1
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Kim J, Goldstein M, Zecchel L, Ghorayeb R, Maxwell CA, Weidberg H. ATAD1 prevents clogging of TOM and damage caused by un-imported mitochondrial proteins. Cell Rep 2024; 43:114473. [PMID: 39024102 DOI: 10.1016/j.celrep.2024.114473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 05/26/2024] [Accepted: 06/24/2024] [Indexed: 07/20/2024] Open
Abstract
Mitochondria require the constant import of nuclear-encoded proteins for proper functioning. Impaired protein import not only depletes mitochondria of essential factors but also leads to toxic accumulation of un-imported proteins outside the organelle. Here, we investigate the consequences of impaired mitochondrial protein import in human cells. We demonstrate that un-imported proteins can clog the mitochondrial translocase of the outer membrane (TOM). ATAD1, a mitochondrial ATPase, removes clogged proteins from TOM to clear the entry gate into the mitochondria. ATAD1 interacts with both TOM and stalled proteins, and its knockout results in extensive accumulation of mitochondrial precursors as well as decreased protein import. Increased ATAD1 expression contributes to improved fitness of cells with inefficient mitochondrial protein import. Overall, we demonstrate the importance of the ATAD1 quality control pathway in surveilling protein import and its contribution to cellular health.
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Affiliation(s)
- John Kim
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Madeleine Goldstein
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Lauren Zecchel
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Ryan Ghorayeb
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
| | - Christopher A Maxwell
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada; Michael Cuccione Childhood Cancer Research Program, British Columbia Children's Hospital, Vancouver, BC, Canada
| | - Hilla Weidberg
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada.
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2
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Pines O, Horwitz M, Herrmann JM. Privileged proteins with a second residence: dual targeting and conditional re-routing of mitochondrial proteins. FEBS J 2024. [PMID: 38857249 DOI: 10.1111/febs.17191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/15/2024] [Accepted: 05/22/2024] [Indexed: 06/12/2024]
Abstract
Almost all mitochondrial proteins are encoded by nuclear genes and synthesized in the cytosol as precursor proteins. Signals in the amino acid sequence of these precursors ensure their targeting and translocation into mitochondria. However, in many cases, only a certain fraction of a specific protein is transported into mitochondria, while the rest either remains in the cytosol or undergoes reverse translocation to the cytosol, and can populate other cellular compartments. This phenomenon is called dual localization which can be instigated by different mechanisms. These include alternative start or stop codons, differential transcripts, and ambiguous or competing targeting sequences. In many cases, dual localization might serve as an economic strategy to reduce the number of required genes; for example, when the same groups of enzymes are required both in mitochondria and chloroplasts or both in mitochondria and the nucleus/cytoplasm. Such cases frequently employ ambiguous targeting sequences to distribute proteins between both organelles. However, alternative localizations can also be used for signaling, for example when non-imported precursors serve as mitophagy signals or when they represent transcription factors in the nucleus to induce the mitochondrial unfolded stress response. This review provides an overview regarding the mechanisms and the physiological consequences of dual targeting.
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Affiliation(s)
- Ophry Pines
- Microbiology and Genetics, Faculty of Medicine, Hebrew University of Jerusalem, Israel
| | - Margalit Horwitz
- Microbiology and Genetics, Faculty of Medicine, Hebrew University of Jerusalem, Israel
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3
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Borgert L, Becker T, den Brave F. Conserved quality control mechanisms of mitochondrial protein import. J Inherit Metab Dis 2024. [PMID: 38790152 DOI: 10.1002/jimd.12756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 04/15/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024]
Abstract
Mitochondria carry out essential functions for the cell, including energy production, various biosynthesis pathways, formation of co-factors and cellular signalling in apoptosis and inflammation. The functionality of mitochondria requires the import of about 900-1300 proteins from the cytosol in baker's yeast Saccharomyces cerevisiae and human cells, respectively. The vast majority of these proteins pass the outer membrane in a largely unfolded state through the translocase of the outer mitochondrial membrane (TOM) complex. Subsequently, specific protein translocases sort the precursor proteins into the outer and inner membranes, the intermembrane space and matrix. Premature folding of mitochondrial precursor proteins, defects in the mitochondrial protein translocases or a reduction of the membrane potential across the inner mitochondrial membrane can cause stalling of precursors at the protein import apparatus. Consequently, the translocon is clogged and non-imported precursor proteins accumulate in the cell, which in turn leads to proteotoxic stress and eventually cell death. To prevent such stress situations, quality control mechanisms remove non-imported precursor proteins from the TOM channel. The highly conserved ubiquitin-proteasome system of the cytosol plays a critical role in this process. Thus, the surveillance of protein import via the TOM complex involves the coordinated activity of mitochondria-localized and cytosolic proteins to prevent proteotoxic stress in the cell.
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Affiliation(s)
- Lion Borgert
- Faculty of Medicine, Institute of Biochemistry and Molecular Biology, University of Bonn, Bonn, Germany
| | - Thomas Becker
- Faculty of Medicine, Institute of Biochemistry and Molecular Biology, University of Bonn, Bonn, Germany
| | - Fabian den Brave
- Faculty of Medicine, Institute of Biochemistry and Molecular Biology, University of Bonn, Bonn, Germany
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4
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Yamano K, Kinefuchi H, Kojima W. Mitochondrial quality control via organelle and protein degradation. J Biochem 2024; 175:487-494. [PMID: 38102729 DOI: 10.1093/jb/mvad106] [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: 10/04/2023] [Revised: 11/07/2023] [Accepted: 11/20/2023] [Indexed: 12/17/2023] Open
Abstract
Mitochondria are essential eukaryotic organelles that produce ATP as well as synthesize various macromolecules. They also participate in signalling pathways such as the innate immune response and apoptosis. These diverse functions are performed by >1,000 different mitochondrial proteins. Although mitochondria are continuously exposed to potentially damaging conditions such as reactive oxygen species, proteases/peptidases localized in different mitochondrial subcompartments, termed mitoproteases, maintain mitochondrial quality and integrity. In addition to processing incoming precursors and degrading damaged proteins, mitoproteases also regulate metabolic reactions, mitochondrial protein half-lives and gene transcription. Impaired mitoprotease function is associated with various pathologies. In this review, we highlight recent advances in our understanding of mitochondrial quality control regulated by autophagy, ubiquitin-proteasomes and mitoproteases.
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Affiliation(s)
- Koji Yamano
- Department of Biomolecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Hiroki Kinefuchi
- Department of Biomolecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
- Department of Biosciences, School of Science, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
| | - Waka Kojima
- Department of Biomolecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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5
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Geng K, Merino LG, Veiga RG, Sommerauer C, Epperlein J, Brinkman EK, Kutter C. Intrinsic deletion at 10q23.31, including the PTEN gene locus, is aggravated upon CRISPR-Cas9-mediated genome engineering in HAP1 cells mimicking cancer profiles. Life Sci Alliance 2024; 7:e202302128. [PMID: 37984988 PMCID: PMC10662290 DOI: 10.26508/lsa.202302128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 11/22/2023] Open
Abstract
The CRISPR-Cas9 system is a powerful tool for studying gene functions and holds potential for disease treatment. However, precise genome editing requires thorough assessments to minimize unintended on- and off-target effects. Here, we report an unexpected 283-kb deletion on Chromosome 10 (10q23.31) in chronic myelogenous leukemia-derived HAP1 cells, which are frequently used in CRISPR screens. The deleted region encodes regulatory genes, including PAPSS2, ATAD1, KLLN, and PTEN We found that this deletion was not a direct consequence of CRISPR-Cas9 off-targeting but rather occurred frequently during the generation of CRISPR-Cas9-modified cells. The deletion was associated with global changes in histone acetylation and gene expression, affecting fundamental cellular processes such as cell cycle and DNA replication. We detected this deletion in cancer patient genomes. As in HAP1 cells, the deletion contributed to similar gene expression patterns among cancer patients despite interindividual differences. Our findings suggest that the unintended deletion of 10q23.31 can confound CRISPR-Cas9 studies and underscore the importance to assess unintended genomic changes in CRISPR-Cas9-modified cells, which could impact cancer research.
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Affiliation(s)
- Keyi Geng
- https://ror.org/056d84691 Department of Microbiology, Tumor, and Cell Biology, Science for Life Laboratory, Karolinska Institute, Solna, Sweden
| | - Lara G Merino
- https://ror.org/056d84691 Department of Microbiology, Tumor, and Cell Biology, Science for Life Laboratory, Karolinska Institute, Solna, Sweden
| | - Raül G Veiga
- https://ror.org/056d84691 Department of Microbiology, Tumor, and Cell Biology, Science for Life Laboratory, Karolinska Institute, Solna, Sweden
| | - Christian Sommerauer
- https://ror.org/056d84691 Department of Microbiology, Tumor, and Cell Biology, Science for Life Laboratory, Karolinska Institute, Solna, Sweden
| | - Janine Epperlein
- https://ror.org/056d84691 Department of Microbiology, Tumor, and Cell Biology, Science for Life Laboratory, Karolinska Institute, Solna, Sweden
| | - Eva K Brinkman
- https://ror.org/056d84691 Department of Microbiology, Tumor, and Cell Biology, Science for Life Laboratory, Karolinska Institute, Solna, Sweden
| | - Claudia Kutter
- https://ror.org/056d84691 Department of Microbiology, Tumor, and Cell Biology, Science for Life Laboratory, Karolinska Institute, Solna, Sweden
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6
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Yang EJN, Liao PC, Pon L. Mitochondrial protein and organelle quality control-Lessons from budding yeast. IUBMB Life 2024; 76:72-87. [PMID: 37731280 PMCID: PMC10842221 DOI: 10.1002/iub.2783] [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: 06/30/2023] [Accepted: 08/11/2023] [Indexed: 09/22/2023]
Abstract
Mitochondria are essential for normal cellular function and have emerged as key aging determinants. Indeed, defects in mitochondrial function have been linked to cardiovascular, skeletal muscle and neurodegenerative diseases, premature aging, and age-linked diseases. Here, we describe mechanisms for mitochondrial protein and organelle quality control. These surveillance mechanisms mediate repair or degradation of damaged or mistargeted mitochondrial proteins, segregate mitochondria based on their functional state during asymmetric cell division, and modulate cellular fitness, the response to stress, and lifespan control in yeast and other eukaryotes.
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Affiliation(s)
- Emily Jie-Ning Yang
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032
| | - Pin-Chao Liao
- Institute of Molecular Medicine & Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30013
| | - Liza Pon
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032
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7
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Ronayne CT, Latorre-Muro P. Navigating the landscape of mitochondrial-ER communication in health and disease. Front Mol Biosci 2024; 11:1356500. [PMID: 38323074 PMCID: PMC10844478 DOI: 10.3389/fmolb.2024.1356500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 01/10/2024] [Indexed: 02/08/2024] Open
Abstract
Intracellular organelle communication enables the maintenance of tissue homeostasis and health through synchronized adaptive processes triggered by environmental cues. Mitochondrial-Endoplasmic Reticulum (ER) communication sustains cellular fitness by adjusting protein synthesis and degradation, and metabolite and protein trafficking through organelle membranes. Mitochondrial-ER communication is bidirectional and requires that the ER-components of the Integrated Stress Response signal to mitochondria upon activation and, likewise, mitochondria signal to the ER under conditions of metabolite and protein overload to maintain proper functionality and ensure cellular survival. Declines in the mitochondrial-ER communication occur upon ageing and correlate with the onset of a myriad of heterogeneous age-related diseases such as obesity, type 2 diabetes, cancer, or neurodegenerative pathologies. Thus, the exploration of the molecular mechanisms of mitochondrial-ER signaling and regulation will provide insights into the most fundamental cellular adaptive processes with important therapeutical opportunities. In this review, we will discuss the pathways and mechanisms of mitochondrial-ER communication at the mitochondrial-ER interface and their implications in health and disease.
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Affiliation(s)
- Conor T. Ronayne
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
- Department of Cell Biology, Harvard Medical School, Boston, MA, United States
| | - Pedro Latorre-Muro
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
- Department of Cell Biology, Harvard Medical School, Boston, MA, United States
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8
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Zhou Q, Yang Y, Xu Z, Deng K, Zhang Z, Hao J, Li N, Wang Y, Wang Z, Chen H, Yang Y, Xiao F, Zhang X, Gao S, Li Y. ATAD1 inhibits hepatitis C virus infection by removing the viral TA-protein NS5B from mitochondria. EMBO Rep 2023; 24:e56614. [PMID: 37789674 PMCID: PMC10626439 DOI: 10.15252/embr.202256614] [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: 12/06/2022] [Revised: 08/24/2023] [Accepted: 09/01/2023] [Indexed: 10/05/2023] Open
Abstract
ATPase family AAA domain-containing protein 1 (ATAD1) maintains mitochondrial homeostasis by removing mislocalized tail-anchored (TA) proteins from the mitochondrial outer membrane (MOM). Hepatitis C virus (HCV) infection induces mitochondrial fragmentation, and viral NS5B protein is a TA protein. Here, we investigate whether ATAD1 plays a role in regulating HCV infection. We find that HCV infection has no effect on ATAD1 expression, but knockout of ATAD1 significantly enhances HCV infection; this enhancement is suppressed by ATAD1 complementation. NS5B partially localizes to mitochondria, dependent on its transmembrane domain (TMD), and induces mitochondrial fragmentation, which is further enhanced by ATAD1 knockout. ATAD1 interacts with NS5B, dependent on its three internal domains (TMD, pore-loop 1, and pore-loop 2), and induces the proteasomal degradation of NS5B. In addition, we provide evidence that ATAD1 augments the antiviral function of MAVS upon HCV infection. Taken together, we show that the mitochondrial quality control exerted by ATAD1 can be extended to a novel antiviral function through the extraction of the viral TA-protein NS5B from the mitochondrial outer membrane.
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Affiliation(s)
- Qing Zhou
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
- Technology Center, China Tobacco Henan Industrial Co., LtdZhengzhouChina
- Department of Infectious DiseasesThe Third Affiliated Hospital of Sun Yat‐Sen UniversityGuangzhouChina
| | - Yuhao Yang
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
| | - Zhanxue Xu
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
| | - Kai Deng
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
- Guangzhou Eighth People's HospitalGuangzhou Medical UniversityGuangzhouChina
| | - Zhenzhen Zhang
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
| | - Jiawei Hao
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
| | - Ni Li
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
- Department of Infectious DiseasesThe Third Affiliated Hospital of Sun Yat‐Sen UniversityGuangzhouChina
| | - Yanling Wang
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
| | - Ziwen Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - Haihang Chen
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
| | - Yang Yang
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
| | - Fei Xiao
- Department of Infectious DiseaseThe Fifth Affiliated Hospital of Sun Yat‐sen UniversityZhuhaiChina
| | - Xiaohong Zhang
- Department of Infectious DiseasesThe Third Affiliated Hospital of Sun Yat‐Sen UniversityGuangzhouChina
| | - Song Gao
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - Yi‐Ping Li
- Institute of Human Virology, Department of Pathogen Biology and Biosecurity, and Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
- Department of Infectious DiseasesThe Third Affiliated Hospital of Sun Yat‐Sen UniversityGuangzhouChina
- Department of Infectious DiseaseThe Fifth Affiliated Hospital of Sun Yat‐sen UniversityZhuhaiChina
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9
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Gerber M, Suppanz I, Oeljeklaus S, Niemann M, Käser S, Warscheid B, Schneider A, Dewar CE. A Msp1-containing complex removes orphaned proteins in the mitochondrial outer membrane of T. brucei. Life Sci Alliance 2023; 6:e202302004. [PMID: 37586887 PMCID: PMC10432679 DOI: 10.26508/lsa.202302004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 08/18/2023] Open
Abstract
The AAA-ATPase Msp1 extracts mislocalised outer membrane proteins and thus contributes to mitochondrial proteostasis. Using pulldown experiments, we show that trypanosomal Msp1 localises to both glycosomes and the mitochondrial outer membrane, where it forms a complex with four outer membrane proteins. The trypanosome-specific pATOM36 mediates complex assembly of α-helically anchored mitochondrial outer membrane proteins such as protein translocase subunits. Inhibition of their assembly triggers a pathway that results in the proteasomal digestion of unassembled substrates. Using inducible single, double, and triple RNAi cell lines combined with proteomic analyses, we demonstrate that not only Msp1 but also the trypanosomal homolog of the AAA-ATPase VCP are implicated in this quality control pathway. Moreover, in the absence of VCP three out of the four Msp1-interacting mitochondrial proteins are required for efficient proteasomal digestion of pATOM36 substrates, suggesting they act in concert with Msp1. pATOM36 is a functional analog of the yeast mitochondrial import complex complex and possibly of human mitochondrial animal-specific carrier homolog 2, suggesting that similar mitochondrial quality control pathways linked to Msp1 might also exist in yeast and humans.
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Affiliation(s)
- Markus Gerber
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Ida Suppanz
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Silke Oeljeklaus
- Faculty of Chemistry and Pharmacy, Biochemistry II, Theodor Boveri-Institute, University of Würzburg, Würzburg, Germany
| | - Moritz Niemann
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Sandro Käser
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Bettina Warscheid
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
- Faculty of Chemistry and Pharmacy, Biochemistry II, Theodor Boveri-Institute, University of Würzburg, Würzburg, Germany
| | - André Schneider
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
- Institute for Advanced Study (Wissenschaftskolleg) Berlin, Berlin, Germany
| | - Caroline E Dewar
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
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10
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Uoselis L, Nguyen TN, Lazarou M. Mitochondrial degradation: Mitophagy and beyond. Mol Cell 2023; 83:3404-3420. [PMID: 37708893 DOI: 10.1016/j.molcel.2023.08.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 08/10/2023] [Accepted: 08/17/2023] [Indexed: 09/16/2023]
Abstract
Mitochondria are central hubs of cellular metabolism that also play key roles in signaling and disease. It is therefore fundamentally important that mitochondrial quality and activity are tightly regulated. Mitochondrial degradation pathways contribute to quality control of mitochondrial networks and can also regulate the metabolic profile of mitochondria to ensure cellular homeostasis. Here, we cover the many and varied ways in which cells degrade or remove their unwanted mitochondria, ranging from mitophagy to mitochondrial extrusion. The molecular signals driving these varied pathways are discussed, including the cellular and physiological contexts under which the different degradation pathways are engaged.
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Affiliation(s)
- Louise Uoselis
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD 20185, USA
| | - Thanh Ngoc Nguyen
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD 20185, USA.
| | - Michael Lazarou
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia; Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD 20185, USA.
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11
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Rödl S, Herrmann JM. The role of the proteasome in mitochondrial protein quality control. IUBMB Life 2023; 75:868-879. [PMID: 37178401 DOI: 10.1002/iub.2734] [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: 02/21/2023] [Accepted: 04/15/2023] [Indexed: 05/15/2023]
Abstract
The abundance of each cellular protein is dynamically adjusted to the prevailing metabolic and stress conditions by modulation of their synthesis and degradation rates. The proteasome represents the major machinery for the degradation of proteins in eukaryotic cells. How the ubiquitin-proteasome system (UPS) controls protein levels and removes superfluous and damaged proteins from the cytosol and the nucleus is well characterized. However, recent studies showed that the proteasome also plays a crucial role in mitochondrial protein quality control. This mitochondria-associated degradation (MAD) thereby acts on two layers: first, the proteasome removes mature, functionally compromised or mis-localized proteins from the mitochondrial surface; and second, the proteasome cleanses the mitochondrial import pore of import intermediates of nascent proteins that are stalled during translocation. In this review, we provide an overview about the components and their specific functions that facilitate proteasomal degradation of mitochondrial proteins in the yeast Saccharomyces cerevisiae. Thereby we explain how the proteasome, in conjunction with a set of intramitochondrial proteases, maintains mitochondrial protein homeostasis and dynamically adapts the levels of mitochondrial proteins to specific conditions.
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Affiliation(s)
- Saskia Rödl
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
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12
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Homberg B, Rehling P, Cruz-Zaragoza LD. The multifaceted mitochondrial OXA insertase. Trends Cell Biol 2023; 33:765-772. [PMID: 36863885 DOI: 10.1016/j.tcb.2023.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 03/04/2023]
Abstract
Most mitochondrial proteins are synthesized in the cytosol and transported into mitochondria by protein translocases. Yet, mitochondria contain their own genome and gene expression system, which generates proteins that are inserted in the inner membrane by the oxidase assembly (OXA) insertase. OXA contributes to targeting proteins from both genetic origins. Recent data provides insights into how OXA cooperates with the mitochondrial ribosome during synthesis of mitochondrial-encoded proteins. A picture of OXA emerges in which it coordinates insertion of OXPHOS core subunits and their assembly into protein complexes but also participates in the biogenesis of select imported proteins. These functions position the OXA as a multifunctional protein insertase that facilitates protein transport, assembly, and stability at the inner membrane.
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Affiliation(s)
- Bettina Homberg
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Peter Rehling
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), 37073 University of Göttingen, Germany; Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Translational Neuroinflammation and Automated Microscopy TNM, 37075 Göttingen, Germany; Max Planck Institute for Multidisciplinary Science, 37077 Göttingen, Germany.
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13
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Verhoeven N, Oshima Y, Cartier E, Neutzner A, Boyman L, Karbowski M. Outer mitochondrial membrane E3 Ub ligase MARCH5 controls mitochondrial steps in peroxisome biogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.31.555756. [PMID: 37693581 PMCID: PMC10491203 DOI: 10.1101/2023.08.31.555756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Peroxisome de novo biogenesis requires yet unidentified mitochondrial proteins. We report that the outer mitochondrial membrane (OMM)-associated E3 Ub ligase MARCH5 is vital for generating mitochondria-derived pre-peroxisomes. MARCH5 knockout results in accumulation of immature peroxisomes and lower expression of various peroxisomal proteins. Upon fatty acid-induced peroxisomal biogenesis, MARCH5 redistributes to newly formed peroxisomes; the peroxisomal biogenesis under these conditions is inhibited in MARCH5 knockout cells. MARCH5 activity-deficient mutants are stalled on peroxisomes and induce accumulation of peroxisomes containing high levels of the OMM protein Tom20 (mitochondria-derived pre-peroxisomes). Furthermore, depletion of peroxisome biogenesis factor Pex14 leads to the formation of MARCH5- and Tom20-positive peroxisomes, while no peroxisomes are detected in Pex14/MARCH5 dko cells. Reexpression of WT, but not MARCH5 mutants, restores Tom20-positive pre-peroxisomes in Pex14/MARCH5 dko cells. Thus, MARCH5 acts upstream of Pex14 in mitochondrial steps of peroxisome biogenesis. Our data validate the hybrid, mitochondria-dependent model of peroxisome biogenesis and reveal that MARCH5 is an essential mitochondrial protein in this process. Summary The authors found that mitochondrial E3 Ub ligase MARCH5 controls the formation of mitochondria-derived pre-peroxisomes. The data support the hybrid, mitochondria-dependent model of peroxisome biogenesis and reveal that MARCH5 is an essential mitochondrial protein in this process.
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Anton V, Buntenbroich I, Simões T, Joaquim M, Müller L, Buettner R, Odenthal M, Hoppe T, Escobar-Henriques M. E4 ubiquitin ligase promotes mitofusin turnover and mitochondrial stress response. Mol Cell 2023; 83:2976-2990.e9. [PMID: 37595558 PMCID: PMC10434984 DOI: 10.1016/j.molcel.2023.07.021] [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: 07/08/2022] [Revised: 05/31/2023] [Accepted: 07/18/2023] [Indexed: 08/20/2023]
Abstract
Ubiquitin-dependent control of mitochondrial dynamics is important for protein quality and neuronal integrity. Mitofusins, mitochondrial fusion factors, can integrate cellular stress through their ubiquitylation, which is carried out by multiple E3 enzymes in response to many different stimuli. However, the molecular mechanisms that enable coordinated responses are largely unknown. Here we show that yeast Ufd2, a conserved ubiquitin chain-elongating E4 enzyme, is required for mitochondrial shape adjustments. Under various stresses, Ufd2 translocates to mitochondria and triggers mitofusin ubiquitylation. This elongates ubiquitin chains on mitofusin and promotes its proteasomal degradation, leading to mitochondrial fragmentation. Ufd2 and its human homologue UBE4B also target mitofusin mutants associated with Charcot-Marie-Tooth disease, a hereditary sensory and motor neuropathy characterized by progressive loss of the peripheral nerves. This underscores the pathophysiological importance of E4-mediated ubiquitylation in neurodegeneration. In summary, we identify E4-dependent mitochondrial stress adaptation by linking various metabolic processes to mitochondrial fusion and fission dynamics.
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Affiliation(s)
- Vincent Anton
- Institute for Genetics, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Ira Buntenbroich
- Institute for Genetics, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Tânia Simões
- Institute for Genetics, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Mariana Joaquim
- Institute for Genetics, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), Cologne, Germany
| | - Leonie Müller
- Institute for Genetics, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Reinhard Buettner
- Center for Molecular Medicine Cologne (CMMC), Cologne, Germany; Institute of Pathology, Medical Faculty, University Hospital, University of Cologne, Germany
| | - Margarete Odenthal
- Center for Molecular Medicine Cologne (CMMC), Cologne, Germany; Institute of Pathology, Medical Faculty, University Hospital, University of Cologne, Germany
| | - Thorsten Hoppe
- Institute for Genetics, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), Cologne, Germany
| | - Mafalda Escobar-Henriques
- Institute for Genetics, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), Cologne, Germany.
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15
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Li C, Zhang H, Tong K, Cai M, Gao F, Yang J, Xu Y, Wang H, Chen H, Hu Y, He W, Zhang J. Genetic Deletion of Thorase Causes Purkinje Cell Loss and Impaired Motor Coordination Behavior. Cells 2023; 12:2032. [PMID: 37626842 PMCID: PMC10453921 DOI: 10.3390/cells12162032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 07/30/2023] [Accepted: 08/04/2023] [Indexed: 08/27/2023] Open
Abstract
Thorase belongs to the AAA+ ATPase family, which plays a critical role in maintaining cellular homeostasis. Our previous work reported that Thorase was highly expressed in brain tissue, especially in the cerebellum. However, the roles of Thorase in the cerebellum have still not been characterized. In this study, we generated conditional knockout mice (cKO) with Thorase deletion in Purkinje cells. Thorase cKO mice exhibited cerebellar degenerative diseases-like behavior and significant impairment in motor coordination. Thorase deletion resulted in more Purkinje neuron apoptosis, leading to Purkinje cell loss in the cerebellum of Thorase cKO mice. We also found enhanced expression of the inflammatory protein ASC, IL-1β, IL-6 and TNF-α in the Thorase cKO cerebellum, which contributed to the pathogenesis of cerebellar degenerative disease. Our findings provide a better understanding of the role of Thorase in the cerebellum, which is a theoretical basis for Thorase as a therapeutic drug target for neurodegenerative diseases.
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Affiliation(s)
- Chao Li
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
| | - Han Zhang
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
| | - Kexin Tong
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
| | - Menghua Cai
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
| | - Fei Gao
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
| | - Jia Yang
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
| | - Yi Xu
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
| | - Huaishan Wang
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
| | - Hui Chen
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
- Changzhou Xitaihu Institute for Frontier Technology of Cell Therapy, Changzhou 213000, China
- Haihe Laboratory of Cell Ecosystem, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300010, China
| | - Yu Hu
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
- Changzhou Xitaihu Institute for Frontier Technology of Cell Therapy, Changzhou 213000, China
- Haihe Laboratory of Cell Ecosystem, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300010, China
| | - Wei He
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
| | - Jianmin Zhang
- Department of Immunology, CAMS Key Laboratory T Cell and Cancer Immunotherapy, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, Beijing 100005, China; (C.L.); (H.Z.); (K.T.); (M.C.); (F.G.); (J.Y.); (Y.X.); (H.W.); (H.C.); (Y.H.)
- Changzhou Xitaihu Institute for Frontier Technology of Cell Therapy, Changzhou 213000, China
- Haihe Laboratory of Cell Ecosystem, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300010, China
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16
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Pleiner T, Hazu M, Pinton Tomaleri G, Nguyen VN, Januszyk K, Voorhees RM. A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER. J Cell Biol 2023; 222:e202212007. [PMID: 37199759 PMCID: PMC10200711 DOI: 10.1083/jcb.202212007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 03/31/2023] [Accepted: 04/20/2023] [Indexed: 05/19/2023] Open
Abstract
Tail-anchored (TA) proteins play essential roles in mammalian cells, and their accurate localization is critical for proteostasis. Biophysical similarities lead to mistargeting of mitochondrial TA proteins to the ER, where they are delivered to the insertase, the ER membrane protein complex (EMC). Leveraging an improved structural model of the human EMC, we used mutagenesis and site-specific crosslinking to map the path of a TA protein from its cytosolic capture by methionine-rich loops to its membrane insertion through a hydrophilic vestibule. Positively charged residues at the entrance to the vestibule function as a selectivity filter that uses charge-repulsion to reject mitochondrial TA proteins. Similarly, this selectivity filter retains the positively charged soluble domains of multipass substrates in the cytosol, thereby ensuring they adopt the correct topology and enforcing the "positive-inside" rule. Substrate discrimination by the EMC provides a biochemical explanation for one role of charge in TA protein sorting and protects compartment integrity by limiting protein misinsertion.
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Affiliation(s)
- Tino Pleiner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Masami Hazu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Giovani Pinton Tomaleri
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Vy N. Nguyen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Kurt Januszyk
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Rebecca M. Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
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17
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Abstract
Peroxisomes are involved in a multitude of metabolic and catabolic pathways, as well as the innate immune system. Their dysfunction is linked to severe peroxisome-specific diseases, as well as cancer and neurodegenerative diseases. To ensure the ability of peroxisomes to fulfill their many roles in the organism, more than 100 different proteins are post-translationally imported into the peroxisomal membrane and matrix, and their functionality must be closely monitored. In this Review, we briefly discuss the import of peroxisomal membrane proteins, and we emphasize an updated view of both classical and alternative peroxisomal matrix protein import pathways. We highlight different quality control pathways that ensure the degradation of dysfunctional peroxisomal proteins. Finally, we compare peroxisomal matrix protein import with other systems that transport folded proteins across membranes, in particular the twin-arginine translocation (Tat) system and the nuclear pore.
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Affiliation(s)
- Markus Rudowitz
- Systems Biochemistry , Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany
| | - Ralf Erdmann
- Systems Biochemistry , Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany
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18
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He J, Liu K, Wu Y, Zhao C, Yan S, Chen JH, Hu L, Wang D, Zheng F, Wei W, Xu C, Huang C, Liu X, Yao X, Ding L, Fang Z, Tang AH, Fu C. The AAA-ATPase Yta4/ATAD1 interacts with the mitochondrial divisome to inhibit mitochondrial fission. PLoS Biol 2023; 21:e3002247. [PMID: 37590302 PMCID: PMC10465003 DOI: 10.1371/journal.pbio.3002247] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 08/29/2023] [Accepted: 07/12/2023] [Indexed: 08/19/2023] Open
Abstract
Mitochondria are in a constant balance of fusion and fission. Excessive fission or deficient fusion leads to mitochondrial fragmentation, causing mitochondrial dysfunction and physiological disorders. How the cell prevents excessive fission of mitochondria is not well understood. Here, we report that the fission yeast AAA-ATPase Yta4, which is the homolog of budding yeast Msp1 responsible for clearing mistargeted tail-anchored (TA) proteins on mitochondria, plays a critical role in preventing excessive mitochondrial fission. The absence of Yta4 leads to mild mitochondrial fragmentation in a Dnm1-dependent manner but severe mitochondrial fragmentation upon induction of mitochondrial depolarization. Overexpression of Yta4 delocalizes the receptor proteins of Dnm1, i.e., Fis1 (a TA protein) and Mdv1 (the bridging protein between Fis1 and Dnm1), from mitochondria and reduces the localization of Dnm1 to mitochondria. The effect of Yta4 overexpression on Fis1 and Mdv1, but not Dnm1, depends on the ATPase and translocase activities of Yta4. Moreover, Yta4 interacts with Dnm1, Mdv1, and Fis1. In addition, Yta4 competes with Dnm1 for binding Mdv1 and decreases the affinity of Dnm1 for GTP and inhibits Dnm1 assembly in vitro. These findings suggest a model, in which Yta4 inhibits mitochondrial fission by inhibiting the function of the mitochondrial divisome composed of Fis1, Mdv1, and Dnm1. Therefore, the present work reveals an uncharacterized molecular mechanism underlying the inhibition of mitochondrial fission.
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Affiliation(s)
- Jiajia He
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Ke Liu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Yifan Wu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Chenhui Zhao
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Shuaijie Yan
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Jia-Hui Chen
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei, China
| | - Lizhu Hu
- Anhui Province Key Laboratory of Medical Physics and Technology, Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - Dongmei Wang
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Fan Zheng
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Wenfan Wei
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Chao Xu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Chengdong Huang
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Xing Liu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Xuebiao Yao
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Lijun Ding
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Zhiyou Fang
- Anhui Province Key Laboratory of Medical Physics and Technology, Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - Ai-Hui Tang
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei, China
| | - Chuanhai Fu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
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19
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Fresenius HL, Gaur D, Wohlever ML. The AAA+ protein Msp1 selects substrates by recognizing a hydrophobic mismatch between the substrate transmembrane domain and the lipid bilayer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.11.548587. [PMID: 37502992 PMCID: PMC10369969 DOI: 10.1101/2023.07.11.548587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
An essential aspect of protein quality control is enzymatic removal of membrane proteins from the lipid bilayer. Failures in this essential cellular process are associated with neurodegenerative diseases and cancer. Msp1 is a AAA+ ( A TPases A ssociated with diverse cellular A ctivities) protein that removes mistargeted proteins from the outer mitochondrial membrane (OMM). How Msp1 selectively recognizes and extracts substrates within the complex OMM ecosystem, and the role of the lipid bilayer on these processes is unknown. Here, we describe the development of fully defined, rapid, and quantitative extraction assay that retains physiological substrate selectivity. Using this new assay, we systematically modified both substrates and the lipid environment to demonstrate that Msp1 recognizes substrates by a hydrophobic mismatch between the substrate TMD and the lipid bilayer. We further demonstrate that the rate limiting step in Msp1 activity is extraction of the TMD from the lipid bilayer. Together, these results provide foundational insights into how the lipid bilayer influences AAA+ mediated membrane protein extraction.
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20
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Abstract
Protein translocases, such as the bacterial SecY complex, the Sec61 complex of the endoplasmic reticulum (ER) and the mitochondrial translocases, facilitate the transport of proteins across membranes. In addition, they catalyze the insertion of integral membrane proteins into the lipid bilayer. Several membrane insertases cooperate with these translocases, thereby promoting the topogenesis, folding and assembly of membrane proteins. Oxa1 and BamA family members serve as core components in the two major classes of membrane insertases. They facilitate the integration of proteins with α-helical transmembrane domains and of β-barrel proteins into lipid bilayers, respectively. Members of the Oxa1 family were initially found in the internal membranes of bacteria, mitochondria and chloroplasts. Recent studies, however, also identified several Oxa1-type insertases in the ER, where they serve as catalytically active core subunits in the ER membrane protein complex (EMC), the guided entry of tail-anchored (GET) and the GET- and EMC-like (GEL) complex. The outer membrane of bacteria, mitochondria and chloroplasts contain β-barrel proteins, which are inserted by members of the BamA family. In this Cell Science at a Glance article and the accompanying poster, we provide an overview of these different types of membrane insertases and discuss their function.
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Affiliation(s)
- Büsra Kizmaz
- Cell Biology, University of Kaiserslautern, Kaiserslautern 67663, Germany
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21
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Onishi M, Kubota M, Duan L, Tian Y, Okamoto K. The GET pathway serves to activate Atg32-mediated mitophagy by ER targeting of the Ppg1-Far complex. Life Sci Alliance 2023; 6:e202201640. [PMID: 36697253 PMCID: PMC9880027 DOI: 10.26508/lsa.202201640] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 01/09/2023] [Accepted: 01/09/2023] [Indexed: 01/27/2023] Open
Abstract
Mitophagy removes defective or superfluous mitochondria via selective autophagy. In yeast, the pro-mitophagic protein Atg32 localizes to the mitochondrial surface and interacts with the scaffold protein Atg11 to promote degradation of mitochondria. Although Atg32-Atg11 interactions are thought to be stabilized by Atg32 phosphorylation, how this posttranslational modification is regulated remains obscure. Here, we show that cells lacking the guided entry of the tail-anchored protein (GET) pathway exhibit reduced Atg32 phosphorylation and Atg32-Atg11 interactions, which can be rescued by additional loss of the ER-resident Ppg1-Far complex, a multi-subunit phosphatase negatively acting in mitophagy. In GET-deficient cells, Ppg1-Far is predominantly localized to mitochondria. An artificial ER anchoring of Ppg1-Far in GET-deficient cells significantly ameliorates defects in Atg32-Atg11 interactions and mitophagy. Moreover, disruption of GET and Msp1, an AAA-ATPase that extracts non-mitochondrial proteins localized to the mitochondrial surface, elicits synthetic defects in mitophagy. Collectively, we propose that the GET pathway mediates ER targeting of Ppg1-Far, thereby preventing dysregulated suppression of mitophagy activation.
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Affiliation(s)
- Mashun Onishi
- Laboratory of Mitochondrial Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Mitsutaka Kubota
- Laboratory of Mitochondrial Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Lan Duan
- Laboratory of Mitochondrial Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Yuan Tian
- Laboratory of Mitochondrial Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Koji Okamoto
- Laboratory of Mitochondrial Dynamics, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
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22
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McKenna MJ, Shao S. The Endoplasmic Reticulum and the Fidelity of Nascent Protein Localization. Cold Spring Harb Perspect Biol 2023; 15:a041249. [PMID: 36041782 PMCID: PMC9979852 DOI: 10.1101/cshperspect.a041249] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
High-fidelity protein localization is essential to define the identities and functions of different organelles and to maintain cellular homeostasis. Accurate localization of nascent proteins requires specific protein targeting pathways as well as quality control (QC) mechanisms to remove mislocalized proteins. The endoplasmic reticulum (ER) is the first destination for approximately one-third of the eukaryotic proteome and a major site of protein biosynthesis and QC. In mammalian cells, trafficking from the ER provides nascent proteins access to the extracellular space and essentially every cellular membrane and organelle except for mitochondria and possibly peroxisomes. Here, we discuss the biosynthetic mechanisms that deliver nascent proteins to the ER and the QC mechanisms that interface with the ER to correct or degrade mislocalized proteins.
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Affiliation(s)
- Michael J McKenna
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, Boston, Massachusetts 02115, USA
| | - Sichen Shao
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, Boston, Massachusetts 02115, USA
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23
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Shen X, Sun P, Zhang H, Yang H. Mitochondrial quality control in the brain: The physiological and pathological roles. Front Neurosci 2022; 16:1075141. [PMID: 36578825 PMCID: PMC9791200 DOI: 10.3389/fnins.2022.1075141] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 11/24/2022] [Indexed: 12/14/2022] Open
Abstract
The human brain has high energetic expenses and consumes over 20% of total oxygen metabolism. Abnormal brain energy homeostasis leads to various brain diseases. Among multiple factors that contribute to these diseases, mitochondrial dysfunction is one of the most common causes. Maintenance of mitochondrial integrity and functionality is of pivotal importance to brain energy generation. Mitochondrial quality control (MQC), employing the coordination of multiple mechanisms, is evolved to overcome many mitochondrial defects. Thus, not surprisingly, aberrant mitochondrial quality control results in a wide range of brain disorders. Targeting MQC to preserve and restore mitochondrial function has emerged as a promising therapeutic strategy for the prevention and treatment of brain diseases. Here, we set out to summarize the current understanding of mitochondrial quality control in brain homeostasis. We also evaluate potential pharmaceutically and clinically relevant targets in MQC-associated brain disorders.
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24
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Winter JM, Fresenius HL, Cunningham CN, Wei P, Keys HR, Berg J, Bott A, Yadav T, Ryan J, Sirohi D, Tripp SR, Barta P, Agarwal N, Letai A, Sabatini DM, Wohlever ML, Rutter J. Collateral deletion of the mitochondrial AAA+ ATPase ATAD1 sensitizes cancer cells to proteasome dysfunction. eLife 2022; 11:82860. [PMID: 36409067 DOI: 10.7554/elife.82860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 11/20/2022] [Indexed: 11/23/2022] Open
Abstract
The tumor suppressor gene PTEN is the second most commonly deleted gene in cancer. Such deletions often include portions of the chromosome 10q23 locus beyond the bounds of PTEN itself, which frequently disrupts adjacent genes. Coincidental loss of PTEN-adjacent genes might impose vulnerabilities that could either affect patient outcome basally or be exploited therapeutically. Here, we describe how the loss of ATAD1, which is adjacent to and frequently co-deleted with PTEN, predisposes cancer cells to apoptosis triggered by proteasome dysfunction and correlates with improved survival in cancer patients. ATAD1 directly and specifically extracts the pro-apoptotic protein BIM from mitochondria to inactivate it. Cultured cells and mouse xenografts lacking ATAD1 are hypersensitive to clinically used proteasome inhibitors, which activate BIM and trigger apoptosis. This work furthers our understanding of mitochondrial protein homeostasis and could lead to new therapeutic options for the hundreds of thousands of cancer patients who have tumors with chromosome 10q23 deletion.
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Affiliation(s)
- Jacob M Winter
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Heidi L Fresenius
- Department of Chemistry & Biochemistry, University of Toledo, Toledo, United States
| | - Corey N Cunningham
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Peng Wei
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Heather R Keys
- Whitehead Institute for Biomedical Research, Cambridge, United States
| | - Jordan Berg
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Alex Bott
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Tarun Yadav
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Jeremy Ryan
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, United States
| | - Deepika Sirohi
- University of Utah and ARUP Laboratories, Salt Lake City, United States
| | - Sheryl R Tripp
- University of Utah and ARUP Laboratories, Salt Lake City, United States
| | - Paige Barta
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Neeraj Agarwal
- Huntsman Cancer Institute, University of Utah, Salt Lake City, United States
| | - Anthony Letai
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, United States
| | - David M Sabatini
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Matthew L Wohlever
- Department of Chemistry & Biochemistry, University of Toledo, Toledo, United States
| | - Jared Rutter
- Department of Biochemistry, University of Utah, Salt Lake City, United States.,Huntsman Cancer Institute, University of Utah, Salt Lake City, United States.,Howard Hughes Medical Institute, Salt Lake City, United States
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25
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McKenna MJ, Adams BM, Chu V, Paulo JA, Shao S. ATP13A1 prevents ERAD of folding-competent mislocalized and misoriented proteins. Mol Cell 2022; 82:4277-4289.e10. [PMID: 36283413 PMCID: PMC9675726 DOI: 10.1016/j.molcel.2022.09.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 08/18/2022] [Accepted: 09/26/2022] [Indexed: 11/18/2022]
Abstract
The biosynthesis of thousands of proteins requires targeting a signal sequence or transmembrane segment (TM) to the endoplasmic reticulum (ER). These hydrophobic ɑ helices must localize to the appropriate cellular membrane and integrate in the correct topology to maintain a high-fidelity proteome. Here, we show that the P5A-ATPase ATP13A1 prevents the accumulation of mislocalized and misoriented proteins, which are eliminated by different ER-associated degradation (ERAD) pathways in mammalian cells. Without ATP13A1, mitochondrial tail-anchored proteins mislocalize to the ER through the ER membrane protein complex and are cleaved by signal peptide peptidase for ERAD. ATP13A1 also facilitates the topogenesis of a subset of proteins with an N-terminal TM or signal sequence that should insert into the ER membrane with a cytosolic N terminus. Without ATP13A1, such proteins accumulate in the wrong orientation and are targeted for ERAD by distinct ubiquitin ligases. Thus, ATP13A1 prevents ERAD of diverse proteins capable of proper folding.
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Affiliation(s)
- Michael J McKenna
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Benjamin M Adams
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Vincent Chu
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Sichen Shao
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA.
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26
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Mitochondrial proteotoxicity: implications and ubiquitin-dependent quality control mechanisms. Cell Mol Life Sci 2022; 79:574. [DOI: 10.1007/s00018-022-04604-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 06/04/2022] [Accepted: 10/17/2022] [Indexed: 11/27/2022]
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27
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Bittner E, Stehlik T, Freitag J. Sharing the wealth: The versatility of proteins targeted to peroxisomes and other organelles. Front Cell Dev Biol 2022; 10:934331. [PMID: 36225313 PMCID: PMC9549241 DOI: 10.3389/fcell.2022.934331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 07/27/2022] [Indexed: 11/13/2022] Open
Abstract
Peroxisomes are eukaryotic organelles with critical functions in cellular energy and lipid metabolism. Depending on the organism, cell type, and developmental stage, they are involved in numerous other metabolic and regulatory pathways. Many peroxisomal functions require factors also relevant to other cellular compartments. Here, we review proteins shared by peroxisomes and at least one different site within the cell. We discuss the mechanisms to achieve dual targeting, their regulation, and functional consequences. Characterization of dual targeting is fundamental to understand how peroxisomes are integrated into the metabolic and regulatory circuits of eukaryotic cells.
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Affiliation(s)
| | | | - Johannes Freitag
- Department of Biology, Philipps-University Marburg, Marburg, Germany
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28
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Umanah GKE, Abalde-Atristain L, Khan MR, Mitra J, Dar MA, Chang M, Tangella K, McNamara A, Bennett S, Chen R, Aggarwal V, Cortes M, Worley PF, Ha T, Dawson TM, Dawson VL. AAA + ATPase Thorase inhibits mTOR signaling through the disassembly of the mTOR complex 1. Nat Commun 2022; 13:4836. [PMID: 35977929 PMCID: PMC9385847 DOI: 10.1038/s41467-022-32365-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 07/26/2022] [Indexed: 11/09/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) signals through the mTOR complex 1 (mTORC1) and the mTOR complex 2 to maintain cellular and organismal homeostasis. Failure to finely tune mTOR activity results in metabolic dysregulation and disease. While there is substantial understanding of the molecular events leading mTORC1 activation at the lysosome, remarkably little is known about what terminates mTORC1 signaling. Here, we show that the AAA + ATPase Thorase directly binds mTOR, thereby orchestrating the disassembly and inactivation of mTORC1. Thorase disrupts the association of mTOR to Raptor at the mitochondria-lysosome interface and this action is sensitive to amino acids. Lack of Thorase causes accumulation of mTOR-Raptor complexes and altered mTORC1 disassembly/re-assembly dynamics upon changes in amino acid availability. The resulting excessive mTORC1 can be counteracted with rapamycin in vitro and in vivo. Collectively, we reveal Thorase as a key component of the mTOR pathway that disassembles and thus inhibits mTORC1.
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Affiliation(s)
- George K E Umanah
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Division of Neuroscience, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Leire Abalde-Atristain
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Cellular and Molecular Medicine Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Vollum Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Mohammed Repon Khan
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Jaba Mitra
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Mohamad Aasif Dar
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Melissa Chang
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Kavya Tangella
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Amy McNamara
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Samuel Bennett
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Rong Chen
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Vasudha Aggarwal
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Marisol Cortes
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Paul F Worley
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Taekjip Ha
- Departments of Biophysics and Biophysical Chemistry, Biophysics and Biomedical Engineering, JHU Howard Hughes Medical Institute, Baltimore, MD, 21205, USA
| | - Ted M Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Cellular and Molecular Medicine Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
| | - Valina L Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Cellular and Molecular Medicine Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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29
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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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30
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Sinning I, McDowell MA. Cryo-EM insights into tail-anchored membrane protein biogenesis in eukaryotes. Curr Opin Struct Biol 2022; 75:102428. [PMID: 35850079 DOI: 10.1016/j.sbi.2022.102428] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/10/2022] [Accepted: 06/16/2022] [Indexed: 11/03/2022]
Abstract
Tail-anchored (TA) proteins are a biologically significant class of membrane proteins, which require specialised cellular pathways to insert their single C-terminal transmembrane domain into the correct membrane. Cryo-electron microscopy has recently provided new insights into the organelle-specific machineries for TA protein biogenesis. Structures of targeting and insertase complexes within the canonical guided entry of TA proteins (GET) pathway indicate how substrates are faithfully chaperoned into the endoplasmic reticulum (ER) membrane in metazoans. The core of the GET insertase is conserved within structures of the ER membrane protein complex (EMC), which acts in parallel to insert a different subset of TA proteins. Furthermore, structures of the dislocases Spf1 and Msp1 show how they remove mislocalised TA proteins from the ER and outer mitochondrial membranes respectively.
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Affiliation(s)
- Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
| | - Melanie A McDowell
- Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt Am Main, Germany.
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31
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Matsumoto S, Ono S, Shinoda S, Kakuta C, Okada S, Ito T, Numata T, Endo T. GET pathway mediates transfer of mislocalized tail-anchored proteins from mitochondria to the ER. J Cell Biol 2022; 221:213171. [PMID: 35442388 DOI: 10.1083/jcb.202104076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 01/18/2022] [Accepted: 03/14/2022] [Indexed: 11/22/2022] Open
Abstract
Tail-anchored (TA) membrane proteins have a potential risk to be mistargeted to the mitochondrial outer membrane (OM). Such mislocalized TA proteins can be extracted by the mitochondrial AAA-ATPase Msp1 from the OM and transferred to the ER for ER protein quality control involving ubiquitination by the ER-resident Doa10 complex. Yet it remains unclear how the extracted TA proteins can move to the ER crossing the aqueous cytosol and whether this transfer to the ER is essential for the clearance of mislocalized TA proteins. Here we show by time-lapse microscopy that mislocalized TA proteins, including an authentic ER-TA protein, indeed move from mitochondria to the ER in a manner strictly dependent on Msp1 expression. The Msp1-dependent mitochondria-to-ER transfer of TA proteins is blocked by defects in the GET system, and this block is not due to impaired Doa10 functions. Thus, the GET pathway facilitates the transfer of mislocalized TA proteins from mitochondria to the ER.
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Affiliation(s)
- Shunsuke Matsumoto
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Kyoto, Japan.,Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Suzuka Ono
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Kyoto, Japan
| | - Saori Shinoda
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
| | - Chika Kakuta
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
| | - Satoshi Okada
- Department of Biochemistry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Takashi Ito
- Department of Biochemistry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Tomoyuki Numata
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Toshiya Endo
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Kyoto, Japan
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32
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Wang L, Toutkoushian H, Belyy V, Kokontis CY, Walter P. Conserved structural elements specialize ATAD1 as a membrane protein extraction machine. eLife 2022; 11:e73941. [PMID: 35550246 PMCID: PMC9273213 DOI: 10.7554/elife.73941] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 05/12/2022] [Indexed: 11/13/2022] Open
Abstract
The mitochondrial AAA (ATPase Associated with diverse cellular Activities) protein ATAD1 (in humans; Msp1 in yeast) removes mislocalized membrane proteins, as well as stuck import substrates from the mitochondrial outer membrane, facilitating their re-insertion into their cognate organelles and maintaining mitochondria's protein import capacity. In doing so, it helps to maintain proteostasis in mitochondria. How ATAD1 tackles the energetic challenge to extract hydrophobic membrane proteins from the lipid bilayer and what structural features adapt ATAD1 for its particular function has remained a mystery. Previously, we determined the structure of Msp1 in complex with a peptide substrate (Wang et al., 2020). The structure showed that Msp1's mechanism follows the general principle established for AAA proteins while adopting several structural features that specialize it for its function. Among these features in Msp1 was the utilization of multiple aromatic amino acids to firmly grip the substrate in the central pore. However, it was not clear whether the aromatic nature of these amino acids were required, or if they could be functionally replaced by aliphatic amino acids. In this work, we determined the cryo-EM structures of the human ATAD1 in complex with a peptide substrate at near atomic resolution. The structures show that phylogenetically conserved structural elements adapt ATAD1 for its function while generally adopting a conserved mechanism shared by many AAA proteins. We developed a microscopy-based assay reporting on protein mislocalization, with which we directly assessed ATAD1's activity in live cells and showed that both aromatic amino acids in pore-loop 1 are required for ATAD1's function and cannot be substituted by aliphatic amino acids. A short α-helix at the C-terminus strongly facilitates ATAD1's oligomerization, a structural feature that distinguishes ATAD1 from its closely related proteins.
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Affiliation(s)
- Lan Wang
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, University of California at San FranciscoSan FranciscoUnited States
| | - Hannah Toutkoushian
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, University of California at San FranciscoSan FranciscoUnited States
| | - Vladislav Belyy
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, University of California at San FranciscoSan FranciscoUnited States
| | - Claire Y Kokontis
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
| | - Peter Walter
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, University of California at San FranciscoSan FranciscoUnited States
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33
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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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34
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Song J, Becker T. Fidelity of organellar protein targeting. Curr Opin Cell Biol 2022; 75:102071. [DOI: 10.1016/j.ceb.2022.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 11/26/2022]
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35
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Jomaa A, Gamerdinger M, Hsieh HH, Wallisch A, Chandrasekaran V, Ulusoy Z, Scaiola A, Hegde RS, Shan SO, Ban N, Deuerling E. Mechanism of signal sequence handover from NAC to SRP on ribosomes during ER-protein targeting. Science 2022; 375:839-844. [PMID: 35201867 PMCID: PMC7612438 DOI: 10.1126/science.abl6459] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The nascent polypeptide-associated complex (NAC) interacts with newly synthesized proteins at the ribosomal tunnel exit and competes with the signal recognition particle (SRP) to prevent mistargeting of cytosolic and mitochondrial polypeptides to the endoplasmic reticulum (ER). How NAC antagonizes SRP and how this is overcome by ER targeting signals are unknown. Here, we found that NAC uses two domains with opposing effects to control SRP access. The core globular domain prevented SRP from binding to signal-less ribosomes, whereas a flexibly attached domain transiently captured SRP to permit scanning of nascent chains. The emergence of an ER-targeting signal destabilized NAC's globular domain and facilitated SRP access to the nascent chain. These findings elucidate how NAC hands over the signal sequence to SRP and imparts specificity of protein localization.
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Affiliation(s)
- Ahmad Jomaa
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
| | - Martin Gamerdinger
- Department of Biology, Molecular Microbiology, University of Konstanz, 78457 Konstanz, Germany
| | - Hao-Hsuan Hsieh
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Annalena Wallisch
- Department of Biology, Molecular Microbiology, University of Konstanz, 78457 Konstanz, Germany
| | | | - Zeynel Ulusoy
- Department of Biology, Molecular Microbiology, University of Konstanz, 78457 Konstanz, Germany
| | - Alain Scaiola
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
| | | | - Shu-ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Nenad Ban
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
| | - Elke Deuerling
- Department of Biology, Molecular Microbiology, University of Konstanz, 78457 Konstanz, Germany
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36
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Hegde RS, Keenan RJ. The mechanisms of integral membrane protein biogenesis. Nat Rev Mol Cell Biol 2022; 23:107-124. [PMID: 34556847 DOI: 10.1038/s41580-021-00413-2] [Citation(s) in RCA: 84] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/06/2021] [Indexed: 02/08/2023]
Abstract
Roughly one quarter of all genes code for integral membrane proteins that are inserted into the plasma membrane of prokaryotes or the endoplasmic reticulum membrane of eukaryotes. Multiple pathways are used for the targeting and insertion of membrane proteins on the basis of their topological and biophysical characteristics. Multipass membrane proteins span the membrane multiple times and face the additional challenges of intramembrane folding. In many cases, integral membrane proteins require assembly with other proteins to form multi-subunit membrane protein complexes. Recent biochemical and structural analyses have provided considerable clarity regarding the molecular basis of membrane protein targeting and insertion, with tantalizing new insights into the poorly understood processes of multipass membrane protein biogenesis and multi-subunit protein complex assembly.
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Affiliation(s)
- Ramanujan S Hegde
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, UK.
| | - Robert J Keenan
- Gordon Center for Integrative Science, The University of Chicago, Chicago, IL, USA.
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37
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Hsieh HH, Shan SO. Fidelity of Cotranslational Protein Targeting to the Endoplasmic Reticulum. Int J Mol Sci 2021; 23:ijms23010281. [PMID: 35008707 PMCID: PMC8745203 DOI: 10.3390/ijms23010281] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 02/04/2023] Open
Abstract
Fidelity of protein targeting is essential for the proper biogenesis and functioning of organelles. Unlike replication, transcription and translation processes, in which multiple mechanisms to recognize and reject noncognate substrates are established in energetic and molecular detail, the mechanisms by which cells achieve a high fidelity in protein localization remain incompletely understood. Signal recognition particle (SRP), a conserved pathway to mediate the localization of membrane and secretory proteins to the appropriate cellular membrane, provides a paradigm to understand the molecular basis of protein localization in the cell. In this chapter, we review recent progress in deciphering the molecular mechanisms and substrate selection of the mammalian SRP pathway, with an emphasis on the key role of the cotranslational chaperone NAC in preventing protein mistargeting to the ER and in ensuring the organelle specificity of protein localization.
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38
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den Brave F, Gupta A, Becker T. Protein Quality Control at the Mitochondrial Surface. Front Cell Dev Biol 2021; 9:795685. [PMID: 34926473 PMCID: PMC8678412 DOI: 10.3389/fcell.2021.795685] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 11/05/2021] [Indexed: 12/14/2022] Open
Abstract
Mitochondria contain two membranes, the outer and inner membrane. The outer membrane fulfills crucial functions for the communication of mitochondria with the cellular environment like exchange of lipids via organelle contact sites, the transport of metabolites and the formation of a signaling platform in apoptosis and innate immunity. The translocase of the outer membrane (TOM complex) forms the entry gate for the vast majority of precursor proteins that are produced on cytosolic ribosomes. Surveillance of the functionality of outer membrane proteins is critical for mitochondrial functions and biogenesis. Quality control mechanisms remove defective and mistargeted proteins from the outer membrane as well as precursor proteins that clog the TOM complex. Selective degradation of single proteins is also an important mode to regulate mitochondrial dynamics and initiation of mitophagy pathways. Whereas inner mitochondrial compartments are equipped with specific proteases, the ubiquitin-proteasome system is a central player in protein surveillance on the mitochondrial surface. In this review, we summarize our current knowledge about the molecular mechanisms that govern quality control of proteins at the outer mitochondrial membrane.
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Affiliation(s)
- Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Arushi Gupta
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
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39
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Mehlhorn DG, Asseck LY, Grefen C. Looking for a safe haven: tail-anchored proteins and their membrane insertion pathways. PLANT PHYSIOLOGY 2021; 187:1916-1928. [PMID: 35235667 PMCID: PMC8644595 DOI: 10.1093/plphys/kiab298] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/05/2021] [Indexed: 06/14/2023]
Abstract
Insertion of membrane proteins into the lipid bilayer is a crucial step during their biosynthesis. Eukaryotic cells face many challenges in directing these proteins to their predestined target membrane. The hydrophobic signal peptide or transmembrane domain (TMD) of the nascent protein must be shielded from the aqueous cytosol and its target membrane identified followed by transport and insertion. Components that evolved to deal with each of these challenging steps range from chaperones to receptors, insertases, and sophisticated translocation complexes. One prominent translocation pathway for most proteins is the signal recognition particle (SRP)-dependent pathway which mediates co-translational translocation of proteins across or into the endoplasmic reticulum (ER) membrane. This textbook example of protein insertion is stretched to its limits when faced with secretory or membrane proteins that lack an amino-terminal signal sequence or TMD. Particularly, a large group of so-called tail-anchored (TA) proteins that harbor a single carboxy-terminal TMD require an alternative, post-translational insertion route into the ER membrane. In this review, we summarize the current research in TA protein insertion with a special focus on plants, address challenges, and highlight future research avenues.
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Affiliation(s)
- Dietmar G Mehlhorn
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Lisa Y Asseck
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Christopher Grefen
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
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40
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Vögtle FN, Meisinger C. Mitochondria as emergency landing for abandoned peroxins. EMBO Rep 2021; 22:e53790. [PMID: 34414648 PMCID: PMC8490976 DOI: 10.15252/embr.202153790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 11/28/2022] Open
Abstract
Zellweger spectrum disorder (ZSD) is the most severe peroxisomal biogenesis disorder (PBD). Why ZSD patients not only loose functional peroxisomes but also present with severe mitochondrial dysfunction was a long‐standing mystery. In this issue, Nuebel et al (2021) identified that loss of peroxisomes leads to re‐routing of peroxisomal proteins to mitochondria, thereby impairing mitochondrial structure and function. The findings provide the first molecular understanding of the mitochondrial‐peroxisomal link in ZSD.
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Affiliation(s)
- F-Nora Vögtle
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Network Aging Research, Heidelberg University, Heidelberg, Germany.,CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Chris Meisinger
- CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany.,Faculty of Medicine, Institute of Biochemistry and Molecular Biology, ZBMZ, 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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Koch C, Schuldiner M, Herrmann JM. ER-SURF: Riding the Endoplasmic Reticulum Surface to Mitochondria. Int J Mol Sci 2021; 22:9655. [PMID: 34502567 PMCID: PMC8432098 DOI: 10.3390/ijms22179655] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 08/29/2021] [Indexed: 02/08/2023] Open
Abstract
Most mitochondrial proteins are synthesized in the cytosol and targeted to the mitochondrial surface in a post-translational manner. The surface of the endoplasmic reticulum (ER) plays an active role in this targeting reaction. ER-associated chaperones interact with certain mitochondrial membrane protein precursors and transfer them onto receptor proteins of the mitochondrial surface in a process termed ER-SURF. ATP-driven proteins in the membranes of mitochondria (Msp1, ATAD1) and the ER (Spf1, P5A-ATPase) serve as extractors for the removal of mislocalized proteins. If the re-routing to mitochondria fails, precursors can be degraded by ER or mitochondria-associated degradation (ERAD or MAD respectively) in a proteasome-mediated reaction. This review summarizes the current knowledge about the cooperation of the ER and mitochondria in the targeting and quality control of mitochondrial precursor proteins.
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Affiliation(s)
- Christian Koch
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany;
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel;
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42
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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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43
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Abstract
Lipid droplets (LDs) are endoplasmic reticulum-derived organelles that consist of a core of neutral lipids encircled by a phospholipid monolayer decorated with proteins. As hubs of cellular lipid and energy metabolism, LDs are inherently involved in the etiology of prevalent metabolic diseases such as obesity and nonalcoholic fatty liver disease. The functions of LDs are regulated by a unique set of associated proteins, the LD proteome, which includes integral membrane and peripheral proteins. These proteins control key activities of LDs such as triacylglycerol synthesis and breakdown, nutrient sensing and signal integration, and interactions with other organelles. Here we review the mechanisms that regulate the composition of the LD proteome, such as pathways that mediate selective and bulk LD protein degradation and potential connections between LDs and cellular protein quality control.
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Affiliation(s)
- Melissa A Roberts
- Department of Molecular and Cell Biology and Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720, USA;
| | - James A Olzmann
- Department of Molecular and Cell Biology and Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720, USA; .,Chan Zuckerberg Biohub, San Francisco, California 94158, USA
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44
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Nuebel E, Morgan JT, Fogarty S, Winter JM, Lettlova S, Berg JA, Chen YC, Kidwell CU, Maschek JA, Clowers KJ, Argyriou C, Chen L, Wittig I, Cox JE, Roh-Johnson M, Braverman N, Bonkowsky J, Gygi SP, Rutter J. The biochemical basis of mitochondrial dysfunction in Zellweger Spectrum Disorder. EMBO Rep 2021; 22:e51991. [PMID: 34351705 DOI: 10.15252/embr.202051991] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 06/21/2021] [Accepted: 07/12/2021] [Indexed: 01/09/2023] Open
Abstract
Peroxisomal biogenesis disorders (PBDs) are genetic disorders of peroxisome biogenesis and metabolism that are characterized by profound developmental and neurological phenotypes. The most severe class of PBDs-Zellweger spectrum disorder (ZSD)-is caused by mutations in peroxin genes that result in both non-functional peroxisomes and mitochondrial dysfunction. It is unclear, however, how defective peroxisomes contribute to mitochondrial impairment. In order to understand the molecular basis of this inter-organellar relationship, we investigated the fate of peroxisomal mRNAs and proteins in ZSD model systems. We found that peroxins were still expressed and a subset of them accumulated on the mitochondrial membrane, which resulted in gross mitochondrial abnormalities and impaired mitochondrial metabolic function. We showed that overexpression of ATAD1, a mitochondrial quality control factor, was sufficient to rescue several aspects of mitochondrial function in human ZSD fibroblasts. Together, these data suggest that aberrant peroxisomal protein localization is necessary and sufficient for the devastating mitochondrial morphological and metabolic phenotypes in ZSDs.
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Affiliation(s)
- Esther Nuebel
- Howard Hughes Medical Institute, Salt Lake City, UT, USA.,Department of Biochemistry, University of Utah, Salt Lake City, UT, USA.,Department of Biomedical Sciences, Noorda College of Osteopathic Medicine, Provo, USA
| | - Jeffrey T Morgan
- Howard Hughes Medical Institute, Salt Lake City, UT, USA.,Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Sarah Fogarty
- Howard Hughes Medical Institute, Salt Lake City, UT, USA.,Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Jacob M Winter
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Sandra Lettlova
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Jordan A Berg
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Yu-Chan Chen
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Chelsea U Kidwell
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - J Alan Maschek
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA.,Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA.,Metabolomics, Proteomics and Mass Spectrometry Core Research Facilities, University of Utah, Salt Lake City, UT, USA
| | - Katie J Clowers
- Department of Cell Biology, Harvard University School of Medicine, Boston, MA, USA
| | | | - Lingxiao Chen
- Department of Pathology, McGill University, Montreal, ON, Canada
| | - Ilka Wittig
- Functional Proteomics, Faculty of Medicine, Goethe University, Frankfurt am Main, Germany
| | - James E Cox
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA.,Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA.,Metabolomics, Proteomics and Mass Spectrometry Core Research Facilities, University of Utah, Salt Lake City, UT, USA
| | - Minna Roh-Johnson
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Nancy Braverman
- Department of Human Genetics, McGill University, Montreal, ON, Canada.,Department of Pediatrics, Research Institute of the McGill University Health Centre, Montreal, ON, Canada
| | - Joshua Bonkowsky
- Primary Children's Hospital, University of Utah, Salt Lake City, UT, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard University School of Medicine, Boston, MA, USA
| | - Jared Rutter
- Howard Hughes Medical Institute, Salt Lake City, UT, USA.,Department of Biochemistry, University of Utah, Salt Lake City, UT, USA.,Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
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45
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Friedlander JE, Shen N, Zeng A, Korm S, Feng H. Failure to Guard: Mitochondrial Protein Quality Control in Cancer. Int J Mol Sci 2021; 22:ijms22158306. [PMID: 34361072 PMCID: PMC8348654 DOI: 10.3390/ijms22158306] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 07/20/2021] [Accepted: 07/27/2021] [Indexed: 02/07/2023] Open
Abstract
Mitochondria are energetic and dynamic organelles with a crucial role in bioenergetics, metabolism, and signaling. Mitochondrial proteins, encoded by both nuclear and mitochondrial DNA, must be properly regulated to ensure proteostasis. Mitochondrial protein quality control (MPQC) serves as a critical surveillance system, employing different pathways and regulators as cellular guardians to ensure mitochondrial protein quality and quantity. In this review, we describe key pathways and players in MPQC, such as mitochondrial protein translocation-associated degradation, mitochondrial stress responses, chaperones, and proteases, and how they work together to safeguard mitochondrial health and integrity. Deregulated MPQC leads to proteotoxicity and dysfunctional mitochondria, which contributes to numerous human diseases, including cancer. We discuss how alterations in MPQC components are linked to tumorigenesis, whether they act as drivers, suppressors, or both. Finally, we summarize recent advances that seek to target these alterations for the development of anti-cancer drugs.
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Affiliation(s)
- Joseph E. Friedlander
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; (J.E.F.); (N.S.); (A.Z.); (S.K.)
| | - Ning Shen
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; (J.E.F.); (N.S.); (A.Z.); (S.K.)
- Department of Medicine, Section of Hematology and Medical Oncology, Boston University School of Medicine, Boston, MA 02118, USA
| | - Aozhuo Zeng
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; (J.E.F.); (N.S.); (A.Z.); (S.K.)
| | - Sovannarith Korm
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; (J.E.F.); (N.S.); (A.Z.); (S.K.)
| | - Hui Feng
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA; (J.E.F.); (N.S.); (A.Z.); (S.K.)
- Department of Medicine, Section of Hematology and Medical Oncology, Boston University School of Medicine, Boston, MA 02118, USA
- Correspondence: ; Tel.: +1-617-358-4688; Fax: +1-617-358-1599
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46
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Phillips BP, Miller EA. Membrane protein folding and quality control. Curr Opin Struct Biol 2021; 69:50-54. [PMID: 33857720 PMCID: PMC8422161 DOI: 10.1016/j.sbi.2021.03.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/01/2021] [Accepted: 03/09/2021] [Indexed: 12/21/2022]
Abstract
Membrane proteins account for a quarter of cellular proteins, and most are synthesised at the endoplasmic reticulum (ER). Insertion and folding of polypeptides in the membrane environment is prone to error, necessitating diverse quality control systems. Recent discoveries have demonstrated how forces act on the nascent chain during insertion, and revealed new translocon components and accessories that facilitate the correct biogenesis of substrates. Our understanding of one of the best studied quality control systems-ER-associated degradation-has been advanced through new structural and functional studies of the core Hrd1 complex, and through the discovery of a new branch of this degradative pathway. New data also reveal how cells resolve clogged translocons, which would otherwise be unable to function. Finally, new work elucidates how mitochondrial tail-anchored proteins that have been mistargeted to the ER are identified and destroyed. Overall, we describe an emerging picture of an increasingly complex quality control network.
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Affiliation(s)
- Ben P Phillips
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Elizabeth A Miller
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK.
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47
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Farkas Á, Bohnsack KE. Capture and delivery of tail-anchored proteins to the endoplasmic reticulum. J Cell Biol 2021; 220:212470. [PMID: 34264263 PMCID: PMC8287540 DOI: 10.1083/jcb.202105004] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/20/2021] [Accepted: 06/22/2021] [Indexed: 11/22/2022] Open
Abstract
Tail-anchored (TA) proteins fulfill diverse cellular functions within different organellar membranes. Their characteristic C-terminal transmembrane segment renders TA proteins inherently prone to aggregation and necessitates their posttranslational targeting. The guided entry of TA proteins (GET in yeast)/transmembrane recognition complex (TRC in humans) pathway represents a major route for TA proteins to the endoplasmic reticulum (ER). Here, we review important new insights into the capture of nascent TA proteins at the ribosome by the GET pathway pretargeting complex and the mechanism of their delivery into the ER membrane by the GET receptor insertase. Interestingly, several alternative routes by which TA proteins can be targeted to the ER have emerged, raising intriguing questions about how selectivity is achieved during TA protein capture. Furthermore, mistargeting of TA proteins is a fundamental cellular problem, and we discuss the recently discovered quality control machineries in the ER and outer mitochondrial membrane for displacing mislocalized TA proteins.
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Affiliation(s)
- Ákos Farkas
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
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48
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Dederer V, Lemberg MK. Transmembrane dislocases: a second chance for protein targeting. Trends Cell Biol 2021; 31:898-911. [PMID: 34147299 DOI: 10.1016/j.tcb.2021.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/11/2021] [Accepted: 05/14/2021] [Indexed: 12/31/2022]
Abstract
Precise distribution of proteins is essential to sustain the viability of cells. A complex network of protein synthesis and targeting factors cooperate with protein quality control systems to ensure protein homeostasis. Defective proteins are inevitably degraded by the ubiquitin-proteasome system and lysosomes. However, due to overlapping targeting information and limited targeting fidelity, certain proteins become mislocalized. In this review, we present the idea that transmembrane dislocases recognize and remove mislocalized membrane proteins from cellular organelles. This enables other targeting attempts and prevents degradation of mislocalized but otherwise functional proteins. These transmembrane dislocases can be found in the outer mitochondrial membrane (OMM) and endoplasmic reticulum (ER). We highlight common principles regarding client recognition and outline open questions in our understanding of transmembrane dislocases.
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Affiliation(s)
- Verena Dederer
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; Current address: Institute for Pharmaceutical Biology and Buchmann Institute for Molecular Life Science, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Marius K Lemberg
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, 50931 Cologne, Germany.
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49
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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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50
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Bentebbal SA, Meqbel BR, Salter A, Allan V, Burke B, Horn HF. A human infertility-associated KASH5 variant promotes mitochondrial localization. Sci Rep 2021; 11:10133. [PMID: 33980926 PMCID: PMC8115505 DOI: 10.1038/s41598-021-89439-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 04/22/2021] [Indexed: 02/03/2023] Open
Abstract
KASH5 is the most recently identified member of the KASH domain family of tail anchored, outer nuclear membrane (ONM) and endoplasmic reticulum (ER) proteins. During meiosis prophase I, KASH5 and SUN1 form a complex that spans the nuclear envelope and which links the telomeres of meiotic chromosomes to cytoplasmic dynein. This connection is essential for homologous chromosome dynamics and pairing. A recent study identified a variant in human KASH5 (L535Q) that correlated with male infertility associated with azoospermia. However, no molecular mechanism was described. Here, we report that this amino acid substitution, within the KASH5 transmembrane domain (TMD) has no predicted effects on secondary structure. However, the overall hydrophobicity of the L535Q TMD, is calculated to be lower than the wild-type KASH5, based on the GES (Goldman-Engelman-Steitz) amino acid hydrophobicity scale. This change in hydrophobicity profoundly affects the subcellular localization of KASH5. Through a series of amino acid substitution studies, we show that the L535Q substitution perturbs KASH5 localization to the ER and ONM and instead results in mistargeting to the mitochondria membrane. We suggest that this mislocalization accounts for the infertility and azoospermia phenotype in patients.
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Affiliation(s)
- Sana A. Bentebbal
- grid.452146.00000 0004 1789 3191College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| | - Bakhita R. Meqbel
- grid.452146.00000 0004 1789 3191College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| | - Anna Salter
- grid.5379.80000000121662407Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT UK ,grid.185448.40000 0004 0637 0221Laboratory of Nuclear Dynamics and Architecture, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Victoria Allan
- grid.5379.80000000121662407Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT UK
| | - Brian Burke
- grid.185448.40000 0004 0637 0221Laboratory of Nuclear Dynamics and Architecture, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Henning F. Horn
- grid.452146.00000 0004 1789 3191College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
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