1
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Busto JV, Ganesan I, Mathar H, Steiert C, Schneider EF, Straub SP, Ellenrieder L, Song J, Stiller SB, Lübbert P, Chatterjee R, Elsaesser J, Melchionda L, Schug C, den Brave F, Schulte U, Klecker T, Kraft C, Fakler B, Becker T, Wiedemann N. Role of the small protein Mco6 in the mitochondrial sorting and assembly machinery. Cell Rep 2024; 43:113805. [PMID: 38377000 DOI: 10.1016/j.celrep.2024.113805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 12/22/2023] [Accepted: 01/31/2024] [Indexed: 02/22/2024] Open
Abstract
The majority of mitochondrial precursor proteins are imported through the Tom40 β-barrel channel of the translocase of the outer membrane (TOM). The sorting and assembly machinery (SAM) is essential for β-barrel membrane protein insertion into the outer membrane and thus required for the assembly of the TOM complex. Here, we demonstrate that the α-helical outer membrane protein Mco6 co-assembles with the mitochondrial distribution and morphology protein Mdm10 as part of the SAM machinery. MCO6 and MDM10 display a negative genetic interaction, and a mco6-mdm10 yeast double mutant displays reduced levels of the TOM complex. Cells lacking Mco6 affect the levels of Mdm10 and show assembly defects of the TOM complex. Thus, this work uncovers a role of the SAMMco6 complex for the biogenesis of the mitochondrial outer membrane.
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Affiliation(s)
- Jon V Busto
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Iniyan Ganesan
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Hannah Mathar
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Conny Steiert
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Eva F Schneider
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sebastian P Straub
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Lars Ellenrieder
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jiyao Song
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Sebastian B Stiller
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Philipp Lübbert
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ritwika Chatterjee
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Jana Elsaesser
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Laura Melchionda
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christina Schug
- Institute of Cell Biology, University of Bayreuth, Bayreuth, Germany
| | - Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Uwe Schulte
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Till Klecker
- Institute of Cell Biology, University of Bayreuth, Bayreuth, Germany
| | - Claudine Kraft
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany; Center for Basics in NeuroModulation, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany.
| | - Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany.
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2
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Muthukumar G, Stevens TA, Inglis AJ, Esantsi TK, Saunders RA, Schulte F, Voorhees RM, Guna A, Weissman JS. Triaging of α-helical proteins to the mitochondrial outer membrane by distinct chaperone machinery based on substrate topology. Mol Cell 2024; 84:1101-1119.e9. [PMID: 38428433 DOI: 10.1016/j.molcel.2024.01.028] [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: 07/31/2023] [Revised: 12/08/2023] [Accepted: 01/31/2024] [Indexed: 03/03/2024]
Abstract
Mitochondrial outer membrane ⍺-helical proteins play critical roles in mitochondrial-cytoplasmic communication, but the rules governing the targeting and insertion of these biophysically diverse proteins remain unknown. Here, we first defined the complement of required mammalian biogenesis machinery through genome-wide CRISPRi screens using topologically distinct membrane proteins. Systematic analysis of nine identified factors across 21 diverse ⍺-helical substrates reveals that these components are organized into distinct targeting pathways that act on substrates based on their topology. NAC is required for the efficient targeting of polytopic proteins, whereas signal-anchored proteins require TTC1, a cytosolic chaperone that physically engages substrates. Biochemical and mutational studies reveal that TTC1 employs a conserved TPR domain and a hydrophobic groove in its C-terminal domain to support substrate solubilization and insertion into mitochondria. Thus, the targeting of diverse mitochondrial membrane proteins is achieved through topological triaging in the cytosol using principles with similarities to ER membrane protein biogenesis systems.
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Affiliation(s)
- Gayathri Muthukumar
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Taylor A Stevens
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Alison J Inglis
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Theodore K Esantsi
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Reuben A Saunders
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA; Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Fabian Schulte
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Rebecca M Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Alina Guna
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA.
| | - Jonathan S Weissman
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA; David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
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3
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den Brave F, Pfanner N, Becker T. Mitochondrial entry gate as regulatory hub. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119529. [PMID: 37951505 DOI: 10.1016/j.bbamcr.2023.119529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 06/18/2023] [Accepted: 06/23/2023] [Indexed: 11/14/2023]
Abstract
Mitochondria import 1000-1300 different precursor proteins from the cytosol. The main mitochondrial entry gate is formed by the translocase of the outer membrane (TOM complex). Molecular coupling and modification of TOM subunits control and modulate protein import in response to cellular signaling. The TOM complex functions as regulatory hub to integrate mitochondrial protein biogenesis and quality control into the cellular proteostasis network.
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Affiliation(s)
- Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany.
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4
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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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5
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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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6
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den Brave F, Schulte U, Fakler B, Pfanner N, Becker T. Mitochondrial complexome and import network. Trends Cell Biol 2023:S0962-8924(23)00208-8. [PMID: 37914576 DOI: 10.1016/j.tcb.2023.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/02/2023] [Accepted: 10/04/2023] [Indexed: 11/03/2023]
Abstract
Mitochondria perform crucial functions in cellular metabolism, protein and lipid biogenesis, quality control, and signaling. The systematic analysis of protein complexes and interaction networks provided exciting insights into the structural and functional organization of mitochondria. Most mitochondrial proteins do not act as independent units, but are interconnected by stable or dynamic protein-protein interactions. Protein translocases are responsible for importing precursor proteins into mitochondria and form central elements of several protein interaction networks. These networks include molecular chaperones and quality control factors, metabolite channels and respiratory chain complexes, and membrane and organellar contact sites. Protein translocases link the distinct networks into an overarching network, the mitochondrial import network (MitimNet), to coordinate biogenesis, membrane organization and function of mitochondria.
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Affiliation(s)
- Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany
| | - Uwe Schulte
- Institute of Physiology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Nikolaus Pfanner
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany.
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7
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Kamradt ML, Makarewich CA. Mitochondrial microproteins: critical regulators of protein import, energy production, stress response pathways, and programmed cell death. Am J Physiol Cell Physiol 2023; 325:C807-C816. [PMID: 37642234 DOI: 10.1152/ajpcell.00189.2023] [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: 05/05/2023] [Revised: 08/15/2023] [Accepted: 08/16/2023] [Indexed: 08/31/2023]
Abstract
Mitochondria rely upon the coordination of protein import, protein translation, and proper functioning of oxidative phosphorylation (OXPHOS) complexes I-V to sustain the activities of life for an organism. Each process is dependent upon the function of profoundly large protein complexes found in the mitochondria [translocase of the outer mitochondrial membrane (TOMM) complex, translocase of the inner mitochondrial membrane (TIMM) complex, OXPHOS complexes, mitoribosomes]. These massive protein complexes, in some instances more than one megadalton, are built up from numerous protein subunits of varying sizes, including many proteins that are ≤100-150 amino acids. However, these small proteins, termed microproteins, not only act as cogs in large molecular machines but also have important steps in inhibiting or promoting the intrinsic pathway of apoptosis, coordinate responses to cellular stress, and even act as hormones. This review focuses on microproteins that occupy the mitochondria and are critical for its function. Although the microprotein field is relatively new, researchers have long recognized the existence of these mitochondrial proteins as critical components of virtually all aspects of mitochondrial biology. Thus, recent studies estimating that hundreds of new microproteins of unknown function exist and are missing from current genome annotations suggests that the mitochondrial "microproteome" is a rich area for future biological investigation.
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Affiliation(s)
- Michael L Kamradt
- Division of Molecular Cardiovascular Biology, Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
| | - Catherine A Makarewich
- Division of Molecular Cardiovascular Biology, Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States
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8
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Muthukumar G, Stevens TA, Inglis AJ, Esantsi TK, Saunders RA, Schulte F, Voorhees RM, Guna A, Weissman JS. Triaging of α-helical proteins to the mitochondrial outer membrane by distinct chaperone machinery based on substrate topology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.16.553624. [PMID: 37645817 PMCID: PMC10462106 DOI: 10.1101/2023.08.16.553624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Mitochondrial outer membrane α-helical proteins play critical roles in mitochondrial-cytoplasmic communication, but the rules governing the targeting and insertion of these biophysically diverse substrates remain unknown. Here, we first defined the complement of required mammalian biogenesis machinery through genome-wide CRISPRi screens using topologically distinct membrane proteins. Systematic analysis of nine identified factors across 21 diverse α-helical substrates reveals that these components are organized into distinct targeting pathways which act on substrates based on their topology. NAC is required for efficient targeting of polytopic proteins whereas signal-anchored proteins require TTC1, a novel cytosolic chaperone which physically engages substrates. Biochemical and mutational studies reveal that TTC1 employs a conserved TPR domain and a hydrophobic groove in its C-terminal domain to support substrate solubilization and insertion into mitochondria. Thus, targeting of diverse mitochondrial membrane proteins is achieved through topological triaging in the cytosol using principles with similarities to ER membrane protein biogenesis systems.
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Affiliation(s)
- Gayathri Muthukumar
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Taylor A. Stevens
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Alison J. Inglis
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Theodore K. Esantsi
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Reuben A. Saunders
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Fabian Schulte
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
| | - Rebecca M. Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Alina Guna
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Jonathan S. Weissman
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute Technology, Cambridge 02142, MA
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9
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Kadam A, Jadiya P, Tomar D. Post-translational modifications and protein quality control of mitochondrial channels and transporters. Front Cell Dev Biol 2023; 11:1196466. [PMID: 37601094 PMCID: PMC10434574 DOI: 10.3389/fcell.2023.1196466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 07/24/2023] [Indexed: 08/22/2023] Open
Abstract
Mitochondria play a critical role in energy metabolism and signal transduction, which is tightly regulated by proteins, metabolites, and ion fluxes. Metabolites and ion homeostasis are mainly mediated by channels and transporters present on mitochondrial membranes. Mitochondria comprise two distinct compartments, the outer mitochondrial membrane (OMM) and the inner mitochondrial membrane (IMM), which have differing permeabilities to ions and metabolites. The OMM is semipermeable due to the presence of non-selective molecular pores, while the IMM is highly selective and impermeable due to the presence of specialized channels and transporters which regulate ion and metabolite fluxes. These channels and transporters are modulated by various post-translational modifications (PTMs), including phosphorylation, oxidative modifications, ions, and metabolites binding, glycosylation, acetylation, and others. Additionally, the mitochondrial protein quality control (MPQC) system plays a crucial role in ensuring efficient molecular flux through the mitochondrial membranes by selectively removing mistargeted or defective proteins. Inefficient functioning of the transporters and channels in mitochondria can disrupt cellular homeostasis, leading to the onset of various pathological conditions. In this review, we provide a comprehensive overview of the current understanding of mitochondrial channels and transporters in terms of their functions, PTMs, and quality control mechanisms.
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Affiliation(s)
- Ashlesha Kadam
- Department of Internal Medicine, Section of Cardiovascular Medicine, Section of Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, United States
| | - Pooja Jadiya
- Department of Internal Medicine, Section of Gerontology and Geriatric Medicine, Section of Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, United States
| | - Dhanendra Tomar
- Department of Internal Medicine, Section of Cardiovascular Medicine, Section of Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, United States
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10
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Busch JD, Fielden LF, Pfanner N, Wiedemann N. Mitochondrial protein transport: Versatility of translocases and mechanisms. Mol Cell 2023; 83:890-910. [PMID: 36931257 DOI: 10.1016/j.molcel.2023.02.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 03/17/2023]
Abstract
Biogenesis of mitochondria requires the import of approximately 1,000 different precursor proteins into and across the mitochondrial membranes. Mitochondria exhibit a wide variety of mechanisms and machineries for the translocation and sorting of precursor proteins. Five major import pathways that transport proteins to their functional intramitochondrial destination have been elucidated; these pathways range from the classical amino-terminal presequence-directed pathway to pathways using internal or even carboxy-terminal targeting signals in the precursors. Recent studies have provided important insights into the structural organization of membrane-embedded preprotein translocases of mitochondria. A comparison of the different translocases reveals the existence of at least three fundamentally different mechanisms: two-pore-translocase, β-barrel switching, and transport cavities open to the lipid bilayer. In addition, translocases are physically engaged in dynamic interactions with respiratory chain complexes, metabolite transporters, quality control factors, and machineries controlling membrane morphology. Thus, mitochondrial preprotein translocases are integrated into multi-functional networks of mitochondrial and cellular machineries.
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Affiliation(s)
- Jakob D Busch
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Laura F Fielden
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
| | - Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
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11
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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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12
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The Journey of Mitochondrial Protein Import and the Roadmap to Follow. Int J Mol Sci 2023; 24:ijms24032479. [PMID: 36768800 PMCID: PMC9916854 DOI: 10.3390/ijms24032479] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/19/2023] [Accepted: 01/25/2023] [Indexed: 01/31/2023] Open
Abstract
Mitochondria are double membrane-bound organelles that play critical functions in cells including metabolism, energy production, regulation of intrinsic apoptosis, and maintenance of calcium homeostasis. Mitochondria are fascinatingly equipped with their own genome and machinery for transcribing and translating 13 essential proteins of the oxidative phosphorylation system (OXPHOS). The rest of the proteins (99%) that function in mitochondria in the various pathways described above are nuclear-transcribed and synthesized as precursors in the cytosol. These proteins are imported into the mitochondria by the unique mitochondrial protein import system that consists of seven machineries. Proper functioning of the mitochondrial protein import system is crucial for optimal mitochondrial deliverables, as well as mitochondrial and cellular homeostasis. Impaired mitochondrial protein import leads to proteotoxic stress in both mitochondria and cytosol, inducing mitochondrial unfolded protein response (UPRmt). Altered UPRmt is associated with the development of various disease conditions including neurodegenerative and cardiovascular diseases, as well as cancer. This review sheds light on the molecular mechanisms underlying the import of nuclear-encoded mitochondrial proteins, the consequences of defective mitochondrial protein import, and the pathological conditions that arise due to altered UPRmt.
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13
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He L, Tronstad KJ, Maheshwari A. Mitochondrial Dynamics during Development. NEWBORN (CLARKSVILLE, MD.) 2023; 2:19-44. [PMID: 37206581 PMCID: PMC10193651 DOI: 10.5005/jp-journals-11002-0053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Mitochondria are dynamic membrane-bound organelles in eukaryotic cells. These are important for the generation of chemical energy needed to power various cellular functions and also support metabolic, energetic, and epigenetic regulation in various cells. These organelles are also important for communication with the nucleus and other cellular structures, to maintain developmental sequences and somatic homeostasis, and for cellular adaptation to stress. Increasing information shows mitochondrial defects as an important cause of inherited disorders in different organ systems. In this article, we provide an extensive review of ontogeny, ultrastructural morphology, biogenesis, functional dynamics, important clinical manifestations of mitochondrial dysfunction, and possibilities for clinical intervention. We present information from our own clinical and laboratory research in conjunction with information collected from an extensive search in the databases PubMed, EMBASE, and Scopus.
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Affiliation(s)
- Ling He
- Department of Pediatrics and Pharmacology, Johns Hopkins University, Baltimore, United States of America
| | | | - Akhil Maheshwari
- Founding Chairman, Global Newborn Society, Clarksville, Maryland, United States of America
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14
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Schulte U, den Brave F, Haupt A, Gupta A, Song J, Müller CS, Engelke J, Mishra S, Mårtensson C, Ellenrieder L, Priesnitz C, Straub SP, Doan KN, Kulawiak B, Bildl W, Rampelt H, Wiedemann N, Pfanner N, Fakler B, Becker T. Mitochondrial complexome reveals quality-control pathways of protein import. Nature 2023; 614:153-159. [PMID: 36697829 PMCID: PMC9892010 DOI: 10.1038/s41586-022-05641-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 12/09/2022] [Indexed: 01/26/2023]
Abstract
Mitochondria have crucial roles in cellular energetics, metabolism, signalling and quality control1-4. They contain around 1,000 different proteins that often assemble into complexes and supercomplexes such as respiratory complexes and preprotein translocases1,3-7. The composition of the mitochondrial proteome has been characterized1,3,5,6; however, the organization of mitochondrial proteins into stable and dynamic assemblies is poorly understood for major parts of the proteome1,4,7. Here we report quantitative mapping of mitochondrial protein assemblies using high-resolution complexome profiling of more than 90% of the yeast mitochondrial proteome, termed MitCOM. An analysis of the MitCOM dataset resolves >5,200 protein peaks with an average of six peaks per protein and demonstrates a notable complexity of mitochondrial protein assemblies with distinct appearance for respiration, metabolism, biogenesis, dynamics, regulation and redox processes. We detect interactors of the mitochondrial receptor for cytosolic ribosomes, of prohibitin scaffolds and of respiratory complexes. The identification of quality-control factors operating at the mitochondrial protein entry gate reveals pathways for preprotein ubiquitylation, deubiquitylation and degradation. Interactions between the peptidyl-tRNA hydrolase Pth2 and the entry gate led to the elucidation of a constitutive pathway for the removal of preproteins. The MitCOM dataset-which is accessible through an interactive profile viewer-is a comprehensive resource for the identification, organization and interaction of mitochondrial machineries and pathways.
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Affiliation(s)
- Uwe Schulte
- grid.5963.9Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,grid.5963.9CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Fabian den Brave
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Alexander Haupt
- grid.5963.9Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Arushi Gupta
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany ,grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jiyao Song
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany ,grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Catrin S. Müller
- grid.5963.9Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jeannine Engelke
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Swadha Mishra
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Christoph Mårtensson
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,Present Address: MTIP, Basel, Switzerland
| | - Lars Ellenrieder
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,grid.419481.10000 0001 1515 9979Present Address: Novartis, Basel, Switzerland
| | - Chantal Priesnitz
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sebastian P. Straub
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,grid.5963.9Faculty of Biology, University of Freiburg, Freiburg, Germany ,grid.482402.8Present Address: Sanofi-Aventis (Suisse), Vernier, Switzerland
| | - Kim Nguyen Doan
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Bogusz Kulawiak
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,grid.413454.30000 0001 1958 0162Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Wolfgang Bildl
- grid.5963.9Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Heike Rampelt
- grid.5963.9CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany ,grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Nils Wiedemann
- grid.5963.9CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany ,grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany ,grid.5963.9BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Nikolaus Pfanner
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany. .,Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany. .,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany.
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany. .,CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany. .,Center for Basics in NeuroModulation, Freiburg, Germany.
| | - Thomas Becker
- grid.10388.320000 0001 2240 3300Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
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15
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Guna A, Stevens TA, Inglis AJ, Replogle JM, Esantsi TK, Muthukumar G, Shaffer KCL, Wang ML, Pogson AN, Jones JJ, Lomenick B, Chou TF, Weissman JS, Voorhees RM. MTCH2 is a mitochondrial outer membrane protein insertase. Science 2022; 378:317-322. [PMID: 36264797 PMCID: PMC9674023 DOI: 10.1126/science.add1856] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In the mitochondrial outer membrane, α-helical transmembrane proteins play critical roles in cytoplasmic-mitochondrial communication. Using genome-wide CRISPR screens, we identified MTCH2, and its paralog MTCH1, and showed that it is required for insertion of biophysically diverse tail-anchored (TA), signal-anchored, and multipass proteins, but not outer membrane β-barrel proteins. Purified MTCH2 was sufficient to mediate insertion into reconstituted proteoliposomes. Functional and mutational studies suggested that MTCH2 has evolved from a solute carrier transporter. MTCH2 uses membrane-embedded hydrophilic residues to function as a gatekeeper for the outer membrane, controlling mislocalization of TAs into the endoplasmic reticulum and modulating the sensitivity of leukemia cells to apoptosis. Our identification of MTCH2 as an insertase provided a mechanistic explanation for the diverse phenotypes and disease states associated with MTCH2 dysfunction. We showed that MTCH2 was both necessary and sufficient for insertion of diverse α-helical proteins into the mitochondrial outer membrane, and was the defining member of a family of insertases that have co-opted the SLC25 transporter fold.
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Affiliation(s)
- Alina Guna
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Taylor A Stevens
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Alison J Inglis
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Joseph M Replogle
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Medical Scientist Training Program, University of California, San Francisco, San Francisco, CA 94158, USA.,Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Theodore K Esantsi
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Gayathri Muthukumar
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Kelly C L Shaffer
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Maxine L Wang
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Angela N Pogson
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Jeff J Jones
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Brett Lomenick
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Tsui-Fen Chou
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Jonathan S Weissman
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Rebecca M Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
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16
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Modeling Adsorption, Conformation, and Orientation of the Fis1 Tail Anchor at the Mitochondrial Outer Membrane. MEMBRANES 2022; 12:membranes12080752. [PMID: 36005667 PMCID: PMC9413518 DOI: 10.3390/membranes12080752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/28/2022] [Accepted: 07/28/2022] [Indexed: 12/04/2022]
Abstract
Proteins can be targeted to organellar membranes by using a tail anchor (TA), a stretch of hydrophobic amino acids found at the polypeptide carboxyl-terminus. The Fis1 protein (Fis1p), which promotes mitochondrial and peroxisomal division in the yeast Saccharomyces cerevisiae, is targeted to those organelles by its TA. Substantial evidence suggests that Fis1p insertion into the mitochondrial outer membrane can occur without the need for a translocation machinery. However, recent findings raise the possibility that Fis1p insertion into mitochondria might be promoted by a proteinaceous complex. Here, we have performed atomistic and coarse-grained molecular dynamics simulations to analyze the adsorption, conformation, and orientation of the Fis1(TA). Our results support stable insertion at the mitochondrial outer membrane in a monotopic, rather than a bitopic (transmembrane), configuration. Once inserted in the monotopic orientation, unassisted transition to the bitopic orientation is expected to be blocked by the highly charged nature of the TA carboxyl-terminus and by the Fis1p cytosolic domain. Our results are consistent with a model in which Fis1p does not require a translocation machinery for insertion at mitochondria.
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17
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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: 5] [Impact Index Per Article: 2.5] [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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18
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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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19
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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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20
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Diederichs KA, Pitt AS, Varughese JT, Hackel TN, Buchanan SK, Shaw PL. Mechanistic insights into fungal mitochondrial outer membrane protein biogenesis. Curr Opin Struct Biol 2022; 74:102383. [DOI: 10.1016/j.sbi.2022.102383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 02/11/2022] [Accepted: 03/16/2022] [Indexed: 11/30/2022]
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21
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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: 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: 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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22
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Hoffmann JJ, Becker T. Crosstalk between Mitochondrial Protein Import and Lipids. Int J Mol Sci 2022; 23:ijms23095274. [PMID: 35563660 PMCID: PMC9101885 DOI: 10.3390/ijms23095274] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/29/2022] [Accepted: 05/05/2022] [Indexed: 12/10/2022] Open
Abstract
Mitochondria import about 1000 precursor proteins from the cytosol. The translocase of the outer membrane (TOM complex) forms the major entry site for precursor proteins. Subsequently, membrane-bound protein translocases sort the precursor proteins into the outer and inner membrane, the intermembrane space, and the matrix. The phospholipid composition of mitochondrial membranes is critical for protein import. Structural and biochemical data revealed that phospholipids affect the stability and activity of mitochondrial protein translocases. Integration of proteins into the target membrane involves rearrangement of phospholipids and distortion of the lipid bilayer. Phospholipids are present in the interface between subunits of protein translocases and affect the dynamic coupling of partner proteins. Phospholipids are required for full activity of the respiratory chain to generate membrane potential, which in turn drives protein import across and into the inner membrane. Finally, outer membrane protein translocases are closely linked to organellar contact sites that mediate lipid trafficking. Altogether, intensive crosstalk between mitochondrial protein import and lipid biogenesis controls mitochondrial biogenesis.
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23
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Sayyed UMH, Mahalakshmi R. Mitochondrial protein translocation machinery: From TOM structural biogenesis to functional regulation. J Biol Chem 2022; 298:101870. [PMID: 35346689 PMCID: PMC9052162 DOI: 10.1016/j.jbc.2022.101870] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 03/13/2022] [Accepted: 03/14/2022] [Indexed: 01/15/2023] Open
Abstract
The human mitochondrial outer membrane is biophysically unique as it is the only membrane possessing transmembrane β-barrel proteins (mitochondrial outer membrane proteins, mOMPs) in the cell. The most vital of the three mOMPs is the core protein of the translocase of the outer mitochondrial membrane (TOM) complex. Identified first as MOM38 in Neurospora in 1990, the structure of Tom40, the core 19-stranded β-barrel translocation channel, was solved in 2017, after nearly three decades. Remarkably, the past four years have witnessed an exponential increase in structural and functional studies of yeast and human TOM complexes. In addition to being conserved across all eukaryotes, the TOM complex is the sole ATP-independent import machinery for nearly all of the ∼1000 to 1500 known mitochondrial proteins. Recent cryo-EM structures have provided detailed insight into both possible assembly mechanisms of the TOM core complex and organizational dynamics of the import machinery and now reveal novel regulatory interplay with other mOMPs. Functional characterization of the TOM complex using biochemical and structural approaches has also revealed mechanisms for substrate recognition and at least five defined import pathways for precursor proteins. In this review, we discuss the discovery, recently solved structures, molecular function, and regulation of the TOM complex and its constituents, along with the implications these advances have for alleviating human diseases.
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Affiliation(s)
- Ulfat Mohd Hanif Sayyed
- Molecular Biophysics Laboratory, Indian Institute of Science Education and Research, Bhopal, India
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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: 74] [Impact Index Per Article: 37.0] [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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Zhou J, Jung M, Dimmer KS, Rapaport D. The multi-factor modulated biogenesis of the mitochondrial multi-span protein Om14. J Biophys Biochem Cytol 2022; 221:213056. [PMID: 35262629 PMCID: PMC8916117 DOI: 10.1083/jcb.202112030] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/26/2022] [Accepted: 02/03/2022] [Indexed: 12/14/2022] Open
Abstract
The mitochondrial outer membrane (MOM) harbors proteins that traverse the membrane via several helical segments and are called multi-span proteins. To obtain new insights into the biogenesis of these proteins, we utilized yeast mitochondria and the multi-span protein Om14. Testing different truncation variants, we show that while only the full-length protein contains all the information that assures perfect targeting specificity, shorter variants are targeted to mitochondria with compromised fidelity. Employing a specific insertion assay and various deletion strains, we show that proteins exposed to the cytosol do not contribute significantly to the biogenesis process. We further demonstrate that Mim1 and Porin support optimal membrane integration of Om14 but none of them are absolutely required. Unfolding of newly synthesized Om14, its optimal hydrophobicity, and higher fluidity of the membrane enhanced the import capacity of Om14. Collectively, these findings suggest that MOM multi-span proteins follow different biogenesis pathways in which proteinaceous elements and membrane behavior contribute to a variable extent to the combined efficiency.
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Affiliation(s)
- Jialin Zhou
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Martin Jung
- Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Kai S Dimmer
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
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26
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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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27
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Li X, Straub J, Medeiros TC, Mehra C, den Brave F, Peker E, Atanassov I, Stillger K, Michaelis JB, Burbridge E, Adrain C, Münch C, Riemer J, Becker T, Pernas LF. Mitochondria shed their outer membrane in response to infection-induced stress. Science 2022; 375:eabi4343. [PMID: 35025629 DOI: 10.1126/science.abi4343] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Xianhe Li
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Julian Straub
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | | | - Chahat Mehra
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Esra Peker
- Institute of Biochemistry, University of Cologne, Cologne, Germany
| | - Ilian Atanassov
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | | | - Jonas Benjamin Michaelis
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, Frankfurt am Main, Germany
| | - Emma Burbridge
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, Northern Ireland.,Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Colin Adrain
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, Northern Ireland.,Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Christian Münch
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, Frankfurt am Main, Germany
| | - Jan Riemer
- Institute of Biochemistry, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Lena F Pernas
- Max Planck Institute for Biology of Ageing, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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28
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Eaglesfield R, Tokatlidis K. Targeting and Insertion of Membrane Proteins in Mitochondria. Front Cell Dev Biol 2022; 9:803205. [PMID: 35004695 PMCID: PMC8740019 DOI: 10.3389/fcell.2021.803205] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/09/2021] [Indexed: 01/26/2023] Open
Abstract
Mitochondrial membrane proteins play an essential role in all major mitochondrial functions. The respiratory complexes of the inner membrane are key for the generation of energy. The carrier proteins for the influx/efflux of essential metabolites to/from the matrix. Many other inner membrane proteins play critical roles in the import and processing of nuclear encoded proteins (∼99% of all mitochondrial proteins). The outer membrane provides another lipidic barrier to nuclear-encoded protein translocation and is home to many proteins involved in the import process, maintenance of ionic balance, as well as the assembly of outer membrane components. While many aspects of the import and assembly pathways of mitochondrial membrane proteins have been elucidated, many open questions remain, especially surrounding the assembly of the respiratory complexes where certain highly hydrophobic subunits are encoded by the mitochondrial DNA and synthesised and inserted into the membrane from the matrix side. This review will examine the various assembly pathways for inner and outer mitochondrial membrane proteins while discussing the most recent structural and biochemical data examining the biogenesis process.
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Affiliation(s)
- Ross Eaglesfield
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, University Avenue, Scotland, United Kingdom
| | - Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, University Avenue, Scotland, United Kingdom
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29
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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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30
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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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31
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Whitley P, Grau B, Gumbart JC, Martínez-Gil L, Mingarro I. Folding and Insertion of Transmembrane Helices at the ER. Int J Mol Sci 2021; 22:ijms222312778. [PMID: 34884581 PMCID: PMC8657811 DOI: 10.3390/ijms222312778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 01/16/2023] Open
Abstract
In eukaryotic cells, the endoplasmic reticulum (ER) is the entry point for newly synthesized proteins that are subsequently distributed to organelles of the endomembrane system. Some of these proteins are completely translocated into the lumen of the ER while others integrate stretches of amino acids into the greasy 30 Å wide interior of the ER membrane bilayer. It is generally accepted that to exist in this non-aqueous environment the majority of membrane integrated amino acids are primarily non-polar/hydrophobic and adopt an α-helical conformation. These stretches are typically around 20 amino acids long and are known as transmembrane (TM) helices. In this review, we will consider how transmembrane helices achieve membrane integration. We will address questions such as: Where do the stretches of amino acids fold into a helical conformation? What is/are the route/routes that these stretches take from synthesis at the ribosome to integration through the ER translocon? How do these stretches ‘know’ to integrate and in which orientation? How do marginally hydrophobic stretches of amino acids integrate and survive as transmembrane helices?
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Affiliation(s)
- Paul Whitley
- Department of Biology and Biochemistry, Centre for Regenerative Medicine, University of Bath, Bath BA2 7AY, UK;
| | - Brayan Grau
- Department of Biochemistry and Molecular Biology, Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain; (B.G.); (L.M.-G.)
| | - James C. Gumbart
- School of Physics, School of Chemistry and Biochemistry, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Luis Martínez-Gil
- Department of Biochemistry and Molecular Biology, Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain; (B.G.); (L.M.-G.)
| | - Ismael Mingarro
- Department of Biochemistry and Molecular Biology, Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain; (B.G.); (L.M.-G.)
- Correspondence: ; Tel.: +34-963543796
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32
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Dimogkioka AR, Lees J, Lacko E, Tokatlidis K. Protein import in mitochondria biogenesis: guided by targeting signals and sustained by dedicated chaperones. RSC Adv 2021; 11:32476-32493. [PMID: 35495482 PMCID: PMC9041937 DOI: 10.1039/d1ra04497d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 09/25/2021] [Indexed: 12/31/2022] Open
Abstract
Mitochondria have a central role in cellular metabolism; they are responsible for the biosynthesis of amino acids, lipids, iron-sulphur clusters and regulate apoptosis. About 99% of mitochondrial proteins are encoded by nuclear genes, so the biogenesis of mitochondria heavily depends on protein import pathways into the organelle. An intricate system of well-studied import machinery facilitates the import of mitochondrial proteins. In addition, folding of the newly synthesized proteins takes place in a busy environment. A system of folding helper proteins, molecular chaperones and co-chaperones, are present to maintain proper conformation and thus avoid protein aggregation and premature damage. The components of the import machinery are well characterised, but the targeting signals and how they are recognised and decoded remains in some cases unclear. Here we provide some detail on the types of targeting signals involved in the protein import process. Furthermore, we discuss the very elaborate chaperone systems of the intermembrane space that are needed to overcome the particular challenges for the folding process in this compartment. The mechanisms that sustain productive folding in the face of aggregation and damage in mitochondria are critical components of the stress response and play an important role in cell homeostasis.
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Affiliation(s)
- Anna-Roza Dimogkioka
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow University Avenue Glasgow G12 8QQ Scotland UK
| | - Jamie Lees
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow University Avenue Glasgow G12 8QQ Scotland UK
| | - Erik Lacko
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow University Avenue Glasgow G12 8QQ Scotland UK
| | - Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow University Avenue Glasgow G12 8QQ Scotland UK
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33
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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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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: 4] [Impact Index Per Article: 1.3] [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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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: 8] [Impact Index Per Article: 2.7] [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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36
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Needs HI, Protasoni M, Henley JM, Prudent J, Collinson I, Pereira GC. Interplay between Mitochondrial Protein Import and Respiratory Complexes Assembly in Neuronal Health and Degeneration. Life (Basel) 2021; 11:432. [PMID: 34064758 PMCID: PMC8151517 DOI: 10.3390/life11050432] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/27/2021] [Accepted: 05/02/2021] [Indexed: 12/14/2022] Open
Abstract
The fact that >99% of mitochondrial proteins are encoded by the nuclear genome and synthesised in the cytosol renders the process of mitochondrial protein import fundamental for normal organelle physiology. In addition to this, the nuclear genome comprises most of the proteins required for respiratory complex assembly and function. This means that without fully functional protein import, mitochondrial respiration will be defective, and the major cellular ATP source depleted. When mitochondrial protein import is impaired, a number of stress response pathways are activated in order to overcome the dysfunction and restore mitochondrial and cellular proteostasis. However, prolonged impaired mitochondrial protein import and subsequent defective respiratory chain function contributes to a number of diseases including primary mitochondrial diseases and neurodegeneration. This review focuses on how the processes of mitochondrial protein translocation and respiratory complex assembly and function are interlinked, how they are regulated, and their importance in health and disease.
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Affiliation(s)
- Hope I. Needs
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
| | - Margherita Protasoni
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
| | - Jeremy M. Henley
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
- Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Julien Prudent
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
| | - Gonçalo C. Pereira
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
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Maity S, Chakrabarti O. Mitochondrial protein import as a quality control sensor. Biol Cell 2021; 113:375-400. [PMID: 33870508 DOI: 10.1111/boc.202100002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/04/2021] [Accepted: 04/09/2021] [Indexed: 12/17/2022]
Abstract
Mitochondria are organelles involved in various functions related to cellular metabolism and homoeostasis. Though mitochondria contain own genome, their nuclear counterparts encode most of the different mitochondrial proteins. These are synthesised as precursors in the cytosol and have to be delivered into the mitochondria. These organelles hence have elaborate machineries for the import of precursor proteins from cytosol. The protein import machineries present in both mitochondrial membrane and aqueous compartments show great variability in pre-protein recognition, translocation and sorting across or into it. Mitochondrial protein import machineries also interact transiently with other protein complexes of the respiratory chain or those involved in the maintenance of membrane architecture. Hence mitochondrial protein translocation is an indispensable part of the regulatory network that maintains protein biogenesis, bioenergetics, membrane dynamics and quality control of the organelle. Various stress conditions and diseases that are associated with mitochondrial import defects lead to changes in cellular transcriptomic and proteomic profiles. Dysfunction in mitochondrial protein import also causes over-accumulation of precursor proteins and their aggregation in the cytosol. Multiple pathways may be activated for buffering these harmful consequences. Here, we present a comprehensive picture of import machinery and its role in cellular quality control in response to defective mitochondrial import. We also discuss the pathological consequences of dysfunctional mitochondrial protein import in neurodegeneration and cancer.
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Affiliation(s)
- Sebabrata Maity
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, 700064, India.,Homi Bhabha National Institute, India
| | - Oishee Chakrabarti
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, 700064, India.,Homi Bhabha National Institute, India
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38
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Backes S, Bykov YS, Flohr T, Räschle M, Zhou J, Lenhard S, Krämer L, Mühlhaus T, Bibi C, Jann C, Smith JD, Steinmetz LM, Rapaport D, Storchová Z, Schuldiner M, Boos F, Herrmann JM. The chaperone-binding activity of the mitochondrial surface receptor Tom70 protects the cytosol against mitoprotein-induced stress. Cell Rep 2021; 35:108936. [PMID: 33826901 PMCID: PMC7615001 DOI: 10.1016/j.celrep.2021.108936] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/22/2020] [Accepted: 03/11/2021] [Indexed: 02/08/2023] Open
Abstract
Most mitochondrial proteins are synthesized as precursors in the cytosol and post-translationally transported into mitochondria. The mitochondrial surface protein Tom70 acts at the interface of the cytosol and mitochondria. In vitro import experiments identified Tom70 as targeting receptor, particularly for hydrophobic carriers. Using in vivo methods and high-content screens, we revisit the question of Tom70 function and considerably expand the set of Tom70-dependent mitochondrial proteins. We demonstrate that the crucial activity of Tom70 is its ability to recruit cytosolic chaperones to the outer membrane. Indeed, tethering an unrelated chaperone-binding domain onto the mitochondrial surface complements most of the defects caused by Tom70 deletion. Tom70-mediated chaperone recruitment reduces the proteotoxicity of mitochondrial precursor proteins, particularly of hydrophobic inner membrane proteins. Thus, our work suggests that the predominant function of Tom70 is to tether cytosolic chaperones to the outer mitochondrial membrane, rather than to serve as a mitochondrion-specifying targeting receptor.
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Affiliation(s)
- Sandra Backes
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Yury S Bykov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tamara Flohr
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Markus Räschle
- Molecular Genetics, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Jialin Zhou
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Svenja Lenhard
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Lena Krämer
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Timo Mühlhaus
- Computational Systems Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Chen Bibi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Cosimo Jann
- Genome Biology Unit, EMBL, Meyerhofstraße 1, 69117 Heidelberg, Germany; Department of Biology, Institute of Biochemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Justin D Smith
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lars M Steinmetz
- Genome Biology Unit, EMBL, Meyerhofstraße 1, 69117 Heidelberg, Germany; Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Zuzana Storchová
- Molecular Genetics, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Felix Boos
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
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Lynch S, Boyett JE, Smith MR, Giordano-Mooga S. Sex Hormone Regulation of Proteins Modulating Mitochondrial Metabolism, Dynamics and Inter-Organellar Cross Talk in Cardiovascular Disease. Front Cell Dev Biol 2021; 8:610516. [PMID: 33644031 PMCID: PMC7905018 DOI: 10.3389/fcell.2020.610516] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 11/30/2020] [Indexed: 12/11/2022] Open
Abstract
Cardiovascular disease (CVD) is the leading cause of death in the U.S. and worldwide. Sex-related disparities have been identified in the presentation and incidence rate of CVD. Mitochondrial dysfunction plays a role in both the etiology and pathology of CVD. Recent work has suggested that the sex hormones play a role in regulating mitochondrial dynamics, metabolism, and cross talk with other organelles. Specifically, the female sex hormone, estrogen, has both a direct and an indirect role in regulating mitochondrial biogenesis via PGC-1α, dynamics through Opa1, Mfn1, Mfn2, and Drp1, as well as metabolism and redox signaling through the antioxidant response element. Furthermore, data suggests that testosterone is cardioprotective in males and may regulate mitochondrial biogenesis through PGC-1α and dynamics via Mfn1 and Drp1. These cell-signaling hubs are essential in maintaining mitochondrial integrity and cell viability, ultimately impacting CVD survival. PGC-1α also plays a crucial role in inter-organellar cross talk between the mitochondria and other organelles such as the peroxisome. This inter-organellar signaling is an avenue for ameliorating rampant ROS produced by dysregulated mitochondria and for regulating intrinsic apoptosis by modulating intracellular Ca2+ levels through interactions with the endoplasmic reticulum. There is a need for future research on the regulatory role of the sex hormones, particularly testosterone, and their cardioprotective effects. This review hopes to highlight the regulatory role of sex hormones on mitochondrial signaling and their function in the underlying disparities between men and women in CVD.
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Affiliation(s)
- Shannon Lynch
- Biomedical Sciences Program, Graduate School, University of Alabama at Birmingham, Birmingham, AL, United States
| | - James E Boyett
- Biomedical Sciences Program, Department of Clinical and Diagnostic Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - M Ryan Smith
- Division of Pulmonary, Allergy and Critical Care Medicine, Emory University, Atlanta, GA, United States
| | - Samantha Giordano-Mooga
- Biomedical Sciences Program, Department of Clinical and Diagnostic Science, University of Alabama at Birmingham, Birmingham, AL, United States
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40
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Jiang H. Quality control pathways of tail-anchored proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118922. [PMID: 33285177 DOI: 10.1016/j.bbamcr.2020.118922] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/14/2020] [Accepted: 12/01/2020] [Indexed: 12/20/2022]
Abstract
Tail-anchored (TA) proteins have an N-terminal domain in the cytosol and a C-terminal transmembrane domain anchored to a variety of organelle membranes. TA proteins are recognized by targeting factors at the transmembrane domain and C-terminal sequence and are guided to distinct membranes. The promiscuity of targeting sequences and the dysfunction of targeting pathways cause mistargeting of TA proteins. TA proteins are under surveillance by quality control pathways. For resident TA proteins at mitochondrial and ER membranes, intrinsic instability or stimuli induced degrons of the cytosolic and transmembrane domains are sensed by quality control factors to initiate degradation of TA proteins. These pathways are summarized as TA protein degradation-Cytosol (TAD-C) and TAD-Membrane (TAD-M) pathways. For mistargeted and a subset of solitary TA proteins at mitochondrial and peroxisomal membranes, a unique pathway has been revealed in recent years. Msp1/ATAD1 is an AAA-ATPase dually-localized to mitochondrial and peroxisomal membranes. It directly recognizes mistargeted and solitary TA proteins and dislocates them out of membrane. Dislocated substrates are subsequently ubiquitinated by the ER-resident Doa10 ubiquitin E3 ligase complex for degradation. We summarize and discuss the substrate recognition, dislocation and degradation mechanisms of the Msp1 pathway.
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Affiliation(s)
- Hui Jiang
- National Institute of Biological Sciences, Beijing 102206, China; Beijing Key Laboratory of Cell Biology for Animal Aging, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100871, China.
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41
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Goyal S, Chaturvedi RK. Mitochondrial Protein Import Dysfunction in Pathogenesis of Neurodegenerative Diseases. Mol Neurobiol 2020; 58:1418-1437. [PMID: 33180216 DOI: 10.1007/s12035-020-02200-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023]
Abstract
Mitochondria play an essential role in maintaining energy homeostasis and cellular survival. In the brain, higher ATP production is required by mature neurons for communication. Most of the mitochondrial proteins transcribe in the nucleus and import in mitochondria through different pathways of the mitochondrial protein import machinery. This machinery plays a crucial role in determining mitochondrial morphology and functions through mitochondrial biogenesis. Failure of this machinery and any alterations during mitochondrial biogenesis underlies neurodegeneration resulting in Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD) etc. Current knowledge has revealed the different pathways of mitochondrial protein import machinery such as translocase of the outer mitochondrial membrane complex, the presequence pathway, carrier pathway, β-barrel pathway, and mitochondrial import and assembly machinery etc. In this review, we have discussed the recent studies regarding protein import machinery, beyond the well-known effects of increased oxidative stress and bioenergetics dysfunctions. We have elucidated in detail how these types of machinery help to import and locate the precursor proteins to their specific location inside the mitochondria and play a major role in mitochondrial biogenesis. We further discuss their involvement in mitochondrial dysfunctioning and the induction of toxic aggregates in neurodegenerative diseases like AD and PD. The review supports the importance of import machinery in neuronal functions and its association with toxic aggregated proteins in mitochondrial impairment, suggesting a critical role in fostering and maintaining neurodegeneration and therapeutic response.
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Affiliation(s)
- Shweta Goyal
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, Uttar Pradesh, 226001, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Rajnish Kumar Chaturvedi
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, Uttar Pradesh, 226001, India. .,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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42
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Gupta A, Becker T. Mechanisms and pathways of mitochondrial outer membrane protein biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148323. [PMID: 33035511 DOI: 10.1016/j.bbabio.2020.148323] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/26/2020] [Accepted: 09/29/2020] [Indexed: 11/29/2022]
Abstract
Outer membrane proteins integrate mitochondria into the cellular environment. They warrant exchange of small molecules like metabolites and ions, transport proteins into mitochondria, form contact sites to other cellular organelles for lipid exchange, constitute a signaling platform for apoptosis and inflammation and mediate organelle fusion and fission. The outer membrane contains two types of integral membrane proteins. Proteins with a transmembrane β-barrel structure and proteins with a single or multiple α-helical membrane spans. All outer membrane proteins are produced on cytosolic ribosomes and imported into the target organelle. Precursors of β-barrel and α-helical proteins are transported into the outer membrane via distinct import routes. The translocase of the outer membrane (TOM complex) transports β-barrel precursors across the outer membrane and the sorting and assembly machinery (SAM complex) inserts them into the target membrane. The mitochondrial import (MIM) complex constitutes the major integration site for α-helical embedded proteins. The import of some MIM-substrates involves TOM receptors, while others are imported in a TOM-independent manner. Remarkably, TOM, SAM and MIM complexes dynamically interact to import a large set of different proteins and to coordinate their assembly into protein complexes. Thus, protein import into the mitochondrial outer membrane involves a dynamic platform of protein translocases.
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Affiliation(s)
- Arushi Gupta
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany
| | - Thomas Becker
- Institut für Biochemie und Molekularbiologie, Medizinische Fakultät, Universität Bonn, Nussallee 11, 53115 Bonn, Germany.
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Wang L, Walter P. Msp1/ATAD1 in Protein Quality Control and Regulation of Synaptic Activities. Annu Rev Cell Dev Biol 2020; 36:141-164. [DOI: 10.1146/annurev-cellbio-031220-015840] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mitochondrial function depends on the efficient import of proteins synthesized in the cytosol. When cells experience stress, the efficiency and faithfulness of the mitochondrial protein import machinery are compromised, leading to homeostatic imbalances and damage to the organelle. Yeast Msp1 (mitochondrial sorting of proteins 1) and mammalian ATAD1 (ATPase family AAA domain–containing 1) are orthologous AAA proteins that, fueled by ATP hydrolysis, recognize and extract mislocalized membrane proteins from the outer mitochondrial membrane. Msp1 also extracts proteins that have become stuck in the import channel. The extracted proteins are targeted for proteasome-dependent degradation or, in the case of mistargeted tail-anchored proteins, are given another chance to be routed correctly. In addition, ATAD1 is implicated in the regulation of synaptic plasticity, mediating the release of neurotransmitter receptors from postsynaptic scaffolds to allow their trafficking. Here we discuss how structural and functional specialization imparts the unique properties that allow Msp1/ATAD1 ATPases to fulfill these diverse functions and also highlight outstanding questions in the field.
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Affiliation(s)
- Lan Wang
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94143, USA;,
| | - Peter Walter
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94143, USA;,
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94122, USA
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Kreimendahl S, Rassow J. The Mitochondrial Outer Membrane Protein Tom70-Mediator in Protein Traffic, Membrane Contact Sites and Innate Immunity. Int J Mol Sci 2020; 21:E7262. [PMID: 33019591 PMCID: PMC7583919 DOI: 10.3390/ijms21197262] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 02/08/2023] Open
Abstract
Tom70 is a versatile adaptor protein of 70 kDa anchored in the outer membrane of mitochondria in metazoa, fungi and amoeba. The tertiary structure was resolved for the Tom70 of yeast, showing 26 α-helices, most of them participating in the formation of 11 tetratricopeptide repeat (TPR) motifs. Tom70 serves as a docking site for cytosolic chaperone proteins and co-chaperones and is thereby involved in the uptake of newly synthesized chaperone-bound proteins in mitochondrial biogenesis. In yeast, Tom70 additionally mediates ER-mitochondria contacts via binding to sterol transporter Lam6/Ltc1. In mammalian cells, TOM70 promotes endoplasmic reticulum (ER) to mitochondria Ca2+ transfer by association with the inositol-1,4,5-triphosphate receptor type 3 (IP3R3). TOM70 is specifically targeted by the Bcl-2-related protein MCL-1 that acts as an anti-apoptotic protein in macrophages infected by intracellular pathogens, but also in many cancer cells. By participating in the recruitment of PINK1 and the E3 ubiquitin ligase Parkin, TOM70 can be implicated in the development of Parkinson's disease. TOM70 acts as receptor of the mitochondrial antiviral-signaling protein (MAVS) and thereby participates in the corresponding system of innate immunity against viral infections. The protein encoded by Orf9b in the genome of SARS-CoV-2 binds to TOM70, probably compromising the synthesis of type I interferons.
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Affiliation(s)
| | - Joachim Rassow
- Institute for Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44801 Bochum, Germany;
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Muñoz-Gómez SA, Snyder SN, Montoya SJ, Wideman JG. Independent accretion of TIM22 complex subunits in the animal and fungal lineages. F1000Res 2020; 9:1060. [PMID: 33014348 PMCID: PMC7523481 DOI: 10.12688/f1000research.25904.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/21/2020] [Indexed: 12/25/2022] Open
Abstract
Background: The mitochondrial protein import complexes arose early in eukaryogenesis. Most of the components of the protein import pathways predate the last eukaryotic common ancestor. For example, the carrier-insertase TIM22 complex comprises the widely conserved Tim22 channel core. However, the auxiliary components of fungal and animal TIM22 complexes are exceptions to this ancient conservation. Methods: Using comparative genomics and phylogenetic approaches, we identified precisely when each TIM22 accretion occurred. Results: In animals, we demonstrate that Tim29 and Tim10b arose early in the holozoan lineage. Tim29 predates the metazoan lineage being present in the animal sister lineages, choanoflagellate and filastereans, whereas the erroneously named Tim10b arose from a duplication of Tim9 at the base of metazoans. In fungi, we show that Tim54 has representatives present in every holomycotan lineage including microsporidians and fonticulids, whereas Tim18 and Tim12 appeared much later in fungal evolution. Specifically, Tim18 and Tim12 arose from duplications of Sdh3 and Tim10, respectively, early in the Saccharomycotina. Surprisingly, we show that Tim54 is distantly related to AGK suggesting that AGK and Tim54 are extremely divergent orthologues and the origin of AGK/Tim54 interaction with Tim22 predates the divergence of animals and fungi. Conclusions: We argue that the evolutionary history of the TIM22 complex is best understood as the neutral structural divergence of an otherwise strongly functionally conserved protein complex. This view suggests that many of the differences in structure/subunit composition of multi-protein complexes are non-adaptive. Instead, most of the phylogenetic variation of functionally conserved molecular machines, which have been under stable selective pressures for vast phylogenetic spans, such as the TIM22 complex, is most likely the outcome of the interplay of random genetic drift and mutation pressure.
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Affiliation(s)
- Sergio A. Muñoz-Gómez
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Shannon N. Snyder
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Samantha J. Montoya
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Jeremy G. Wideman
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
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Ferdigg A, Dimmer KS, Rapaport D, Vitali DG. Hydrogenosomal tail-anchored proteins are targeted to both mitochondria and ER upon their expression in yeast cells. PLoS One 2020; 15:e0237982. [PMID: 32817700 PMCID: PMC7446849 DOI: 10.1371/journal.pone.0237982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 08/06/2020] [Indexed: 11/18/2022] Open
Abstract
Some organisms, like Trichomonas vaginalis, contain mitochondria-related hydrogen-producing organelles, called hydrogenosomes. The protein targeting into these organelles is proposed to be similar to the well-studied mitochondria import. Indeed, S. cerevisiae mitochondria and T. vaginalis hydrogenosomes share some components of protein import complexes. However, it is still unknown whether targeting signals directing substrate proteins to hydrogenosomes can support in other eukaryotes specific mitochondrial localization. To address this issue, we investigated the intracellular localization of three hydrogenosomal tail-anchored proteins expressed in yeast cells. We observed that these proteins were targeted to both mitochondria and ER with a variable dependency on the mitochondrial MIM complex. Our results suggest that the targeting signal of TA proteins are only partially conserved between hydrogenosomes and yeast mitochondria.
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Affiliation(s)
- Andrè Ferdigg
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Kai S. Dimmer
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
- * E-mail: (DR); (DGV)
| | - Daniela G. Vitali
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
- * E-mail: (DR); (DGV)
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