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Benaroya H. Mitochondria and MICOS - function and modeling. Rev Neurosci 2024; 0:revneuro-2024-0004. [PMID: 38369708 DOI: 10.1515/revneuro-2024-0004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 01/14/2024] [Indexed: 02/20/2024]
Abstract
An extensive review is presented on mitochondrial structure and function, mitochondrial proteins, the outer and inner membranes, cristae, the role of F1FO-ATP synthase, the mitochondrial contact site and cristae organizing system (MICOS), the sorting and assembly machinery morphology and function, and phospholipids, in particular cardiolipin. Aspects of mitochondrial regulation under physiological and pathological conditions are outlined, in particular the role of dysregulated MICOS protein subunit Mic60 in Parkinson's disease, the relations between mitochondrial quality control and proteins, and mitochondria as signaling organelles. A mathematical modeling approach of cristae and MICOS using mechanical beam theory is introduced and outlined. The proposed modeling is based on the premise that an optimization framework can be used for a better understanding of critical mitochondrial function and also to better map certain experiments and clinical interventions.
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Affiliation(s)
- Haym Benaroya
- Department of Mechanical and Aerospace Engineering, Rutgers University, 98 Brett Road, Piscataway, NJ 08854, USA
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2
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Benaroya H. Understanding mitochondria and the utility of optimization as a canonical framework for identifying and modeling mitochondrial pathways. Rev Neurosci 2022; 33:657-690. [PMID: 35219282 DOI: 10.1515/revneuro-2021-0138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 01/25/2022] [Indexed: 11/15/2022]
Abstract
The goal of this paper is to provide an overview of our current understanding of mitochondrial function as a framework to motivate the hypothesis that mitochondrial behavior is governed by optimization principles that are constrained by the laws of the physical and biological sciences. Then, mathematical optimization tools can generally be useful to model some of these processes under reasonable assumptions and limitations. We are specifically interested in optimizations via variational methods, which are briefly summarized. Within such an optimization framework, we suggest that the numerous mechanical instigators of cell and intracellular functioning can be modeled utilizing some of the principles of mechanics that govern engineered systems, as well as by the frequently observed feedback and feedforward mechanisms that coordinate the multitude of processes within cells. These mechanical aspects would need to be coupled to governing biochemical rules. Of course, biological systems are significantly more complex than engineered systems, and require considerably more experimentation to ascertain and characterize parameters and subsequent behavior. That complexity requires well-defined limitations and assumptions for any derived models. Optimality is being motivated as a framework to help us understand how cellular decisions are made, especially those that transition between physiological behaviors and dysfunctions along pathophysiological pathways. We elaborate on our interpretation of optimality and cellular decision making within the body of this paper, as we revisit these ideas in the numerous different contexts of mitochondrial functions.
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Affiliation(s)
- Haym Benaroya
- Department of Mechanical and Aerospace Engineering, Rutgers University, 98 Brett Road, Piscataway, NJ 08901, USA
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3
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Pánek T, Eliáš M, Vancová M, Lukeš J, Hashimi H. Returning to the Fold for Lessons in Mitochondrial Crista Diversity and Evolution. Curr Biol 2021; 30:R575-R588. [PMID: 32428499 DOI: 10.1016/j.cub.2020.02.053] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cristae are infoldings of the mitochondrial inner membrane jutting into the organelle's innermost compartment from narrow stems at their base called crista junctions. They are emblematic of aerobic mitochondria, being the fabric for the molecular machinery driving cellular respiration. Electron microscopy revealed that diverse eukaryotes possess cristae of different shapes. Yet, crista diversity has not been systematically examined in light of our current knowledge about eukaryotic evolution. Since crista form and function are intricately linked, we take a holistic view of factors that may underlie both crista diversity and the adherence of cristae to a recognizable form. Based on electron micrographs of 226 species from all major lineages, we propose a rational crista classification system that postulates cristae as variations of two general morphotypes: flat and tubulo-vesicular. The latter is most prevalent and likely ancestral, but both morphotypes are found interspersed throughout the eukaryotic tree. In contrast, crista junctions are remarkably conserved, supporting their proposed role as diffusion barriers that sequester cristae contents. Since cardiolipin, ATP synthase dimers, the MICOS complex, and dynamin-like Opa1/Mgm1 are known to be involved in shaping cristae, we examined their variation in the context of crista diversity. Moreover, we have identified both commonalities and differences that may collectively be manifested as diverse variations of crista form and function.
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Affiliation(s)
- Tomáš Pánek
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava 710 00, Czech Republic
| | - Marek Eliáš
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava 710 00, Czech Republic
| | - Marie Vancová
- Institute of Parasitology, Biology Center, Czech Academy of Sciences and Faculty of Science, University of South Bohemia, České Budějovice 370 05, Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Center, Czech Academy of Sciences and Faculty of Science, University of South Bohemia, České Budějovice 370 05, Czech Republic
| | - Hassan Hashimi
- Institute of Parasitology, Biology Center, Czech Academy of Sciences and Faculty of Science, University of South Bohemia, České Budějovice 370 05, Czech Republic.
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4
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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: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [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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5
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Emerging Roles of the MICOS Complex in Cristae Dynamics and Biogenesis. BIOLOGY 2021; 10:biology10070600. [PMID: 34209580 PMCID: PMC8301002 DOI: 10.3390/biology10070600] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/23/2021] [Accepted: 06/24/2021] [Indexed: 12/19/2022]
Abstract
Simple Summary Mitochondria possess an outer and inner membrane. The part of the inner membrane parallel to the outer membrane is termed the inner boundary membrane, while the cristae membrane folds towards the mitochondrial matrix and houses the respiratory chain complexes. Crista junctions are located at the interface of the inner boundary membrane and the cristae membrane and contain the important ‘mitochondrial contact site and cristae organizing system’ complex. Despite the growing evidence that the mitochondrial inner membrane could remodel, cristae membranes were largely considered static for nearly seventy years, as the observations were mostly based on electron microscopy and tomography. Recently, using fluorescence super-resolution techniques, several studies showed that cristae membranes undergo dynamic remodeling in living cells, and probably even fission and fusion of the inner membrane. In this review, we discuss the important recent literature conveying the emerging role of the MICOS complex in cristae dynamics and its relation to cristae biogenesis. As the aberrant inner membrane architecture is connected to various pathologies such as cardiomyopathies, neurodegeneration and diabetes, understanding the roles of various molecules connected with cristae biogenesis and dynamics would shed light on the pathophysiology, probably leading to therapeutics in the near future. Abstract Mitochondria are double membrane-enclosed organelles performing important cellular and metabolic functions such as ATP generation, heme biogenesis, apoptosis, ROS production and calcium buffering. The mitochondrial inner membrane (IM) is folded into cristae membranes (CMs) of variable shapes using molecular players including the ‘mitochondrial contact site and cristae organizing system’ (MICOS) complex, the dynamin-like GTPase OPA1, the F1FO ATP synthase and cardiolipin. Aberrant cristae structures are associated with different disorders such as diabetes, neurodegeneration, cancer and hepato-encephalopathy. In this review, we provide an updated view on cristae biogenesis by focusing on novel roles of the MICOS complex in cristae dynamics and shaping of cristae. For over seven decades, cristae were considered as static structures. It was recently shown that cristae constantly undergo rapid dynamic remodeling events. Several studies have re-oriented our perception on the dynamic internal ambience of mitochondrial compartments. In addition, we discuss the recent literature which sheds light on the still poorly understood aspect of cristae biogenesis, focusing on the role of MICOS and its subunits. Overall, we provide an integrated and updated view on the relation between the biogenesis of cristae and the novel aspect of cristae dynamics.
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Tarasenko D, Meinecke M. Protein-dependent membrane remodeling in mitochondrial morphology and clathrin-mediated endocytosis. EUROPEAN BIOPHYSICS JOURNAL: EBJ 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] [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] [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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Jiang YF, Lin HL, Wang LJ, Hsu T, Fu CY. Coordinated organization of mitochondrial lamellar cristae and gain of COX function during mitochondrial maturation in Drosophila. Mol Biol Cell 2019; 31:18-26. [PMID: 31746672 PMCID: PMC6938269 DOI: 10.1091/mbc.e19-08-0450] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial cristae contain electron transport chain complexes and are distinct from the inner boundary membrane (IBM). While many details regarding the regulation of mitochondrial structure are known, the relationship between cristae structure and function during organelle development is not fully described. Here, we used serial-section tomography to characterize the formation of lamellar cristae in immature mitochondria during a period of dramatic mitochondrial development that occurs after Drosophila emergence as an adult. We found that the formation of lamellar cristae was associated with the gain of cytochrome c oxidase (COX) function, and the COX subunit, COX4, was localized predominantly to organized lamellar cristae. Interestingly, 3D tomography showed some COX-positive lamellar cristae were not connected to IBM. We hypothesize that some lamellar cristae may be organized by a vesicle germination process in the matrix, in addition to invagination of IBM. OXA1 protein, which mediates membrane insertion of COX proteins, was also localized to cristae and reticular structures isolated in the matrix additional to the IBM, suggesting that it may participate in the formation of vesicle germination-derived cristae. Overall, our study elaborates on how cristae morphogenesis and functional maturation are intricately associated. Our data support the vesicle germination and membrane invagination models of cristae formation.
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Affiliation(s)
- Yi-Fan Jiang
- Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei 106, Taiwan
| | - Hsiang-Ling Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Li-Jie Wang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Tian Hsu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Chi-Yu Fu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
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10
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Bouvier B. Curvature as a Collective Coordinate in Enhanced Sampling Membrane Simulations. J Chem Theory Comput 2019; 15:6551-6561. [DOI: 10.1021/acs.jctc.9b00716] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Benjamin Bouvier
- Laboratoire de Glycochimie, des Antimicrobiens et des Agroressources, CNRS UMR7378/Université de Picardie Jules Verne, 10, rue Baudelocque, 80039 Amiens Cedex, France
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11
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Lesus J, Arias K, Kulaga J, Sobkiv S, Patel A, Babu V, Kambalyal A, Patel M, Padron F, Mozaffari P, Jayakumar A, Ghatalah L, Laban N, Bahari R, Perkins G, Lysakowski A. Why study inner ear hair cell mitochondria? HNO 2019; 67:429-433. [PMID: 30969353 DOI: 10.1007/s00106-019-0662-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In several systems of the body (muscle, liver, nerves), new studies have examined the internal structure of mitochondria and brought to light striking new findings about how mitochondria are constructed and how their structure affects cell function. In the inner ear field, however, we have little structural knowledge about hair cell and supporting cell mitochondria, and virtually none about mitochondrial subtypes or how they function in health and disease. The need for such knowledge is discussed in this short review.
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Affiliation(s)
- J Lesus
- Dept. of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., M/C 512, 60612, Chicago, IL, USA
| | - K Arias
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - J Kulaga
- Dept. of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., M/C 512, 60612, Chicago, IL, USA
| | - S Sobkiv
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - A Patel
- Dept. of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., M/C 512, 60612, Chicago, IL, USA
| | - V Babu
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - A Kambalyal
- Dept. of Economics, University of Illinois at Chicago, Chicago, IL, USA
| | - M Patel
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - F Padron
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - P Mozaffari
- Dept. of Economics, University of Illinois at Chicago, Chicago, IL, USA
| | - A Jayakumar
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - L Ghatalah
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - N Laban
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - R Bahari
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - G Perkins
- National Center for Microscopy and Imaging Research (NCMIR), University of California, San Diego, La Jolla, CA, USA
| | - A Lysakowski
- Dept. of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., M/C 512, 60612, Chicago, IL, USA. .,Dept. of Otolaryngology, University of Illinois at Chicago, Chicago, IL, USA.
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12
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Könnel A, Bugaeva W, Gügel IL, Philippar K. BANFF: bending of bilayer membranes by amphiphilic α-helices is necessary for form and function of organelles 1. Biochem Cell Biol 2018; 97:243-256. [PMID: 30208283 DOI: 10.1139/bcb-2018-0150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
By binding to and inserting into the lipid bilayer, amphiphilic α-helices of proteins are involved in the curvature of biological membranes in all organisms. In particular, they are involved in establishing the complex membrane architecture of intracellular organelles like the endoplasmatic reticulum, Golgi apparatus, mitochondria, and chloroplasts. Thus, amphiphilic α-helices are essential for maintenance of cellular metabolism and fitness of organisms. Here we focus on the structure and function of membrane-intrinsic proteins, which are involved in membrane curvature by amphiphilic α-helices, in mitochondria and chloroplasts of the eukaryotic model organisms yeast and Arabidopsis thaliana. Further, we propose a model for transport of fatty acids and lipid compounds across the envelope of chloroplasts in which amphiphilic α-helices might play a role.
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Affiliation(s)
- Anne Könnel
- a Center for Human- and Molecular Biology (ZHMB) - Plant Biology, Saarland University, Campus A 2.4, 66123 Saarbrücken, Germany
| | - Wassilina Bugaeva
- a Center for Human- and Molecular Biology (ZHMB) - Plant Biology, Saarland University, Campus A 2.4, 66123 Saarbrücken, Germany
| | - Irene L Gügel
- b Department of Biology I - Botany, Ludwig-Maximilians University München, Großhaderner-Str. 2, 82152 Planegg-Martinsried, Germany
| | - Katrin Philippar
- a Center for Human- and Molecular Biology (ZHMB) - Plant Biology, Saarland University, Campus A 2.4, 66123 Saarbrücken, Germany
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13
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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] [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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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] [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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