane β-barrel proteins. Purified MTCH2 was sufficient to mediate insertion into reconstituted proteoliposomes. Functional and mutational studies suggested that MTCH2 has evolved from a solute carrier transporter. MTCH2 uses membrane-embedded hydrophilic residues to function as a gatekeeper for the outer membrane, controlling mislocalization of TAs into the endoplasmic reticulum and modulating the sensitivity of leukemia cells to apoptosis. Our identification of MTCH2 as an insertase provided a mechanistic explanation for the diverse phenotypes and disease states associated with MTCH2 dysfunction. We showed that MTCH2 was both necessary and sufficient for insertion of diverse α-helical proteins into the mitochondrial outer membrane, and was the defining member of a family of insertases that have co-opted the SLC25 transporter fold.
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Affiliation(s)
- Alina Guna
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Taylor A Stevens
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Alison J Inglis
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Joseph M Replogle
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Medical Scientist Training Program, University of California, San Francisco, San Francisco, CA 94158, USA.,Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Theodore K Esantsi
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Gayathri Muthukumar
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Kelly C L Shaffer
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Maxine L Wang
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Angela N Pogson
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Jeff J Jones
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Brett Lomenick
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Tsui-Fen Chou
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Jonathan S Weissman
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Rebecca M Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
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6
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Wang L, Yang Z, He X, Pu S, Yang C, Wu Q, Zhou Z, Cen X, Zhao H. Mitochondrial protein dysfunction in pathogenesis of neurological diseases. Front Mol Neurosci 2022; 15:974480. [PMID: 36157077 PMCID: PMC9489860 DOI: 10.3389/fnmol.2022.974480] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 08/08/2022] [Indexed: 11/21/2022] Open
Abstract
Mitochondria are essential organelles for neuronal function and cell survival. Besides the well-known bioenergetics, additional mitochondrial roles in calcium signaling, lipid biogenesis, regulation of reactive oxygen species, and apoptosis are pivotal in diverse cellular processes. The mitochondrial proteome encompasses about 1,500 proteins encoded by both the nuclear DNA and the maternally inherited mitochondrial DNA. Mutations in the nuclear or mitochondrial genome, or combinations of both, can result in mitochondrial protein deficiencies and mitochondrial malfunction. Therefore, mitochondrial quality control by proteins involved in various surveillance mechanisms is critical for neuronal integrity and viability. Abnormal proteins involved in mitochondrial bioenergetics, dynamics, mitophagy, import machinery, ion channels, and mitochondrial DNA maintenance have been linked to the pathogenesis of a number of neurological diseases. The goal of this review is to give an overview of these pathways and to summarize the interconnections between mitochondrial protein dysfunction and neurological diseases.
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Affiliation(s)
- Liang Wang
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu, China
| | - Ziyun Yang
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu, China
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Xiumei He
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Shiming Pu
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Cheng Yang
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Qiong Wu
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Zuping Zhou
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
| | - Xiaobo Cen
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital of Sichuan University, Chengdu, China
| | - Hongxia Zhao
- School of Life Sciences, Guangxi Normal University, Guilin, China
- Guangxi Universities, Key Laboratory of Stem Cell and Biopharmaceutical Technology, Guangxi Normal University, Guilin, China
- Research Center for Biomedical Sciences, Guangxi Normal University, Guilin, China
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
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7
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Chen Y, Qin Q, Zhao W, Luo D, Huang Y, Liu G, Kuang Y, Cao Y, Chen Y. Carnosol Reduced Pathogenic Protein Aggregation and Cognitive Impairment in Neurodegenerative Diseases Models via Improving Proteostasis and Ameliorating Mitochondrial Disorders. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:10490-10505. [PMID: 35973126 DOI: 10.1021/acs.jafc.2c02665] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Neurodegenerative diseases (NDs) such as Alzheimer's disease, Parkinson's disease, and Huntington's disease are incurable diseases with progressive loss of neural function and require urgent development of effective treatments. Carnosol (CL) reportedly has a pharmacological effect in the prevention of dementia. Nevertheless, the mechanisms of CL's neuroprotection are not entirely clear. The present study aimed to investigate the effects and mechanisms of CL-mediated neuroprotection through Caenorhabditis elegans models. First, CL restored ND protein homeostasis via inhibiting the IIS pathway, regulating MAPK signaling, and simultaneously activating molecular chaperone, thus inhibiting amyloid peptide (Aβ), polyglutamine (polyQ), and α-synuclein (α-syn) deposition and reducing protein disruption-mediated behavioral and cognitive impairments as well as neuronal damages. Furthermore, CL could repair mitochondrial structural damage via improving the mitochondrial membrane protein function and mitochondrial structural homeostasis and improve mitochondrial functional defects via increasing adenosine triphosphate contents, mitochondrial membrane potential, and reactive oxygen species levels, suggesting that CL could improve the ubiquitous mitochondrial defects in NDs. More importantly, we found that CL activated mitochondrial kinetic homeostasis related genes to improve the mitochondrial homeostasis and dysfunction in NDs. Meanwhile, CL up-regulated unc-17, cho-1, and cha-1 genes to alleviate Aβ-mediated cholinergic neurological disorders and activated Notch signaling and the Wnt pathway to diminish polyQ- and α-syn-induced ASH neurons as well as dopaminergic neuron damages. Overall, our study clarified the beneficial anti-ND neuroprotective effects of CL in different aspects and provided new insights into developing CL into products with preventive and therapeutic effects on NDs.
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Affiliation(s)
- Yun Chen
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, 510640 Guangdong, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510640 Guangdong, China
| | - Qiao Qin
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, 510640 Guangdong, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510640 Guangdong, China
| | - Wen Zhao
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, 510640 Guangdong, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510640 Guangdong, China
| | - Danxia Luo
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, 510640 Guangdong, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510640 Guangdong, China
| | - Yingyin Huang
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, 510640 Guangdong, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510640 Guangdong, China
| | - Guo Liu
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, 510640 Guangdong, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510640 Guangdong, China
| | - Yong Kuang
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, 510640 Guangdong, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510640 Guangdong, China
| | - Yong Cao
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, 510640 Guangdong, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510640 Guangdong, China
| | - Yunjiao Chen
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, 510640 Guangdong, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510640 Guangdong, China
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8
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Drwesh L, Heim B, Graf M, Kehr L, Hansen-Palmus L, Franz-Wachtel M, Macek B, Kalbacher H, Buchner J, Rapaport D. A network of cytosolic (co)chaperones promotes the biogenesis of mitochondrial signal-anchored outer membrane proteins. eLife 2022; 11:77706. [PMID: 35876647 PMCID: PMC9355564 DOI: 10.7554/elife.77706] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 07/25/2022] [Indexed: 11/21/2022] Open
Abstract
Signal-anchored (SA) proteins are anchored into the mitochondrial outer membrane (OM) via a single transmembrane segment at their N-terminus while the bulk of the proteins is facing the cytosol. These proteins are encoded by nuclear DNA, translated on cytosolic ribosomes, and are then targeted to the organelle and inserted into its OM by import factors. Recently, research on the insertion mechanisms of these proteins into the mitochondrial OM have gained a lot of attention. In contrast, the early cytosolic steps of their biogenesis are unresolved. Using various proteins from this category and a broad set of in vivo, in organello, and in vitro assays, we reconstituted the early steps of their biogenesis. We identified a subset of molecular (co)chaperones that interact with newly synthesized SA proteins, namely, Hsp70 and Hsp90 chaperones and co-chaperones from the Hsp40 family like Ydj1 and Sis1. These interactions were mediated by the hydrophobic transmembrane segments of the SA proteins. We further demonstrate that interfering with these interactions inhibits the biogenesis of SA proteins to a various extent. Finally, we could demonstrate direct interaction of peptides corresponding to the transmembrane segments of SA proteins with the (co)chaperones and reconstitute in vitro the transfer of such peptides from the Hsp70 chaperone to the mitochondrial Tom70 receptor. Collectively, this study unravels an array of cytosolic chaperones and mitochondrial import factors that facilitates the targeting and membrane integration of mitochondrial SA proteins.
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Affiliation(s)
- Layla Drwesh
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
| | - Benjamin Heim
- Department of Chemistry, Technische Universität München, Munich, Germany
| | - Max Graf
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
| | - Linda Kehr
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
| | - Lea Hansen-Palmus
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
| | - Mirita Franz-Wachtel
- Proteome Center Tübingen, Interfaculty Institute for Cell Biology,, University of Tübingen, Tübingen, Germany
| | - Boris Macek
- Proteome Center Tübingen, Interfaculty Institute for Cell Biology,, University of Tübingen, Tübingen, Germany
| | - Hubert Kalbacher
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
| | - Johannes Buchner
- Department of Chemistry, Technische Universität München, Garching, Germany
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, Tuebingen, Germany
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9
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Diederichs KA, Pitt AS, Varughese JT, Hackel TN, Buchanan SK, Shaw PL. Mechanistic insights into fungal mitochondrial outer membrane protein biogenesis. Curr Opin Struct Biol 2022; 74:102383. [DOI: 10.1016/j.sbi.2022.102383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 02/11/2022] [Accepted: 03/16/2022] [Indexed: 11/30/2022]
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10
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Hoffmann JJ, Becker T. Crosstalk between Mitochondrial Protein Import and Lipids. Int J Mol Sci 2022; 23:ijms23095274. [PMID: 35563660 PMCID: PMC9101885 DOI: 10.3390/ijms23095274] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/29/2022] [Accepted: 05/05/2022] [Indexed: 12/10/2022] Open
Abstract
Mitochondria import about 1000 precursor proteins from the cytosol. The translocase of the outer membrane (TOM complex) forms the major entry site for precursor proteins. Subsequently, membrane-bound protein translocases sort the precursor proteins into the outer and inner membrane, the intermembrane space, and the matrix. The phospholipid composition of mitochondrial membranes is critical for protein import. Structural and biochemical data revealed that phospholipids affect the stability and activity of mitochondrial protein translocases. Integration of proteins into the target membrane involves rearrangement of phospholipids and distortion of the lipid bilayer. Phospholipids are present in the interface between subunits of protein translocases and affect the dynamic coupling of partner proteins. Phospholipids are required for full activity of the respiratory chain to generate membrane potential, which in turn drives protein import across and into the inner membrane. Finally, outer membrane protein translocases are closely linked to organellar contact sites that mediate lipid trafficking. Altogether, intensive crosstalk between mitochondrial protein import and lipid biogenesis controls mitochondrial biogenesis.
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11
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Sayyed UMH, Mahalakshmi R. Mitochondrial protein translocation machinery: From TOM structural biogenesis to functional regulation. J Biol Chem 2022; 298:101870. [PMID: 35346689 PMCID: PMC9052162 DOI: 10.1016/j.jbc.2022.101870] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 03/13/2022] [Accepted: 03/14/2022] [Indexed: 01/15/2023] Open
Abstract
The human mitochondrial outer membrane is biophysically unique as it is the only membrane possessing transmembrane β-barrel proteins (mitochondrial outer membrane proteins, mOMPs) in the cell. The most vital of the three mOMPs is the core protein of the translocase of the outer mitochondrial membrane (TOM) complex. Identified first as MOM38 in Neurospora in 1990, the structure of Tom40, the core 19-stranded β-barrel translocation channel, was solved in 2017, after nearly three decades. Remarkably, the past four years have witnessed an exponential increase in structural and functional studies of yeast and human TOM complexes. In addition to being conserved across all eukaryotes, the TOM complex is the sole ATP-independent import machinery for nearly all of the ∼1000 to 1500 known mitochondrial proteins. Recent cryo-EM structures have provided detailed insight into both possible assembly mechanisms of the TOM core complex and organizational dynamics of the import machinery and now reveal novel regulatory interplay with other mOMPs. Functional characterization of the TOM complex using biochemical and structural approaches has also revealed mechanisms for substrate recognition and at least five defined import pathways for precursor proteins. In this review, we discuss the discovery, recently solved structures, molecular function, and regulation of the TOM complex and its constituents, along with the implications these advances have for alleviating human diseases.
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Affiliation(s)
- Ulfat Mohd Hanif Sayyed
- Molecular Biophysics Laboratory, Indian Institute of Science Education and Research, Bhopal, India
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12
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Eldeeb MA, Thomas RA, Ragheb MA, Fallahi A, Fon EA. Mitochondrial quality control in health and in Parkinson's disease. Physiol Rev 2022; 102:1721-1755. [PMID: 35466694 DOI: 10.1152/physrev.00041.2021] [Citation(s) in RCA: 79] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
As a central hub for cellular metabolism and intracellular signalling, the mitochondrion is a pivotal organelle, dysfunction of which has been linked to several human diseases including neurodegenerative disorders, and in particular Parkinson's disease. An inherent challenge that mitochondria face is the continuous exposure to diverse stresses which increase their likelihood of dysregulation. In response, eukaryotic cells have evolved sophisticated quality control mechanisms to monitor, identify, repair and/or eliminate abnormal or misfolded proteins within the mitochondrion and/or the dysfunctional mitochondrion itself. Chaperones identify unstable or otherwise abnormal conformations in mitochondrial proteins and can promote their refolding to recover their correct conformation and stability. However, if repair is not possible, the abnormal protein is selectively degraded to prevent potentially damaging interactions with other proteins or its oligomerization into toxic multimeric complexes. The autophagic-lysosomal system and the ubiquitin-proteasome system mediate the selective and targeted degradation of such abnormal or misfolded protein species. Mitophagy (a specific kind of autophagy) mediates the selective elimination of dysfunctional mitochondria, in order to prevent the deleterious effects the dysfunctional organelles within the cell. Despite our increasing understanding of the molecular responses toward dysfunctional mitochondria, many key aspects remain relatively poorly understood. Herein, we review the emerging mechanisms of mitochondrial quality control including quality control strategies coupled to mitochondrial import mechanisms. In addition, we review the molecular mechanisms regulating mitophagy with an emphasis on the regulation of PINK1/PARKIN-mediated mitophagy in cellular physiology and in the context of Parkinson's disease cell biology.
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Affiliation(s)
- Mohamed A Eldeeb
- McGill Parkinson Program, Neurodegenerative Diseases Group, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Rhalena A Thomas
- McGill Parkinson Program, Neurodegenerative Diseases Group, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Mohamed A Ragheb
- Chemistry Department (Biochemistry Division), Faculty of Science, Cairo University, Giza, Egypt
| | - Armaan Fallahi
- McGill Parkinson Program, Neurodegenerative Diseases Group, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Edward A Fon
- McGill Parkinson Program, Neurodegenerative Diseases Group, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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13
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Eaglesfield R, Tokatlidis K. Targeting and Insertion of Membrane Proteins in Mitochondria. Front Cell Dev Biol 2022; 9:803205. [PMID: 35004695 PMCID: PMC8740019 DOI: 10.3389/fcell.2021.803205] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/09/2021] [Indexed: 01/26/2023] Open
Abstract
Mitochondrial membrane proteins play an essential role in all major mitochondrial functions. The respiratory complexes of the inner membrane are key for the generation of energy. The carrier proteins for the influx/efflux of essential metabolites to/from the matrix. Many other inner membrane proteins play critical roles in the import and processing of nuclear encoded proteins (∼99% of all mitochondrial proteins). The outer membrane provides another lipidic barrier to nuclear-encoded protein translocation and is home to many proteins involved in the import process, maintenance of ionic balance, as well as the assembly of outer membrane components. While many aspects of the import and assembly pathways of mitochondrial membrane proteins have been elucidated, many open questions remain, especially surrounding the assembly of the respiratory complexes where certain highly hydrophobic subunits are encoded by the mitochondrial DNA and synthesised and inserted into the membrane from the matrix side. This review will examine the various assembly pathways for inner and outer mitochondrial membrane proteins while discussing the most recent structural and biochemical data examining the biogenesis process.
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Affiliation(s)
- Ross Eaglesfield
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, University Avenue, Scotland, United Kingdom
| | - Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, University Avenue, Scotland, United Kingdom
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14
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Quality control of protein import into mitochondria. Biochem J 2021; 478:3125-3143. [PMID: 34436539 DOI: 10.1042/bcj20190584] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/29/2021] [Accepted: 08/03/2021] [Indexed: 12/19/2022]
Abstract
Mitochondria import about 1000 proteins that are produced as precursors on cytosolic ribosomes. Defects in mitochondrial protein import result in the accumulation of non-imported precursor proteins and proteotoxic stress. The cell is equipped with different quality control mechanisms to monitor protein transport into mitochondria. First, molecular chaperones guide unfolded proteins to mitochondria and deliver non-imported proteins to proteasomal degradation. Second, quality control factors remove translocation stalled precursor proteins from protein translocases. Third, protein translocases monitor protein sorting to mitochondrial subcompartments. Fourth, AAA proteases of the mitochondrial subcompartments remove mislocalized or unassembled proteins. Finally, impaired efficiency of protein transport is an important sensor for mitochondrial dysfunction and causes the induction of cellular stress responses, which could eventually result in the removal of the defective mitochondria by mitophagy. In this review, we summarize our current understanding of quality control mechanisms that govern mitochondrial protein transport.
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15
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Chaudhuri M, Tripathi A, Gonzalez FS. Diverse Functions of Tim50, a Component of the Mitochondrial Inner Membrane Protein Translocase. Int J Mol Sci 2021; 22:7779. [PMID: 34360547 PMCID: PMC8346121 DOI: 10.3390/ijms22157779] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 12/17/2022] Open
Abstract
Mitochondria are essential in eukaryotes. Besides producing 80% of total cellular ATP, mitochondria are involved in various cellular functions such as apoptosis, inflammation, innate immunity, stress tolerance, and Ca2+ homeostasis. Mitochondria are also the site for many critical metabolic pathways and are integrated into the signaling network to maintain cellular homeostasis under stress. Mitochondria require hundreds of proteins to perform all these functions. Since the mitochondrial genome only encodes a handful of proteins, most mitochondrial proteins are imported from the cytosol via receptor/translocase complexes on the mitochondrial outer and inner membranes known as TOMs and TIMs. Many of the subunits of these protein complexes are essential for cell survival in model yeast and other unicellular eukaryotes. Defects in the mitochondrial import machineries are also associated with various metabolic, developmental, and neurodegenerative disorders in multicellular organisms. In addition to their canonical functions, these protein translocases also help maintain mitochondrial structure and dynamics, lipid metabolism, and stress response. This review focuses on the role of Tim50, the receptor component of one of the TIM complexes, in different cellular functions, with an emphasis on the Tim50 homologue in parasitic protozoan Trypanosoma brucei.
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Affiliation(s)
- Minu Chaudhuri
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, TN 37208, USA; (A.T.); (F.S.G.)
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16
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The Diversity of the Mitochondrial Outer Membrane Protein Import Channels: Emerging Targets for Modulation. Molecules 2021; 26:molecules26134087. [PMID: 34279427 PMCID: PMC8272145 DOI: 10.3390/molecules26134087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 06/30/2021] [Accepted: 07/01/2021] [Indexed: 12/21/2022] Open
Abstract
The functioning of mitochondria and their biogenesis are largely based on the proper function of the mitochondrial outer membrane channels, which selectively recognise and import proteins but also transport a wide range of other molecules, including metabolites, inorganic ions and nucleic acids. To date, nine channels have been identified in the mitochondrial outer membrane of which at least half represent the mitochondrial protein import apparatus. When compared to the mitochondrial inner membrane, the presented channels are mostly constitutively open and consequently may participate in transport of different molecules and contribute to relevant changes in the outer membrane permeability based on the channel conductance. In this review, we focus on the channel structure, properties and transported molecules as well as aspects important to their modulation. This information could be used for future studies of the cellular processes mediated by these channels, mitochondrial functioning and therapies for mitochondria-linked diseases.
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17
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Drwesh L, Rapaport D. Biogenesis pathways of α-helical mitochondrial outer membrane proteins. Biol Chem 2021; 401:677-686. [PMID: 32017702 DOI: 10.1515/hsz-2019-0440] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 01/21/2020] [Indexed: 01/23/2023]
Abstract
Mitochondria harbor in their outer membrane (OM) proteins of different topologies. These proteins are encoded by the nuclear DNA, translated on cytosolic ribosomes and inserted into their target organelle by sophisticated protein import machineries. Recently, considerable insights have been accumulated on the insertion pathways of proteins into the mitochondrial OM. In contrast, little is known regarding the early cytosolic stages of their biogenesis. It is generally presumed that chaperones associate with these proteins following their synthesis in the cytosol, thereby keeping them in an import-competent conformation and preventing their aggregation and/or mis-folding and degradation. In this review, we outline the current knowledge about the biogenesis of different mitochondrial OM proteins with various topologies, and highlight the recent findings regarding their import pathways starting from early cytosolic events until their recognition on the mitochondrial surface that lead to their final insertion into the mitochondrial OM.
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Affiliation(s)
- Layla Drwesh
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
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18
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Bausewein T, Naveed H, Liang J, Nussberger S. The structure of the TOM core complex in the mitochondrial outer membrane. Biol Chem 2021; 401:687-697. [PMID: 32142473 DOI: 10.1515/hsz-2020-0104] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 03/03/2020] [Indexed: 02/05/2023]
Abstract
In the past three decades, significant advances have been made in providing the biochemical background of TOM (translocase of the outer mitochondrial membrane)-mediated protein translocation into mitochondria. In the light of recent cryoelectron microscopy-derived structures of TOM isolated from Neurospora crassa and Saccharomyces cerevisiae, the interpretation of biochemical and biophysical studies of TOM-mediated protein transport into mitochondria now rests on a solid basis. In this review, we compare the subnanometer structure of N. crassa TOM core complex with that of yeast. Both structures reveal remarkably well-conserved symmetrical dimers of 10 membrane protein subunits. The structural data also validate predictions of weakly stable regions in the transmembrane β-barrel domains of the protein-conducting subunit Tom40, which signal the existence of β-strands located in interfaces of protein-protein interactions.
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Affiliation(s)
- Thomas Bausewein
- Max-Planck-Institute of Biophysics, Department of Structural Biology, Max-von-Laue-Str. 3, D-60438Frankfurt am Main, Germany
| | - Hammad Naveed
- National University of Computer and Emerging Sciences, Department of Computer Science, A. K. Brohi Road H-11/4, Islamabad 44000, Pakistan
| | - Jie Liang
- Richard and Loan Hill Department of Bioengineering, MC-063, University of Illinois, Chicago, IL 60607-7052, USA
| | - Stephan Nussberger
- University of Stuttgart, Institute of Biomaterials and Biomolecular Systems, Department of Biophysics, Pfaffenwaldring 57, D-70569Stuttgart, Germany
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19
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Doan KN, Grevel A, Mårtensson CU, Ellenrieder L, Thornton N, Wenz LS, Opaliński Ł, Guiard B, Pfanner N, Becker T. The Mitochondrial Import Complex MIM Functions as Main Translocase for α-Helical Outer Membrane Proteins. Cell Rep 2021; 31:107567. [PMID: 32348752 DOI: 10.1016/j.celrep.2020.107567] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 02/19/2020] [Accepted: 04/02/2020] [Indexed: 01/08/2023] Open
Abstract
The mitochondrial outer membrane contains integral proteins with α-helical membrane anchors or a transmembrane β-barrel. The translocase of the outer membrane (TOM) cooperates with the sorting and assembly machinery (SAM) in the import of β-barrel proteins, whereas the mitochondrial import (MIM) complex inserts precursors of multi-spanning α-helical proteins. Single-spanning proteins constitute more than half of the integral outer membrane proteins; however, their biogenesis is poorly understood. We report that the yeast MIM complex promotes the insertion of proteins with N-terminal (signal-anchored) or C-terminal (tail-anchored) membrane anchors. The MIM complex exists in three dynamic populations. MIM interacts with TOM to accept precursor proteins from the receptor Tom70. Free MIM complexes insert single-spanning proteins that are imported in a Tom70-independent manner. Finally, coupling of MIM and SAM promotes early assembly steps of TOM subunits. We conclude that the MIM complex is a major and versatile protein translocase of the mitochondrial outer membrane.
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Affiliation(s)
- Kim Nguyen Doan
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Alexander Grevel
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Christoph U Mårtensson
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Lars Ellenrieder
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Nicolas Thornton
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Lena-Sophie Wenz
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Łukasz Opaliński
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Bernard Guiard
- Centre de Génétique Moléculaire, CNRS, 91190 Gif-sur-Yvette, France
| | - 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.
| | - Thomas Becker
- 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.
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20
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Maity S, Chakrabarti O. Mitochondrial protein import as a quality control sensor. Biol Cell 2021; 113:375-400. [PMID: 33870508 DOI: 10.1111/boc.202100002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/04/2021] [Accepted: 04/09/2021] [Indexed: 12/17/2022]
Abstract
Mitochondria are organelles involved in various functions related to cellular metabolism and homoeostasis. Though mitochondria contain own genome, their nuclear counterparts encode most of the different mitochondrial proteins. These are synthesised as precursors in the cytosol and have to be delivered into the mitochondria. These organelles hence have elaborate machineries for the import of precursor proteins from cytosol. The protein import machineries present in both mitochondrial membrane and aqueous compartments show great variability in pre-protein recognition, translocation and sorting across or into it. Mitochondrial protein import machineries also interact transiently with other protein complexes of the respiratory chain or those involved in the maintenance of membrane architecture. Hence mitochondrial protein translocation is an indispensable part of the regulatory network that maintains protein biogenesis, bioenergetics, membrane dynamics and quality control of the organelle. Various stress conditions and diseases that are associated with mitochondrial import defects lead to changes in cellular transcriptomic and proteomic profiles. Dysfunction in mitochondrial protein import also causes over-accumulation of precursor proteins and their aggregation in the cytosol. Multiple pathways may be activated for buffering these harmful consequences. Here, we present a comprehensive picture of import machinery and its role in cellular quality control in response to defective mitochondrial import. We also discuss the pathological consequences of dysfunctional mitochondrial protein import in neurodegeneration and cancer.
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Affiliation(s)
- Sebabrata Maity
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, 700064, India.,Homi Bhabha National Institute, India
| | - Oishee Chakrabarti
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, 700064, India.,Homi Bhabha National Institute, India
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21
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Kotrasová V, Keresztesová B, Ondrovičová G, Bauer JA, Havalová H, Pevala V, Kutejová E, Kunová N. Mitochondrial Kinases and the Role of Mitochondrial Protein Phosphorylation in Health and Disease. Life (Basel) 2021; 11:life11020082. [PMID: 33498615 PMCID: PMC7912454 DOI: 10.3390/life11020082] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 02/07/2023] Open
Abstract
The major role of mitochondria is to provide cells with energy, but no less important are their roles in responding to various stress factors and the metabolic changes and pathological processes that might occur inside and outside the cells. The post-translational modification of proteins is a fast and efficient way for cells to adapt to ever changing conditions. Phosphorylation is a post-translational modification that signals these changes and propagates these signals throughout the whole cell, but it also changes the structure, function and interaction of individual proteins. In this review, we summarize the influence of kinases, the proteins responsible for phosphorylation, on mitochondrial biogenesis under various cellular conditions. We focus on their role in keeping mitochondria fully functional in healthy cells and also on the changes in mitochondrial structure and function that occur in pathological processes arising from the phosphorylation of mitochondrial proteins.
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Affiliation(s)
- Veronika Kotrasová
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská Cesta 21, 845 51 Bratislava, Slovakia; (V.K.); (B.K.); (G.O.); (J.A.B.); (H.H.); (V.P.)
| | - Barbora Keresztesová
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská Cesta 21, 845 51 Bratislava, Slovakia; (V.K.); (B.K.); (G.O.); (J.A.B.); (H.H.); (V.P.)
- First Faculty of Medicine, Institute of Biology and Medical Genetics, Charles University, 128 00 Prague, Czech Republic
| | - Gabriela Ondrovičová
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská Cesta 21, 845 51 Bratislava, Slovakia; (V.K.); (B.K.); (G.O.); (J.A.B.); (H.H.); (V.P.)
| | - Jacob A. Bauer
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská Cesta 21, 845 51 Bratislava, Slovakia; (V.K.); (B.K.); (G.O.); (J.A.B.); (H.H.); (V.P.)
| | - Henrieta Havalová
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská Cesta 21, 845 51 Bratislava, Slovakia; (V.K.); (B.K.); (G.O.); (J.A.B.); (H.H.); (V.P.)
| | - Vladimír Pevala
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská Cesta 21, 845 51 Bratislava, Slovakia; (V.K.); (B.K.); (G.O.); (J.A.B.); (H.H.); (V.P.)
| | - Eva Kutejová
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská Cesta 21, 845 51 Bratislava, Slovakia; (V.K.); (B.K.); (G.O.); (J.A.B.); (H.H.); (V.P.)
- Correspondence: (E.K.); (N.K.)
| | - Nina Kunová
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská Cesta 21, 845 51 Bratislava, Slovakia; (V.K.); (B.K.); (G.O.); (J.A.B.); (H.H.); (V.P.)
- First Faculty of Medicine, Institute of Biology and Medical Genetics, Charles University, 128 00 Prague, Czech Republic
- Correspondence: (E.K.); (N.K.)
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22
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Chaudhuri M, Darden C, Soto Gonzalez F, Singha UK, Quinones L, Tripathi A. Tim17 Updates: A Comprehensive Review of an Ancient Mitochondrial Protein Translocator. Biomolecules 2020; 10:E1643. [PMID: 33297490 PMCID: PMC7762337 DOI: 10.3390/biom10121643] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/02/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023] Open
Abstract
The translocases of the mitochondrial outer and inner membranes, the TOM and TIMs, import hundreds of nucleus-encoded proteins into mitochondria. TOM and TIMs are multi-subunit protein complexes that work in cooperation with other complexes to import proteins in different sub-mitochondrial destinations. The overall architecture of these protein complexes is conserved among yeast/fungi, animals, and plants. Recent studies have revealed unique characteristics of this machinery, particularly in the eukaryotic supergroup Excavata. Despite multiple differences, homologues of Tim17, an essential component of one of the TIM complexes and a member of the Tim17/Tim22/Tim23 family, have been found in all eukaryotes. Here, we review the structure and function of Tim17 and Tim17-containing protein complexes in different eukaryotes, and then compare them to the single homologue of this protein found in Trypanosoma brucei, a unicellular parasitic protozoan.
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Affiliation(s)
- Minu Chaudhuri
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, 1005 Dr. D.B. Todd, Jr., Blvd, Nashville, TN 37208, USA; (C.D.); (F.S.G.); (U.K.S.); (L.Q.); (A.T.)
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23
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Goyal S, Chaturvedi RK. Mitochondrial Protein Import Dysfunction in Pathogenesis of Neurodegenerative Diseases. Mol Neurobiol 2020; 58:1418-1437. [PMID: 33180216 DOI: 10.1007/s12035-020-02200-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023]
Abstract
Mitochondria play an essential role in maintaining energy homeostasis and cellular survival. In the brain, higher ATP production is required by mature neurons for communication. Most of the mitochondrial proteins transcribe in the nucleus and import in mitochondria through different pathways of the mitochondrial protein import machinery. This machinery plays a crucial role in determining mitochondrial morphology and functions through mitochondrial biogenesis. Failure of this machinery and any alterations during mitochondrial biogenesis underlies neurodegeneration resulting in Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD) etc. Current knowledge has revealed the different pathways of mitochondrial protein import machinery such as translocase of the outer mitochondrial membrane complex, the presequence pathway, carrier pathway, β-barrel pathway, and mitochondrial import and assembly machinery etc. In this review, we have discussed the recent studies regarding protein import machinery, beyond the well-known effects of increased oxidative stress and bioenergetics dysfunctions. We have elucidated in detail how these types of machinery help to import and locate the precursor proteins to their specific location inside the mitochondria and play a major role in mitochondrial biogenesis. We further discuss their involvement in mitochondrial dysfunctioning and the induction of toxic aggregates in neurodegenerative diseases like AD and PD. The review supports the importance of import machinery in neuronal functions and its association with toxic aggregated proteins in mitochondrial impairment, suggesting a critical role in fostering and maintaining neurodegeneration and therapeutic response.
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Affiliation(s)
- Shweta Goyal
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, Uttar Pradesh, 226001, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Rajnish Kumar Chaturvedi
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, Uttar Pradesh, 226001, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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24
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Fukuda T, Ebi Y, Saigusa T, Furukawa K, Yamashita SI, Inoue K, Kobayashi D, Yoshida Y, Kanki T. Atg43 tethers isolation membranes to mitochondria to promote starvation-induced mitophagy in fission yeast. eLife 2020; 9:61245. [PMID: 33138913 PMCID: PMC7609059 DOI: 10.7554/elife.61245] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 10/09/2020] [Indexed: 12/23/2022] Open
Abstract
Degradation of mitochondria through mitophagy contributes to the maintenance of mitochondrial function. In this study, we identified that Atg43, a mitochondrial outer membrane protein, serves as a mitophagy receptor in the model organism Schizosaccharomyces pombe to promote the selective degradation of mitochondria. Atg43 contains an Atg8-family-interacting motif essential for mitophagy. Forced recruitment of Atg8 to mitochondria restores mitophagy in Atg43-deficient cells, suggesting that Atg43 tethers expanding isolation membranes to mitochondria. We found that the mitochondrial import factors, including the Mim1–Mim2 complex and Tom70, are crucial for mitophagy. Artificial mitochondrial loading of Atg43 bypasses the requirement of the import factors, suggesting that they contribute to mitophagy through Atg43. Atg43 not only maintains growth ability during starvation but also facilitates vegetative growth through its mitophagy-independent function. Thus, Atg43 is a useful model to study the mechanism and physiological roles, as well as the origin and evolution, of mitophagy in eukaryotes.
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Affiliation(s)
- Tomoyuki Fukuda
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yuki Ebi
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Tetsu Saigusa
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Kentaro Furukawa
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Shun-Ichi Yamashita
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Keiichi Inoue
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Daiki Kobayashi
- Omics Unit, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yutaka Yoshida
- Department of Structural Pathology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Tomotake Kanki
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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25
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Qin Q, Zhao T, Zou W, Shen K, Wang X. An Endoplasmic Reticulum ATPase Safeguards Endoplasmic Reticulum Identity by Removing Ectopically Localized Mitochondrial Proteins. Cell Rep 2020; 33:108363. [DOI: 10.1016/j.celrep.2020.108363] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 08/05/2020] [Accepted: 10/19/2020] [Indexed: 11/29/2022] Open
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26
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Gupta A, Becker T. Mechanisms and pathways of mitochondrial outer membrane protein biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148323. [PMID: 33035511 DOI: 10.1016/j.bbabio.2020.148323] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/26/2020] [Accepted: 09/29/2020] [Indexed: 11/29/2022]
Abstract
Outer membrane proteins integrate mitochondria into the cellular environment. They warrant exchange of small molecules like metabolites and ions, transport proteins into mitochondria, form contact sites to other cellular organelles for lipid exchange, constitute a signaling platform for apoptosis and inflammation and mediate organelle fusion and fission. The outer membrane contains two types of integral membrane proteins. Proteins with a transmembrane β-barrel structure and proteins with a single or multiple α-helical membrane spans. All outer membrane proteins are produced on cytosolic ribosomes and imported into the target organelle. Precursors of β-barrel and α-helical proteins are transported into the outer membrane via distinct import routes. The translocase of the outer membrane (TOM complex) transports β-barrel precursors across the outer membrane and the sorting and assembly machinery (SAM complex) inserts them into the target membrane. The mitochondrial import (MIM) complex constitutes the major integration site for α-helical embedded proteins. The import of some MIM-substrates involves TOM receptors, while others are imported in a TOM-independent manner. Remarkably, TOM, SAM and MIM complexes dynamically interact to import a large set of different proteins and to coordinate their assembly into protein complexes. Thus, protein import into the mitochondrial outer membrane involves a dynamic platform of protein translocases.
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Affiliation(s)
- Arushi Gupta
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany
| | - Thomas Becker
- Institut für Biochemie und Molekularbiologie, Medizinische Fakultät, Universität Bonn, Nussallee 11, 53115 Bonn, Germany.
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27
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Kreimendahl S, Rassow J. The Mitochondrial Outer Membrane Protein Tom70-Mediator in Protein Traffic, Membrane Contact Sites and Innate Immunity. Int J Mol Sci 2020; 21:E7262. [PMID: 33019591 PMCID: PMC7583919 DOI: 10.3390/ijms21197262] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 02/08/2023] Open
Abstract
Tom70 is a versatile adaptor protein of 70 kDa anchored in the outer membrane of mitochondria in metazoa, fungi and amoeba. The tertiary structure was resolved for the Tom70 of yeast, showing 26 α-helices, most of them participating in the formation of 11 tetratricopeptide repeat (TPR) motifs. Tom70 serves as a docking site for cytosolic chaperone proteins and co-chaperones and is thereby involved in the uptake of newly synthesized chaperone-bound proteins in mitochondrial biogenesis. In yeast, Tom70 additionally mediates ER-mitochondria contacts via binding to sterol transporter Lam6/Ltc1. In mammalian cells, TOM70 promotes endoplasmic reticulum (ER) to mitochondria Ca2+ transfer by association with the inositol-1,4,5-triphosphate receptor type 3 (IP3R3). TOM70 is specifically targeted by the Bcl-2-related protein MCL-1 that acts as an anti-apoptotic protein in macrophages infected by intracellular pathogens, but also in many cancer cells. By participating in the recruitment of PINK1 and the E3 ubiquitin ligase Parkin, TOM70 can be implicated in the development of Parkinson's disease. TOM70 acts as receptor of the mitochondrial antiviral-signaling protein (MAVS) and thereby participates in the corresponding system of innate immunity against viral infections. The protein encoded by Orf9b in the genome of SARS-CoV-2 binds to TOM70, probably compromising the synthesis of type I interferons.
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Affiliation(s)
| | - Joachim Rassow
- Institute for Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44801 Bochum, Germany;
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28
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Muñoz-Gómez SA, Snyder SN, Montoya SJ, Wideman JG. Independent accretion of TIM22 complex subunits in the animal and fungal lineages. F1000Res 2020; 9:1060. [PMID: 33014348 PMCID: PMC7523481 DOI: 10.12688/f1000research.25904.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/21/2020] [Indexed: 12/25/2022] Open
Abstract
Background: The mitochondrial protein import complexes arose early in eukaryogenesis. Most of the components of the protein import pathways predate the last eukaryotic common ancestor. For example, the carrier-insertase TIM22 complex comprises the widely conserved Tim22 channel core. However, the auxiliary components of fungal and animal TIM22 complexes are exceptions to this ancient conservation. Methods: Using comparative genomics and phylogenetic approaches, we identified precisely when each TIM22 accretion occurred. Results: In animals, we demonstrate that Tim29 and Tim10b arose early in the holozoan lineage. Tim29 predates the metazoan lineage being present in the animal sister lineages, choanoflagellate and filastereans, whereas the erroneously named Tim10b arose from a duplication of Tim9 at the base of metazoans. In fungi, we show that Tim54 has representatives present in every holomycotan lineage including microsporidians and fonticulids, whereas Tim18 and Tim12 appeared much later in fungal evolution. Specifically, Tim18 and Tim12 arose from duplications of Sdh3 and Tim10, respectively, early in the Saccharomycotina. Surprisingly, we show that Tim54 is distantly related to AGK suggesting that AGK and Tim54 are extremely divergent orthologues and the origin of AGK/Tim54 interaction with Tim22 predates the divergence of animals and fungi. Conclusions: We argue that the evolutionary history of the TIM22 complex is best understood as the neutral structural divergence of an otherwise strongly functionally conserved protein complex. This view suggests that many of the differences in structure/subunit composition of multi-protein complexes are non-adaptive. Instead, most of the phylogenetic variation of functionally conserved molecular machines, which have been under stable selective pressures for vast phylogenetic spans, such as the TIM22 complex, is most likely the outcome of the interplay of random genetic drift and mutation pressure.
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Affiliation(s)
- Sergio A. Muñoz-Gómez
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Shannon N. Snyder
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Samantha J. Montoya
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Jeremy G. Wideman
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
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29
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Grevel A, Pfanner N, Becker T. Coupling of import and assembly pathways in mitochondrial protein biogenesis. Biol Chem 2020; 401:117-129. [PMID: 31513529 DOI: 10.1515/hsz-2019-0310] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 08/13/2019] [Indexed: 12/14/2022]
Abstract
Biogenesis and function of mitochondria depend on the import of about 1000 precursor proteins that are produced on cytosolic ribosomes. The translocase of the outer membrane (TOM) forms the entry gate for most proteins. After passage through the TOM channel, dedicated preprotein translocases sort the precursor proteins into the mitochondrial subcompartments. Many proteins have to be assembled into oligomeric membrane-integrated complexes in order to perform their functions. In this review, we discuss a dual role of mitochondrial preprotein translocases in protein translocation and oligomeric assembly, focusing on the biogenesis of the TOM complex and the respiratory chain. The sorting and assembly machinery (SAM) of the outer mitochondrial membrane forms a dynamic platform for coupling transport and assembly of TOM subunits. The biogenesis of the cytochrome c oxidase of the inner membrane involves a molecular circuit to adjust translation of mitochondrial-encoded core subunits to the availability of nuclear-encoded partner proteins. Thus, mitochondrial protein translocases not only import precursor proteins but can also support their assembly into functional complexes.
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Affiliation(s)
- Alexander Grevel
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany.,Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany.,CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, D-79104 Freiburg, Germany
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany.,CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, D-79104 Freiburg, Germany
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30
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Cytosolic Events in the Biogenesis of Mitochondrial Proteins. Trends Biochem Sci 2020; 45:650-667. [DOI: 10.1016/j.tibs.2020.04.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 03/18/2020] [Accepted: 04/02/2020] [Indexed: 01/08/2023]
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31
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Avendaño-Monsalve MC, Ponce-Rojas JC, Funes S. From cytosol to mitochondria: the beginning of a protein journey. Biol Chem 2020; 401:645-661. [DOI: 10.1515/hsz-2020-0110] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 02/24/2020] [Indexed: 01/18/2023]
Abstract
AbstractMitochondrial protein import is one of the key processes during mitochondrial biogenesis that involves a series of events necessary for recognition and delivery of nucleus-encoded/cytosol-synthesized mitochondrial proteins into the organelle. The past research efforts have mainly unraveled how membrane translocases ensure the correct protein sorting within the different mitochondrial subcompartments. However, early steps of recognition and delivery remain relatively uncharacterized. In this review, we discuss our current understanding about the signals on mitochondrial proteins, as well as in the mRNAs encoding them, which with the help of cytosolic chaperones and membrane receptors support protein targeting to the organelle in order to avoid improper localization. In addition, we discuss recent findings that illustrate how mistargeting of mitochondrial proteins triggers stress responses, aiming to restore cellular homeostasis.
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Affiliation(s)
- Maria Clara Avendaño-Monsalve
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n Ciudad Universitaria Coyoacán, México, Cd.Mx. 04510, Mexico
| | - José Carlos Ponce-Rojas
- Department of Molecular, Cellular, and Developmental Biology, University of California at Santa Barbara, Santa Barbara, CA 93106-9625, USA
| | - Soledad Funes
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n Ciudad Universitaria Coyoacán, México, Cd.Mx. 04510, Mexico
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32
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Vitali DG, Drwesh L, Cichocki BA, Kolb A, Rapaport D. The Biogenesis of Mitochondrial Outer Membrane Proteins Show Variable Dependence on Import Factors. iScience 2019; 23:100779. [PMID: 31945731 PMCID: PMC6965732 DOI: 10.1016/j.isci.2019.100779] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 11/12/2019] [Accepted: 12/12/2019] [Indexed: 12/14/2022] Open
Abstract
Biogenesis of mitochondrial outer membrane proteins involves their integration into the lipid bilayer. Among these proteins are those that form a single-span topology, but our understanding of their biogenesis is scarce. In this study, we found that the MIM complex is required for the membrane insertion of some single-span proteins. However, other such proteins integrate into the membrane in a MIM-independent manner. Moreover, the biogenesis of the studied proteins was dependent to a variable degree on the TOM receptors Tom20 and Tom70. We found that Atg32 C-terminal domain mediates dependency on Tom20, whereas the cytosolic domains of Atg32 and Gem1 facilitate MIM involvement. Collectively, our findings (1) enlarge the repertoire of MIM substrates to include also tail-anchored proteins, (2) provide new mechanistic insights to the functions of the MIM complex and TOM import receptors, and (3) demonstrate that the biogenesis of MOM single-span proteins shows variable dependence on import factors.
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Affiliation(s)
- Daniela G Vitali
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
| | - Layla Drwesh
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
| | - Bogdan A Cichocki
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
| | - Antonia Kolb
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany.
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33
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Heinemeyer T, Stemmet M, Bardien S, Neethling A. Underappreciated Roles of the Translocase of the Outer and Inner Mitochondrial Membrane Protein Complexes in Human Disease. DNA Cell Biol 2018; 38:23-40. [PMID: 30481057 DOI: 10.1089/dna.2018.4292] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mitochondria are critical for cellular survival, and for their proper functioning, translocation of ∼1500 proteins across the mitochondrial membranes is required. The translocase of the outer (TOMM) and inner mitochondrial membrane (TIMM) complexes are major components of this translocation machinery. Through specific processes, preproteins and other molecules are imported, translocated, and directed to specific mitochondrial compartments for their function. In this study, we review the association of subunits of these complexes with human disease. Pathogenic mutations have been identified in the TIMM8A (DDP) and DNAJC19 (TIMM14) genes and are linked to Mohr-Tranebjærg syndrome and dilated cardiomyopathy syndrome (with and without ataxia), respectively. Polymorphisms in TOMM40 have been associated with Alzheimer's disease, frontotemporal lobar degeneration, Parkinson's disease with dementia, dementia with Lewy bodies, nonpathological cognitive aging, and various cardiovascular-related traits. Furthermore, reduced protein expression levels of several complex subunits have been associated with Parkinson's disease, Meniere's disease, and cardiovascular disorders. However, increased mRNA and protein levels of complex subunits are found in cancers. This review highlights the importance of the mitochondrial import machinery in human disease and stresses the need for further studies. Ultimately, this knowledge may prove to be critical for the development of therapeutic modalities for these conditions.
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Affiliation(s)
- Thea Heinemeyer
- Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University , Cape Town, South Africa
| | - Monique Stemmet
- Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University , Cape Town, South Africa
| | - Soraya Bardien
- Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University , Cape Town, South Africa
| | - Annika Neethling
- Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University , Cape Town, South Africa
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34
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Cichocki BA, Krumpe K, Vitali DG, Rapaport D. Pex19 is involved in importing dually targeted tail-anchored proteins to both mitochondria and peroxisomes. Traffic 2018; 19:770-785. [DOI: 10.1111/tra.12604] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 07/17/2018] [Accepted: 07/19/2018] [Indexed: 12/31/2022]
Affiliation(s)
- Bogdan A. Cichocki
- Interfaculty Institute of Biochemistry; University of Tübingen; Tübingen Germany
| | - Katrin Krumpe
- Interfaculty Institute of Biochemistry; University of Tübingen; Tübingen Germany
| | - Daniela G. Vitali
- Interfaculty Institute of Biochemistry; University of Tübingen; Tübingen Germany
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry; University of Tübingen; Tübingen Germany
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35
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Abstract
Evidence is accumulating that unrelated species have independently evolved the same way of importing proteins in their mitochondria.
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Affiliation(s)
- Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom
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36
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Vitali DG, Käser S, Kolb A, Dimmer KS, Schneider A, Rapaport D. Independent evolution of functionally exchangeable mitochondrial outer membrane import complexes. eLife 2018; 7:34488. [PMID: 29923829 PMCID: PMC6010339 DOI: 10.7554/elife.34488] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 05/06/2018] [Indexed: 11/13/2022] Open
Abstract
Assembly and/or insertion of a subset of mitochondrial outer membrane (MOM) proteins, including subunits of the main MOM translocase, require the fungi-specific Mim1/Mim2 complex. So far it was unclear which proteins accomplish this task in other eukaryotes. Here, we show by reciprocal complementation that the MOM protein pATOM36 of trypanosomes is a functional analogue of yeast Mim1/Mim2 complex, even though these proteins show neither sequence nor topological similarity. Expression of pATOM36 rescues almost all growth, mitochondrial biogenesis, and morphology defects in yeast cells lacking Mim1 and/or Mim2. Conversely, co-expression of Mim1 and Mim2 restores the assembly and/or insertion defects of MOM proteins in trypanosomes ablated for pATOM36. Mim1/Mim2 and pATOM36 form native-like complexes when heterologously expressed, indicating that additional proteins are not part of these structures. Our findings indicate that Mim1/Mim2 and pATOM36 are the products of convergent evolution and arose only after the ancestors of fungi and trypanosomatids diverged.
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Affiliation(s)
- Daniela G Vitali
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Sandro Käser
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Antonia Kolb
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Kai S Dimmer
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Andre Schneider
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
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37
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Verechshagina NA, Konstantinov YM, Kamenski PA, Mazunin IO. Import of Proteins and Nucleic Acids into Mitochondria. BIOCHEMISTRY (MOSCOW) 2018; 83:643-661. [DOI: 10.1134/s0006297918060032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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38
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Becker T, Wagner R. Mitochondrial Outer Membrane Channels: Emerging Diversity in Transport Processes. Bioessays 2018; 40:e1800013. [DOI: 10.1002/bies.201800013] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 03/29/2018] [Indexed: 01/06/2023]
Affiliation(s)
- Thomas Becker
- Faculty of MedicineInstitute of Biochemistry and Molecular Biology, ZBMZUniversity of FreiburgFreiburgD‐79104Germany
- BIOSS Centre for Biological Signalling StudiesUniversity of FreiburgFreiburgD‐79104Germany
| | - Richard Wagner
- Biophysics, Life Sciences & ChemistryJacobs University BremenBremenD‐28759Germany
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39
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Checchetto V, Szabo I. Novel Channels of the Outer Membrane of Mitochondria: Recent Discoveries Change Our View. Bioessays 2018; 40:e1700232. [PMID: 29682771 DOI: 10.1002/bies.201700232] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/09/2018] [Indexed: 01/12/2023]
Abstract
Ion channels mediate ion flux across biological membranes and regulate important organellar and cellular tasks. A recent study revealed the presence of four new proteins, the MIM complex (composed by Mim1 and Mim2), Ayr1, OMC7, and OMC8, that are able to form ion-conducting channels in the outer mitochondria membrane (OMM). These findings strongly indicate that the OMM is endowed with many solute-specific channels, in addition to porins and known channels mediating protein import into mitochondria. These solute-specific channels provide essential pathways for the controlled transport of ions and metabolites and may thus add a further layer of specificity to the regulation of mitochondrial function at the organelle-cytosol and/or inter-organellar interface. Future studies will be required to fully understand the way(s) of regulation of these new channels and to integrate them into signaling pathways within the cells.
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Affiliation(s)
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padua 35121, Italy
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40
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Krüger V, Becker T, Becker L, Montilla-Martinez M, Ellenrieder L, Vögtle FN, Meyer HE, Ryan MT, Wiedemann N, Warscheid B, Pfanner N, Wagner R, Meisinger C. Identification of new channels by systematic analysis of the mitochondrial outer membrane. J Cell Biol 2017; 216:3485-3495. [PMID: 28916712 PMCID: PMC5674900 DOI: 10.1083/jcb.201706043] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 08/03/2017] [Accepted: 08/22/2017] [Indexed: 02/08/2023] Open
Abstract
Channels in the mitochondrial outer membrane exchange metabolites, ions, and proteins with the rest of the cell. Kruger et al. identify several new types of channel and suggest that the outer mitochondrial membrane is a more selective molecular sieve with a greater variety of channel-forming proteins than previously appreciated. The mitochondrial outer membrane is essential for communication between mitochondria and the rest of the cell and facilitates the transport of metabolites, ions, and proteins. All mitochondrial outer membrane channels known to date are β-barrel membrane proteins, including the abundant voltage-dependent anion channel and the cation-preferring protein-conducting channels Tom40, Sam50, and Mdm10. We analyzed outer membrane fractions of yeast mitochondria and identified four new channel activities: two anion-preferring channels and two cation-preferring channels. We characterized the cation-preferring channels at the molecular level. The mitochondrial import component Mim1 forms a channel that is predicted to have an α-helical structure for protein import. The short-chain dehydrogenase-related protein Ayr1 forms an NADPH-regulated channel. We conclude that the mitochondrial outer membrane contains a considerably larger variety of channel-forming proteins than assumed thus far. These findings challenge the traditional view of the outer membrane as an unspecific molecular sieve and indicate a higher degree of selectivity and regulation of metabolite fluxes at the mitochondrial boundary.
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Affiliation(s)
- Vivien Krüger
- Division of Biophysics, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.,Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Lars Becker
- Division of Biophysics, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | | | - Lars Ellenrieder
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - F-Nora Vögtle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Helmut E Meyer
- Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Dortmund, Germany
| | - Michael T Ryan
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia
| | - Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Bettina Warscheid
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany.,Institute of Biology II, Biochemistry - Functional Proteomics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany .,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Richard Wagner
- Division of Biophysics, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany .,Biophysics, Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Chris Meisinger
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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41
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Straub SP, Stiller SB, Wiedemann N, Pfanner N. Dynamic organization of the mitochondrial protein import machinery. Biol Chem 2017; 397:1097-1114. [PMID: 27289000 DOI: 10.1515/hsz-2016-0145] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 05/17/2016] [Indexed: 01/12/2023]
Abstract
Mitochondria contain elaborate machineries for the import of precursor proteins from the cytosol. The translocase of the outer mitochondrial membrane (TOM) performs the initial import of precursor proteins and transfers the precursors to downstream translocases, including the presequence translocase and the carrier translocase of the inner membrane, the mitochondrial import and assembly machinery of the intermembrane space, and the sorting and assembly machinery of the outer membrane. Although the protein translocases can function as separate entities in vitro, recent studies revealed a close and dynamic cooperation of the protein import machineries to facilitate efficient transfer of precursor proteins in vivo. In addition, protein translocases were found to transiently interact with distinct machineries that function in the respiratory chain or in the maintenance of mitochondrial membrane architecture. Mitochondrial protein import is embedded in a regulatory network that ensures protein biogenesis, membrane dynamics, bioenergetic activity and quality control.
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Prasai K. Regulation of mitochondrial structure and function by protein import: A current review. ACTA ACUST UNITED AC 2017; 24:107-122. [PMID: 28400074 DOI: 10.1016/j.pathophys.2017.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 12/14/2022]
Abstract
By generating the majority of a cell's ATP, mitochondria permit a vast range of reactions necessary for life. Mitochondria also perform other vital functions including biogenesis and assembly of iron-sulfur proteins, maintenance of calcium homeostasis, and activation of apoptosis. Accordingly, mitochondrial dysfunction has been linked with the pathology of many clinical conditions including cancer, type 2 diabetes, cardiomyopathy, and atherosclerosis. The ongoing maintenance of mitochondrial structure and function requires the import of nuclear-encoded proteins and for this reason, mitochondrial protein import is indispensible for cell viability. As mitochondria play central roles in determining if cells live or die, a comprehensive understanding of mitochondrial structure, protein import, and function is necessary for identifying novel drugs that may destroy harmful cells while rescuing or protecting normal ones to preserve tissue integrity. This review summarizes our current knowledge on mitochondrial architecture, mitochondrial protein import, and mitochondrial function. Our current comprehension of how mitochondrial functions maintain cell homeostasis and how cell death occurs as a result of mitochondrial stress are also discussed.
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Affiliation(s)
- Kanchanjunga Prasai
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130, USA.
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43
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Abstract
Mitochondria are essential organelles with numerous functions in cellular metabolism and homeostasis. Most of the >1,000 different mitochondrial proteins are synthesized as precursors in the cytosol and are imported into mitochondria by five transport pathways. The protein import machineries of the mitochondrial membranes and aqueous compartments reveal a remarkable variability of mechanisms for protein recognition, translocation, and sorting. The protein translocases do not operate as separate entities but are connected to each other and to machineries with functions in energetics, membrane organization, and quality control. Here, we discuss the versatility and dynamic organization of the mitochondrial protein import machineries. Elucidating the molecular mechanisms of mitochondrial protein translocation is crucial for understanding the integration of protein translocases into a large network that controls organelle biogenesis, function, and dynamics.
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Affiliation(s)
- Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, and BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany; ,
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, and BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany; ,
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44
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Bruggisser J, Käser S, Mani J, Schneider A. Biogenesis of a Mitochondrial Outer Membrane Protein in Trypanosoma brucei: TARGETING SIGNAL AND DEPENDENCE ON A UNIQUE BIOGENESIS FACTOR. J Biol Chem 2017; 292:3400-3410. [PMID: 28100781 DOI: 10.1074/jbc.m116.755983] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 01/16/2017] [Indexed: 11/06/2022] Open
Abstract
The mitochondrial outer membrane (OM) contains single and multiple membrane-spanning proteins that need to contain signals that ensure correct targeting and insertion into the OM. The biogenesis of such proteins has so far essentially only been studied in yeast and related organisms. Here we show that POMP10, an OM protein of the early diverging protozoan Trypanosoma brucei, is signal-anchored. Transgenic cells expressing variants of POMP10 fused to GFP demonstrate that the N-terminal membrane-spanning domain flanked by a few positively charged or neutral residues is both necessary and sufficient for mitochondrial targeting. Carbonate extraction experiments indicate that although the presence of neutral instead of positively charged residues did not interfere with POMP10 localization, it weakened its interaction with the OM. Expression of GFP-tagged POMP10 in inducible RNAi cell lines shows that its mitochondrial localization depends on pATOM36 but does not require Sam50 or ATOM40, the trypanosomal analogue of the Tom40 import pore. pATOM36 is a kinetoplastid-specific OM protein that has previously been implicated in the assembly of OM proteins and in mitochondrial DNA inheritance. In summary, our results show that although the features of the targeting signal in signal-anchored proteins are widely conserved, the protein machinery that mediates their biogenesis is not.
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Affiliation(s)
- Julia Bruggisser
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Sandro Käser
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Jan Mani
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
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45
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Abstract
Mitochondria have to import the vast majority of their proteins, which are synthesized as precursors on cytosolic ribosomes. The translocase of the outer membrane (TOM complex) forms the general entry gate for the precursor proteins, which are subsequently sorted by protein machineries into the mitochondrial subcompartments: the outer and inner membrane, the intermembrane space and the mitochondrial matrix. The transport across and into the inner membrane is driven by the membrane potential, which is generated by the respiratory chain. Recent studies revealed that the lipid composition of mitochondrial membranes is important for the biogenesis of mitochondrial proteins. Cardiolipin and phosphatidylethanolamine exhibit unexpectedly specific functions for the activity of distinct protein translocases. Both phospholipids are required for full activity of respiratory chain complexes and thus to maintain the membrane potential for protein import. In addition, cardiolipin is required to maintain structural integrity of mitochondrial protein translocases. Finally, the low sterol content in the mitochondrial outer membrane may contribute to the targeting of some outer membrane proteins with a single α-helical membrane anchor. Altogether, mitochondrial lipids modulate protein import on various levels involving precursor targeting, membrane potential generation, stability and activity of protein translocases.
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46
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Mancha-Agresti P, Drumond MM, Carmo FLRD, Santos MM, Santos JSCD, Venanzi F, Chatel JM, Leclercq SY, Azevedo V. A New Broad Range Plasmid for DNA Delivery in Eukaryotic Cells Using Lactic Acid Bacteria: In Vitro and In Vivo Assays. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2016; 4:83-91. [PMID: 28344994 PMCID: PMC5363290 DOI: 10.1016/j.omtm.2016.12.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 12/15/2016] [Indexed: 12/30/2022]
Abstract
Lactococcus lactis is well documented as a promising candidate for development of novel oral live vaccines. It has been broadly engineered for heterologous expression, as well as for plasmid expression vector delivery, directly inside eukaryotic cells, for DNA vaccine, or as therapeutic vehicle. This work describes the characteristics of a new plasmid, pExu (extra chromosomal unit), for DNA delivery using L. lactis and evaluates its functionality both by in vitro and in vivo assays. This plasmid exhibits the following features: (1) a theta origin of replication and (2) an expression cassette containing a multiple cloning site and a eukaryotic promoter, the cytomegalovirus (pCMV). The functionality of pExu:egfp was evaluated by fluorescence microscopy. The L. lactis MG1363 (pExu:egfp) strains were administered by gavage to Balb/C mice and the eGFP expression was monitored by fluorescence microscopy. The pExu vector has demonstrated an excellent stability either in L. lactis or in Escherichia coli. The eGFP expression at different times in in vitro assay showed that 15.8% of CHO cells were able to express the protein after transfection. The enterocytes of mice showed the expression of eGFP protein. Thus, L. lactis carrying the pExu is a good candidate to deliver genes into eukaryotic cells.
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Affiliation(s)
- Pamela Mancha-Agresti
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), 31270-901 Belo Horizonte, Brazil
| | - Mariana Martins Drumond
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), 31270-901 Belo Horizonte, Brazil; CEFET - Centro Federal de Educação Tecnológica de Minas Gerais, Coordenação de Ciências, Campus I, 30421-169 Belo Horizonte, Brazil
| | - Fillipe Luiz Rosa do Carmo
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), 31270-901 Belo Horizonte, Brazil
| | - Monica Morais Santos
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), 31270-901 Belo Horizonte, Brazil
| | | | - Franco Venanzi
- School of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino, Italy
| | - Jean-Marc Chatel
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Sophie Yvette Leclercq
- Laboratório de Inovação Biotecnológica, Fundação Ezequiel Dias (FUNED), Belo Horizonte, 30510-010 Minas Gerais, Brazil
| | - Vasco Azevedo
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (ICB/UFMG), 31270-901 Belo Horizonte, Brazil
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47
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Wasilewski M, Chojnacka K, Chacinska A. Protein trafficking at the crossroads to mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:125-137. [PMID: 27810356 DOI: 10.1016/j.bbamcr.2016.10.019] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/25/2016] [Accepted: 10/27/2016] [Indexed: 12/14/2022]
Abstract
Mitochondria are central power stations in the cell, which additionally serve as metabolic hubs for a plethora of anabolic and catabolic processes. The sustained function of mitochondria requires the precisely controlled biogenesis and expression coordination of proteins that originate from the nuclear and mitochondrial genomes. Accuracy of targeting, transport and assembly of mitochondrial proteins is also needed to avoid deleterious effects on protein homeostasis in the cell. Checkpoints of mitochondrial protein transport can serve as signals that provide information about the functional status of the organelles. In this review, we summarize recent advances in our understanding of mitochondrial protein transport and discuss examples that involve communication with the nucleus and cytosol.
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Affiliation(s)
- Michal Wasilewski
- International Institute of Molecular and Cell Biology in Warsaw, Poland.
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48
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Manganas P, MacPherson L, Tokatlidis K. Oxidative protein biogenesis and redox regulation in the mitochondrial intermembrane space. Cell Tissue Res 2016; 367:43-57. [PMID: 27632163 PMCID: PMC5203823 DOI: 10.1007/s00441-016-2488-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/05/2016] [Indexed: 12/22/2022]
Abstract
Mitochondria are organelles that play a central role in cellular metabolism, as they are responsible for processes such as iron/sulfur cluster biogenesis, respiration and apoptosis. Here, we describe briefly the various protein import pathways for sorting of mitochondrial proteins into the different subcompartments, with an emphasis on the targeting to the intermembrane space. The discovery of a dedicated redox-controlled pathway in the intermembrane space that links protein import to oxidative protein folding raises important questions on the redox regulation of this process. We discuss the salient features of redox regulation in the intermembrane space and how such mechanisms may be linked to the more general redox homeostasis balance that is crucial not only for normal cell physiology but also for cellular dysfunction.
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Affiliation(s)
- Phanee Manganas
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Lisa MacPherson
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Kostas Tokatlidis
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
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49
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Outer membrane protein functions as integrator of protein import and DNA inheritance in mitochondria. Proc Natl Acad Sci U S A 2016; 113:E4467-75. [PMID: 27436903 DOI: 10.1073/pnas.1605497113] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Trypanosomatids are one of the earliest diverging eukaryotes that have fully functional mitochondria. pATOM36 is a trypanosomatid-specific essential mitochondrial outer membrane protein that has been implicated in protein import. Changes in the mitochondrial proteome induced by ablation of pATOM36 and in vitro assays show that pATOM36 is required for the assembly of the archaic translocase of the outer membrane (ATOM), the functional analog of the TOM complex in other organisms. Reciprocal pull-down experiments and immunofluorescence analyses demonstrate that a fraction of pATOM36 interacts and colocalizes with TAC65, a previously uncharacterized essential component of the tripartite attachment complex (TAC). The TAC links the single-unit mitochondrial genome to the basal body of the flagellum and mediates the segregation of the replicated mitochondrial genomes. RNAi experiments show that pATOM36, in line with its dual localization, is not only essential for ATOM complex assembly but also for segregation of the replicated mitochondrial genomes. However, the two functions are distinct, as a truncated version of pATOM36 lacking the 75 C-terminal amino acids can rescue kinetoplast DNA missegregation but not the lack of ATOM complex assembly. Thus, pATOM36 has a dual function and integrates mitochondrial protein import with mitochondrial DNA inheritance.
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50
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Effects of lipids on mitochondrial functions. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:102-113. [PMID: 27349299 DOI: 10.1016/j.bbalip.2016.06.015] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 06/16/2016] [Accepted: 06/21/2016] [Indexed: 11/23/2022]
Abstract
Mitochondria contain two membranes: the outer and inner membrane. Whereas the outer membrane is particularly enriched in phospholipids, the inner membrane has an unusual high protein content and forms large invaginations termed cristae. The proper phospholipid composition of the membranes is crucial for mitochondrial functions. Phospholipids affect activity, biogenesis and stability of protein complexes including protein translocases and respiratory chain supercomplexes. Negatively charged phospholipids such as cardiolipin are important for the architecture of the membranes and recruit soluble factors to the membranes to support mitochondrial dynamics. Thus, phospholipids not only form the hydrophobic core of biological membranes that surround mitochondria, but also create a specific environment to promote functions of various protein machineries. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.
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