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Stephan T, Stoldt S, Barbot M, Carney TD, Lange F, Bates M, Bou Dib P, Inamdar K, Shcherbata HR, Meinecke M, Riedel D, Dennerlein S, Rehling P, Jakobs S. Drosophila MIC10b can polymerize into cristae-shaping filaments. Life Sci Alliance 2024; 7:e202302177. [PMID: 38253420 PMCID: PMC10803214 DOI: 10.26508/lsa.202302177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 01/24/2024] Open
Abstract
Cristae are invaginations of the mitochondrial inner membrane that are crucial for cellular energy metabolism. The formation of cristae requires the presence of a protein complex known as MICOS, which is conserved across eukaryotic species. One of the subunits of this complex, MIC10, is a transmembrane protein that supports cristae formation by oligomerization. In Drosophila melanogaster, three MIC10-like proteins with different tissue-specific expression patterns exist. We demonstrate that CG41128/MINOS1b/DmMIC10b is the major MIC10 orthologue in flies. Its loss destabilizes MICOS, disturbs cristae architecture, and reduces the life span and fertility of flies. We show that DmMIC10b has a unique ability to polymerize into bundles of filaments, which can remodel mitochondrial crista membranes. The formation of these filaments relies on conserved glycine and cysteine residues, and can be suppressed by the co-expression of other Drosophila MICOS proteins. These findings provide new insights into the regulation of MICOS in flies, and suggest potential mechanisms for the maintenance of mitochondrial ultrastructure.
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Affiliation(s)
- Till Stephan
- https://ror.org/03av75f26 Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Stefan Stoldt
- https://ror.org/03av75f26 Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Mariam Barbot
- https://ror.org/03av75f26 Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Travis D Carney
- Institute of Cell Biochemistry, Hannover Medical School, Hanover, Germany
- Mount Desert Island Biological Laboratory, Bar Harbor, ME, USA
| | - Felix Lange
- https://ror.org/03av75f26 Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Mark Bates
- https://ror.org/03av75f26 Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Department of Optical Nanoscopy, Institute for Nanophotonics, Göttingen, Germany
| | - Peter Bou Dib
- https://ror.org/03av75f26 Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Kaushik Inamdar
- https://ror.org/03av75f26 Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Halyna R Shcherbata
- Institute of Cell Biochemistry, Hannover Medical School, Hanover, Germany
- Mount Desert Island Biological Laboratory, Bar Harbor, ME, USA
| | - Michael Meinecke
- Biochemistry Center (BZH), Heidelberg University, Heidelberg, Germany
| | - Dietmar Riedel
- Laboratory of Electron Microscopy, Max Planck Institute for Multidisciplinary Science, Göttingen, Germany
| | - Sven Dennerlein
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Peter Rehling
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology, Translational Neuroinflammation and Automated Microscopy, Göttingen, Germany
- Max Planck Institute for Multidisciplinary Science, Göttingen, Germany
| | - Stefan Jakobs
- https://ror.org/03av75f26 Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology, Translational Neuroinflammation and Automated Microscopy, Göttingen, Germany
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2
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Nguyen A, Lugarini F, David C, Hosnani P, Alagöz Ç, Friedrich A, Schlütermann D, Knotkova B, Patel A, Parfentev I, Urlaub H, Meinecke M, Stork B, Faesen AC. Metamorphic proteins at the basis of human autophagy initiation and lipid transfer. Mol Cell 2023:S1097-2765(23)00321-0. [PMID: 37209685 DOI: 10.1016/j.molcel.2023.04.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 02/23/2023] [Accepted: 04/27/2023] [Indexed: 05/22/2023]
Abstract
Autophagy is a conserved intracellular degradation pathway that generates de novo double-membrane autophagosomes to target a wide range of material for lysosomal degradation. In multicellular organisms, autophagy initiation requires the timely assembly of a contact site between the ER and the nascent autophagosome. Here, we report the in vitro reconstitution of a full-length seven-subunit human autophagy initiation supercomplex built on a core complex of ATG13-101 and ATG9. Assembly of this core complex requires the rare ability of ATG13 and ATG101 to switch between distinct folds. The slow spontaneous metamorphic conversion is rate limiting for the self-assembly of the supercomplex. The interaction of the core complex with ATG2-WIPI4 enhances tethering of membrane vesicles and accelerates lipid transfer of ATG2 by both ATG9 and ATG13-101. Our work uncovers the molecular basis of the contact site and its assembly mechanisms imposed by the metamorphosis of ATG13-101 to regulate autophagosome biogenesis in space and time.
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Affiliation(s)
- Anh Nguyen
- Max-Planck Institute for Multidisciplinary Sciences, Laboratory of Biochemistry of Signal Dynamics, Göttingen, Germany
| | - Francesca Lugarini
- Max-Planck Institute for Multidisciplinary Sciences, Laboratory of Biochemistry of Signal Dynamics, Göttingen, Germany
| | - Céline David
- Institute of Molecular Medicine I, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University, Düsseldorf, Germany
| | - Pouya Hosnani
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany; University Medical Centre Göttingen, Department of Cellular Biochemistry, Göttingen, Germany
| | - Çağla Alagöz
- Max-Planck Institute for Multidisciplinary Sciences, Laboratory of Biochemistry of Signal Dynamics, Göttingen, Germany
| | - Annabelle Friedrich
- Institute of Molecular Medicine I, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University, Düsseldorf, Germany
| | - David Schlütermann
- Institute of Molecular Medicine I, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University, Düsseldorf, Germany
| | - Barbora Knotkova
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany; University Medical Centre Göttingen, Department of Cellular Biochemistry, Göttingen, Germany
| | - Anoshi Patel
- Max-Planck Institute for Multidisciplinary Sciences, Laboratory of Biochemistry of Signal Dynamics, Göttingen, Germany
| | - Iwan Parfentev
- Max-Planck Institute for Multidisciplinary Sciences, Bioanalytical Mass Spectrometry, Göttingen, Germany
| | - Henning Urlaub
- Max-Planck Institute for Multidisciplinary Sciences, Bioanalytical Mass Spectrometry, Göttingen, Germany; University Medical Centre Göttingen, Institute of Clinical Chemistry, Bioanalytics Group, Göttingen, Germany
| | - Michael Meinecke
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany; University Medical Centre Göttingen, Department of Cellular Biochemistry, Göttingen, Germany
| | - Björn Stork
- Institute of Molecular Medicine I, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University, Düsseldorf, Germany
| | - Alex C Faesen
- Max-Planck Institute for Multidisciplinary Sciences, Laboratory of Biochemistry of Signal Dynamics, Göttingen, Germany.
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3
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Ghosh M, Denkert N, Reuter M, Klümper J, Reglinski K, Peschel R, Schliebs W, Erdmann R, Meinecke M. Dynamics of the translocation pore of the human peroxisomal protein import machinery. Biol Chem 2023; 404:169-178. [PMID: 35977096 DOI: 10.1515/hsz-2022-0170] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 07/05/2022] [Indexed: 01/15/2023]
Abstract
Peroxisomal matrix proteins are synthesized on cytosolic ribosomes and imported in a posttranslational manner. Intricate protein import machineries have evolved that catalyze the different stages of translocation. In humans, PEX5L was found to be an essential component of the peroxisomal translocon. PEX5L is the main receptor for substrate proteins carrying a peroxisomal targeting signal (PTS). Substrates are bound by soluble PEX5L in the cytosol after which the cargo-receptor complex is recruited to peroxisomal membranes. Here, PEX5L interacts with the docking protein PEX14 and becomes part of an integral membrane protein complex that facilitates substrate translocation into the peroxisomal lumen in a still unknown process. In this study, we show that PEX5L containing complexes purified from human peroxisomal membranes constitute water-filled pores when reconstituted into planar-lipid membranes. Channel characteristics were highly dynamic in terms of conductance states, selectivity and voltage- and substrate-sensitivity. Our results show that a PEX5L associated pore exists in human peroxisomes, which can be activated by receptor-cargo complexes.
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Affiliation(s)
- Mausumi Ghosh
- Biochemistry Center (BZH), Heidelberg University, D-69120 Heidelberg, Germany.,Institute for Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany
| | - Niels Denkert
- Biochemistry Center (BZH), Heidelberg University, D-69120 Heidelberg, Germany.,Institute for Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany
| | - Maren Reuter
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Jessica Klümper
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Katharina Reglinski
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Rebecca Peschel
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Wolfgang Schliebs
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Ralf Erdmann
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Michael Meinecke
- Biochemistry Center (BZH), Heidelberg University, D-69120 Heidelberg, Germany.,Institute for Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany
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4
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Patron M, Tarasenko D, Nolte H, Kroczek L, Ghosh M, Ohba Y, Lasarzewski Y, Ahmadi ZA, Cabrera-Orefice A, Eyiama A, Kellermann T, Rugarli EI, Brandt U, Meinecke M, Langer T. Regulation of mitochondrial proteostasis by the proton gradient. EMBO J 2022; 41:e110476. [PMID: 35912435 PMCID: PMC9379554 DOI: 10.15252/embj.2021110476] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 06/29/2022] [Accepted: 07/01/2022] [Indexed: 12/11/2022] Open
Abstract
Mitochondria adapt to different energetic demands reshaping their proteome. Mitochondrial proteases are emerging as key regulators of these adaptive processes. Here, we use a multiproteomic approach to demonstrate the regulation of the m‐AAA protease AFG3L2 by the mitochondrial proton gradient, coupling mitochondrial protein turnover to the energetic status of mitochondria. We identify TMBIM5 (previously also known as GHITM or MICS1) as a Ca2+/H+ exchanger in the mitochondrial inner membrane, which binds to and inhibits the m‐AAA protease. TMBIM5 ensures cell survival and respiration, allowing Ca2+ efflux from mitochondria and limiting mitochondrial hyperpolarization. Persistent hyperpolarization, however, triggers degradation of TMBIM5 and activation of the m‐AAA protease. The m‐AAA protease broadly remodels the mitochondrial proteome and mediates the proteolytic breakdown of respiratory complex I to confine ROS production and oxidative damage in hyperpolarized mitochondria. TMBIM5 thus integrates mitochondrial Ca2+ signaling and the energetic status of mitochondria with protein turnover rates to reshape the mitochondrial proteome and adjust the cellular metabolism.
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Affiliation(s)
- Maria Patron
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Daryna Tarasenko
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Hendrik Nolte
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Lara Kroczek
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Mausumi Ghosh
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.,Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Yohsuke Ohba
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | | | - Zeinab Alsadat Ahmadi
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Alfredo Cabrera-Orefice
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Akinori Eyiama
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Tim Kellermann
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Elena I Rugarli
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.,Institute for Genetics, University of Cologne, Cologne, Germany
| | - Ulrich Brandt
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.,Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Thomas Langer
- 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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5
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Mukherjee I, Ghosh M, Meinecke M. MICOS and the mitochondrial inner membrane morphology - when things get out of shape. FEBS Lett 2021; 595:1159-1183. [PMID: 33837538 DOI: 10.1002/1873-3468.14089] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/31/2021] [Accepted: 04/01/2021] [Indexed: 12/21/2022]
Abstract
Mitochondria play a key role in cellular signalling, metabolism and energetics. Proper architecture and remodelling of the inner mitochondrial membrane are essential for efficient respiration, apoptosis and quality control in the cell. Several protein complexes including mitochondrial contact site and cristae organizing system (MICOS), F1 FO -ATP synthase, and Optic Atrophy 1 (OPA1), facilitate formation, maintenance and stability of cristae membranes. MICOS, the F1 FO -ATP synthase, OPA1 and inner membrane phospholipids such as cardiolipin and phosphatidylethanolamine interact with each other to organize the inner membrane ultra-structure and remodel cristae in response to the cell's demands. Functional alterations in these proteins or in the biosynthesis pathway of cardiolipin and phosphatidylethanolamine result in an aberrant inner membrane architecture and impair mitochondrial function. Mitochondrial dysfunction and abnormalities hallmark several human conditions and diseases including neurodegeneration, cardiomyopathies and diabetes mellitus. Yet, they have long been regarded as secondary pathological effects. This review discusses emerging evidence of a direct relationship between protein- and lipid-dependent regulation of the inner mitochondrial membrane morphology and diseases such as fatal encephalopathy, Leigh syndrome, Parkinson's disease, and cancer.
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Affiliation(s)
- Indrani Mukherjee
- Department of Cellular Biochemistry, University Medical Center Göttingen, Germany
| | - Mausumi Ghosh
- Department of Cellular Biochemistry, University Medical Center Göttingen, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University Medical Center Göttingen, Germany.,Göttinger Zentrum für Molekulare Biowissenschaften - GZMB, Göttingen, Germany
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6
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Tarasenko D, Meinecke M. Protein-dependent membrane remodeling in mitochondrial morphology and clathrin-mediated endocytosis. Eur Biophys J 2021; 50:295-306. [PMID: 33527201 PMCID: PMC8071792 DOI: 10.1007/s00249-021-01501-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 01/04/2021] [Accepted: 01/13/2021] [Indexed: 11/30/2022]
Abstract
Cellular membranes can adopt a plethora of complex and beautiful shapes, most of which are believed to have evolved for a particular physiological reason. The closely entangled relationship between membrane morphology and cellular physiology is strikingly seen in membrane trafficking pathways. During clathrin-mediated endocytosis, for example, over the course of a minute, a patch of the more or less flat plasma membrane is remodeled into a highly curved clathrin-coated vesicle. Such vesicles are internalized by the cell to degrade or recycle plasma membrane receptors or to take up extracellular ligands. Other, steadier, membrane morphologies can be observed in organellar membranes like the endoplasmic reticulum or mitochondria. In the case of mitochondria, which are double membrane-bound, ubiquitous organelles of eukaryotic cells, especially the mitochondrial inner membrane displays an intricated ultrastructure. It is highly folded and consequently has a much larger surface than the mitochondrial outer membrane. It can adopt different shapes in response to cellular demands and changes of the inner membrane morphology often accompany severe diseases, including neurodegenerative- and metabolic diseases and cancer. In recent years, progress was made in the identification of molecules that are important for the aforementioned membrane remodeling events. In this review, we will sum up recent results and discuss the main players of membrane remodeling processes that lead to the mitochondrial inner membrane ultrastructure and in clathrin-mediated endocytosis. We will compare differences and similarities between the molecular mechanisms that peripheral and integral membrane proteins use to deform membranes.
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Affiliation(s)
- Daryna Tarasenko
- Department of Cellular Biochemistry, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
- Göttinger Zentrum für Molekulare Biowissenschaften - GZMB, 37077, Göttingen, Germany.
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7
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Abstract
Cellular membranes are anything but flat structures. They display a wide variety of complex and beautiful shapes, most of which have evolved for a particular physiological reason and are adapted to accommodate certain cellular demands. In membrane trafficking events, the dynamic remodelling of cellular membranes is apparent. In clathrin-mediated endocytosis for example, the plasma membrane undergoes heavy deformation to generate and internalize a highly curved clathrin-coated vesicle. This process has become a model system to study proteins with the ability to sense and induce membrane curvature and over the last two decades numerous membrane remodelling molecules and molecular mechanisms have been identified in this process. In this review, we discuss the interaction of epsin1 ENTH domain with membranes, which is one of the best-studied examples of a peripheral and transiently membrane bending protein important for clathrin-mediated endocytosis.
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Affiliation(s)
- Claudia Steinem
- Institute for Organic and Biomolecular Chemistry, University of Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
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8
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Kroppen B, Teske N, Yambire KF, Denkert N, Mukherjee I, Tarasenko D, Jaipuria G, Zweckstetter M, Milosevic I, Steinem C, Meinecke M. Cooperativity of membrane-protein and protein-protein interactions control membrane remodeling by epsin 1 and affects clathrin-mediated endocytosis. Cell Mol Life Sci 2020; 78:2355-2370. [PMID: 32997199 PMCID: PMC7966211 DOI: 10.1007/s00018-020-03647-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 08/11/2020] [Accepted: 09/12/2020] [Indexed: 01/01/2023]
Abstract
Membrane remodeling is a critical process for many membrane trafficking events, including clathrin-mediated endocytosis. Several molecular mechanisms for protein-induced membrane curvature have been described in some detail. Contrary, the effect that the physico-chemical properties of the membrane have on these processes is far less well understood. Here, we show that the membrane binding and curvature-inducing ENTH domain of epsin1 is regulated by phosphatidylserine (PS). ENTH binds to membranes in a PI(4,5)P2-dependent manner but only induces curvature in the presence of PS. On PS-containing membranes, the ENTH domain forms rigid homo-oligomers and assembles into clusters. Membrane binding and membrane remodeling can be separated by structure-to-function mutants. Such oligomerization mutants bind to membranes but do not show membrane remodeling activity. In vivo, they are not able to rescue defects in epidermal growth factor receptor (EGFR) endocytosis in epsin knock-down cells. Together, these data show that the membrane lipid composition is important for the regulation of protein-dependent membrane deformation during clathrin-mediated endocytosis.
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Affiliation(s)
- Benjamin Kroppen
- Department of Cellular Biochemistry, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Nelli Teske
- Institute for Organic and Biomolecular Chemistry, University of Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
| | - King F Yambire
- European Neuroscience Institute, Göttingen - A Joint Initiative of the University Medical Center Göttingen and the Max-Planck-Society, Grisebachstr. 5, 37077, Göttingen, Germany
| | - Niels Denkert
- Department of Cellular Biochemistry, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Indrani Mukherjee
- Department of Cellular Biochemistry, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Daryna Tarasenko
- Department of Cellular Biochemistry, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Garima Jaipuria
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, 37075, Göttingen, Germany
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, 37075, Göttingen, Germany
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Ira Milosevic
- European Neuroscience Institute, Göttingen - A Joint Initiative of the University Medical Center Göttingen and the Max-Planck-Society, Grisebachstr. 5, 37077, Göttingen, Germany
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, OX3 7BN, UK
| | - Claudia Steinem
- Institute for Organic and Biomolecular Chemistry, University of Göttingen, Tammannstr. 2, 37077, Göttingen, Germany.
- Göttinger Zentrum für Molekulare Biowissenschaften - GZMB, 37077, Göttingen, Germany.
- Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077, Göttingen, Germany.
| | - Michael Meinecke
- Department of Cellular Biochemistry, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
- Göttinger Zentrum für Molekulare Biowissenschaften - GZMB, 37077, Göttingen, Germany.
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9
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Munzel L, Neumann P, Otto FB, Krick R, Metje-Sprink J, Kroppen B, Karedla N, Enderlein J, Meinecke M, Ficner R, Thumm M. Atg21 organizes Atg8 lipidation at the contact of the vacuole with the phagophore. Autophagy 2020; 17:1458-1478. [PMID: 32515645 DOI: 10.1080/15548627.2020.1766332] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Coupling of Atg8 to phosphatidylethanolamine is crucial for the expansion of the crescent-shaped phagophore during cargo engulfment. Atg21, a PtdIns3P-binding beta-propeller protein, scaffolds Atg8 and its E3-like complex Atg12-Atg5-Atg16 during lipidation. The crystal structure of Atg21, in complex with the Atg16 coiled-coil domain, showed its binding at the bottom side of the Atg21 beta-propeller. Our structure allowed detailed analyses of the complex formation of Atg21 with Atg16 and uncovered the orientation of the Atg16 coiled-coil domain with respect to the membrane. We further found that Atg21 was restricted to the phagophore edge, near the vacuole, known as the vacuole isolation membrane contact site (VICS). We identified a specialized vacuolar subdomain at the VICS, typical of organellar contact sites, where the membrane protein Vph1 was excluded, while Vac8 was concentrated. Furthermore, Vac8 was required for VICS formation. Our results support a specialized organellar contact involved in controlling phagophore elongation. Abbreviations: FCCS: fluorescence cross correlation spectroscopy; NVJ: nucleus-vacuole junction; PAS: phagophore assembly site; PE: phosphatidylethanolamine; PROPPIN: beta-propeller that binds phosphoinositides; PtdIns3P: phosphatidylinositol- 3-phosphate; VICS: vacuole isolation membrane contact site.
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Affiliation(s)
- Lena Munzel
- Department of Cellular Biochemistry, University Medicine, Goettingen, Germany
| | - Piotr Neumann
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, University of Goettingen, Goettingen, Germany
| | - Florian B Otto
- Department of Cellular Biochemistry, University Medicine, Goettingen, Germany
| | - Roswitha Krick
- Department of Cellular Biochemistry, University Medicine, Goettingen, Germany
| | - Janina Metje-Sprink
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - Benjamin Kroppen
- Department of Cellular Biochemistry, University Medicine, Goettingen, Germany
| | - Narain Karedla
- Physics Department III, University of Goettingen, Goettingen, Germany
| | - Jörg Enderlein
- Physics Department III, University of Goettingen, Goettingen, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University Medicine, Goettingen, Germany
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, University of Goettingen, Goettingen, Germany
| | - Michael Thumm
- Department of Cellular Biochemistry, University Medicine, Goettingen, Germany
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10
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Marcos S, Meinecke M, Kilzer A, Petermann M. Study of L–L water-in-oil dispersions generated in SMX-Plus static mixers with dissolved CO 2 under high pressure. J Supercrit Fluids 2018. [DOI: 10.1016/j.supflu.2017.05.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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11
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Denkert N, Schendzielorz AB, Barbot M, Versemann L, Richter F, Rehling P, Meinecke M. Cation selectivity of the presequence translocase channel Tim23 is crucial for efficient protein import. eLife 2017; 6. [PMID: 28857742 PMCID: PMC5578737 DOI: 10.7554/elife.28324] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/31/2017] [Indexed: 01/09/2023] Open
Abstract
Virtually all mitochondrial matrix proteins and a considerable number of inner membrane proteins carry a positively charged, N-terminal presequence and are imported by the TIM23 complex (presequence translocase) located in the inner mitochondrial membrane. The voltage-regulated Tim23 channel constitutes the actual protein-import pore wide enough to allow the passage of polypeptides with a secondary structure. In this study, we identify amino acids important for the cation selectivity of Tim23. Structure based mutants show that selectivity is provided by highly conserved, pore-lining amino acids. Mutations of these amino acid residues lead to reduced selectivity properties, reduced protein import capacity and they render the Tim23 channel insensitive to substrates. We thus show that the cation selectivity of the Tim23 channel is a key feature for substrate recognition and efficient protein import. The cells of animals, plants and other eukaryotic organisms contain compartments known as organelles that play many different roles. For example, compartments called mitochondria are responsible for supplying the chemical energy cells need to survive and grow. Two membranes surround each mitochondrion and energy is converted on the surface of the inner one. Mitochondria contain over 1,000 different proteins, most of which are produced in the main part of the cell and have to be transported into the mitochondria. A transport protein called Tim23 is part of a larger group or ‘complex’ of proteins that helps to import many other proteins into the mitochondria. This complex sits in the inner membrane, with the Tim23 protein forming a large, water-filled pore through its core that provides a route for proteins to pass through the membrane. Proteins are made of building blocks called amino acids. The proteins transported by the complex containing Tim23 all have a short chain of amino acids at one end known as an N-terminal presequence. However, it is not clear how the inside of the Tim23 channel identifies and transports this presequence to allow the right proteins to pass through the inner membrane. Denkert, Schendzielorz et al. studied the normal and mutant versions of a Tim23 channel from yeast to find out which parts of the protein are involved in detecting the N-terminal presequence after it enters the pore. The experiments show that there are several amino acids in Tim23 that play important roles in this process. Furthermore, mitochondria containing mutant Tim23 channels, that are less able to identify the N-terminal presequence, are impaired in their ability to import proteins. Tim23 proteins in humans and other organisms also contain most or all of the specific amino acids identified in this study, suggesting that the findings of Denkert, Schendzielorz et al. will also apply to other species. Furthermore, the experimental strategy used in this study could be adapted to investigate transport proteins in other cell compartments.
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Affiliation(s)
- Niels Denkert
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | | | - Mariam Barbot
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Lennart Versemann
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Frank Richter
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Peter Rehling
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.,Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,Göttinger Zentrum für Molekulare Biowissenschaften, Göttingen, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.,Göttinger Zentrum für Molekulare Biowissenschaften, Göttingen, Germany.,European Neuroscience Institute Göttingen, Göttingen, Germany
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12
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Tarasenko D, Barbot M, Jans DC, Kroppen B, Sadowski B, Heim G, Möbius W, Jakobs S, Meinecke M. The MICOS component Mic60 displays a conserved membrane-bending activity that is necessary for normal cristae morphology. J Cell Biol 2017; 216:889-899. [PMID: 28254827 PMCID: PMC5379949 DOI: 10.1083/jcb.201609046] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 01/04/2017] [Accepted: 01/13/2017] [Indexed: 12/16/2022] Open
Abstract
The multisubunit mitochondrial contact site and cristae organizing system (MICOS) plays an important role in cristae junction formation. Tarasenko et al. show that the MICOS component Mic60 actively bends membranes and that this activity is evolutionarily conserved and necessary for cristae structure. The inner membrane (IM) of mitochondria displays an intricate, highly folded architecture and can be divided into two domains: the inner boundary membrane adjacent to the outer membrane and invaginations toward the matrix, called cristae. Both domains are connected by narrow, tubular membrane segments called cristae junctions (CJs). The formation and maintenance of CJs is of vital importance for the organization of the mitochondrial IM and for mitochondrial and cellular physiology. The multisubunit mitochondrial contact site and cristae organizing system (MICOS) was found to be a major factor in CJ formation. In this study, we show that the MICOS core component Mic60 actively bends membranes and, when inserted into prokaryotic membranes, induces the formation of cristae-like plasma membrane invaginations. The intermembrane space domain of Mic60 has a lipid-binding capacity and induces membrane curvature even in the absence of the transmembrane helix. Mic60 homologues from α-proteobacteria display the same membrane deforming activity and are able to partially overcome the deletion of Mic60 in eukaryotic cells. Our results show that membrane bending by Mic60 is an ancient mechanism, important for cristae formation, and had already evolved before α-proteobacteria developed into mitochondria.
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Affiliation(s)
- Daryna Tarasenko
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Mariam Barbot
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Daniel C Jans
- Department of Neurology, University Medical Center Göttingen, 37075 Göttingen, Germany.,Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Benjamin Kroppen
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Boguslawa Sadowski
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.,Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37073 Göttingen, Germany
| | - Gudrun Heim
- Electron Microscopy Facility, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Wiebke Möbius
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.,Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37073 Göttingen, Germany
| | - Stefan Jakobs
- Department of Neurology, University Medical Center Göttingen, 37075 Göttingen, Germany.,Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany .,European Neuroscience Institute Göttingen, 37077 Göttingen, Germany.,Göttinger Zentrum für Molekulare Biowissenschaften, 37077 Göttingen, Germany
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13
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Barbot M, Meinecke M. Reconstitutions of mitochondrial inner membrane remodeling. J Struct Biol 2016; 196:20-28. [DOI: 10.1016/j.jsb.2016.07.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 07/20/2016] [Accepted: 07/21/2016] [Indexed: 02/03/2023]
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14
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Gleisner M, Kroppen B, Fricke C, Teske N, Kliesch TT, Janshoff A, Meinecke M, Steinem C. Epsin N-terminal Homology Domain (ENTH) Activity as a Function of Membrane Tension. J Biol Chem 2016; 291:19953-61. [PMID: 27466364 DOI: 10.1074/jbc.m116.731612] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Indexed: 12/18/2022] Open
Abstract
The epsin N-terminal homology domain (ENTH) is a major player in clathrin-mediated endocytosis. To investigate the influence of initial membrane tension on ENTH binding and activity, we established a bilayer system based on adhered giant unilamellar vesicles (GUVs) to be able to control and adjust the membrane tension σ covering a broad regime. The shape of each individual adhered GUV as well as its adhesion area was monitored by spinning disc confocal laser microscopy. Control of σ in a range of 0.08-1.02 mN/m was achieved by altering the Mg(2+) concentration in solution, which changes the surface adhesion energy per unit area of the GUVs. Specific binding of ENTH to phosphatidylinositol 4,5-bisphosphate leads to a substantial increase in adhesion area of the sessile GUV. At low tension (<0.1 mN/m) binding of ENTH can induce tubular structures, whereas at higher membrane tension the ENTH interaction deflates the sessile GUV and thereby increases the adhesion area. The increase in adhesion area is mainly attributed to a decrease in the area compressibility modulus KA We propose that the insertion of the ENTH helix-0 into the membrane is largely responsible for the observed decrease in KA, which is supported by the observation that the mutant ENTH L6E shows a reduced increase in adhesion area. These results demonstrate that even in the absence of tubule formation, the area compressibility modulus and, as such, the bending rigidity of the membrane is considerably reduced upon ENTH binding. This renders membrane bending and tubule formation energetically less costly.
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Affiliation(s)
- Martin Gleisner
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Benjamin Kroppen
- Department of Cellular Biochemistry, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Christian Fricke
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Nelli Teske
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Torben-Tobias Kliesch
- Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany, and
| | - Andreas Janshoff
- Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany, and Göttingen Center for Molecular Biosciences, 37077 Göttingen, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany, European Neuroscience Institute, 37073 Göttingen, Germany,
| | - Claudia Steinem
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany, Göttingen Center for Molecular Biosciences, 37077 Göttingen, Germany
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15
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Montilla-Martinez M, Beck S, Klümper J, Meinecke M, Schliebs W, Wagner R, Erdmann R. Distinct Pores for Peroxisomal Import of PTS1 and PTS2 Proteins. Cell Rep 2015; 13:2126-34. [PMID: 26673321 DOI: 10.1016/j.celrep.2015.11.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 09/10/2015] [Accepted: 11/03/2015] [Indexed: 11/29/2022] Open
Abstract
Two peroxisomal targeting signals, PTS1 and PTS2, recognized by cytosolic receptors Pex5 and cooperating Pex7/Pex18, direct folded proteins to the peroxisomal matrix. A pore consisting of the PTS1 receptor Pex5 and the docking protein Pex14 imports PTS1 proteins. We identified a distinct PTS2-specific pore, which contains the PTS2 co-receptor Pex18 and the Pex14/Pex17-docking complex as major constituents. The estimated maximal pore size of ∼ 4.7 nm is large enough to allow import of folded PTS2 proteins. PTS2 cargo proteins modulate complex gating, open probability, and subconductance states of the pore. While the PTS1 channel is transiently activated by arriving receptor-cargo complexes, the reconstituted PTS2 channel is constitutively present in an open state. However, the cargo-loaded PTS2 channel is largely impermeable to solutes and ions. Our results demonstrate that import of PTS1 and PTS2 proteins does not converge at the peroxisomal membrane as previously anticipated but is performed by distinct pores.
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Affiliation(s)
| | - Sabrina Beck
- Institut für Biochemie und Pathobiochemie, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Jessica Klümper
- Institut für Biochemie und Pathobiochemie, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Michael Meinecke
- Institut für Zelluläre Biochemie, Universitätsmedizin Göttingen, 37073 Göttingen, Germany
| | - Wolfgang Schliebs
- Institut für Biochemie und Pathobiochemie, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Richard Wagner
- Biophysik, Fachbereich Biologie/Chemie, Universität Osnabrück, 49069 Osnabrück, Germany; MOLIFE Research Center, Jacobs University Bremen, 28759 Bremen, Germany.
| | - Ralf Erdmann
- Institut für Biochemie und Pathobiochemie, Ruhr-Universität Bochum, 44780 Bochum, Germany.
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16
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Barbot M, Jans DC, Schulz C, Denkert N, Kroppen B, Hoppert M, Jakobs S, Meinecke M. Mic10 oligomerizes to bend mitochondrial inner membranes at cristae junctions. Cell Metab 2015; 21:756-63. [PMID: 25955211 DOI: 10.1016/j.cmet.2015.04.006] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/06/2015] [Accepted: 04/01/2015] [Indexed: 11/25/2022]
Abstract
The mitochondrial inner membrane is highly folded and displays a complex molecular architecture. Cristae junctions are highly curved tubular openings that separate cristae membrane invaginations from the surrounding boundary membrane. Despite their central role in many vital cellular processes like apoptosis, the details of cristae junction formation remain elusive. Here we identify Mic10, a core subunit of the recently discovered MICOS complex, as an inner mitochondrial membrane protein with the ability to change membrane morphology in vitro and in vivo. We show that Mic10 spans the inner membrane in a hairpin topology and that its ability to sculpt membranes depends on oligomerization through a glycine-rich motif. Oligomerization mutants fail to induce curvature in model membranes, and when expressed in yeast, mitochondria display an altered inner membrane architecture characterized by drastically decreased numbers of cristae junctions. Thus, we demonstrate that membrane sculpting by Mic10 is essential for cristae junction formation.
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Affiliation(s)
- Mariam Barbot
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Daniel C Jans
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany; Department of Neurology, University Medical Center, 37075 Göttingen, Germany
| | - Christian Schulz
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Niels Denkert
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Benjamin Kroppen
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Michael Hoppert
- Institute of Microbiology and Genetics, Georg-August-University, 37077 Göttingen, Germany
| | - Stefan Jakobs
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany; Department of Neurology, University Medical Center, 37075 Göttingen, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany; European Neuroscience Institute Göttingen, 37077 Göttingen, Germany.
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17
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Harz J, Herrmann B, Klasen M, Kovařík K, Meinecke M. SUSY-QCD corrections to stop annihilation into electroweak final states including Coulomb enhancement effects. Int J Clin Exp Med 2015. [DOI: 10.1103/physrevd.91.034012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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18
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Gleisner M, Mey I, Barbot M, Dreker C, Meinecke M, Steinem C. Driving a planar model system into the 3(rd) dimension: generation and control of curved pore-spanning membrane arrays. Soft Matter 2014; 10:6228-6236. [PMID: 25012509 DOI: 10.1039/c4sm00702f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The generation of a regular array of micrometre-sized pore-spanning membranes that protrude from the underlying surface as a function of osmotic pressure is reported. Giant unilamellar vesicles are spread onto non-functionalized Si/SiO(2) substrates containing a highly ordered array of cavities with pore diameters of 850 nm, an interpore distance of 4 μm and a pore depth of 10 μm. The shape of the resulting pore-spanning membranes is controlled by applying an osmotic pressure difference between the bulk solution and the femtoliter-sized cavity underneath each membrane. By applying Young-Laplace's law assuming moderate lateral membrane tensions, the response of the membranes to the osmotic pressure difference can be theoretically well described. Protruded pore-spanning membranes containing the receptor lipid PIP(2) specifically bind the ENTH domain of epsin resulting in an enlargement of the protrusions and disappearance as a result of ENTH-domain induced defects in the membranes. These results are discussed in the context of an ENTH-domain induced reduction of lateral membrane tension and formation of defects as a result of helix insertion of the protein in the bilayer.
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Affiliation(s)
- Martin Gleisner
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany.
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19
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Santos AJM, Meinecke M, Fessler MB, Holden DW, Boucrot E. Preferential invasion of mitotic cells by Salmonella reveals that cell surface cholesterol is maximal during metaphase. J Cell Sci 2013; 126:2990-6. [PMID: 23687374 DOI: 10.1242/jcs.115253] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cell surface-exposed cholesterol is crucial for cell attachment and invasion of many viruses and bacteria, including the bacterium Salmonella, which causes typhoid fever and gastroenteritis. Using flow cytometry and 3D confocal fluorescence microscopy, we found that mitotic cells, although representing only 1-4% of an exponentially growing population, were much more efficiently targeted for invasion by Salmonella. This targeting was not dependent on the spherical shape of mitotic cells, but was instead SipB and cholesterol dependent. Thus, we measured the levels of plasma membrane and cell surface cholesterol throughout the cell cycle using, respectively, brief staining with filipin and a fluorescent ester of polyethylene glycol-cholesterol that cannot flip through the plasma membrane, and found that both were maximal during mitosis. This increase was due not only to the rise in global cell cholesterol levels along the cell cycle but also to a transient loss in cholesterol asymmetry at the plasma membrane during mitosis. We measured that cholesterol, but not phosphatidylserine, changed from a ∼2080 outerinner leaflet repartition during interphase to ∼5050 during metaphase, suggesting this was specific to cholesterol and not due to a broad change of lipid asymmetry during metaphase. This explains the increase in outer surface levels that make dividing cells more susceptible to Salmonella invasion and perhaps to other viruses and bacteria entering cells in a cholesterol-dependent manner. The change in cholesterol partitioning also favoured the recruitment of activated ERM (Ezrin, Radixin, Moesin) proteins at the plasma membrane and thus supported mitotic cell rounding.
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Affiliation(s)
- António J M Santos
- Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
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20
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Meinecke M, Boucrot E, Camdere G, Hon WC, Mittal R, McMahon HT. Cooperative recruitment of dynamin and BIN/amphiphysin/Rvs (BAR) domain-containing proteins leads to GTP-dependent membrane scission. J Biol Chem 2013; 288:6651-61. [PMID: 23297414 PMCID: PMC3585104 DOI: 10.1074/jbc.m112.444869] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Dynamin mediates various membrane fission events, including the scission of clathrin-coated vesicles. Here, we provide direct evidence for cooperative membrane recruitment of dynamin with the BIN/amphiphysin/Rvs (BAR) proteins, endophilin and amphiphysin. Surprisingly, endophilin and amphiphysin recruitment to membranes was also dependent on binding to dynamin due to auto-inhibition of BAR-membrane interactions. Consistent with reciprocal recruitment in vitro, dynamin recruitment to the plasma membrane in cells was strongly reduced by concomitant depletion of endophilin and amphiphysin, and conversely, depletion of dynamin dramatically reduced the recruitment of endophilin. In addition, amphiphysin depletion was observed to severely inhibit clathrin-mediated endocytosis. Furthermore, GTP-dependent membrane scission by dynamin was dramatically elevated by BAR domain proteins. Thus, BAR domain proteins and dynamin act in synergy in membrane recruitment and GTP-dependent vesicle scission.
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Affiliation(s)
- Michael Meinecke
- Laboratory of Molecular Biology, Medical Research Council, Hills Road, Cambridge CB2 0QH, United Kingdom
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21
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Krüger V, Deckers M, Hildenbeutel M, van der Laan M, Hellmers M, Dreker C, Preuss M, Herrmann JM, Rehling P, Wagner R, Meinecke M. The mitochondrial oxidase assembly protein1 (Oxa1) insertase forms a membrane pore in lipid bilayers. J Biol Chem 2012; 287:33314-26. [PMID: 22829595 DOI: 10.1074/jbc.m112.387563] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The inner membrane of mitochondria is especially protein-rich. To direct proteins into the inner membrane, translocases mediate transport and membrane insertion of precursor proteins. Although the majority of mitochondrial proteins are imported from the cytoplasm, core subunits of respiratory chain complexes are inserted into the inner membrane from the matrix. Oxa1, a conserved membrane protein, mediates the insertion of mitochondrion-encoded precursors into the inner mitochondrial membrane. The molecular mechanism by which Oxa1 mediates insertion of membrane spans, entailing the translocation of hydrophilic domains across the inner membrane, is still unknown. We investigated if Oxa1 could act as a protein-conducting channel for precursor transport. Using a biophysical approach, we show that Oxa1 can form a pore capable of accommodating a translocating protein segment. After purification and reconstitution, Oxa1 acts as a cation-selective channel that specifically responds to mitochondrial export signals. The aqueous pore formed by Oxa1 displays highly dynamic characteristics with a restriction zone diameter between 0.6 and 2 nm, which would suffice for polypeptide translocation across the membrane. Single channel analyses revealed four discrete channels per active unit, suggesting that the Oxa1 complex forms several cooperative hydrophilic pores in the inner membrane. Hence, Oxa1 behaves as a pore-forming translocase that is regulated in a membrane potential and substrate-dependent manner.
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Affiliation(s)
- Vivien Krüger
- Biophysik, Universität Osnabrück, FB Biologie/Chemie, D-49034 Osnabrück, Germany
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22
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Culham DE, Meinecke M, Wood JM. Impacts of the osmolality and the lumenal ionic strength on osmosensory transporter ProP in proteoliposomes. J Biol Chem 2012; 287:27813-22. [PMID: 22740696 DOI: 10.1074/jbc.m112.387936] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
H(+) symporter ProP serves as a paradigm for the study of osmosensing. ProP attains the same activity at the same osmolality when the medium outside cells or proteoliposomes is supplemented with diverse, membrane-impermeant solutes. The osmosensory mechanism of ProP has been probed by varying the solvent within membrane vesicles and proteoliposomes. ProP activation was not ion specific, did not require K(+), and could be elicited by large, uncharged solutes polyethylene glycols (PEGS). We hypothesized that ProP is an ionic strength sensor and lumenal macromolecules activate ProP by altering ion activities. The attainable range of lumenal ionic strength was expanded by lowering the phosphate concentration within proteoliposomes. ProP activity at high osmolality, but not the osmolality, yielding half-maximal activity (Π(1/2)/RT), decreased with the lumenal phosphate concentration. This was attributed to acidification of the proteoliposome lumen due to H(+)-proline symport. The ionic strength yielding half-maximal ProP activity was more anion-dependent than Π(1/2)/RT for proteoliposomes loaded with citrate, sulfate, phosphate, chloride, or iodide. The anion effects followed the Hofmeister series. Lumenal bovine serum albumin (BSA) lowered the lumenal ionic strength at which ProP became active. Osmolality measurements documented the non-idealities of solutions including potassium phosphate and other solutes. The impacts of PEGS and BSA on ion activities did not account for their impacts on ProP activity. The effects of the tested solutes on ProP appear to be non-coulombic in nature. They may arise from effects of preferential interactions and macromolecular crowding on the membrane or on ProP.
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Affiliation(s)
- Doreen E Culham
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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23
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Abstract
Clathrin-mediated endocytosis, the major pathway for ligand internalization into eukaryotic cells, is thought to be initiated by the clustering of clathrin and adaptors around receptors destined for internalization. However, here we report that the membrane-sculpting F-BAR domain-containing Fer/Cip4 homology domain-only proteins 1 and 2 (FCHo1/2) were required for plasma membrane clathrin-coated vesicle (CCV) budding and marked sites of CCV formation. Changes in FCHo1/2 expression levels correlated directly with numbers of CCV budding events, ligand endocytosis, and synaptic vesicle marker recycling. FCHo1/2 proteins bound specifically to the plasma membrane and recruited the scaffold proteins eps15 and intersectin, which in turn engaged the adaptor complex AP2. The FCHo F-BAR membrane-bending activity was required, leading to the proposal that FCHo1/2 sculpt the initial bud site and recruit the clathrin machinery for CCV formation.
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Affiliation(s)
- William Mike Henne
- Medical Research Council, Laboratory of Molecular Biology (MRC-LMB), Hills Road, Cambridge CB2 0QH, UK
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Domańska G, Motz C, Meinecke M, Harsman A, Papatheodorou P, Reljic B, Dian-Lothrop EA, Galmiche A, Kepp O, Becker L, Günnewig K, Wagner R, Rassow J. Helicobacter pylori VacA toxin/subunit p34: targeting of an anion channel to the inner mitochondrial membrane. PLoS Pathog 2010; 6:e1000878. [PMID: 20442789 PMCID: PMC2861713 DOI: 10.1371/journal.ppat.1000878] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 03/25/2010] [Indexed: 12/13/2022] Open
Abstract
The vacuolating toxin VacA, released by Helicobacter pylori, is an important virulence factor in the pathogenesis of gastritis and gastroduodenal ulcers. VacA contains two subunits: The p58 subunit mediates entry into target cells, and the p34 subunit mediates targeting to mitochondria and is essential for toxicity. In this study we found that targeting to mitochondria is dependent on a unique signal sequence of 32 uncharged amino acid residues at the p34 N-terminus. Mitochondrial import of p34 is mediated by the import receptor Tom20 and the import channel of the outer membrane TOM complex, leading to insertion of p34 into the mitochondrial inner membrane. p34 assembles in homo-hexamers of extraordinary high stability. CD spectra of the purified protein indicate a content of >40% beta-strands, similar to pore-forming beta-barrel proteins. p34 forms an anion channel with a conductivity of about 12 pS in 1.5 M KCl buffer. Oligomerization and channel formation are independent both of the 32 uncharged N-terminal residues and of the p58 subunit of the toxin. The conductivity is efficiently blocked by 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), a reagent known to inhibit VacA-mediated apoptosis. We conclude that p34 essentially acts as a small pore-forming toxin, targeted to the mitochondrial inner membrane by a special hydrophobic N-terminal signal.
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Affiliation(s)
- Grażyna Domańska
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
| | - Christian Motz
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
| | - Michael Meinecke
- Institut für Biophysik, Universität Osnabrück, Osnabrück, Germany
| | - Anke Harsman
- Institut für Biophysik, Universität Osnabrück, Osnabrück, Germany
| | | | - Boris Reljic
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
| | | | - Antoine Galmiche
- Laboratoire de Biochimie, INSERM ERI12, Hopital Nord, CHU Amiens Picardie, Amiens, France
| | - Oliver Kepp
- INSERM U848, Institute Gustave Roussy, Université Paris Sud, Villejuif, France
| | - Lars Becker
- Institut für Biophysik, Universität Osnabrück, Osnabrück, Germany
| | - Kathrin Günnewig
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
| | - Richard Wagner
- Institut für Biophysik, Universität Osnabrück, Osnabrück, Germany
| | - Joachim Rassow
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
- * E-mail:
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25
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Kozjak-Pavlovic V, Dian-Lothrop EA, Meinecke M, Kepp O, Ross K, Rajalingam K, Harsman A, Hauf E, Brinkmann V, Günther D, Herrmann I, Hurwitz R, Rassow J, Wagner R, Rudel T. Bacterial porin disrupts mitochondrial membrane potential and sensitizes host cells to apoptosis. PLoS Pathog 2009; 5:e1000629. [PMID: 19851451 PMCID: PMC2759283 DOI: 10.1371/journal.ppat.1000629] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 09/24/2009] [Indexed: 11/28/2022] Open
Abstract
The bacterial PorB porin, an ATP-binding β-barrel protein of pathogenic Neisseria gonorrhoeae, triggers host cell apoptosis by an unknown mechanism. PorB is targeted to and imported by host cell mitochondria, causing the breakdown of the mitochondrial membrane potential (ΔΨm). Here, we show that PorB induces the condensation of the mitochondrial matrix and the loss of cristae structures, sensitizing cells to the induction of apoptosis via signaling pathways activated by BH3-only proteins. PorB is imported into mitochondria through the general translocase TOM but, unexpectedly, is not recognized by the SAM sorting machinery, usually required for the assembly of β-barrel proteins in the mitochondrial outer membrane. PorB integrates into the mitochondrial inner membrane, leading to the breakdown of ΔΨm. The PorB channel is regulated by nucleotides and an isogenic PorB mutant defective in ATP-binding failed to induce ΔΨm loss and apoptosis, demonstrating that dissipation of ΔΨm is a requirement for cell death caused by neisserial infection. PorB is a bacterial porin that plays an important role in the pathogenicity of Neisseria gonorrhoeae. Upon infection with these bacteria, PorB is transported into mitochondria of infected cells, causing the loss of mitochondrial membrane potential and eventually leading to apoptotic cell death. Here, we show that PorB enters mitochondria through the TOM complex, similar to other mitochondria-targeted proteins, but then bypasses the SAM complex machinery that assembles all other porin-like proteins into the outer mitochondrial membrane. This leads to the accumulation of PorB in the intermembrane space and the integration of a fraction of PorB into the inner mitochondrial membrane (IMM). In the IMM, ATP-regulated pores are formed, leading to dissipation of membrane potential and the loss of cristae structure in affected mitochondria, the necessary first steps in induction of apoptosis. Our work offers, for the first time, a detailed analysis of the mechanism by which PorB targets and damages host cell mitochondria.
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Affiliation(s)
- Vera Kozjak-Pavlovic
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
- Biocenter, Chair of Microbiology, University of Würzburg, Würzburg, Germany
| | | | - Michael Meinecke
- Department of Biology/Chemistry, Division of Biophysics, University of Osnabrück, Osnabrück, Germany
| | - Oliver Kepp
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Katharina Ross
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Krishnaraj Rajalingam
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Anke Harsman
- Protein Purification Core Facility, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Eva Hauf
- Microscopy Core Facility, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Volker Brinkmann
- Microscopy Core Facility, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Dirk Günther
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Ines Herrmann
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Robert Hurwitz
- Protein Purification Core Facility, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Joachim Rassow
- Institute for Physiological Chemistry, Ruhr-University Bochum, Bochum, Germany
| | - Richard Wagner
- Department of Biology/Chemistry, Division of Biophysics, University of Osnabrück, Osnabrück, Germany
| | - Thomas Rudel
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
- Biocenter, Chair of Microbiology, University of Würzburg, Würzburg, Germany
- * E-mail:
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26
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Kutik S, Stojanovski D, Becker T, Stroud DA, Becker L, Meinecke M, Krüger V, Prinz C, Guiard B, Wagner R, Meisinger C, Pfanner N, Wiedemann N. Response: The Mitochondrial β-Signal and Protein Sorting. Cell 2008. [DOI: 10.1016/j.cell.2008.12.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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27
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van der Laan M, Meinecke M, Dudek J, Hutu DP, Lind M, Perschil I, Guiard B, Wagner R, Pfanner N, Rehling P. Motor-free mitochondrial presequence translocase drives membrane integration of preproteins. Nat Cell Biol 2007; 9:1152-9. [PMID: 17828250 DOI: 10.1038/ncb1635] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Accepted: 08/09/2007] [Indexed: 11/09/2022]
Abstract
The mitochondrial inner membrane is the central energy-converting membrane of eukaryotic cells. The electrochemical proton gradient generated by the respiratory chain drives the ATP synthase. To maintain this proton-motive force, the inner membrane forms a tight barrier and strictly controls the translocation of ions. However, the major preprotein transport machinery of the inner membrane, termed the presequence translocase, translocates polypeptide chains into or across the membrane. Different views exist of the molecular mechanism of the translocase, in particular of the coupling with the import motor of the matrix. We have reconstituted preprotein transport into the mitochondrial inner membrane by incorporating the purified presequence translocase into cardiolipin-containing liposomes. We show that the motor-free form of the presequence translocase integrates preproteins into the membrane. The reconstituted presequence translocase responds to targeting peptides and mediates voltage-driven preprotein translocation, lateral release and insertion into the lipid phase. Thus, the minimal system for preprotein integration into the mitochondrial inner membrane is the presequence translocase, a cardiolipin-rich membrane and a membrane potential.
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Affiliation(s)
- Martin van der Laan
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Universität Freiburg, Hermann-Herder-StraSSe 7, D-79104 Freiburg, Germany
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28
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Meinecke M, Wagner R, Kovermann P, Guiard B, Mick DU, Hutu DP, Voos W, Truscott KN, Chacinska A, Pfanner N, Rehling P. Tim50 Maintains the Permeability Barrier of the Mitochondrial Inner Membrane. Science 2006; 312:1523-6. [PMID: 16763150 DOI: 10.1126/science.1127628] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Transport of metabolites across the mitochondrial inner membrane is highly selective, thereby maintaining the electrochemical proton gradient that functions as the main driving force for cellular adenosine triphosphate synthesis. Mitochondria import many preproteins via the presequence translocase of the inner membrane. However, the reconstituted Tim23 protein constitutes a pore remaining mainly in its open form, a state that would be deleterious in organello. We found that the intermembrane space domain of Tim50 induced the Tim23 channel to close. Presequences overcame this effect and activated the channel for translocation. Thus, the hydrophilic cis domain of Tim50 maintains the permeability barrier of mitochondria by closing the translocation pore in a presequence-regulated manner.
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Affiliation(s)
- Michael Meinecke
- Biophysik, Universität Osnabrück, FB Biologie/Chemie, D-49034 Osnabrück, Germany
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29
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Bertozzi M, Broggi A, Carletti M, Fascioli A, Graf T, Grisleri P, Meinecke M. IR Pedestrian Detection for Advanced Driver Assistance Systems. Lecture Notes in Computer Science 2003. [DOI: 10.1007/978-3-540-45243-0_74] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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30
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Bömmel HM, Reif A, Fröhlich LG, Frey A, Hofmann H, Marecak DM, Groehn V, Kotsonis P, La M, Köster S, Meinecke M, Bernhardt M, Weeger M, Ghisla S, Prestwich GD, Pfleiderer W, Schmidt HH. Anti-pterins as tools to characterize the function of tetrahydrobiopterin in NO synthase. J Biol Chem 1998; 273:33142-9. [PMID: 9837881 DOI: 10.1074/jbc.273.50.33142] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nitric oxide synthases (NOS) are homodimeric enzymes that NADPH-dependently convert L-arginine to nitric oxide and L-citrulline. Interestingly, all NOS also require (6R)-5,6,7, 8-tetrahydro-L-biopterin (H4Bip) for maximal activity although the mechanism is not fully understood. Basal NOS activity, i.e. that in the absence of exogenous H4Bip, has been attributed to enzyme-associated H4Bip. To elucidate further H4Bip function in purified NOS, we developed two types of pterin-based NOS inhibitors, termed anti-pterins. In contrast to type II anti-pterins, type I anti-pterins specifically displaced enzyme-associated H4Bip and inhibited H4Bip-stimulated NOS activity in a fully competitive manner but, surprisingly, had no effect on basal NOS activity. Moreover, for a number of different NOS preparations basal activity (percent of Vmax) was frequently higher than the percentage of pterin saturation and was not affected by preincubation of enzyme with H4Bip. Thus, basal NOS activity appeared to be independent of enzyme-associated H4Bip. The lack of intrinsic 4a-pterincarbinolamine dehydratase activity argued against classical H4Bip redox cycling in NOS. Rather, H4Bip was required for both maximal activity and stability of NOS by binding to the oxygenase/dimerization domain and preventing monomerization and inactivation during L-arginine turnover. Since anti-pterins were also effective in intact cells, they may become useful in modulating states of pathologically high nitric oxide formation.
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Affiliation(s)
- H M Bömmel
- Department of Pharmacology and Toxicology, Julius-Maximilians-University, D-97078 Würzburg, Germany
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31
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Gudi T, Huvar I, Meinecke M, Lohmann SM, Boss GR, Pilz RB. Regulation of gene expression by cGMP-dependent protein kinase. Transactivation of the c-fos promoter. J Biol Chem 1996; 271:4597-600. [PMID: 8617718 DOI: 10.1074/jbc.271.9.4597] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The cAMP/cAMP-dependent protein kinase (A-kinase) and Ca2+/calmodulin-dependent protein kinase (Cam-kinase) signal transduction pathways are well known to regulate gene transcription, but this has not been demonstrated directly for the cGMP/cGMP-dependent protein kinase (G-kinase) signal transduction pathway. Here we report that transfection of G-kinase into G-kinase-deficient cells causes activation of the human c-fos promoter in a strictly cGMP-dependent manner. The effect of G-kinase appeared to be mediated by several sequence elements, most notably the serum response element (SRE), the AP-1 binding site (FAP), and the cAMP response element (CRE). The magnitude of G-kinase transactivation of the fos promoter was similar to that of A-kinase, but there were significant differences between G-kinase and A-kinase activation of single enhancer elements and of a chimeric Gal4-CREB transcription factor. Our results indicate that G-kinase transduces signals to the nucleus independently of A-kinase or Ca2+, although it may target some of the same transcription factors as A-kinase and Cam-kinase.
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Affiliation(s)
- T Gudi
- Department of Medicine and the Cancer Center, University of California at San Diego, La Jolla, 92093-0652, USA
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32
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Meinecke M, Geiger J, Butt E, Sandberg M, Jahnsen T, Chakraborty T, Walter U, Jarchau T, Lohmann SM. Human cyclic GMP-dependent protein kinase I beta overexpression increases phosphorylation of an endogenous focal contact-associated vasodilator-stimulated phosphoprotein without altering the thrombin-evoked calcium response. Mol Pharmacol 1994; 46:283-90. [PMID: 8078490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The role of the cGMP-dependent protein kinase (cGK) and one of its major substrates, the vasodilator-stimulated phosphoprotein (VASP), in the regulation of a receptor-evoked calcium response was investigated. The human type I beta cGK was stably transfected in human embryonic kidney 293 cells and Swiss mouse 3T6 fibroblasts, which contained significant or no detectable levels of the focal adhesion protein VASP, respectively. Western blot analysis and protein kinase activity measurements demonstrated an 8-fold overexpression of cGK-I beta in 293 cells (7-fold in 3T6 cells), representing an intracellular cGK concentration of 0.33 microM. In experiments with intact 293 cells expressing cGK-I beta, beta-phenyl-1,N2-etheno-cGMP and 8-(p-chlorophenylthio)-cGMP were capable of converting up to 30-40% of the 46-kDa VASP to its 50-kDa phospho- form, equivalent to results observed with cGMP analogs that cause a marked inhibition of the stimulated Ca2+ transient in intact human platelets. In contrast to platelets, preincubation of fura-2-loaded 293 and 3T6 cells with 8-(p-chlorophenylthio)-cGMP did not significantly inhibit thrombin-evoked calcium transients, although sufficient cGK-mediated VASP phosphorylation was clearly detectable under these conditions in cGK-I beta-expressing 293 cells. These results demonstrate that cGK inhibition of agonist-evoked calcium mobilization is not a mechanism common to all cell types and that VASP phosphorylation may not be an essential or sufficient component of the cGK effect on calcium levels. In contrast, the observed VASP phosphorylation mediated by recombinant human cGK-I beta in intact 293 cells does support the hypothesis that focal adhesions and their associated proteins are important cellular sites of cGK action.
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Affiliation(s)
- M Meinecke
- Medizinische Universitätsklinik, Klinische Biochemie und Pathobiochemie, Würzburg, Germany
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Büchler W, Meinecke M, Chakraborty T, Jahnsen T, Walter U, Lohmann SM. Regulation of gene expression by transfected subunits of cAMP-dependent protein kinase. Eur J Biochem 1990; 188:253-9. [PMID: 2156696 DOI: 10.1111/j.1432-1033.1990.tb15397.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
cAMP regulates the expression of several genes by activation of a promoter consensus sequence which functions as a cAMP-response element. Evidence indicated that this is accomplished via cAMP dissociation of cAMP-dependent protein kinase into its regulatory (R) and catalytic (C) subunits. Our investigations of the role of these two subunits in gene expression provide direct and quantitative evidence that the C subunit is required for cAMP stimulation of the cAMP-response element in the vasoactive-intestinal-peptide gene in rat pheochromocytoma cells. After cotransfection of a metallothionein-regulated C-subunit expression vector (pCEV) and a vasoactive-intestinal-peptide--chloramphenicol acetyltransferase construct containing a cAMP-response element, we could demonstrate expression of transfected C-alpha-subunit mRNA (truncated size 1.7 kb) by Northern blot and a concentration-dependent C subunit stimulation of chloramphenicol acetyltransferase activity. Basal activity was stimulated 12- and 50-fold by pCEV (30 micrograms), in the absence and presence, respectively, of Zn2+. Metallothionein-regulated expression of C was demonstrated by results that showed a 2-4-fold increase in chloramphenicol acetyltransferase activity in the presence versus the absence of 90 microM Zn2+. In contrast, overexpression of the R-II beta regulatory subunit did not stimulate chloramphenicol acetyltransferase activity, and R-II beta transfected together with C (ratio 2:1 and 4:1) inhibited the stimulation by the C subunit 70% and 90% respectively. Our results indicate that transfection of cAMP-dependent protein kinase subunits results in functional expression of both C-alpha and R-II beta subunits. Expression of the C subunit mediated cAMP-regulated gene expression but this expression could be inhibited by cotransfected R-II beta subunit, indicating intracellular reconstitution of the inactive holoenzyme of cAMP-dependent protein kinase.
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Affiliation(s)
- W Büchler
- Department of Internal Medicine, University of Würzburg, Federal Republic of Germany
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34
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Wegner M, Helftenbein E, Müller F, Meinecke M, Müller S, Grummt F. Identification of an amplification promoting DNA sequence from the hypotrichous ciliate Stylonychia lemnae. Nucleic Acids Res 1989; 17:8783-802. [PMID: 2479911 PMCID: PMC335043 DOI: 10.1093/nar/17.21.8783] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The macronucleus of the hypotrichous ciliate Stylonychia lemnae contains a 1218 bp long DNA molecule which becomes highly amplified during vegetative growth due to a continuous overreplication over a long time range. The region which is located upstream the open reading frame of the overamplified 1.2kbp Stylonychia DNA molecule enabled plasmids containing an inefficiently transcribed thymidine kinase gene to persist and amplify upon transfection into mouse L fibroblasts under selective conditions. This region contains long AT-rich stretches. The AT-rich sequences interact with a previously characterized HMG-I like protein from mouse Ehrlich ascites tumour cells. A binding activity for AT-rich stretches could also be identified in macronuclear extracts from Stylonychia lemnae. We suggest a common mechanism for overamplification in Stylonychia macronuclei during vegetative growth and amplification of plasmid DNA in heterologous mouse cells under the influence of a common element.
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Affiliation(s)
- M Wegner
- Institut für Biochemie, Universität Würzburg, FRG
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