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Coelho-Junior HJ, Marzetti E, Sexton CL, Wu K, Mankowski R, Anton SD, Leeuwenburgh C, Picca A. Mitochondrial quality control measures, systemic inflammation, and lower-limb muscle power in older adults: a PROMPT secondary analysis. J Nutr Health Aging 2024; 28:100408. [PMID: 39504617 DOI: 10.1016/j.jnha.2024.100408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2024] [Revised: 10/21/2024] [Accepted: 10/26/2024] [Indexed: 11/08/2024]
Abstract
OBJECTIVES The study was conducted to explore associations between markers of mitochondrial quality control (MQC) from vastus lateralis muscle biopsies, serum inflammatory markers, and measures of muscle power assessed by two different tools in a sample of older adults. DESIGN Secondary analysis of data collected in the PeppeR develOpMental ProjecT (PROMPT) at the University of Florida (Gainesville, FL, USA). METHODS Forty-three older adults (n = 20 women) were included in the study. Muscle volume of the calf and thigh was quantified by three-dimensional magnetic resonance imaging. Lower-limb muscle power was estimated using 5-time sit-to-stand (5STS) muscle power equations and isokinetic test. Protein markers of MQC were measured in muscle samples by Western immoblotting (n = 12-23), while type I and II fiber cross-sectional area (CSA) and their proportion were quantified using immunohistochemistry (n = 12). Cytochrome C oxidase enzyme activity was measured spectrophotometrically. Finally, inflammatory markers were quantified in the serum using a multiplex immunoassay (n = 39). RESULTS Mean age of participants was 78.1 ± 5.5 years, and the average body mass index was 26.2 ± 4.5 kg/m2. Markers of mitochondrial biogenesis (i.e., PGC-1α), mitochondrial import proteins (i.e., cHsp70 and mtHsp70), and type I fiber CSA were significantly associated with muscle power estimated via both 5STS muscle power equations and isokinetic test (p < 0.05). Specific associations were also found according to the muscle power assessment method. 5STS muscle power measures were negatively correlated with ClvCasp3, P-AMPK, T-AMPK, P-p38, GM-CSF, INF-γ, IL1b, IL6, IL8, and TNF-α, whereas positive associations were found with BAX (p < 0.05). In contrast, isokinetic measures were significantly and positively correlated with RIP140, Hsp60, and type II muscle fiber CSA (p < 0.05). CONCLUSIONS Markers of mitochondrial biogenesis (PGC-1α), mitochondrial import proteins (cHsp70 and mtHsp70), and type I muscle fiber CSA were significantly linked to lower-limb muscle power in older adults. These results suggest that muscle power is influenced by mitochondrial signaling. We also found that the relationship between mitochondrial mediators, inflammatory markers, and muscle power varied according to the assessment tool used.
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Affiliation(s)
| | - Emanuele Marzetti
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCSS, Rome, Italy; Department of Geriatrics, Orthopedics and Rheumatology, Università Cattolica del Sacro Cuore, Rome, Italy.
| | - Casey L Sexton
- Department of Physiology and Aging, University of Florida, Gainesville, FL, United States
| | - Kevin Wu
- Department of Physiology and Aging, University of Florida, Gainesville, FL, United States
| | - Robert Mankowski
- University of Alabama at Birmingham, School of Medicine, Birmingham, AL, United States
| | - Stephen D Anton
- Department of Physiology and Aging, University of Florida, Gainesville, FL, United States
| | | | - Anna Picca
- Department of Geriatrics, Orthopedics and Rheumatology, Università Cattolica del Sacro Cuore, Rome, Italy; Department of Medicine and Surgery, LUM University, Casamassima, Italy.
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2
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Rothemann RA, Stobbe D, Hoehne-Wiechmann MN, Murschall LM, Peker E, Knaup LK, Racho J, Habich M, Gerlich S, Lapacz KJ, Ulrich K, Riemer J. Interaction with the cysteine-free protein HAX1 expands the substrate specificity and function of MIA40 beyond protein oxidation. FEBS J 2024; 291:5506-5522. [PMID: 39564806 DOI: 10.1111/febs.17328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 08/16/2024] [Accepted: 11/11/2024] [Indexed: 11/21/2024]
Abstract
The mitochondrial disulphide relay machinery is essential for the import and oxidative folding of many proteins in the mitochondrial intermembrane space. Its core component, the import receptor MIA40 (also CHCHD4), serves as an oxidoreductase but also as a chaperone holdase, which initially interacts with its substrates non-covalently before introducing disulphide bonds for folding and retaining proteins in the intermembrane space. Interactome studies have identified diverse substrates of MIA40, among them the intrinsically disordered HCLS1-associated protein X-1 (HAX1). Interestingly, this protein does not contain cysteines, raising the question of how and to what end HAX1 can interact with MIA40. Here, we demonstrate that MIA40 non-covalently interacts with HAX1 independent of its redox-active cysteines. While HAX1 import is driven by its weak mitochondrial targeting sequence, its subsequent transient interaction with MIA40 stabilizes the protein in the intermembrane space. HAX1 solely depends on the holdase activity of MIA40, and the absence of MIA40 results in the aggregation, degradation and loss of HAX1. Collectively, our study introduces HAX1 as the first endogenous MIA40 substrate without cysteines and demonstrates the diverse functions of this highly conserved oxidoreductase and import receptor.
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Affiliation(s)
| | - Dylan Stobbe
- Redox Metabolism, Institute of Biochemistry, University of Cologne, Germany
| | | | | | - Esra Peker
- Redox Metabolism, Institute of Biochemistry, University of Cologne, Germany
| | - Lara Katharina Knaup
- Cellular Biochemistry, Institute of Biochemistry, University of Cologne, Germany
| | - Julia Racho
- Redox Metabolism, Institute of Biochemistry, University of Cologne, Germany
| | - Markus Habich
- Redox Metabolism, Institute of Biochemistry, University of Cologne, Germany
| | - Sarah Gerlich
- Redox Metabolism, Institute of Biochemistry, University of Cologne, Germany
| | - Kim Jasmin Lapacz
- Redox Metabolism, Institute of Biochemistry, University of Cologne, Germany
| | - Kathrin Ulrich
- Cellular Biochemistry, Institute of Biochemistry, University of Cologne, Germany
| | - Jan Riemer
- Redox Metabolism, Institute of Biochemistry, University of Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Germany
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3
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Brogyanyi T, Kejík Z, Veselá K, Dytrych P, Hoskovec D, Masařik M, Babula P, Kaplánek R, Přibyl T, Zelenka J, Ruml T, Vokurka M, Martásek P, Jakubek M. Iron chelators as mitophagy agents: Potential and limitations. Biomed Pharmacother 2024; 179:117407. [PMID: 39265234 DOI: 10.1016/j.biopha.2024.117407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Revised: 08/26/2024] [Accepted: 09/02/2024] [Indexed: 09/14/2024] Open
Abstract
Mitochondrial autophagy (mitophagy) is very important process for the maintenance of cellular homeostasis, functionality and survival. Its dysregulation is associated with high risk and progression numerous serious diseases (e.g., oncological, neurodegenerative and cardiovascular ones). Therefore, targeting mitophagy mechanisms is very hot topic in the biological and medicinal research. The interrelationships between the regulation of mitophagy and iron homeostasis are now becoming apparent. In short, mitochondria are central point for the regulation of iron homeostasis, but change in intracellular cheatable iron level can induce/repress mitophagy. In this review, relationships between iron homeostasis and mitophagy are thoroughly discussed and described. Also, therapeutic applicability of mitophagy chelators in the context of individual diseases is comprehensively and critically evaluated.
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Affiliation(s)
- Tereza Brogyanyi
- BIOCEV, First Faculty of Medicine, Charles University, Vestec 252 50, Czech Republic; Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague 120 00, Czech Republic; Institute of Pathological Physiology, First Faculty of Medicine, Charles University in Prague, U Nemocnice 5, 1, Prague 28 53, Czech Republic
| | - Zdeněk Kejík
- BIOCEV, First Faculty of Medicine, Charles University, Vestec 252 50, Czech Republic; Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague 120 00, Czech Republic
| | - Kateřina Veselá
- BIOCEV, First Faculty of Medicine, Charles University, Vestec 252 50, Czech Republic; Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague 120 00, Czech Republic
| | - Petr Dytrych
- 1st Department of Surgery-Department of Abdominal, Thoracic Surgery and Traumatology, First Faculty of Medicine, Charles University and General University Hospital, U Nemocnice 2, Prague 121 08, Czech Republic
| | - David Hoskovec
- 1st Department of Surgery-Department of Abdominal, Thoracic Surgery and Traumatology, First Faculty of Medicine, Charles University and General University Hospital, U Nemocnice 2, Prague 121 08, Czech Republic
| | - Michal Masařik
- BIOCEV, First Faculty of Medicine, Charles University, Vestec 252 50, Czech Republic; Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague 120 00, Czech Republic; Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, Brno CZ-625 00, Czech Republic; Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, Brno 625 00, Czech Republic
| | - Petr Babula
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, Brno CZ-625 00, Czech Republic
| | - Robert Kaplánek
- BIOCEV, First Faculty of Medicine, Charles University, Vestec 252 50, Czech Republic; Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague 120 00, Czech Republic
| | - Tomáš Přibyl
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Prague 166 28, Czech Republic
| | - Jaroslav Zelenka
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Prague 166 28, Czech Republic
| | - Tomáš Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Prague 166 28, Czech Republic
| | - Martin Vokurka
- Institute of Pathological Physiology, First Faculty of Medicine, Charles University in Prague, U Nemocnice 5, 1, Prague 28 53, Czech Republic
| | - Pavel Martásek
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague 120 00, Czech Republic
| | - Milan Jakubek
- BIOCEV, First Faculty of Medicine, Charles University, Vestec 252 50, Czech Republic; Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague 120 00, Czech Republic.
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4
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Maruszczak KK, Chacinska A. Monitoring and analysis of mitochondrial precursor protein aggregates in the cytosol. Methods Enzymol 2024; 706:287-311. [PMID: 39455220 DOI: 10.1016/bs.mie.2024.07.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2024]
Abstract
The vast majority of mitochondrial precursor proteins is synthesized in the cytosol and subsequently imported into the organelle with the help of targeting signals that are present within these proteins. Disruptions in mitochondrial import will result in the accumulation of the organellar precursors in the cytosol of the cell. If mislocalized proteins exceed their critical concentrations, they become prone to aggregation. Under certain circumstances, protein aggregation becomes an irreversible process, which eventually endangers cellular health. Impairment in mitochondrial biogenesis and its effect on cellular protein homeostasis were recently linked to neurodegeneration, therefore placing this process in the center of attention. In this chapter, we are presenting a set of techniques that allows to monitor and study mitochondrial precursor protein aggregates upon mitochondrial dysfunction in the cytosol of both yeast and human cells.
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5
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Drwesh L. In vitro translation in yeast extract to study interactions with cytosolic chaperones. Methods Enzymol 2024; 706:313-344. [PMID: 39455222 DOI: 10.1016/bs.mie.2024.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2024]
Abstract
Saccharomyces cerevisiae, a well-established model organism, serves as a valuable tool for unraveling various eukaryotic cellular processes. Its utility extends to studying protein folding and interactions with chaperones, as it demonstrates a capability to produce and process proteins in a manner closely resembling that of higher eukaryotes. To gain insights into the events taking place following protein synthesis in the cytosol, an in vitro translation system is essential-one that mirrors in vivo processes yet allows for easy manipulation. To address this need, multiple protocols for preparation of cell-free translation lysates from S. cerevisiae have been documented. This chapter introduces an optimized and modified in vitro pull-down approach following protein translation in yeast cell-free extract. The advantages of this system in investigating the interactions of newly synthesized mitochondrial proteins with cytosolic chaperones are described. This procedure exploits the dual advantages of yeast cell-free lysates, serving as both a protein synthesis tool, and a reservoir for cytosolic factors and chaperones. In summary, the depicted approach provides a versatile platform that deepens our understanding of the early cytosolic events in the biogenesis of nascent proteins before reaching their ultimate organelle.
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Affiliation(s)
- Layla Drwesh
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany; Hertie Institute for Clinical Brain Research, Tuebingen, Germany.
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6
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Calvo Santos L, den Brave F. Analysis of quality control pathways for the translocase of the outer mitochondrial membrane. Methods Enzymol 2024; 707:565-584. [PMID: 39488391 DOI: 10.1016/bs.mie.2024.07.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2024]
Abstract
The functionality of mitochondria depends on the import of proteins synthesized on cytosolic ribosomes. Impaired import into mitochondria results in mitochondrial dysfunction and proteotoxic accumulation of precursor proteins in the cytosol. All proteins sorted to inner mitochondrial compartments are imported via the translocase of the outer membrane (TOM) complex. Premature protein folding, a reduction of the mitochondrial membrane potential or defects in translocases can result in precursor arrest during translocation, thereby clogging the TOM channel and blocking protein import. In recent years, different pathways have been identified, which employ the cytosolic ubiquitin-proteasome system in the extraction and turnover of precursor proteins from the TOM complex. Central events in this process are the modification of arrested precursor proteins with ubiquitin, their extraction by AAA-ATPases and subsequent degradation by the 26 S proteasome. Analysis of these processes is largely facilitated by the expression of model proteins that function as efficient "cloggers" of the import machinery. Here we describe the use of such clogger proteins and how their handling by the protein quality control machinery can be monitored. We provide protocols to study the extent of clogging, the ubiquitin-modification of arrested precursor proteins and their turnover by the 26 S proteasome.
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Affiliation(s)
- Lara Calvo Santos
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany.
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7
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Qin X, Li H, Zhao H, Fang L, Wang X. Enhancing healthy aging with small molecules: A mitochondrial perspective. Med Res Rev 2024; 44:1904-1922. [PMID: 38483176 DOI: 10.1002/med.22034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/27/2024] [Accepted: 03/04/2024] [Indexed: 06/10/2024]
Abstract
The pursuit of enhanced health during aging has prompted the exploration of various strategies focused on reducing the decline associated with the aging process. A key area of this exploration is the management of mitochondrial dysfunction, a notable characteristic of aging. This review sheds light on the crucial role that small molecules play in augmenting healthy aging, particularly through influencing mitochondrial functions. Mitochondrial oxidative damage, a significant aspect of aging, can potentially be lessened through interventions such as coenzyme Q10, alpha-lipoic acid, and a variety of antioxidants. Additionally, this review discusses approaches for enhancing mitochondrial proteostasis, emphasizing the importance of mitochondrial unfolded protein response inducers like doxycycline, and agents that affect mitophagy, such as urolithin A, spermidine, trehalose, and taurine, which are vital for sustaining protein quality control. Of equal importance are methods for modulating mitochondrial energy production, which involve nicotinamide adenine dinucleotide boosters, adenosine 5'-monophosphate-activated protein kinase activators, and compounds like metformin and mitochondria-targeted tamoxifen that enhance metabolic function. Furthermore, the review delves into emerging strategies that encourage mitochondrial biogenesis. Together, these interventions present a promising avenue for addressing age-related mitochondrial degradation, thereby setting the stage for the development of innovative treatment approaches to meet this extensive challenge.
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Affiliation(s)
- Xiujiao Qin
- Department of Geriatrics, the First Hospital of Jilin University, Changchun, Jilin, China
| | - Hongyuan Li
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
| | - Huiying Zhao
- Department of Geriatrics, the First Hospital of Jilin University, Changchun, Jilin, China
| | - Le Fang
- Department of Neurology, The China-Japan Union Hospital of Jilin University, Changchun, Jilin, China
| | - Xiaohui Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, China
- Beijing National Laboratory for Molecular Sciences, Beijing, China
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8
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den Brave F, Pfanner N, Becker T. Mitochondrial entry gate as regulatory hub. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119529. [PMID: 37951505 DOI: 10.1016/j.bbamcr.2023.119529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 06/18/2023] [Accepted: 06/23/2023] [Indexed: 11/14/2023]
Abstract
Mitochondria import 1000-1300 different precursor proteins from the cytosol. The main mitochondrial entry gate is formed by the translocase of the outer membrane (TOM complex). Molecular coupling and modification of TOM subunits control and modulate protein import in response to cellular signaling. The TOM complex functions as regulatory hub to integrate mitochondrial protein biogenesis and quality control into the cellular proteostasis network.
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Affiliation(s)
- Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany.
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9
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Nieto-Panqueva F, Rubalcava-Gracia D, Hamel PP, González-Halphen D. The constraints of allotopic expression. Mitochondrion 2023; 73:30-50. [PMID: 37739243 DOI: 10.1016/j.mito.2023.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 08/28/2023] [Accepted: 09/18/2023] [Indexed: 09/24/2023]
Abstract
Allotopic expression is the functional transfer of an organellar gene to the nucleus, followed by synthesis of the gene product in the cytosol and import into the appropriate organellar sub compartment. Here, we focus on mitochondrial genes encoding OXPHOS subunits that were naturally transferred to the nucleus, and critically review experimental evidence that claim their allotopic expression. We emphasize aspects that may have been overlooked before, i.e., when modifying a mitochondrial gene for allotopic expression━besides adapting the codon usage and including sequences encoding mitochondrial targeting signals━three additional constraints should be considered: (i) the average apparent free energy of membrane insertion (μΔGapp) of the transmembrane stretches (TMS) in proteins earmarked for the inner mitochondrial membrane, (ii) the final, functional topology attained by each membrane-bound OXPHOS subunit; and (iii) the defined mechanism by which the protein translocator TIM23 sorts cytosol-synthesized precursors. The mechanistic constraints imposed by TIM23 dictate the operation of two pathways through which alpha-helices in TMS are sorted, that eventually determine the final topology of membrane proteins. We used the biological hydrophobicity scale to assign an average apparent free energy of membrane insertion (μΔGapp) and a "traffic light" color code to all TMS of OXPHOS membrane proteins, thereby predicting which are more likely to be internalized into mitochondria if allotopically produced. We propose that the design of proteins for allotopic expression must make allowance for μΔGapp maximization of highly hydrophobic TMS in polypeptides whose corresponding genes have not been transferred to the nucleus in some organisms.
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Affiliation(s)
- Felipe Nieto-Panqueva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Diana Rubalcava-Gracia
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico; Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Patrice P Hamel
- Department of Molecular Genetics and Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA; Vellore Institute of Technology (VIT), School of BioScience and Technology, Vellore, Tamil Nadu, India
| | - Diego González-Halphen
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico.
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10
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Shan SO. Role of Hsp70 in Post-Translational Protein Targeting: Tail-Anchored Membrane Proteins and Beyond. Int J Mol Sci 2023; 24:1170. [PMID: 36674686 PMCID: PMC9866221 DOI: 10.3390/ijms24021170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/02/2023] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
The Hsp70 family of molecular chaperones acts as a central 'hub' in the cell that interacts with numerous newly synthesized proteins to assist in their biogenesis. Apart from its central and well-established role in facilitating protein folding, Hsp70s also act as key decision points in the cellular chaperone network that direct client proteins to distinct biogenesis and quality control pathways. In this paper, we review accumulating data that illustrate a new branch in the Hsp70 network: the post-translational targeting of nascent membrane and organellar proteins to diverse cellular organelles. Work in multiple pathways suggests that Hsp70, via its ability to interact with components of protein targeting and translocation machineries, can initiate elaborate substrate relays in a sophisticated cascade of chaperones, cochaperones, and receptor proteins, and thus provide a mechanism to safeguard and deliver nascent membrane proteins to the correct cellular membrane. We discuss the mechanistic principles gleaned from better-studied Hsp70-dependent targeting pathways and outline the observations and outstanding questions in less well-studied systems.
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Affiliation(s)
- Shu-Ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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11
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Michaelis JB, Bozkurt S, Schäfer JA, Münch C. Monitoring Mitochondrial Protein Import Using Mitochondrial Targeting Sequence (MTS)-eGFP. Bio Protoc 2022; 12:e4578. [PMID: 36618095 PMCID: PMC9797355 DOI: 10.21769/bioprotoc.4578] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/19/2022] [Accepted: 11/28/2022] [Indexed: 12/24/2022] Open
Abstract
Mitochondria are cellular organelles essential for the function and survival of eukaryotic cells. Nearly all mitochondrial proteins are nuclear-encoded and require mitochondrial import upon their synthesis in the cytosol. Various approaches have been described to study mitochondrial protein import, such as monitoring the entry of radiolabeled proteins into purified mitochondria or quantifying newly synthesized proteins within mitochondria by proteomics. Here, we provide a detailed protocol for a commonly used and straightforward assay that quantitatively examines mitochondrial protein import by monitoring the co-localization of mitochondrially targeted enhanced green fluorescent protein (eGFP) with the mitochondrial fluorescence dye MitoTracker TM Deep Red FM by live cell imaging. We describe the preparation and use of a stable mammalian cell line inducibly expressing a mitochondrial targeting sequence (MTS)-eGFP, followed by quantitative image analysis using an open-source ImageJ-based plugin. This inducible expression system avoids the need for transient transfection while enabling titration of MTS-eGFP expression and thereby avoiding protein folding stress. Overall, the assay provides a simple and robust approach to assess mitochondrial import capacity of cells in various disease-related settings. This protocol was validated in: Mol Cell (2021), DOI: 10.1016/j.molcel.2021.11.004 Graphical abstract.
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Affiliation(s)
- Jonas B. Michaelis
- Institute of Biochemistry II, Goethe University Frankfurt, Faculty of Medicine, Theodor-Stern-Kai 7, Haus 75 60590 Frankfurt am Main, Germany
| | - Süleyman Bozkurt
- Institute of Biochemistry II, Goethe University Frankfurt, Faculty of Medicine, Theodor-Stern-Kai 7, Haus 75 60590 Frankfurt am Main, Germany
| | - Jasmin A. Schäfer
- Institute of Biochemistry II, Goethe University Frankfurt, Faculty of Medicine, Theodor-Stern-Kai 7, Haus 75 60590 Frankfurt am Main, Germany
| | - Christian Münch
- Institute of Biochemistry II, Goethe University Frankfurt, Faculty of Medicine, Theodor-Stern-Kai 7, Haus 75 60590 Frankfurt am Main, Germany
,
Frankfurt Cancer Institute, Frankfurt am Main, Germany
,
Cardio-Pulmonary Institute, Frankfurt am Main, Germany
,
*For correspondence:
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12
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Saini PK, Dawitz H, Aufschnaiter A, Bondarev S, Thomas J, Amblard A, Stewart J, Thierry-Mieg N, Ott M, Pierrel F. The [PSI +] prion modulates cytochrome c oxidase deficiency caused by deletion of COX12. Mol Biol Cell 2022; 33:ar130. [PMID: 36129767 PMCID: PMC9727813 DOI: 10.1091/mbc.e21-10-0499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 09/09/2022] [Accepted: 09/13/2022] [Indexed: 02/04/2023] Open
Abstract
Cytochrome c oxidase (CcO) is a pivotal enzyme of the mitochondrial respiratory chain, which sustains bioenergetics of eukaryotic cells. Cox12, a peripheral subunit of CcO oxidase, is required for full activity of the enzyme, but its exact function is unknown. Here experimental evolution of a Saccharomyces cerevisiae Δcox12 strain for ∼300 generations allowed to restore the activity of CcO oxidase. In one population, the enhanced bioenergetics was caused by a A375V mutation in the cytosolic AAA+ disaggregase Hsp104. Deletion or overexpression of HSP104 also increased respiration of the Δcox12 ancestor strain. This beneficial effect of Hsp104 was related to the loss of the [PSI+] prion, which forms cytosolic amyloid aggregates of the Sup35 protein. Overall, our data demonstrate that cytosolic aggregation of a prion impairs the mitochondrial metabolism of cells defective for Cox12. These findings identify a new functional connection between cytosolic proteostasis and biogenesis of the mitochondrial respiratory chain.
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Affiliation(s)
- Pawan Kumar Saini
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000 Grenoble, France
| | - Hannah Dawitz
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | - Andreas Aufschnaiter
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | - Stanislav Bondarev
- Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg, Russia
| | - Jinsu Thomas
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000 Grenoble, France
| | - Amélie Amblard
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000 Grenoble, France
| | - James Stewart
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany
- Wellcome Centre for Mitochondrial Research, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Nicolas Thierry-Mieg
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000 Grenoble, France
| | - Martin Ott
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg 40530, Sweden
| | - Fabien Pierrel
- Univ. Grenoble Alpes, CNRS, UMR 5525, VetAgro Sup, Grenoble INP, TIMC, 38000 Grenoble, France
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Zara V, De Blasi G, Ferramosca A. Assembly of the Multi-Subunit Cytochrome bc1 Complex in the Yeast Saccharomyces cerevisiae. Int J Mol Sci 2022; 23:ijms231810537. [PMID: 36142449 PMCID: PMC9502982 DOI: 10.3390/ijms231810537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 09/08/2022] [Accepted: 09/09/2022] [Indexed: 11/29/2022] Open
Abstract
The cytochrome bc1 complex is an essential component of the mitochondrial respiratory chain of the yeast Saccharomyces cerevisiae. It is composed of ten protein subunits, three of them playing an important role in electron transfer and proton pumping across the inner mitochondrial membrane. Cytochrome b, the central component of this respiratory complex, is encoded by the mitochondrial genome, whereas all the other subunits are of nuclear origin. The assembly of all these subunits into the mature and functional cytochrome bc1 complex is therefore a complicated process which requires the participation of several chaperone proteins. It has been found that the assembly process of the mitochondrial bc1 complex proceeds through the formation of distinct sub-complexes in an ordered sequence. Most of these sub-complexes have been thoroughly characterized, and their molecular compositions have also been defined. This study critically analyses the results obtained so far and highlights new possible areas of investigation.
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