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Venkatraman K, Lee CT, Garcia GC, Mahapatra A, Milshteyn D, Perkins G, Kim KY, Pasolli HA, Phan S, Lippincott-Schwartz J, Ellisman MH, Rangamani P, Budin I. Cristae formation is a mechanical buckling event controlled by the inner membrane lipidome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.13.532310. [PMID: 36993370 PMCID: PMC10054968 DOI: 10.1101/2023.03.13.532310] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Cristae are high curvature structures in the inner mitochondrial membrane (IMM) that are crucial for ATP production. While cristae-shaping proteins have been defined, analogous mechanisms for lipids have yet to be elucidated. Here we combine experimental lipidome dissection with multi-scale modeling to investigate how lipid interactions dictate IMM morphology and ATP generation. When modulating phospholipid (PL) saturation in engineered yeast strains, we observed a surprisingly abrupt breakpoint in IMM topology driven by a continuous loss of ATP synthase organization at cristae ridges. We found that cardiolipin (CL) specifically buffers the IMM against curvature loss, an effect that is independent of ATP synthase dimerization. To explain this interaction, we developed a continuum model for cristae tubule formation that integrates both lipid and protein-mediated curvatures. The model highlighted a snapthrough instability, which drives IMM collapse upon small changes in membrane properties. We also showed that CL is essential in low oxygen conditions that promote PL saturation. These results demonstrate that the mechanical function of CL is dependent on the surrounding lipid and protein components of the IMM.
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Affiliation(s)
- Kailash Venkatraman
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093
| | - Christopher T Lee
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093
| | - Guadalupe C Garcia
- Computational Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla CA 92097
| | - Arijit Mahapatra
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093
| | - Daniel Milshteyn
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093
| | - Guy Perkins
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA 92093
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA 92093
| | - H Amalia Pasolli
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn VA 20147
| | - Sebastien Phan
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA 92093
| | | | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA 92093
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093
| | - Itay Budin
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093
- Lead contact
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2
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Ito T, Kajita S, Fujii M, Shinohara Y. Plasmodium Parasite Malate-Quinone Oxidoreductase Functionally Complements a Yeast Deletion Mutant of Mitochondrial Malate Dehydrogenase. Microbiol Spectr 2023; 11:e0016823. [PMID: 37036365 PMCID: PMC10269487 DOI: 10.1128/spectrum.00168-23] [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: 01/10/2023] [Accepted: 03/20/2023] [Indexed: 04/11/2023] Open
Abstract
The emergence of drug-resistant variants of malaria-causing Plasmodium parasites is a life-threatening problem worldwide. Investigation of the physiological function of individual parasite proteins is a prerequisite for a deeper understanding of the metabolic pathways required for parasite survival and therefore a requirement for the development of novel antimalarials. A Plasmodium membrane protein, malate-quinone oxidoreductase (MQO), is thought to contribute to the tricarboxylic acid (TCA) cycle and the electron transport chain (ETC) and is an antimalarial drug target. However, there is little information on its expression and function. Here, we investigated the function of Plasmodium falciparum MQO (PfMQO) in mitochondria using a yeast heterologous expression system. Using a yeast deletion mutant of mitochondrial malate dehydrogenase (MDH1), which is expected to be functionally similar to MQO, as a background strain, we successfully constructed PfMQO-expressing yeast. We confirmed that expression of PfMQO complemented the growth defect of the MDH1 deletion, indicating that PfMQO can adopt the metabolic role of MDH1 in energy transduction for growth in the recombinant yeast. Analysis of cell fractions confirmed that PfMQO was expressed and enriched in yeast mitochondria. By measuring MQO activity, we also confirmed that PfMQO expressed in yeast mitochondria was active. Measurement of oxygen consumption rates showed that mitochondrial respiration was driven by the TCA cycle through PfMQO. In addition, we found that MQO activity was enhanced when intact mitochondria were sonicated, indicating that the malate binding site of PfMQO is located facing the mitochondrial matrix. IMPORTANCE We constructed a model organism to study the physiological role and function of P. falciparum malate-quinone oxidoreductase (PfMQO) in a yeast expression system. PfMQO is actively expressed in yeast mitochondria and functions in place of yeast mitochondrial malate dehydrogenase, which catalyzes the oxidation of malate to oxaloacetate in the TCA cycle. The catalytic site for the oxidation of malate in PfMQO, which is a membrane-bound protein, faces into the mitochondrial matrix, not the mitochondrial inner membrane space. Our findings clearly show that PfMQO is a TCA cycle enzyme and is coupled with the ETC via ubiquinone reduction.
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Affiliation(s)
- Takeshi Ito
- Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
- Graduate School of Pharmaceutical Sciences, Tokushima University, Tokushima, Japan
| | - Sayaka Kajita
- Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
- Faculty of Pharmaceutical Sciences, Tokushima University, Tokushima, Japan
| | - Minori Fujii
- Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
- Faculty of Pharmaceutical Sciences, Tokushima University, Tokushima, Japan
| | - Yasuo Shinohara
- Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
- Graduate School of Pharmaceutical Sciences, Tokushima University, Tokushima, Japan
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3
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Tai J, Guerra RM, Rogers SW, Fang Z, Muehlbauer LK, Shishkova E, Overmyer KA, Coon JJ, Pagliarini DJ. Hem25p is a mitochondrial IPP transporter. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.14.532620. [PMID: 36993473 PMCID: PMC10055127 DOI: 10.1101/2023.03.14.532620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Coenzyme Q (CoQ, ubiquinone) is an essential cellular cofactor comprised of a redox-active quinone head group and a long hydrophobic polyisoprene tail. How mitochondria access cytosolic isoprenoids for CoQ biosynthesis is a longstanding mystery. Here, via a combination of genetic screening, metabolic tracing, and targeted uptake assays, we reveal that Hem25p-a mitochondrial glycine transporter required for heme biosynthesis-doubles as an isopentenyl pyrophosphate (IPP) transporter in Saccharomyces cerevisiae. Mitochondria lacking Hem25p fail to efficiently incorporate IPP into early CoQ precursors, leading to loss of CoQ and turnover of CoQ biosynthetic proteins. Expression of Hem25p in Escherichia coli enables robust IPP uptake demonstrating that Hem25p is sufficient for IPP transport. Collectively, our work reveals that Hem25p drives the bulk of mitochondrial isoprenoid transport for CoQ biosynthesis in yeast.
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Affiliation(s)
- Jonathan Tai
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, Madison, WI 53715, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Rachel M. Guerra
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Sean W. Rogers
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Zixiang Fang
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Laura K. Muehlbauer
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Evgenia Shishkova
- National Center for Quantitative Biology of Complex Systems, Madison, WI 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Katherine A. Overmyer
- Morgridge Institute for Research, Madison, WI 53715, USA
- National Center for Quantitative Biology of Complex Systems, Madison, WI 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Joshua J. Coon
- Morgridge Institute for Research, Madison, WI 53715, USA
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
- National Center for Quantitative Biology of Complex Systems, Madison, WI 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - David J. Pagliarini
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, Madison, WI 53715, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
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Aufschnaiter A, Carlström A, Ott M. Yeast Mitoribosome Purification and Analyses by Sucrose Density Centrifugation and Immunoprecipitation. Methods Mol Biol 2023; 2661:119-132. [PMID: 37166635 DOI: 10.1007/978-1-0716-3171-3_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Mitochondrial protein biosynthesis is maintained by an interplay between the mitochondrial ribosome (mitoribosome) and a large set of protein interaction partners. This interactome regulates a diverse set of functions, including mitochondrial gene expression, translation, protein quality control, and respiratory chain assembly. Hence, robust methods to biochemically and structurally analyze this molecular machinery are required to understand the sophisticated regulation of mitochondrial protein biosynthesis. In this chapter, we present detailed protocols for immunoprecipitation, sucrose cushions, and linear sucrose gradients to purify and analyze mitoribosomes and their interaction partners.
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Affiliation(s)
- Andreas Aufschnaiter
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Andreas Carlström
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Martin Ott
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
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Dua N, Seshadri A, Badrinarayanan A. DarT-mediated mtDNA damage induces dynamic reorganization and selective segregation of mitochondria. J Cell Biol 2022; 221:213451. [PMID: 36074064 PMCID: PMC9463037 DOI: 10.1083/jcb.202205104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/23/2022] [Accepted: 08/08/2022] [Indexed: 11/22/2022] Open
Abstract
Mitochondria are dynamic organelles that play essential roles in cell growth and survival. Processes of fission and fusion are critical for the distribution, segregation, and maintenance of mitochondria and their genomes (mtDNA). While recent work has revealed the significance of mitochondrial organization for mtDNA maintenance, the impact of mtDNA perturbations on mitochondrial dynamics remains less understood. Here, we develop a tool to induce mitochondria-specific DNA damage using a mitochondrial-targeted base modifying bacterial toxin, DarT. Following damage, we observe dynamic reorganization of mitochondrial networks, likely driven by mitochondrial dysfunction. Changes in the organization are associated with the loss of mtDNA, independent of mitophagy. Unexpectedly, perturbation to exonuclease function of mtDNA replicative polymerase, Mip1, results in rapid loss of mtDNA. Our data suggest that, under damage, partitioning of defective mtDNA and organelle are de-coupled, with emphasis on mitochondrial segregation independent of its DNA. Together, our work underscores the importance of genome maintenance on mitochondrial function, which can act as a modulator of organelle organization and segregation.
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Affiliation(s)
- Nitish Dua
- National Centre for Biological Sciences - Tata Institute of Fundamental Research, Bangalore, Karnataka, India
| | - Akshaya Seshadri
- National Centre for Biological Sciences - Tata Institute of Fundamental Research, Bangalore, Karnataka, India.,SASTRA University, Thanjavur, Tamil Nadu, India
| | - Anjana Badrinarayanan
- National Centre for Biological Sciences - Tata Institute of Fundamental Research, Bangalore, Karnataka, India
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6
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Wang Y, Luo Y, Huang Y. Schizosaccharomyces pombe
Sls1 is primarily required for
cox1
mRNA translation. Yeast 2022; 39:521-534. [DOI: 10.1002/yea.3813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 07/26/2022] [Accepted: 09/08/2022] [Indexed: 11/10/2022] Open
Affiliation(s)
- Yirong Wang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life SciencesNanjing Normal University1 Wenyuan RoadNanjing210023China
| | - Ying Luo
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life SciencesNanjing Normal University1 Wenyuan RoadNanjing210023China
| | - Ying Huang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life SciencesNanjing Normal University1 Wenyuan RoadNanjing210023China
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7
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Schimanski B, Aeschlimann S, Stettler P, Käser S, Gomez-Fabra Gala M, Bender J, Warscheid B, Vögtle FN, Schneider A. p166 links membrane and intramitochondrial modules of the trypanosomal tripartite attachment complex. PLoS Pathog 2022; 18:e1010207. [PMID: 35709300 PMCID: PMC9242489 DOI: 10.1371/journal.ppat.1010207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 06/29/2022] [Accepted: 05/03/2022] [Indexed: 11/19/2022] Open
Abstract
The protist parasite Trypanosoma brucei has a single mitochondrion with a single unit genome termed kinetoplast DNA (kDNA). Faithfull segregation of replicated kDNA is ensured by a complicated structure termed tripartite attachment complex (TAC). The TAC physically links the basal body of the flagellum with the kDNA spanning the two mitochondrial membranes. Here, we characterized p166 as the only known TAC subunit that is anchored in the inner membrane. Its C-terminal transmembrane domain separates the protein into a large N-terminal region that interacts with the kDNA-localized TAC102 and a 34 aa C-tail that binds to the intermembrane space-exposed loop of the integral outer membrane protein TAC60. Whereas the outer membrane region requires four essential subunits for proper TAC function, the inner membrane integral p166, via its interaction with TAC60 and TAC102, would theoretically suffice to bridge the distance between the OM and the kDNA. Surprisingly, non-functional p166 lacking the C-terminal 34 aa still localizes to the TAC region. This suggests the existence of additional TAC-associated proteins which loosely bind to non-functional p166 lacking the C-terminal 34 aa and keep it at the TAC. However, binding of full length p166 to these TAC-associated proteins alone would not be sufficient to withstand the mechanical load imposed by the segregating basal bodies.
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Affiliation(s)
- Bernd Schimanski
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Salome Aeschlimann
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Philip Stettler
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Sandro Käser
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Maria Gomez-Fabra Gala
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Julian Bender
- Biochemistry II, Theodor Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - Bettina Warscheid
- Biochemistry II, Theodor Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - F.-Nora Vögtle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- CIBSS—Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - André Schneider
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
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8
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Cloning and Organelle Expression of Bamboo Mitochondrial Complex I Subunits Nad1, Nad2, Nad4, and Nad5 in the Yeast Saccharomyces cerevisiae. Int J Mol Sci 2022; 23:ijms23074054. [PMID: 35409414 PMCID: PMC8999482 DOI: 10.3390/ijms23074054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/02/2022] [Accepted: 04/04/2022] [Indexed: 02/04/2023] Open
Abstract
Mitochondrial respiratory complex I catalyzes electron transfer from NADH to ubiquinone and pumps protons from the matrix into the intermembrane space. In particular, the complex I subunits Nad1, Nad2, Nad4, and Nad5, which are encoded by the nad1, nad2, nad4, and nad5 genes, reside at the mitochondrial inner membrane and possibly function as proton (H+) and ion translocators. To understand the individual functional roles of the Nad1, Nad2, Nad4, and Nad5 subunits in bamboo, each cDNA of these four genes was cloned into the pYES2 vector and expressed in the mitochondria of the yeast Saccharomyces cerevisiae. The mitochondrial targeting peptide mt gene (encoding MT) and the egfp marker gene (encoding enhanced green fluorescent protein, EGFP) were fused at the 5'-terminal and 3'-terminal ends, respectively. The constructed plasmids were then transformed into yeast. RNA transcripts and fusion protein expression were observed in the yeast transformants. Mitochondrial localizations of the MT-Nad1-EGFP, MT-Nad2-EGFP, MT-Nad4-EGFP, and MT-Nad5-EGFP fusion proteins were confirmed by fluorescence microscopy. The ectopically expressed bamboo subunits Nad1, Nad2, Nad4, and Nad5 may function in ion translocation, which was confirmed by growth phenotype assays with the addition of different concentrations of K+, Na+, or H+.
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9
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Das S, Mukherjee S, Bedi M, Ghosh A. Mutations in the Yeast Cox12 Subunit Severely Compromise the Activity of the Mitochondrial Complex IV. BIOCHEMISTRY. BIOKHIMIIA 2021; 86:1607-1623. [PMID: 34937540 DOI: 10.1134/s0006297921120105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 10/25/2021] [Accepted: 11/21/2021] [Indexed: 06/14/2023]
Abstract
Cytochrome c oxidase 6B1 (COX6B1) is one of the less characterized subunits of the mitochondrial electron transport chain complex IV (CIV). Here, we studied the pathobiochemical and respiratory functions of Cox12 (yeast ortholog of COX6B1) using Saccharomyces cerevisiae BY4741 (cox12Δ) cells deficient by the Cox12 protein. The cells exhibited severe growth deficiency in the respiratory glycerol-ethanol medium, which could be reverted by complementation with the yeast COX12 or human COX6B1 genes. Cox12 with arginine 17 residue substituted by histidine (R17H) or cysteine (R17C) (mutations analogous to those observed in human patients) failed to complement the loss of Cox12 function. When cox12Δ cells were grown in rich respiratory/fermentative galactose medium, no changes in the expression of individual respiratory chain subunits were observed. Blue native PAGE/Western blotting analysis using antibodies against Rip1 and Cox1, which are specific components of complexes III (CIII) and IV (CIV), respectively, revealed no noticeable decrease in the native CIII2CIV2 and CIII2CIV1 supercomplexes (SCs). However, the association of the respiratory SC factor 2 (Rcf2) and Cox2 subunit within the SCs of cox12Δ cells was reduced, while the specific activity of CIV was downregulated by 90%. Both basal respiration and succinate-ADP stimulated state 3 respiration, as well as the mitochondrial membrane potential, were decreased in cox12Δ cells. Furthermore, cox12Δ cells and cells synthesizing Cox12 mutants R17H and R17C showed higher sensitivity to the H2O2-induced oxidative stress compared to the wild-type (WT) cells. In silico structural modeling of the WT yeast SCs revealed that Cox12 forms a network of interactions with Rcf2 and Cox2. Together, our results establish that Cox12 is essential for the CIV activity.
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Affiliation(s)
- Shubhojit Das
- Department of Biochemistry, University of Calcutta, Kolkata, 700019, India.
| | | | - Minakshi Bedi
- Department of Biochemistry, University of Calcutta, Kolkata, 700019, India.
| | - Alok Ghosh
- Department of Biochemistry, University of Calcutta, Kolkata, 700019, India.
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10
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Mapping protein interactions in the active TOM-TIM23 supercomplex. Nat Commun 2021; 12:5715. [PMID: 34588454 PMCID: PMC8481542 DOI: 10.1038/s41467-021-26016-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 08/19/2021] [Indexed: 11/10/2022] Open
Abstract
Nuclear-encoded mitochondrial proteins destined for the matrix have to be transported across two membranes. The TOM and TIM23 complexes facilitate the transport of precursor proteins with N-terminal targeting signals into the matrix. During transport, precursors are recognized by the TIM23 complex in the inner membrane for handover from the TOM complex. However, we have little knowledge on the organization of the TOM-TIM23 transition zone and on how precursor transfer between the translocases occurs. Here, we have designed a precursor protein that is stalled during matrix transport in a TOM-TIM23-spanning manner and enables purification of the translocation intermediate. Combining chemical cross-linking with mass spectrometric analyses and structural modeling allows us to map the molecular environment of the intermembrane space interface of TOM and TIM23 as well as the import motor interactions with amino acid resolution. Our analyses provide a framework for understanding presequence handover and translocation during matrix protein transport. The TOM and TIM23 complexes facilitate the transport of nuclear-encoded proteins into the mitochondrial matrix. Here, the authors use a stalled client protein to purify the translocation supercomplex and gain insight into the TOM-TIM23 interface and the mechanism of protein handover from the TOM to the TIM23 complex.
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11
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UbiB proteins regulate cellular CoQ distribution in Saccharomyces cerevisiae. Nat Commun 2021; 12:4769. [PMID: 34362905 PMCID: PMC8346625 DOI: 10.1038/s41467-021-25084-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 07/22/2021] [Indexed: 11/08/2022] Open
Abstract
Beyond its role in mitochondrial bioenergetics, Coenzyme Q (CoQ, ubiquinone) serves as a key membrane-embedded antioxidant throughout the cell. However, how CoQ is mobilized from its site of synthesis on the inner mitochondrial membrane to other sites of action remains a longstanding mystery. Here, using a combination of Saccharomyces cerevisiae genetics, biochemical fractionation, and lipid profiling, we identify two highly conserved but poorly characterized mitochondrial proteins, Ypl109c (Cqd1) and Ylr253w (Cqd2), that reciprocally affect this process. Loss of Cqd1 skews cellular CoQ distribution away from mitochondria, resulting in markedly enhanced resistance to oxidative stress caused by exogenous polyunsaturated fatty acids, whereas loss of Cqd2 promotes the opposite effects. The activities of both proteins rely on their atypical kinase/ATPase domains, which they share with Coq8-an essential auxiliary protein for CoQ biosynthesis. Overall, our results reveal protein machinery central to CoQ trafficking in yeast and lend insights into the broader interplay between mitochondria and the rest of the cell.
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12
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Increased mitochondrial protein import and cardiolipin remodelling upon early mtUPR. PLoS Genet 2021; 17:e1009664. [PMID: 34214073 PMCID: PMC8282050 DOI: 10.1371/journal.pgen.1009664] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 07/15/2021] [Accepted: 06/11/2021] [Indexed: 12/11/2022] Open
Abstract
Mitochondrial defects can cause a variety of human diseases and protective mechanisms exist to maintain mitochondrial functionality. Imbalances in mitochondrial proteostasis trigger a transcriptional program, termed mitochondrial unfolded protein response (mtUPR). However, the temporal sequence of events in mtUPR is unclear and the consequences on mitochondrial protein import are controversial. Here, we have quantitatively analyzed all main import pathways into mitochondria after different time spans of mtUPR induction. Kinetic analyses reveal that protein import into all mitochondrial subcompartments strongly increases early upon mtUPR and that this is accompanied by rapid remodelling of the mitochondrial signature lipid cardiolipin. Genetic inactivation of cardiolipin synthesis precluded stimulation of protein import and compromised cellular fitness. At late stages of mtUPR upon sustained stress, mitochondrial protein import efficiency declined. Our work clarifies the enigma of protein import upon mtUPR and identifies sequential mtUPR stages, in which an early increase in protein biogenesis to restore mitochondrial proteostasis is followed by late stages characterized by a decrease in import capacity upon prolonged stress induction. Mitochondria are essential organelles and involved in numerous important functions like ATP production, biosynthesis of metabolites and co-factors or regulation of programmed cell death. To fulfill this plethora of different tasks, mitochondria require an extensive proteome, which is build by import of nuclear-encoded precursor proteins from the cytosol. Mitochondrial defects can cause a variety of severe human disorders that often affect tissues with high energy demand e.g. heart, muscle or brain. However, protective mechanisms exist that are triggered upon mitochondrial dysfunction: Imbalances in mitochondrial proteostasis are sensed by the cell and elicit a nuclear transcriptional response, termed mitochondrial unfolded protein response (mtUPR). Transcription of mitochondrial chaperones and proteases is increased to counteract mitochondrial dysfunctions. In this study, we investigated if mtUPR progresses in different temporal stages and how protein import is affected upon mtUPR. We discover that mtUPR is subdivided into an early phase, in which protein import increases and a late phase, in which it declines. Stimulation of protein import is accompanied by an increase and remodelling of the mitochondrial signature lipid cardiolipin. Our work establishes a novel model how cells respond to dysfunctional mitochondria, in which cardiolipin and protein import are modulated as first protective measures.
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13
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Young DJ, Meydan S, Guydosh NR. 40S ribosome profiling reveals distinct roles for Tma20/Tma22 (MCT-1/DENR) and Tma64 (eIF2D) in 40S subunit recycling. Nat Commun 2021; 12:2976. [PMID: 34016977 PMCID: PMC8137927 DOI: 10.1038/s41467-021-23223-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 04/14/2021] [Indexed: 12/21/2022] Open
Abstract
The recycling of ribosomes at stop codons for use in further rounds of translation is critical for efficient protein synthesis. Removal of the 60S subunit is catalyzed by the ATPase Rli1 (ABCE1) while removal of the 40S is thought to require Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR). However, it remains unclear how these Tma proteins cause 40S removal and control reinitiation of downstream translation. Here we used a 40S ribosome footprinting strategy to directly observe intermediate steps of ribosome recycling in cells. Deletion of the genes encoding these Tma proteins resulted in broad accumulation of unrecycled 40S subunits at stop codons, directly establishing their role in 40S recycling. Furthermore, the Tma20/Tma22 heterodimer was responsible for a majority of 40S recycling events while Tma64 played a minor role. Introduction of an autism-associated mutation into TMA22 resulted in a loss of 40S recycling activity, linking ribosome recycling and neurological disease.
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Affiliation(s)
- David J Young
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Sezen Meydan
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
- Postdoctoral Research Associate Training Program, National Institute of General Medical Sciences, National Institutes of Health, Bethesda, MD, USA
| | - Nicholas R Guydosh
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
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14
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Iadarola DM, Joshi A, Caldwell CB, Gohil VM. Choline restores respiration in Psd1-deficient yeast by replenishing mitochondrial phosphatidylethanolamine. J Biol Chem 2021; 296:100539. [PMID: 33722607 PMCID: PMC8054189 DOI: 10.1016/j.jbc.2021.100539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 03/02/2021] [Accepted: 03/10/2021] [Indexed: 11/23/2022] Open
Abstract
Phosphatidylethanolamine (PE) is essential for mitochondrial respiration in yeast, Saccharomyces cerevisiae, whereas the most abundant mitochondrial phospholipid, phosphatidylcholine (PC), is largely dispensable. Surprisingly, choline (Cho), which is a biosynthetic precursor of PC, has been shown to rescue the respiratory growth of mitochondrial PE-deficient yeast; however, the mechanism underlying this rescue has remained unknown. Using a combination of yeast genetics, lipid biochemistry, and cell biological approaches, we uncover the mechanism by showing that Cho rescues mitochondrial respiration by partially replenishing mitochondrial PE levels in yeast cells lacking the mitochondrial PE-biosynthetic enzyme Psd1. This rescue is dependent on the conversion of Cho to PC via the Kennedy pathway as well as on Psd2, an enzyme catalyzing PE biosynthesis in the endosome. Metabolic labeling experiments reveal that in the absence of exogenously supplied Cho, PE biosynthesized via Psd2 is mostly directed to the methylation pathway for PC biosynthesis and is unavailable for replenishing mitochondrial PE in Psd1-deleted cells. In this setting, stimulating the Kennedy pathway for PC biosynthesis by Cho spares Psd2-synthesized PE from the methylation pathway and redirects it to the mitochondria. Cho-mediated elevation in mitochondrial PE is dependent on Vps39, which has been recently implicated in PE trafficking to the mitochondria. Accordingly, epistasis experiments placed Vps39 downstream of Psd2 in Cho-based rescue. Our work, thus, provides a mechanism of Cho-based rescue of mitochondrial PE deficiency and uncovers an intricate interorganelle phospholipid regulatory network that maintains mitochondrial PE homeostasis.
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Affiliation(s)
- Donna M Iadarola
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, Texas, USA
| | - Alaumy Joshi
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, Texas, USA
| | - Cameron B Caldwell
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, Texas, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, Texas, USA.
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15
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Hoshino S, Kanemura R, Kurita D, Soutome Y, Himeno H, Takaine M, Watanabe M, Nameki N. A stalled-ribosome rescue factor Pth3 is required for mitochondrial translation against antibiotics in Saccharomyces cerevisiae. Commun Biol 2021; 4:300. [PMID: 33686140 PMCID: PMC7940416 DOI: 10.1038/s42003-021-01835-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 02/09/2021] [Indexed: 11/09/2022] Open
Abstract
Mitochondrial translation appears to involve two stalled-ribosome rescue factors (srRFs). One srRF is an ICT1 protein from humans that rescues a "non-stop" type of mitochondrial ribosomes (mitoribosomes) stalled on mRNA lacking a stop codon, while the other, C12orf65, reportedly has functions that overlap with those of ICT1; however, its primary role remains unclear. We herein demonstrated that the Saccharomyces cerevisiae homolog of C12orf65, Pth3 (Rso55), preferentially rescued antibiotic-dependent stalled mitoribosomes, which appear to represent a "no-go" type of ribosomes stalled on intact mRNA. On media containing a non-fermentable carbon source, which requires mitochondrial gene expression, respiratory growth was impaired significantly more by the deletion of PTH3 than that of the ICT1 homolog PTH4 in the presence of antibiotics that inhibit mitochondrial translation, such as tetracyclines and macrolides. Additionally, the in organello labeling of mitochondrial translation products and quantification of mRNA levels by quantitative RT-PCR suggested that in the presence of tetracycline, the deletion of PTH3, but not PTH4, reduced the protein expression of all eight mtDNA-encoded genes at the post-transcriptional or translational level. These results indicate that Pth3 can function as a mitochondrial srRF specific for ribosomes stalled by antibiotics and plays a role in antibiotic resistance in fungi.
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Affiliation(s)
- Soichiro Hoshino
- Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, Japan
| | - Ryohei Kanemura
- Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, Japan
| | - Daisuke Kurita
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Japan
| | - Yukihiro Soutome
- Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, Japan
| | - Hyouta Himeno
- Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Japan
| | - Masak Takaine
- Gunma University Initiative for Advanced Research (GIAR), Gunma University, Maebashi, Japan.,Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
| | - Masakatsu Watanabe
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Nobukazu Nameki
- Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, Japan.
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16
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Garza NM, Griffin AT, Zulkifli M, Qiu C, Kaplan CD, Gohil VM. A genome-wide copper-sensitized screen identifies novel regulators of mitochondrial cytochrome c oxidase activity. J Biol Chem 2021; 296:100485. [PMID: 33662401 PMCID: PMC8027276 DOI: 10.1016/j.jbc.2021.100485] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/22/2021] [Accepted: 02/25/2021] [Indexed: 11/30/2022] Open
Abstract
Copper is essential for the activity and stability of cytochrome c oxidase (CcO), the terminal enzyme of the mitochondrial respiratory chain. Loss-of-function mutations in genes required for copper transport to CcO result in fatal human disorders. Despite the fundamental importance of copper in mitochondrial and organismal physiology, systematic identification of genes that regulate mitochondrial copper homeostasis is lacking. To discover these genes, we performed a genome-wide screen using a library of DNA-barcoded yeast deletion mutants grown in copper-supplemented media. Our screen recovered a number of genes known to be involved in cellular copper homeostasis as well as genes previously not linked to mitochondrial copper biology. These newly identified genes include the subunits of the adaptor protein 3 complex (AP-3) and components of the cellular pH-sensing pathway Rim20 and Rim21, both of which are known to affect vacuolar function. We find that AP-3 and Rim mutants exhibit decreased vacuolar acidity, which in turn perturbs mitochondrial copper homeostasis and CcO function. CcO activity of these mutants could be rescued by either restoring vacuolar pH or supplementing growth media with additional copper. Consistent with these genetic data, pharmacological inhibition of the vacuolar proton pump leads to decreased mitochondrial copper content and a concomitant decrease in CcO abundance and activity. Taken together, our study uncovered novel genetic regulators of mitochondrial copper homeostasis and provided a mechanism by which vacuolar pH impacts mitochondrial respiration through copper homeostasis.
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Affiliation(s)
- Natalie M Garza
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Aaron T Griffin
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Mohammad Zulkifli
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Chenxi Qiu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Craig D Kaplan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
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17
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Abstract
Mitochondria contain ribosomes (mitoribosomes) specialized in the synthesis of a handful of proteins essential for oxidative phosphorylation. Therefore, mitoribosome integrity and function are essential for the life of eukaryotic cells and lesions that affect them result in devastating human disorders. To broadly analyze the integrity and assembly state of mitoribosomes it is useful to start by determining the sedimentation profile of these structures by sucrose gradient centrifugation of mitochondrial extracts. During centrifugation, mitoribosome subunits, monosomes and polysomes, and potentially accumulated assembly intermediates will sediment through the gradient at different rates. Sedimentation will depend on the centrifugal force applied and the density and viscosity of the gradient. Importantly, it will also depend on the size, shape, and density of the mitoribosome particles present in the samples under study. Variations of this technique, often coupled with additional downstream approaches, have been used to analyze the process of mitoribosome biogenesis, the composition of assembly intermediates, or to monitor the interaction of extraribosomal proteins with individual mitoribosome subunits or monosomes.
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Affiliation(s)
- Austin Choi
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Antoni Barrientos
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA.
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, USA.
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18
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Mitochondrial Localization of the Yeast Forkhead Factor Hcm1. Int J Mol Sci 2020; 21:ijms21249574. [PMID: 33339134 PMCID: PMC7765673 DOI: 10.3390/ijms21249574] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 12/10/2020] [Accepted: 12/14/2020] [Indexed: 12/24/2022] Open
Abstract
Hcm1 is a member of the forkhead transcription factor family involved in segregation, spindle pole dynamics, and budding in Saccharomyces cerevisiae. Our group described the role of Hcm1 in mitochondrial biogenesis and stress resistance, and in the cellular adaptation to mitochondrial respiratory metabolism when nutrients decrease. Regulation of Hcm1 activity occurs at the protein level, subcellular localization, and transcriptional activity. Here we report that the amount of protein increased in the G1/S transition phase when the factor accumulated in the nucleus. In the G2/M phases, the Hcm1 amount decreased, and it was translocated outside the nucleus with a network-like localization. Preparation of highly purified mitochondria by a sucrose gradient density demonstrated that Hcm1 colocalized with mitochondrial markers, inducing expression of COX1, a mitochondrial encoded subunit of cytochrome oxidase, in the G2/M phases. Taken together, these results show a new localization of Hcm1 and suggest that it acts as a mitochondrial transcription factor regulating the metabolism of this organelle.
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19
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Zulkifli M, Neff JK, Timbalia SA, Garza NM, Chen Y, Watrous JD, Murgia M, Trivedi PP, Anderson SK, Tomar D, Nilsson R, Madesh M, Jain M, Gohil VM. Yeast homologs of human MCUR1 regulate mitochondrial proline metabolism. Nat Commun 2020; 11:4866. [PMID: 32978391 PMCID: PMC7519068 DOI: 10.1038/s41467-020-18704-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 09/02/2020] [Indexed: 12/15/2022] Open
Abstract
Mitochondria house evolutionarily conserved pathways of carbon and nitrogen metabolism that drive cellular energy production. Mitochondrial bioenergetics is regulated by calcium uptake through the mitochondrial calcium uniporter (MCU), a multi-protein complex whose assembly in the inner mitochondrial membrane is facilitated by the scaffold factor MCUR1. Intriguingly, many fungi that lack MCU contain MCUR1 homologs, suggesting alternate functions. Herein, we characterize Saccharomyces cerevisiae homologs Put6 and Put7 of MCUR1 as regulators of mitochondrial proline metabolism. Put6 and Put7 are tethered to the inner mitochondrial membrane in a large hetero-oligomeric complex, whose abundance is regulated by proline. Loss of this complex perturbs mitochondrial proline homeostasis and cellular redox balance. Yeast cells lacking either Put6 or Put7 exhibit a pronounced defect in proline utilization, which can be corrected by the heterologous expression of human MCUR1. Our work uncovers an unexpected role of MCUR1 homologs in mitochondrial proline metabolism.
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Affiliation(s)
- Mohammad Zulkifli
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - John K Neff
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Shrishiv A Timbalia
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Natalie M Garza
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Yingqi Chen
- Departments of Medicine and Pharmacology, University of California, San Diego, 9500 Gilman Avenue, La Jolla, CA, 92093, USA
| | - Jeramie D Watrous
- Departments of Medicine and Pharmacology, University of California, San Diego, 9500 Gilman Avenue, La Jolla, CA, 92093, USA
| | - Marta Murgia
- Department of Biomedical Sciences, University of Padova, 35121, Padua, Italy
- Max-Planck-Institute of Biochemistry, Martinsried, 82152, Germany
| | - Prachi P Trivedi
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Steven K Anderson
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
| | - Dhanendra Tomar
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Roland Nilsson
- Cardiovascular Medicine Unit, Department of Medicine, Karolinska Institutet, SE-171 76, Stockholm, Sweden
- Division of Cardiovascular Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, SE-171 76, Stockholm, Sweden
| | - Muniswamy Madesh
- Department of Medicine, Cardiology Division, Center for Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Mohit Jain
- Departments of Medicine and Pharmacology, University of California, San Diego, 9500 Gilman Avenue, La Jolla, CA, 92093, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA.
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20
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Luongo TS, Eller JM, Lu MJ, Niere M, Raith F, Perry C, Bornstein MR, Oliphint P, Wang L, McReynolds MR, Migaud ME, Rabinowitz JD, Johnson FB, Johnsson K, Ziegler M, Cambronne XA, Baur JA. SLC25A51 is a mammalian mitochondrial NAD + transporter. Nature 2020; 588:174-179. [PMID: 32906142 PMCID: PMC7718333 DOI: 10.1038/s41586-020-2741-7] [Citation(s) in RCA: 153] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 09/01/2020] [Indexed: 12/11/2022]
Abstract
Mitochondria require nicotinamide adenine dinucleotide (NAD+) in order to carry out the fundamental processes that fuel respiration and mediate cellular energy transduction. Mitochondrial NAD+ transporters have been identified in yeast and plants 1,2 but their very existence is controversial in mammals 3–5. Here we demonstrate that mammalian mitochondria are capable of taking up intact NAD+ and identify SLC25A51 (an essential 6,7 mitochondrial protein of previously unknown function, also known as MCART1) as a mammalian mitochondrial NAD+ transporter. Loss of SLC25A51 decreases mitochondrial but not whole-cell NAD+ content, impairs mitochondrial respiration, and blocks the uptake of NAD+ into isolated mitochondria. Conversely, overexpression of SLC25A51 or a nearly identical paralog, SLC25A52, increases mitochondrial NAD+ levels and restores NAD+ uptake into yeast mitochondria lacking endogenous NAD+ transporters. Together, these findings identify SLC25A51 as the first transporter capable of importing NAD+ into mammalian mitochondria.
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Affiliation(s)
- Timothy S Luongo
- Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jared M Eller
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Mu-Jie Lu
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Marc Niere
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Fabio Raith
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany.,Faculty of Chemistry and Earth Sciences, University of Heidelberg, Heidelberg, Germany
| | - Caroline Perry
- Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Marc R Bornstein
- Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Paul Oliphint
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Lin Wang
- Lewis-Sigler Institute for Integrative Genomics, Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Melanie R McReynolds
- Lewis-Sigler Institute for Integrative Genomics, Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Marie E Migaud
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Joshua D Rabinowitz
- Lewis-Sigler Institute for Integrative Genomics, Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - F Brad Johnson
- Department of Pathology and Laboratory Medicine, Perlman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kai Johnsson
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany.,Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Mathias Ziegler
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Xiaolu A Cambronne
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA.
| | - Joseph A Baur
- Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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21
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Toth A, Aufschnaiter A, Fedotovskaya O, Dawitz H, Ädelroth P, Büttner S, Ott M. Membrane-tethering of cytochrome c accelerates regulated cell death in yeast. Cell Death Dis 2020; 11:722. [PMID: 32892209 PMCID: PMC7474732 DOI: 10.1038/s41419-020-02920-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 04/02/2020] [Accepted: 04/03/2020] [Indexed: 12/18/2022]
Abstract
Intrinsic apoptosis as a modality of regulated cell death is intimately linked to permeabilization of the outer mitochondrial membrane and subsequent release of the protein cytochrome c into the cytosol, where it can participate in caspase activation via apoptosome formation. Interestingly, cytochrome c release is an ancient feature of regulated cell death even in unicellular eukaryotes that do not contain an apoptosome. Therefore, it was speculated that cytochrome c release might have an additional, more fundamental role for cell death signalling, because its absence from mitochondria disrupts oxidative phosphorylation. Here, we permanently anchored cytochrome c with a transmembrane segment to the inner mitochondrial membrane of the yeast Saccharomyces cerevisiae, thereby inhibiting its release from mitochondria during regulated cell death. This cytochrome c retains respiratory growth and correct assembly of mitochondrial respiratory chain supercomplexes. However, membrane anchoring leads to a sensitisation to acetic acid-induced cell death and increased oxidative stress, a compensatory elevation of cellular oxygen-consumption in aged cells and a decreased chronological lifespan. We therefore conclude that loss of cytochrome c from mitochondria during regulated cell death and the subsequent disruption of oxidative phosphorylation is not required for efficient execution of cell death in yeast, and that mobility of cytochrome c within the mitochondrial intermembrane space confers a fitness advantage that overcomes a potential role in regulated cell death signalling in the absence of an apoptosome.
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Affiliation(s)
- Alexandra Toth
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Svante Arrheniusväg 16, 106 91, Stockholm, Sweden
| | - Andreas Aufschnaiter
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Svante Arrheniusväg 16, 106 91, Stockholm, Sweden
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria
| | - Olga Fedotovskaya
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Svante Arrheniusväg 16, 106 91, Stockholm, Sweden
| | - Hannah Dawitz
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Svante Arrheniusväg 16, 106 91, Stockholm, Sweden
| | - Pia Ädelroth
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Svante Arrheniusväg 16, 106 91, Stockholm, Sweden
| | - Sabrina Büttner
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria.
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden.
| | - Martin Ott
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Svante Arrheniusväg 16, 106 91, Stockholm, Sweden.
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22
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Ghosh S, Basu Ball W, Madaris TR, Srikantan S, Madesh M, Mootha VK, Gohil VM. An essential role for cardiolipin in the stability and function of the mitochondrial calcium uniporter. Proc Natl Acad Sci U S A 2020; 117:16383-16390. [PMID: 32601238 PMCID: PMC7368250 DOI: 10.1073/pnas.2000640117] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Calcium uptake by the mitochondrial calcium uniporter coordinates cytosolic signaling events with mitochondrial bioenergetics. During the past decade all protein components of the mitochondrial calcium uniporter have been identified, including MCU, the pore-forming subunit. However, the specific lipid requirements, if any, for the function and formation of this channel complex are currently not known. Here we utilize yeast, which lacks the mitochondrial calcium uniporter, as a model system to address this problem. We use heterologous expression to functionally reconstitute human uniporter machinery both in wild-type yeast as well as in mutants defective in the biosynthesis of phosphatidylethanolamine, phosphatidylcholine, or cardiolipin (CL). We uncover a specific requirement of CL for in vivo reconstituted MCU stability and activity. The CL requirement of MCU is evolutionarily conserved with loss of CL triggering rapid turnover of MCU homologs and impaired calcium transport. Furthermore, we observe reduced abundance and activity of endogenous MCU in mammalian cellular models of Barth syndrome, which is characterized by a partial loss of CL. MCU abundance is also decreased in the cardiac tissue of Barth syndrome patients. Our work raises the hypothesis that impaired mitochondrial calcium transport contributes to the pathogenesis of Barth syndrome, and more generally, showcases the utility of yeast phospholipid mutants in dissecting the phospholipid requirements of ion channel complexes.
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Affiliation(s)
- Sagnika Ghosh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843
| | - Writoban Basu Ball
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843
| | - Travis R Madaris
- Department of Medicine, Division of Nephrology, Center for Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
| | - Subramanya Srikantan
- Department of Medicine, Division of Nephrology, Center for Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
| | - Muniswamy Madesh
- Department of Medicine, Division of Nephrology, Center for Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
| | - Vamsi K Mootha
- Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114;
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843;
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23
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Linden A, Deckers M, Parfentev I, Pflanz R, Homberg B, Neumann P, Ficner R, Rehling P, Urlaub H. A Cross-linking Mass Spectrometry Approach Defines Protein Interactions in Yeast Mitochondria. Mol Cell Proteomics 2020; 19:1161-1178. [PMID: 32332106 PMCID: PMC7338081 DOI: 10.1074/mcp.ra120.002028] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/24/2020] [Indexed: 12/13/2022] Open
Abstract
Protein cross-linking and the analysis of cross-linked peptides by mass spectrometry is currently receiving much attention. Not only is this approach applied to isolated complexes to provide information about spatial arrangements of proteins, but it is also increasingly applied to entire cells and their organelles. As in quantitative proteomics, the application of isotopic labeling further makes it possible to monitor quantitative changes in the protein-protein interactions between different states of a system. Here, we cross-linked mitochondria from Saccharomyces cerevisiae grown on either glycerol- or glucose-containing medium to monitor protein-protein interactions under non-fermentative and fermentative conditions. We investigated qualitatively the protein-protein interactions of the 400 most abundant proteins applying stringent data-filtering criteria, i.e. a minimum of two cross-linked peptide spectrum matches and a cut-off in the spectrum scoring of the used search engine. The cross-linker BS3 proved to be equally suited for connecting proteins in all compartments of mitochondria when compared with its water-insoluble but membrane-permeable derivative DSS. We also applied quantitative cross-linking to mitochondria of both the growth conditions using stable-isotope labeled BS3. Significant differences of cross-linked proteins under glycerol and glucose conditions were detected, however, mainly because of the different copy numbers of these proteins in mitochondria under both the conditions. Results obtained from the glycerol condition indicate that the internal NADH:ubiquinone oxidoreductase Ndi1 is part of an electron transport chain supercomplex. We have also detected several hitherto uncharacterized proteins and identified their interaction partners. Among those, Min8 was found to be associated with cytochrome c oxidase. BN-PAGE analyses of min8Δ mitochondria suggest that Min8 promotes the incorporation of Cox12 into cytochrome c oxidase.
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Affiliation(s)
- Andreas Linden
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany; Institute of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Markus Deckers
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Iwan Parfentev
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ralf Pflanz
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Bettina Homberg
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Piotr Neumann
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, Göttingen Center for Molecular Biosciences, Georg-August-University Göttingen, Göttingen, Germany
| | - Ralf Ficner
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany; Department of Molecular Structural Biology, Institute for Microbiology and Genetics, Göttingen Center for Molecular Biosciences, Georg-August-University Göttingen, Göttingen, Germany
| | - Peter Rehling
- Department of Cellular Biochemistry, 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; Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany; Institute of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany.
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24
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Makepeace KAT, Mohammed Y, Rudashevskaya EL, Petrotchenko EV, Vögtle FN, Meisinger C, Sickmann A, Borchers CH. Improving Identification of In-organello Protein-Protein Interactions Using an Affinity-enrichable, Isotopically Coded, and Mass Spectrometry-cleavable Chemical Crosslinker. Mol Cell Proteomics 2020; 19:624-639. [PMID: 32051233 PMCID: PMC7124466 DOI: 10.1074/mcp.ra119.001839] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 01/17/2020] [Indexed: 12/24/2022] Open
Abstract
An experimental and computational approach for identification of protein-protein interactions by ex vivo chemical crosslinking and mass spectrometry (CLMS) has been developed that takes advantage of the specific characteristics of cyanurbiotindipropionylsuccinimide (CBDPS), an affinity-tagged isotopically coded mass spectrometry (MS)-cleavable crosslinking reagent. Utilizing this reagent in combination with a crosslinker-specific data-dependent acquisition strategy based on MS2 scans, and a software pipeline designed for integrating crosslinker-specific mass spectral information led to demonstrated improvements in the application of the CLMS technique, in terms of the detection, acquisition, and identification of crosslinker-modified peptides. This approach was evaluated on intact yeast mitochondria, and the results showed that hundreds of unique protein-protein interactions could be identified on an organelle proteome-wide scale. Both known and previously unknown protein-protein interactions were identified. These interactions were assessed based on their known sub-compartmental localizations. Additionally, the identified crosslinking distance constraints are in good agreement with existing structural models of protein complexes involved in the mitochondrial electron transport chain.
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Affiliation(s)
- Karl A T Makepeace
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Rd., Victoria, BC V8P 5C2, Canada; University of Victoria - Genome British Columbia Proteomics Centre, #3101-4464 Markham Street, Vancouver Island Technology Park, Victoria, BC V8Z7X8, Canada
| | - Yassene Mohammed
- University of Victoria - Genome British Columbia Proteomics Centre, #3101-4464 Markham Street, Vancouver Island Technology Park, Victoria, BC V8Z7X8, Canada; Center for Proteomics and Metabolomics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | | | - Evgeniy V Petrotchenko
- University of Victoria - Genome British Columbia Proteomics Centre, #3101-4464 Markham Street, Vancouver Island Technology Park, Victoria, BC V8Z7X8, Canada; Segal Cancer Proteomics Centre, Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Quebec, H3T 1E2, Canada
| | - F-Nora Vögtle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Germany
| | - Chris Meisinger
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Germany
| | - Albert Sickmann
- Leibniz Institut für Analytische Wissenschaften - ISAS - e.V., Dortmund, Germany.
| | - Christoph H Borchers
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Rd., Victoria, BC V8P 5C2, Canada; University of Victoria - Genome British Columbia Proteomics Centre, #3101-4464 Markham Street, Vancouver Island Technology Park, Victoria, BC V8Z7X8, Canada; Segal Cancer Proteomics Centre, Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Quebec, H3T 1E2, Canada; Gerald Bronfman Department of Oncology, Jewish General Hospital, Montreal, Quebec, H3T 1E2, Canada; Department of Data Intensive Science and Engineering, Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Nobel St., Moscow 143026, Russia.
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25
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Matta SK, Kumar A, D'Silva P. Mgr2 regulates mitochondrial preprotein import by associating with channel-forming Tim23 subunit. Mol Biol Cell 2020; 31:1112-1123. [PMID: 32186971 PMCID: PMC7353164 DOI: 10.1091/mbc.e19-12-0677] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mgr2, a newly identified subunit of the TIM23 complex, functions as a gatekeeper of presequence translocase and thereby maintains quality control of inner membrane preproteins sorting. However, precise recruitment of the Mgr2 subunit to the core channel and how it influences the assembly of the TIM23 complex during lateral sorting of preproteins are poorly understood. Present findings provide insights into a direct association of Mgr2 with the channel-forming Tim23 subunit. Furthermore, the mutational analysis uncovers the TM1 region of Mgr2 critically required for association with Tim23 and Tim21. On the other hand, the TM2 region of Mgr2 is involved in bridging respiratory complexes to the TIM23 complex via Tim21. Importantly, both TM regions of Mgr2 are essential for lateral sorting of preprotein into the inner membrane, as well as maintaining mitochondrial morphology. Together, our findings provide mechanistic insights into the role of Mgr2 in regulating the dynamicity of the TIM23 complex assembly required for preprotein import and coupling of respiratory pathways.
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Affiliation(s)
- Srujan Kumar Matta
- Department of Biochemistry, New Biological Sciences Building, Indian Institute of Science, Bangalore-560012, India
| | - Abhishek Kumar
- Department of Biochemistry, New Biological Sciences Building, Indian Institute of Science, Bangalore-560012, India
| | - Patrick D'Silva
- Department of Biochemistry, New Biological Sciences Building, Indian Institute of Science, Bangalore-560012, India
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26
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Absolute yeast mitochondrial proteome quantification reveals trade-off between biosynthesis and energy generation during diauxic shift. Proc Natl Acad Sci U S A 2020; 117:7524-7535. [PMID: 32184324 PMCID: PMC7132131 DOI: 10.1073/pnas.1918216117] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
This work offers a unique portrayal of yeast mitochondria through the characterization of its absolute proteome. The study of biophysical changes in the mitochondrial network associated with proteome profiling, throughout yeast growth and the transition from fermentative to respiratory metabolism, lays out the crucial role this organelle has in balancing the overall metabolic status of the cell. Using proteomic mass spectrometry, state of the art fluorescence microscopy, and lipidomics analysis, these data provide a highly quantitative description of key mitochondrial processes across three states of metabolism. In particular, the work highlights the significant contribution of functional and structural remodeling occurring during the diauxic shift of this subcellular organelle. Saccharomyces cerevisiae constitutes a popular eukaryal model for research on mitochondrial physiology. Being Crabtree-positive, this yeast has evolved the ability to ferment glucose to ethanol and respire ethanol once glucose is consumed. Its transition phase from fermentative to respiratory metabolism, known as the diauxic shift, is reflected by dramatic rearrangements of mitochondrial function and structure. To date, the metabolic adaptations that occur during the diauxic shift have not been fully characterized at the organelle level. In this study, the absolute proteome of mitochondria was quantified alongside precise parametrization of biophysical properties associated with the mitochondrial network using state-of-the-art optical-imaging techniques. This allowed the determination of absolute protein abundances at a subcellular level. By tracking the transformation of mitochondrial mass and volume, alongside changes in the absolute mitochondrial proteome allocation, we could quantify how mitochondria balance their dual role as a biosynthetic hub as well as a center for cellular respiration. Furthermore, our findings suggest that in the transition from a fermentative to a respiratory metabolism, the diauxic shift represents the stage where major structural and functional reorganizations in mitochondrial metabolism occur. This metabolic transition, initiated at the mitochondria level, is then extended to the rest of the yeast cell.
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Ccm1p is a 15S rRNA primary transcript processing factor as elucidated by a novel in vivo system in Saccharomyces cerevisiae. Curr Genet 2020; 66:775-789. [PMID: 32152734 DOI: 10.1007/s00294-020-01064-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 02/15/2020] [Accepted: 02/24/2020] [Indexed: 10/24/2022]
Abstract
In Saccharomyces cerevisiae, the mitoribosomal RNA of the minor subunit, 15S rRNA, is transcribed as a bicistronic transcript along with tRNAW. 5' and 3' sequences flanking the mature transcript must be removed by cleavage at the respective junctions before incorporating it into the mitoribosome. An in vivo dose-response triphasic system was created to elucidate the role of Ccm1p in the processing of 15S rRNA: Ccm1p supply ("On"), deprivation ("Off"), and resupply ("Back on"). After 72 h under "Off" status, the cells started to exhibit a complete mutant phenotype as assessed by their lack of growth in glycerol medium, while keeping their mitochondrial DNA integrity (ρ+). Full functionality of mitochondria was reacquired upon "Back on." 15S rRNA levels and phenotype followed the Ccm1p intramitochondrial concentrations throughout the "On-Off-Back on" course. Under "Off" status, cells gradually accumulated unprocessed 5' and 3' junctions, which reached significant levels at 72-96 h, probably due to a saturation of the mitochondrial degradosome (mtEXO). The Ccm1p/mtEXO mutant (Δccm1/Δdss1) showed a copious accumulation of 15S rRNA primary transcript forms, which were cleaved upon Ccm1p resupply. The gene that codes for the RNA component of RNase P was conserved in wild-type and mutant strains. Our results indicate that Ccm1p is crucial in processing the 15S rRNA primary transcript and does not stabilize the already mature 15S rRNA. Consequently, failure of this function in Δccm1 cells results, as it happens to any other unprocessed primary transcripts, in total degradation of 15S rRNA by mtEXO, whose mechanism of action is discussed.
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28
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Defining the Substrate Spectrum of the TIM22 Complex Identifies Pyruvate Carrier Subunits as Unconventional Cargos. Curr Biol 2020; 30:1119-1127.e5. [PMID: 32142709 PMCID: PMC7090383 DOI: 10.1016/j.cub.2020.01.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/27/2019] [Accepted: 01/08/2020] [Indexed: 02/02/2023]
Abstract
In mitochondria, the carrier translocase (TIM22 complex) facilitates membrane insertion of multi-spanning proteins with internal targeting signals into the inner membrane [1, 2, 3]. Tom70, a subunit of TOM complex, represents the major receptor for these precursors [2, 4, 5, 6]. After transport across the outer membrane, the hydrophobic carriers engage with the small TIM protein complex composed of Tim9 and Tim10 for transport across the intermembrane space (IMS) toward the TIM22 complex [7, 8, 9, 10, 11, 12]. Tim22 represents the pore-forming core unit of the complex [13, 14]. Only a small subset of TIM22 cargo molecules, containing four or six transmembrane spans, have been experimentally defined. Here, we used a tim22 temperature-conditional mutant to define the TIM22 substrate spectrum. Along with carrier-like cargo proteins, we identified subunits of the mitochondrial pyruvate carrier (MPC) as unconventional TIM22 cargos. MPC proteins represent substrates with atypical topology for this transport pathway. In agreement with this, a patient affected in TIM22 function displays reduced MPC levels. Our findings broaden the repertoire of carrier pathway substrates and challenge current concepts of TIM22-mediated transport processes. Substrates of mitochondrial TIM22 complex identified by proteomics in S. cerevisiae Carrier proteins with six membrane spans confirmed as substrates Pyruvate carrier (MPC) subunits (two or three membrane spans) transported by TIM22 MPC import dependence on TIM22 is conserved from yeast to human
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29
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Iadarola DM, Basu Ball W, Trivedi PP, Fu G, Nan B, Gohil VM. Vps39 is required for ethanolamine-stimulated elevation in mitochondrial phosphatidylethanolamine. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158655. [PMID: 32058032 DOI: 10.1016/j.bbalip.2020.158655] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 01/03/2020] [Accepted: 02/04/2020] [Indexed: 12/31/2022]
Abstract
Mitochondrial membrane biogenesis requires the import of phospholipids; however, the molecular mechanisms underlying this process remain elusive. Recent work has implicated membrane contact sites between the mitochondria, endoplasmic reticulum (ER), and vacuole in phospholipid transport. Utilizing a genetic approach focused on these membrane contact site proteins, we have discovered a 'moonlighting' role of the membrane contact site and vesicular fusion protein, Vps39, in phosphatidylethanolamine (PE) transport to the mitochondria. We show that the deletion of Vps39 prevents ethanolamine-stimulated elevation of mitochondrial PE levels without affecting PE biosynthesis in the ER or its transport to other sub-cellular organelles. The loss of Vps39 did not alter the levels of other mitochondrial phospholipids that are biosynthesized ex situ, implying a PE-specific role of Vps39. The abundance of Vps39 and its recruitment to the mitochondria and the ER is dependent on PE levels in each of these organelles, directly implicating Vps39 in the PE transport process. Deletion of essential subunits of Vps39-containing complexes, vCLAMP and HOPS, did not abrogate ethanolamine-stimulated PE elevation in the mitochondria, suggesting an independent role of Vps39 in intracellular PE trafficking. Our work thus identifies Vps39 as a novel player in ethanolamine-stimulated PE transport to the mitochondria.
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Affiliation(s)
- Donna M Iadarola
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Writoban Basu Ball
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Prachi P Trivedi
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Guo Fu
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Beiyan Nan
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA.
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30
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Rampelt H, Sucec I, Bersch B, Horten P, Perschil I, Martinou JC, van der Laan M, Wiedemann N, Schanda P, Pfanner N. The mitochondrial carrier pathway transports non-canonical substrates with an odd number of transmembrane segments. BMC Biol 2020; 18:2. [PMID: 31907035 PMCID: PMC6945462 DOI: 10.1186/s12915-019-0733-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 12/17/2019] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The mitochondrial pyruvate carrier (MPC) plays a central role in energy metabolism by transporting pyruvate across the inner mitochondrial membrane. Its heterodimeric composition and homology to SWEET and semiSWEET transporters set the MPC apart from the canonical mitochondrial carrier family (named MCF or SLC25). The import of the canonical carriers is mediated by the carrier translocase of the inner membrane (TIM22) pathway and is dependent on their structure, which features an even number of transmembrane segments and both termini in the intermembrane space. The import pathway of MPC proteins has not been elucidated. The odd number of transmembrane segments and positioning of the N-terminus in the matrix argues against an import via the TIM22 carrier pathway but favors an import via the flexible presequence pathway. RESULTS Here, we systematically analyzed the import pathways of Mpc2 and Mpc3 and report that, contrary to an expected import via the flexible presequence pathway, yeast MPC proteins with an odd number of transmembrane segments and matrix-exposed N-terminus are imported by the carrier pathway, using the receptor Tom70, small TIM chaperones, and the TIM22 complex. The TIM9·10 complex chaperones MPC proteins through the mitochondrial intermembrane space using conserved hydrophobic motifs that are also required for the interaction with canonical carrier proteins. CONCLUSIONS The carrier pathway can import paired and non-paired transmembrane helices and translocate N-termini to either side of the mitochondrial inner membrane, revealing an unexpected versatility of the mitochondrial import pathway for non-cleavable inner membrane proteins.
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Affiliation(s)
- Heike Rampelt
- 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.
| | - Iva Sucec
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38000, Grenoble, France
| | - Beate Bersch
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38000, Grenoble, France
| | - Patrick Horten
- 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
- Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
| | - Inge Perschil
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104, Freiburg, Germany
| | | | - Martin van der Laan
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling, PZMS, Saarland University, 66421 Homburg, Germany
| | - Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104, Freiburg, Germany
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
| | - Paul Schanda
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38000, Grenoble, France
| | - 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.
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31
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Poveda-Huertes D, Matic S, Marada A, Habernig L, Licheva M, Myketin L, Gilsbach R, Tosal-Castano S, Papinski D, Mulica P, Kretz O, Kücükköse C, Taskin AA, Hein L, Kraft C, Büttner S, Meisinger C, Vögtle FN. An Early mtUPR: Redistribution of the Nuclear Transcription Factor Rox1 to Mitochondria Protects against Intramitochondrial Proteotoxic Aggregates. Mol Cell 2020; 77:180-188.e9. [PMID: 31630969 PMCID: PMC6941230 DOI: 10.1016/j.molcel.2019.09.026] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/20/2019] [Accepted: 09/23/2019] [Indexed: 11/29/2022]
Abstract
The mitochondrial proteome is built mainly by import of nuclear-encoded precursors, which are targeted mostly by cleavable presequences. Presequence processing upon import is essential for proteostasis and survival, but the consequences of dysfunctional protein maturation are unknown. We find that impaired presequence processing causes accumulation of precursors inside mitochondria that form aggregates, which escape degradation and unexpectedly do not cause cell death. Instead, cells survive via activation of a mitochondrial unfolded protein response (mtUPR)-like pathway that is triggered very early after precursor accumulation. In contrast to classical stress pathways, this immediate response maintains mitochondrial protein import, membrane potential, and translation through translocation of the nuclear HMG-box transcription factor Rox1 to mitochondria. Rox1 binds mtDNA and performs a TFAM-like function pivotal for transcription and translation. Induction of early mtUPR provides a reversible stress model to mechanistically dissect the initial steps in mtUPR pathways with the stressTFAM Rox1 as the first line of defense.
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Affiliation(s)
- Daniel Poveda-Huertes
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Stanka Matic
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Adinarayana Marada
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Lukas Habernig
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Mariya Licheva
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Lisa Myketin
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Ralf Gilsbach
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Sergi Tosal-Castano
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Daniel Papinski
- Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, 1030 Vienna, Austria
| | - Patrycja Mulica
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Oliver Kretz
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany; Department of Medicine IV, Medical Center and Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - Cansu Kücükköse
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Asli Aras Taskin
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Lutz Hein
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Claudine Kraft
- 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
| | - Sabrina Büttner
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden; Institute for Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Chris Meisinger
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
| | - F-Nora Vögtle
- 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.
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Monteuuis G, Miścicka A, Świrski M, Zenad L, Niemitalo O, Wrobel L, Alam J, Chacinska A, Kastaniotis AJ, Kufel J. Non-canonical translation initiation in yeast generates a cryptic pool of mitochondrial proteins. Nucleic Acids Res 2019; 47:5777-5791. [PMID: 31216041 PMCID: PMC6582344 DOI: 10.1093/nar/gkz301] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 04/12/2019] [Accepted: 04/16/2019] [Indexed: 12/15/2022] Open
Abstract
Utilization of non-AUG alternative translation start sites is most common in bacteria and viruses, but it has been also reported in other organisms. This phenomenon increases proteome complexity by allowing expression of multiple protein isoforms from a single gene. In Saccharomyces cerevisiae, a few described cases concern proteins that are translated from upstream near-cognate start codons as N-terminally extended variants that localize to mitochondria. Using bioinformatics tools, we provide compelling evidence that in yeast the potential for producing alternative protein isoforms by non-AUG translation initiation is much more prevalent than previously anticipated and may apply to as many as a few thousand proteins. Several hundreds of candidates are predicted to gain a mitochondrial targeting signal (MTS), generating an unrecognized pool of mitochondrial proteins. We confirmed mitochondrial localization of a subset of proteins previously not identified as mitochondrial, whose standard forms do not carry an MTS. Our data highlight the potential of non-canonical translation initiation in expanding the capacity of the mitochondrial proteome and possibly also other cellular features.
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Affiliation(s)
- Geoffray Monteuuis
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, FIN-90014 Finland
| | - Anna Miścicka
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
| | - Michał Świrski
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
| | - Lounis Zenad
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
| | - Olli Niemitalo
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, FIN-90014 Finland
| | - Lidia Wrobel
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Jahangir Alam
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, FIN-90014 Finland
| | - Agnieszka Chacinska
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland.,Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Alexander J Kastaniotis
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, FIN-90014 Finland
| | - Joanna Kufel
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
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Mays JN, Camacho-Villasana Y, Garcia-Villegas R, Perez-Martinez X, Barrientos A, Fontanesi F. The mitoribosome-specific protein mS38 is preferentially required for synthesis of cytochrome c oxidase subunits. Nucleic Acids Res 2019; 47:5746-5760. [PMID: 30968120 PMCID: PMC6582356 DOI: 10.1093/nar/gkz266] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 03/26/2019] [Accepted: 04/02/2019] [Indexed: 12/20/2022] Open
Abstract
Message-specific translational regulation mechanisms shape the biogenesis of multimeric oxidative phosphorylation (OXPHOS) enzyme in mitochondria from the yeast Saccharomyces cerevisiae. These mechanisms, driven mainly by the action of mRNA-specific translational activators, help to coordinate synthesis of OXPHOS catalytic subunits by the mitoribosomes with both the import of their nucleus-encoded partners and their assembly to form the holocomplexes. However, little is known regarding the role that the mitoribosome itself may play in mRNA-specific translational regulation. Here, we show that the mitoribosome small subunit protein Cox24/mS38, known to be necessary for mitoribosome-specific intersubunit bridge formation and 15S rRNA H44 stabilization, is required for efficient mitoribogenesis. Consequently, mS38 is necessary to sustain the overall mitochondrial protein synthesis rate, despite an adaptive ∼2-fold increase in mitoribosome abundance in mS38-deleted cells. Additionally, the absence of mS38 preferentially disturbs translation initiation of COX1, COX2, and COX3 mRNAs, without affecting the levels of mRNA-specific translational activators. We propose that mS38 confers the mitochondrial ribosome an intrinsic capacity of translational regulation, probably acquired during evolution from bacterial ribosomes to facilitate the translation of mitochondrial mRNAs, which lack typical anti-Shine-Dalgarno sequences.
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Affiliation(s)
- Jeffri-Noelle Mays
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Yolanda Camacho-Villasana
- Departamento de Genetica Molecular, Instituto de Fisiologiía Celular, Universidad Nacional Autonoma de Mexico, Mexico City 04510, Mexico
| | - Rodolfo Garcia-Villegas
- Departamento de Genetica Molecular, Instituto de Fisiologiía Celular, Universidad Nacional Autonoma de Mexico, Mexico City 04510, Mexico
| | - Xochitl Perez-Martinez
- Departamento de Genetica Molecular, Instituto de Fisiologiía Celular, Universidad Nacional Autonoma de Mexico, Mexico City 04510, Mexico
| | - Antoni Barrientos
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Flavia Fontanesi
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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34
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Orlandi I, Stamerra G, Vai M. Altered Expression of Mitochondrial NAD + Carriers Influences Yeast Chronological Lifespan by Modulating Cytosolic and Mitochondrial Metabolism. Front Genet 2018; 9:676. [PMID: 30619489 PMCID: PMC6305841 DOI: 10.3389/fgene.2018.00676] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 12/04/2018] [Indexed: 01/07/2023] Open
Abstract
Nicotinamide adenine dinucleotide (NAD+) represents an essential cofactor in sustaining cellular bioenergetics and maintaining cellular fitness, and has emerged as a therapeutic target to counteract aging and age-related diseases. Besides NAD+ involvement in multiple redox reactions, it is also required as co-substrate for the activity of Sirtuins, a family of evolutionary conserved NAD+-dependent deacetylases that regulate both metabolism and aging. The founding member of this family is Sir2 of Saccharomyces cerevisiae, a well-established model system for studying aging of post-mitotic mammalian cells. In this context, it refers to chronological aging, in which the chronological lifespan (CLS) is measured. In this paper, we investigated the effects of changes in the cellular content of NAD+ on CLS by altering the expression of mitochondrial NAD+ carriers, namely Ndt1 and Ndt2. We found that the deletion or overexpression of these carriers alters the intracellular levels of NAD+ with opposite outcomes on CLS. In particular, lack of both carriers decreases NAD+ content and extends CLS, whereas NDT1 overexpression increases NAD+ content and reduces CLS. This correlates with opposite cytosolic and mitochondrial metabolic assets shown by the two types of mutants. In the former, an increase in the efficiency of oxidative phosphorylation is observed together with an enhancement of a pro-longevity anabolic metabolism toward gluconeogenesis and trehalose storage. On the contrary, NDT1 overexpression brings about on the one hand, a decrease in the respiratory efficiency generating harmful superoxide anions, and on the other, a decrease in gluconeogenesis and trehalose stores: all this is reflected into a time-dependent loss of mitochondrial functionality during chronological aging.
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Affiliation(s)
- Ivan Orlandi
- SYSBIO Centre for Systems Biology, Milan, Italy.,Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Giulia Stamerra
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
| | - Marina Vai
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
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35
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Motor recruitment to the TIM23 channel's lateral gate restricts polypeptide release into the inner membrane. Nat Commun 2018; 9:4028. [PMID: 30279421 PMCID: PMC6168564 DOI: 10.1038/s41467-018-06492-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 09/07/2018] [Indexed: 01/05/2023] Open
Abstract
The presequence translocase of the mitochondrial inner membrane (TIM23 complex) facilitates anterograde precursor transport into the matrix and lateral release of precursors with stop-transfer signal into the membrane (sorting). Sorting requires precursor exit from the translocation channel into the lipid phase through the lateral gate of the TIM23 complex. How the two transport modes are regulated and balanced against each other is unknown. Here we show that the import motor J-protein Pam18, which is essential for matrix import, controls lateral protein release into the lipid bilayer. Constitutively translocase-associated Pam18 obstructs lateral precursor transport. Concomitantly, Mgr2, implicated in precursor quality control, is displaced from the translocase. We conclude that during motor-dependent matrix protein transport, the transmembrane segment of Pam18 closes the lateral gate to promote anterograde polypeptide movement. This finding explains why a motor-free form of the translocase facilitates the lateral movement of precursors with a stop-transfer signal. The mitochondrial TIM23-complex facilitates anterograde precursor transport across the inner membrane into the matrix and lateral release of precursors into the membrane. Here authors show that the import motor J-protein Pam18 controls lateral protein release into the lipid bilayer.
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36
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Hansen KG, Aviram N, Laborenz J, Bibi C, Meyer M, Spang A, Schuldiner M, Herrmann JM. An ER surface retrieval pathway safeguards the import of mitochondrial membrane proteins in yeast. Science 2018; 361:1118-1122. [PMID: 30213914 DOI: 10.1126/science.aar8174] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 06/27/2018] [Accepted: 08/06/2018] [Indexed: 12/29/2022]
Abstract
The majority of organellar proteins are translated on cytosolic ribosomes and must be sorted correctly to function. Targeting routes have been identified for organelles such as peroxisomes and the endoplasmic reticulum (ER). However, little is known about the initial steps of targeting of mitochondrial proteins. In this study, we used a genome-wide screen in yeast and identified factors critical for the intracellular sorting of the mitochondrial inner membrane protein Oxa1. The screen uncovered an unexpected path, termed ER-SURF, for targeting of mitochondrial membrane proteins. This pathway retrieves mitochondrial proteins from the ER surface and reroutes them to mitochondria with the aid of the ER-localized chaperone Djp1. Hence, cells use the expanse of the ER surfaces as a fail-safe to maximize productive mitochondrial protein targeting.
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Affiliation(s)
- Katja G Hansen
- Division of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Naama Aviram
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Janina Laborenz
- Division of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Chen Bibi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Maren Meyer
- Division of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Anne Spang
- Biozentrum, University of Basel, Basel, Switzerland
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
| | - Johannes M Herrmann
- Division of Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany.
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37
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Hu W, Wang Z, Zheng H. Mitochondrial accumulation of amyloid β (Aβ) peptides requires TOMM22 as a main Aβ receptor in yeast. J Biol Chem 2018; 293:12681-12689. [PMID: 29925587 PMCID: PMC6102147 DOI: 10.1074/jbc.ra118.002713] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/14/2018] [Indexed: 01/26/2023] Open
Abstract
Mitochondrial accumulation of intracellular β-amyloid (Aβ) peptides is present in the brains of individuals with Alzheimer's disease (AD) as well as in related mouse models of AD. This accumulation is extremely toxic because Aβ disrupts the normal functions of many mitochondrial proteins, resulting in significant mitochondrial dysfunction. Therefore, understanding the mitochondrial accumulation of Aβ is useful for future pharmaceutical design of drugs to address mitochondrial dysfunction in AD. However, the detailed molecular mechanism of this accumulation process remains elusive. Here, using yeast mitochondria, we present direct experimental evidence suggesting that Aβ is specifically recognized by translocase of outer mitochondrial membrane subunit 22 (Tom22 in yeast; TOMM22 in human), a noncanonical receptor within the mitochondrial protein import machinery, and that this recognition is critical for Aβ accumulation in mitochondria. Furthermore, we found that residues 25-42 in the Aβ peptide mediate the specific interaction with TOMM22. On the basis of our findings, we propose that cytosolic Aβ is recognized by TOMM22; transferred to another translocase subunit, TOMM40; and transported through the TOMM channel into the mitochondria. Our results not only confirm that yeast mitochondria can be used as a model to study mitochondrial dysfunction caused by Aβ peptides in AD but also pave the way for future studies of the molecular mechanism of mitochondrial Aβ accumulation.
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Affiliation(s)
- Wenxin Hu
- From the Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - Zhiming Wang
- From the Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045
| | - Hongjin Zheng
- From the Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, To whom correspondence should be addressed:
Dept. of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Mail Stop 8101, Aurora, CO 80045. Tel.:
303-724-9374; Fax:
303-724-3215; E-mail:
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38
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Kowalski L, Bragoszewski P, Khmelinskii A, Glow E, Knop M, Chacinska A. Determinants of the cytosolic turnover of mitochondrial intermembrane space proteins. BMC Biol 2018; 16:66. [PMID: 29929515 PMCID: PMC6013907 DOI: 10.1186/s12915-018-0536-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 05/25/2018] [Indexed: 12/31/2022] Open
Abstract
Background The proteome of mitochondria comprises mostly proteins that originate as precursors in the cytosol. Before import into the organelle, such proteins are exposed to cytosolic quality control mechanisms. Multiple lines of evidence indicate a significant contribution of the major cytosolic protein degradation machinery, the ubiquitin-proteasome system, to the quality control of mitochondrial proteins. Proteins that are directed to the mitochondrial intermembrane space (IMS) exemplify an entire class of mitochondrial proteins regulated by proteasomal degradation. However, little is known about how these proteins are selected for degradation. Results The present study revealed the heterogeneous cytosolic stability of IMS proteins. Using a screening approach, we found that different cytosolic factors are responsible for the degradation of specific IMS proteins, with no single common factor involved in the degradation of all IMS proteins. We found that the Cox12 protein is rapidly degraded when localized to the cytosol, thus providing a sensitive experimental model. Using Cox12, we found that lysine residues but not conserved cysteine residues are among the degron features important for protein ubiquitination. We observed the redundancy of ubiquitination components, with significant roles of Ubc4 E2 ubiquitin-conjugating enzyme and Rsp5 E3 ubiquitin ligase. The amount of ubiquitinated Cox12 was inversely related to mitochondrial import efficiency. Importantly, we found that precursor protein ubiquitination blocks its import into mitochondria. Conclusions The present study confirms the involvement of ubiquitin-proteasome system in the quality control of mitochondrial IMS proteins in the cytosol. Notably, ubiquitination of IMS proteins prohibits their import into mitochondria. Therefore, ubiquitination directly affects the availability of precursor proteins for organelle biogenesis. Importantly, despite their structural similarities, IMS proteins are not selected for degradation in a uniform way. Instead, specific IMS proteins rely on discrete components of the ubiquitination machinery to mediate their clearance by the proteasome. Electronic supplementary material The online version of this article (10.1186/s12915-018-0536-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lukasz Kowalski
- Centre of New Technologies, University of Warsaw, Warsaw, Poland.,International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Piotr Bragoszewski
- Centre of New Technologies, University of Warsaw, Warsaw, Poland. .,International Institute of Molecular and Cell Biology, Warsaw, Poland.
| | - Anton Khmelinskii
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany.,Institute of Molecular Biology (IMB), Mainz, Germany
| | - Edyta Glow
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Michael Knop
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Agnieszka Chacinska
- Centre of New Technologies, University of Warsaw, Warsaw, Poland. .,International Institute of Molecular and Cell Biology, Warsaw, Poland.
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39
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Basu Ball W, Baker CD, Neff JK, Apfel GL, Lagerborg KA, Žun G, Petrovič U, Jain M, Gohil VM. Ethanolamine ameliorates mitochondrial dysfunction in cardiolipin-deficient yeast cells. J Biol Chem 2018; 293:10870-10883. [PMID: 29866881 DOI: 10.1074/jbc.ra118.004014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Revised: 05/29/2018] [Indexed: 01/24/2023] Open
Abstract
Cardiolipin (CL) is a signature phospholipid of the mitochondria required for the formation of mitochondrial respiratory chain (MRC) supercomplexes. The destabilization of MRC supercomplexes is the proximal cause of the pathology associated with the depletion of CL in patients with Barth syndrome. Thus, promoting supercomplex formation could ameliorate mitochondrial dysfunction associated with CL depletion. However, to date, physiologically relevant small-molecule regulators of supercomplex formation have not been identified. Here, we report that ethanolamine (Etn) supplementation rescues the MRC defects by promoting supercomplex assembly in a yeast model of Barth syndrome. We discovered this novel role of Etn while testing the hypothesis that elevating mitochondrial phosphatidylethanolamine (PE), a phospholipid suggested to overlap in function with CL, could compensate for CL deficiency. We found that the Etn supplementation rescues the respiratory growth of CL-deficient Saccharomyces cerevisiae cells in a dose-dependent manner but independently of its incorporation into PE. The rescue was specifically dependent on Etn but not choline or serine, the other phospholipid precursors. Etn improved mitochondrial function by restoring the expression of MRC proteins and promoting supercomplex assembly in CL-deficient cells. Consistent with this mechanism, overexpression of Cox4, the MRC complex IV subunit, was sufficient to promote supercomplex formation in CL-deficient cells. Taken together, our work identifies a novel role of a ubiquitous metabolite, Etn, in attenuating mitochondrial dysfunction caused by CL deficiency.
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Affiliation(s)
- Writoban Basu Ball
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Charli D Baker
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - John K Neff
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Gabriel L Apfel
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Kim A Lagerborg
- the Departments of Medicine and Pharmacology, University of California, San Diego, La Jolla, California 92093
| | - Gašper Žun
- the Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Jamova 39, Ljubljana, Slovenia.,the Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia, and
| | - Uroš Petrovič
- the Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Jamova 39, Ljubljana, Slovenia.,the Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Mohit Jain
- the Departments of Medicine and Pharmacology, University of California, San Diego, La Jolla, California 92093
| | - Vishal M Gohil
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843,
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40
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Increased mitochondrial respiration promotes survival from endoplasmic reticulum stress. Cell Death Differ 2018; 26:487-501. [PMID: 29795335 DOI: 10.1038/s41418-018-0133-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 04/20/2018] [Accepted: 05/06/2018] [Indexed: 12/17/2022] Open
Abstract
Protein misfolding in the endoplasmic reticulum (ER) is accompanied by adaptive cellular responses to promote cell survival. We now show that activation of mitochondrial respiration is a critical component of an adaptive ER stress response, requiring the unfolded protein response (UPR) sensor Ire1, and also calcium signaling via calcineurin. In yeast and mammalian cells lacking Ire1 or calcineurin, respiratory activation is impaired in response to ER stress; accumulation of mitochondrial reactive oxygen species (ROS) triggers cell death as abrogation of ROS by antioxidants or loss of the electron transport chain (in yeast) can rescue cells from death. Significantly, cells are rescued from ER stress-induced death by mitochondrial uncoupling by CCCP to increase O2 consumption (and increase the efficiency of electron transfer). Remarkably, genetic and pharmacologic strategies to promote mitochondrial biogenesis and increase O2 consumption also alleviate ER stress-mediated ROS and death in yeast and mammalian cells. Moreover, in a yeast genetic screen, three mitochondrial proteins Mrx9, Mrm1, and Aim19 that increase mitochondrial biogenesis were identified as high copy suppressors of ER stress-mediated cell death. Our results show that enhanced mitochondrial biogenesis, linked to improved efficiency of the electron transport chain, is a powerful strategy to block ROS accumulation and promote cell survival during ER stress in eukaryotic cells.
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41
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Höhr AIC, Lindau C, Wirth C, Qiu J, Stroud DA, Kutik S, Guiard B, Hunte C, Becker T, Pfanner N, Wiedemann N. Membrane protein insertion through a mitochondrial β-barrel gate. Science 2018; 359:359/6373/eaah6834. [PMID: 29348211 DOI: 10.1126/science.aah6834] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 10/12/2017] [Accepted: 12/14/2017] [Indexed: 11/02/2022]
Abstract
The biogenesis of mitochondria, chloroplasts, and Gram-negative bacteria requires the insertion of β-barrel proteins into the outer membranes. Homologous Omp85 proteins are essential for membrane insertion of β-barrel precursors. It is unknown if precursors are threaded through the Omp85-channel interior and exit laterally or if they are translocated into the membrane at the Omp85-lipid interface. We have mapped the interaction of a precursor in transit with the mitochondrial Omp85-channel Sam50 in the native membrane environment. The precursor is translocated into the channel interior, interacts with an internal loop, and inserts into the lateral gate by β-signal exchange. Transport through the Omp85-channel interior followed by release through the lateral gate into the lipid phase may represent a basic mechanism for membrane insertion of β-barrel proteins.
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Affiliation(s)
- Alexandra I C Höhr
- Institute of Biochemistry and Molecular Biology, Centre for Biochemistry and Molecular Cell Research (ZBMZ), Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.,Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Caroline Lindau
- Institute of Biochemistry and Molecular Biology, Centre for Biochemistry and Molecular Cell Research (ZBMZ), Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.,Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Christophe Wirth
- Institute of Biochemistry and Molecular Biology, Centre for Biochemistry and Molecular Cell Research (ZBMZ), Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Jian Qiu
- Institute of Biochemistry and Molecular Biology, Centre for Biochemistry and Molecular Cell Research (ZBMZ), Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - David A Stroud
- Institute of Biochemistry and Molecular Biology, Centre for Biochemistry and Molecular Cell Research (ZBMZ), Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Stephan Kutik
- Institute of Biochemistry and Molecular Biology, Centre for Biochemistry and Molecular Cell Research (ZBMZ), Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Bernard Guiard
- Centre de Génétique Moléculaire, CNRS, 91190 Gif-sur-Yvette, France
| | - Carola Hunte
- Institute of Biochemistry and Molecular Biology, Centre for Biochemistry and Molecular Cell Research (ZBMZ), Faculty of Medicine, 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, Centre for Biochemistry and Molecular Cell Research (ZBMZ), Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, Centre for Biochemistry and Molecular Cell Research (ZBMZ), Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, Centre for Biochemistry and Molecular Cell Research (ZBMZ), Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
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42
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Weidberg H, Amon A. MitoCPR-A surveillance pathway that protects mitochondria in response to protein import stress. Science 2018; 360:eaan4146. [PMID: 29650645 PMCID: PMC6528467 DOI: 10.1126/science.aan4146] [Citation(s) in RCA: 215] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Revised: 12/19/2017] [Accepted: 02/19/2018] [Indexed: 12/13/2022]
Abstract
Mitochondrial functions are essential for cell viability and rely on protein import into the organelle. Various disease and stress conditions can lead to mitochondrial import defects. We found that inhibition of mitochondrial import in budding yeast activated a surveillance mechanism, mitoCPR, that improved mitochondrial import and protected mitochondria during import stress. mitoCPR induced expression of Cis1, which associated with the mitochondrial translocase to reduce the accumulation of mitochondrial precursor proteins at the mitochondrial translocase. Clearance of precursor proteins depended on the Cis1-interacting AAA+ adenosine triphosphatase Msp1 and the proteasome, suggesting that Cis1 facilitates degradation of unimported proteins. mitoCPR was required for maintaining mitochondrial functions when protein import was compromised, demonstrating the importance of mitoCPR in protecting the mitochondrial compartment.
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Affiliation(s)
- Hilla Weidberg
- David H. Koch Institute for Integrative Cancer Research, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Angelika Amon
- David H. Koch Institute for Integrative Cancer Research, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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43
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Vögtle FN, Brändl B, Larson A, Pendziwiat M, Friederich MW, White SM, Basinger A, Kücükköse C, Muhle H, Jähn JA, Keminer O, Helbig KL, Delto CF, Myketin L, Mossmann D, Burger N, Miyake N, Burnett A, van Baalen A, Lovell MA, Matsumoto N, Walsh M, Yu HC, Shinde DN, Stephani U, Van Hove JLK, Müller FJ, Helbig I. Mutations in PMPCB Encoding the Catalytic Subunit of the Mitochondrial Presequence Protease Cause Neurodegeneration in Early Childhood. Am J Hum Genet 2018; 102:557-573. [PMID: 29576218 PMCID: PMC5985287 DOI: 10.1016/j.ajhg.2018.02.014] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 02/19/2018] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial disorders causing neurodegeneration in childhood are genetically heterogeneous, and the underlying genetic etiology remains unknown in many affected individuals. We identified biallelic variants in PMPCB in individuals of four families including one family with two affected siblings with neurodegeneration and cerebellar atrophy. PMPCB encodes the catalytic subunit of the essential mitochondrial processing protease (MPP), which is required for maturation of the majority of mitochondrial precursor proteins. Mitochondria isolated from two fibroblast cell lines and induced pluripotent stem cells derived from one affected individual and differentiated neuroepithelial stem cells showed reduced PMPCB levels and accumulation of the processing intermediate of frataxin, a sensitive substrate for MPP dysfunction. Introduction of the identified PMPCB variants into the homologous S. cerevisiae Mas1 protein resulted in a severe growth and MPP processing defect leading to the accumulation of mitochondrial precursor proteins and early impairment of the biogenesis of iron-sulfur clusters, which are indispensable for a broad range of crucial cellular functions. Analysis of biopsy materials of an affected individual revealed changes and decreased activity in iron-sulfur cluster-containing respiratory chain complexes and dysfunction of mitochondrial and cytosolic Fe-S cluster-dependent enzymes. We conclude that biallelic mutations in PMPCB cause defects in MPP proteolytic activity leading to dysregulation of iron-sulfur cluster biogenesis and triggering a complex neurological phenotype of neurodegeneration in early childhood.
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Affiliation(s)
- F-Nora Vögtle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany.
| | - Björn Brändl
- Department of Psychiatry and Psychotherapy, University Hospital Schleswig Holstein, Kiel 24105, Germany
| | - Austin Larson
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, CO 80045, USA
| | - Manuela Pendziwiat
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany
| | - Marisa W Friederich
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, CO 80045, USA
| | - Susan M White
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, VIC 3052, Australia; Department of Paediatrics, University of Melbourne, Melbourne, VIC 3052, Australia
| | - Alice Basinger
- Cook Children's Physician Network, Department of Genetics, Fort Worth, TX 76102, USA
| | - Cansu Kücükköse
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany; Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Hiltrud Muhle
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany
| | - Johanna A Jähn
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany
| | - Oliver Keminer
- Fraunhofer-Institut für Molekularbiologie und Angewandte Ökologie IME, ScreeningPort, Hamburg 22525, Germany
| | - Katherine L Helbig
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Carolyn F Delto
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg 97080, Germany
| | - Lisa Myketin
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany
| | - Dirk Mossmann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany
| | - Nils Burger
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany
| | - Noriko Miyake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan
| | - Audrey Burnett
- Cook Children's Physician Network, Department of Genetics, Fort Worth, TX 76102, USA
| | - Andreas van Baalen
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany
| | - Mark A Lovell
- Department of Pathology, University of Colorado, Aurora, CO 80045, USA
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan
| | - Maie Walsh
- Adult Genetic Medicine, Royal Melbourne Hospital, Melbourne, VIC 3052, Australia
| | - Hung-Chun Yu
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, CO 80045, USA
| | - Deepali N Shinde
- Division of Clinical Genomics, Ambry Genetics, Aliso Viejo, CA 92656, USA
| | - Ulrich Stephani
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany
| | - Johan L K Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, CO 80045, USA
| | - Franz-Josef Müller
- Department of Psychiatry and Psychotherapy, University Hospital Schleswig Holstein, Kiel 24105, Germany; Max Planck Institute for Molecular Genetics, Berlin 14195, Germany
| | - Ingo Helbig
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany; Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
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44
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Topf U, Suppanz I, Samluk L, Wrobel L, Böser A, Sakowska P, Knapp B, Pietrzyk MK, Chacinska A, Warscheid B. Quantitative proteomics identifies redox switches for global translation modulation by mitochondrially produced reactive oxygen species. Nat Commun 2018; 9:324. [PMID: 29358734 PMCID: PMC5778013 DOI: 10.1038/s41467-017-02694-8] [Citation(s) in RCA: 133] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 12/19/2017] [Indexed: 11/09/2022] Open
Abstract
The generation of reactive oxygen species (ROS) is inevitably linked to life. However, the precise role of ROS in signalling and specific targets is largely unknown. We perform a global proteomic analysis to delineate the yeast redoxome to a depth of more than 4,300 unique cysteine residues in over 2,200 proteins. Mapping of redox-active thiols in proteins exposed to exogenous or endogenous mitochondria-derived oxidative stress reveals ROS-sensitive sites in several components of the translation apparatus. Mitochondria are the major source of cellular ROS. We demonstrate that increased levels of intracellular ROS caused by dysfunctional mitochondria serve as a signal to attenuate global protein synthesis. Hence, we propose a universal mechanism that controls protein synthesis by inducing reversible changes in the translation machinery upon modulating the redox status of proteins involved in translation. This crosstalk between mitochondria and protein synthesis may have an important contribution to pathologies caused by dysfunctional mitochondria.
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Affiliation(s)
- Ulrike Topf
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109, Warsaw, Poland.,Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097, Warsaw, Poland
| | - Ida Suppanz
- Faculty of Biology, Institute of Biology II, Biochemistry-Functional Proteomics, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 18, 79104, Freiburg, Germany
| | - Lukasz Samluk
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109, Warsaw, Poland.,Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097, Warsaw, Poland
| | - Lidia Wrobel
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109, Warsaw, Poland
| | - Alexander Böser
- Faculty of Biology, Institute of Biology II, Biochemistry-Functional Proteomics, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Paulina Sakowska
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109, Warsaw, Poland
| | - Bettina Knapp
- Faculty of Biology, Institute of Biology II, Biochemistry-Functional Proteomics, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Martyna K Pietrzyk
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109, Warsaw, Poland.,Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097, Warsaw, Poland
| | - Agnieszka Chacinska
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109, Warsaw, Poland. .,Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097, Warsaw, Poland.
| | - Bettina Warscheid
- Faculty of Biology, Institute of Biology II, Biochemistry-Functional Proteomics, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany. .,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 18, 79104, Freiburg, Germany. .,ZBSA Centre for Biological Systems Analysis, University of Freiburg, Habsburgerstrasse 49, 79104, Freiburg, Germany.
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45
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Liu J, Li Y, Chen J, Wang Y, Zou M, Su R, Huang Y. The fission yeast Schizosaccharomyces pombe Mtf2 is required for mitochondrial cox1 gene expression. MICROBIOLOGY-SGM 2018; 164:400-409. [PMID: 29458562 DOI: 10.1099/mic.0.000602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mitochondrial gene expression is essential for adenosine triphosphate synthesis via oxidative phosphorylation, which is the universal energy currency of cells. Here, we report the identification and characterization of a homologue of Saccharomyces cerevisiae Mtf2 (also called Nam1) in Schizosaccharomyces pombe. The Δmtf2 mutant with the intron-containing mitochondrial DNA (mtDNA) exhibited impaired growth on a rich medium containing the non-fermentable carbon source glycerol, suggesting that mtf2 is involved in mitochondrial function. mtf2 deletion in a mitochondrial intron-containing background resulted in a barely detectable level of the cox1 mRNA and a reduction in the level of the cob1 mRNA, and severely impaired cox1 translation. In contrast, mtf2 deletion in a mitochondrial intron-less background did not affect the levels of cox1 and cob1 mRNAs. However, Cox1 synthesis could not be restored to the control level in the Δmtf2 mutant with intron-less mtDNA. Our results suggest that unlike its counterpart in S. cerevisiae which plays a general role in synthesis of mtDNA-encoded proteins, S. pombe Mtf2 primarily functions in cox1 translation and the effect of mtf2 deletion on splicing of introns in mtDNA is likely due to a deficiency in the synthesis of intron-encoded maturases.
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Affiliation(s)
- Jinyu Liu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China
| | - Yan Li
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China
| | - Jie Chen
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China
| | - Yirong Wang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China
| | - Mengting Zou
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China
| | - Ruyue Su
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China
| | - Ying Huang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China
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46
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Pan D, Lindau C, Lagies S, Wiedemann N, Kammerer B. Metabolic profiling of isolated mitochondria and cytoplasm reveals compartment-specific metabolic responses. Metabolomics 2018; 14:59. [PMID: 29628813 PMCID: PMC5878833 DOI: 10.1007/s11306-018-1352-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/20/2018] [Indexed: 01/07/2023]
Abstract
INTRODUCTION Subcellular compartmentalization enables eukaryotic cells to carry out different reactions at the same time, resulting in different metabolite pools in the subcellular compartments. Thus, mutations affecting the mitochondrial energy metabolism could cause different metabolic alterations in mitochondria compared to the cytoplasm. Given that the metabolite pool in the cytosol is larger than that of other subcellular compartments, metabolic profiling of total cells could miss these compartment-specific metabolic alterations. OBJECTIVES To reveal compartment-specific metabolic differences, mitochondria and the cytoplasmic fraction of baker's yeast Saccharomyces cerevisiae were isolated and subjected to metabolic profiling. METHODS Mitochondria were isolated through differential centrifugation and were analyzed together with the remaining cytoplasm by gas chromatography-mass spectrometry (GC-MS) based metabolic profiling. RESULTS Seventy-two metabolites were identified, of which eight were found exclusively in mitochondria and sixteen exclusively in the cytoplasm. Based on the metabolic signature of mitochondria and of the cytoplasm, mutants of the succinate dehydrogenase (respiratory chain complex II) and of the FOF1-ATP-synthase (complex V) can be discriminated in both compartments by principal component analysis from wild-type and each other. These mitochondrial oxidative phosphorylation machinery mutants altered not only citric acid cycle related metabolites but also amino acids, fatty acids, purine and pyrimidine intermediates and others. CONCLUSION By applying metabolomics to isolated mitochondria and the corresponding cytoplasm, compartment-specific metabolic signatures can be identified. This subcellular metabolomics analysis is a powerful tool to study the molecular mechanism of compartment-specific metabolic homeostasis in response to mutations affecting the mitochondrial metabolism.
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Affiliation(s)
- Daqiang Pan
- grid.5963.9Center for Biological Systems Analysis, ZBSA, Albert-Ludwigs-University Freiburg, Habsburgerstraße 49, 79104 Freiburg, Germany
- grid.5963.9Institute of Pharmaceutical Sciences, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Caroline Lindau
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Stefan-Meier-Str. 17, 79104 Freiburg, Germany
- grid.5963.9Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Simon Lagies
- grid.5963.9Center for Biological Systems Analysis, ZBSA, Albert-Ludwigs-University Freiburg, Habsburgerstraße 49, 79104 Freiburg, Germany
- grid.5963.9Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
- grid.5963.9Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Nils Wiedemann
- grid.5963.9Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Stefan-Meier-Str. 17, 79104 Freiburg, Germany
- grid.5963.9BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Bernd Kammerer
- grid.5963.9Center for Biological Systems Analysis, ZBSA, Albert-Ludwigs-University Freiburg, Habsburgerstraße 49, 79104 Freiburg, Germany
- grid.5963.9BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
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Naumenko N, Morgenstern M, Rucktäschel R, Warscheid B, Rehling P. INA complex liaises the F 1F o-ATP synthase membrane motor modules. Nat Commun 2017; 8:1237. [PMID: 29093463 PMCID: PMC5665977 DOI: 10.1038/s41467-017-01437-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Accepted: 09/18/2017] [Indexed: 01/11/2023] Open
Abstract
The F1F0-ATP synthase translates a proton flux across the inner mitochondrial membrane into a mechanical rotation, driving anhydride bond formation in the catalytic portion. The complex’s membrane-embedded motor forms a proteinaceous channel at the interface between Atp9 ring and Atp6. To prevent unrestricted proton flow dissipating the H+-gradient, channel formation is a critical and tightly controlled step during ATP synthase assembly. Here we show that the INA complex (INAC) acts at this decisive step promoting Atp9-ring association with Atp6. INAC binds to newly synthesized mitochondrial-encoded Atp6 and Atp8 in complex with maturation factors. INAC association is retained until the F1-portion is built on Atp6/8 and loss of INAC causes accumulation of the free F1. An independent complex is formed between INAC and the Atp9 ring. We conclude that INAC maintains assembly intermediates of the F1 F0-ATP synthase in a primed state for the terminal assembly step–motor module formation. The inner membrane assembly complex (INAC) interacts with components of the F1F0-ATP synthase but its function remains unclear. Here the authors show that INAC associates with two distinct complexes during F1F0-ATP synthase formation, which points towards a safeguarding role during proton-conducting channel assembly.
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Affiliation(s)
- Nataliia Naumenko
- Department of Cellular Biochemistry, University Medical Center Göttingen, GZMB, D-37073, Göttingen, Germany
| | - Marcel Morgenstern
- Department of Biochemistry and Functional Proteomics, Faculty of Biology, University Freiburg, D-79104, Freiburg, Germany
| | - Robert Rucktäschel
- Department of Cellular Biochemistry, University Medical Center Göttingen, GZMB, D-37073, Göttingen, Germany
| | - Bettina Warscheid
- Department of Biochemistry and Functional Proteomics, Faculty of Biology, University Freiburg, D-79104, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, D-79104, Freiburg, Germany
| | - Peter Rehling
- Department of Cellular Biochemistry, University Medical Center Göttingen, GZMB, D-37073, Göttingen, Germany. .,Max Planck Institute for Biophysical Chemistry, D-37077, Göttingen, Germany.
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48
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Krüger V, Becker T, Becker L, Montilla-Martinez M, Ellenrieder L, Vögtle FN, Meyer HE, Ryan MT, Wiedemann N, Warscheid B, Pfanner N, Wagner R, Meisinger C. Identification of new channels by systematic analysis of the mitochondrial outer membrane. J Cell Biol 2017; 216:3485-3495. [PMID: 28916712 PMCID: PMC5674900 DOI: 10.1083/jcb.201706043] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 08/03/2017] [Accepted: 08/22/2017] [Indexed: 02/08/2023] Open
Abstract
Channels in the mitochondrial outer membrane exchange metabolites, ions, and proteins with the rest of the cell. Kruger et al. identify several new types of channel and suggest that the outer mitochondrial membrane is a more selective molecular sieve with a greater variety of channel-forming proteins than previously appreciated. The mitochondrial outer membrane is essential for communication between mitochondria and the rest of the cell and facilitates the transport of metabolites, ions, and proteins. All mitochondrial outer membrane channels known to date are β-barrel membrane proteins, including the abundant voltage-dependent anion channel and the cation-preferring protein-conducting channels Tom40, Sam50, and Mdm10. We analyzed outer membrane fractions of yeast mitochondria and identified four new channel activities: two anion-preferring channels and two cation-preferring channels. We characterized the cation-preferring channels at the molecular level. The mitochondrial import component Mim1 forms a channel that is predicted to have an α-helical structure for protein import. The short-chain dehydrogenase-related protein Ayr1 forms an NADPH-regulated channel. We conclude that the mitochondrial outer membrane contains a considerably larger variety of channel-forming proteins than assumed thus far. These findings challenge the traditional view of the outer membrane as an unspecific molecular sieve and indicate a higher degree of selectivity and regulation of metabolite fluxes at the mitochondrial boundary.
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Affiliation(s)
- Vivien Krüger
- Division of Biophysics, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.,Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Lars Becker
- Division of Biophysics, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | | | - Lars Ellenrieder
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - F-Nora Vögtle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Helmut E Meyer
- Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Dortmund, Germany
| | - Michael T Ryan
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia
| | - Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Bettina Warscheid
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany.,Institute of Biology II, Biochemistry - Functional Proteomics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany .,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Richard Wagner
- Division of Biophysics, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany .,Biophysics, Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Chris Meisinger
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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49
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Weir NR, Kamber RA, Martenson JS, Denic V. The AAA protein Msp1 mediates clearance of excess tail-anchored proteins from the peroxisomal membrane. eLife 2017; 6:28507. [PMID: 28906250 PMCID: PMC5633344 DOI: 10.7554/elife.28507] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 09/12/2017] [Indexed: 12/29/2022] Open
Abstract
Msp1 is a conserved AAA ATPase in budding yeast localized to mitochondria where it prevents accumulation of mistargeted tail-anchored (TA) proteins, including the peroxisomal TA protein Pex15. Msp1 also resides on peroxisomes but it remains unknown how native TA proteins on mitochondria and peroxisomes evade Msp1 surveillance. We used live-cell quantitative cell microscopy tools and drug-inducible gene expression to dissect Msp1 function. We found that a small fraction of peroxisomal Pex15, exaggerated by overexpression, is turned over by Msp1. Kinetic measurements guided by theoretical modeling revealed that Pex15 molecules at mitochondria display age-independent Msp1 sensitivity. By contrast, Pex15 molecules at peroxisomes are rapidly converted from an initial Msp1-sensitive to an Msp1-resistant state. Lastly, we show that Pex15 interacts with the peroxisomal membrane protein Pex3, which shields Pex15 from Msp1-dependent turnover. In sum, our work argues that Msp1 selects its substrates on the basis of their solitary membrane existence.
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Affiliation(s)
- Nicholas R Weir
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Roarke A Kamber
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - James S Martenson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Vladimir Denic
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
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50
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Wang Y, Yan J, Zhang Q, Ma X, Zhang J, Su M, Wang X, Huang Y. The Schizosaccharomyces pombe PPR protein Ppr10 associates with a novel protein Mpa1 and acts as a mitochondrial translational activator. Nucleic Acids Res 2017; 45:3323-3340. [PMID: 28334955 PMCID: PMC5389468 DOI: 10.1093/nar/gkx127] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 02/14/2017] [Indexed: 01/15/2023] Open
Abstract
The pentatricopeptide repeat (PPR) proteins characterized by tandem repeats of a degenerate 35-amino-acid motif function in all aspects of organellar RNA metabolism, many of which are essential for organellar gene expression. In this study, we report the characterization of a fission yeast Schizosaccharomyces pombe PPR protein, Ppr10 and a novel Ppr10-associated protein, designated Mpa1. The ppr10 deletion mutant exhibits growth defects in respiratory media, and is dramatically impaired for viability during the late-stationary phase. Deletion of ppr10 affects the accumulation of specific mitochondrial mRNAs. Furthermore, deletion of ppr10 severely impairs mitochondrial protein synthesis, suggesting that Ppr10 plays a general role in mitochondrial protein synthesis. Ppr10 interacts with Mpa1 in vivo and in vitro and the two proteins colocalize in the mitochondrial matrix. The ppr10 and mpa1 deletion mutants exhibit very similar phenotypes. One of Mpa1's functions is to maintain the normal protein level of Ppr10 protein by protecting it from degradation by the mitochondrial matrix protease Lon1. Our findings suggest that Ppr10 functions as a general mitochondrial translational activator, likely through interaction with mitochondrial mRNAs and mitochondrial translation initiation factor Mti2, and that Ppr10 requires Mpa1 association for stability and function.
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Affiliation(s)
- Yirong Wang
- Jiangsu Key Laboratory for Microbes and Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Jianhua Yan
- Jiangsu Key Laboratory for Microbes and Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Qingzhen Zhang
- Jiangsu Key Laboratory for Microbes and Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Xuting Ma
- Jiangsu Key Laboratory for Microbes and Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Juan Zhang
- Jiangsu Key Laboratory for Microbes and Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Minghui Su
- Jiangsu Key Laboratory for Microbes and Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Xiaojun Wang
- Jiangsu Key Laboratory for Microbes and Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Ying Huang
- Jiangsu Key Laboratory for Microbes and Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
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