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Hirata R, Mogi Y, Takahashi K, Nozaki H, Higashiyama T, Yoshida Y. Simple prerequisite of presequence for mitochondrial protein import in the unicellular red alga Cyanidioschyzon merolae. J Cell Sci 2024; 137:jcs262042. [PMID: 38940185 PMCID: PMC11298712 DOI: 10.1242/jcs.262042] [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: 02/19/2024] [Accepted: 06/13/2024] [Indexed: 06/29/2024] Open
Abstract
Mitochondrial biogenesis relies on hundreds of proteins that are derived from genes encoded in the nucleus. According to the characteristic properties of N-terminal targeting peptides (TPs) and multi-step authentication by the protein translocase called the TOM complex, nascent polypeptides satisfying the requirements are imported into mitochondria. However, it is unknown whether eukaryotic cells with a single mitochondrion per cell have a similar complexity of presequence requirements for mitochondrial protein import compared to other eukaryotes with multiple mitochondria. Based on putative mitochondrial TP sequences in the unicellular red alga Cyanidioschyzon merolae, we designed synthetic TPs and showed that functional TPs must have at least one basic residue and a specific amino acid composition, although their physicochemical properties are not strictly determined. Combined with the simple composition of the TOM complex in C. merolae, our results suggest that a regional positive charge in TPs is verified solely by TOM22 for mitochondrial protein import in C. merolae. The simple authentication mechanism indicates that the monomitochondrial C. merolae does not need to increase the cryptographic complexity of the lock-and-key mechanism for mitochondrial protein import.
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Affiliation(s)
- Riko Hirata
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yuko Mogi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Kohei Takahashi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Hisayoshi Nozaki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
- Biodiversity Division, National Institute for Environmental Studies, Ibaraki 305-8506, Japan
| | - Tetsuya Higashiyama
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yamato Yoshida
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
- Japan Science and Technology Agency (JST), PRESTO, Tokyo 113-0033, Japan
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Seyed Hajizadeh H, Azizi S, Aghaee A, Karakus S, Kaya O. Nano-silicone and Ascophyllum nodosum-based biostimulant down-regulates the negative effect of in vitro induced-salinity in Rosa damascena. BMC PLANT BIOLOGY 2023; 23:560. [PMID: 37957557 PMCID: PMC10644502 DOI: 10.1186/s12870-023-04584-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 11/06/2023] [Indexed: 11/15/2023]
Abstract
BACKGROUND Rosa damascena is extensively cultivated in various regions of Iran due to its aesthetic attributes, medicinal qualities, and essential oil production. This study investigated the efficacy of Ascophyllum nodosum extract (AnE) at concentrations of 0, 2, and 3 g L- 1 and Nano-silicon (nSiO2) at concentrations of 0, 50, and 100 mg L- 1 in ameliorating the impact of salinity on two genotypes of Damask rose ('Chaharfasl' and 'Kashan') under in vitro culture conditions. Additionally, various physio-chemical characteristics of R. damascena explants were assessed. RESULTS The findings revealed that exposure to 100 mM NaCl resulted in a substantial reduction in the Relative Water Content (RWC), Membrane Stability Index (MSI), leaf pigments (Chlorophyll b, Chlorophyll a, total Chlorophyll, and carotenoids), chlorophyll fluorescence parameters, and protein content in both genotypes when compared to control conditions. Salinity induced a significant increase in the parameter F0 and a decrease in the parameter Fv/Fm compared to the control conditions in both genotypes. Nonetheless, the genotype Kashan treated with 3 g L- 1 AnE + 100 mg L- 1 nSiO2 exhibited the maximum Fm value under control conditions, with a significant difference compared to other treatments. Furthermore, salinity caused a considerable reduction in Fm in both 'Kashan' and 'Chaharfasl' by 22% and 17%, respectively, when compared to the control condition. 'Kashan' displayed the maximum Fv/Fm compared to the other genotype. The maximum levels of Malondialdehyde (MAD) and hydrogen peroxide (H2O2) were also observed in explants affected by salinity. The combination of 3 g L- 1 AnE + 100 mg L- 1 nSiO2, followed by 2 g L- 1 AnE + 100 mg L- 1 nSiO2, exhibited substantial positive effects. Salinity also led to an increase in proline content and the activity of peroxidase (POD), superoxide dismutase (SOD), guaiacol peroxidase (GPX), and catalase (CAT) in both genotypes. The activity of these enzymes was further enhanced when AnE was applied at concentrations of 2 and 3 g L- 1 in combination with 100 mg L- 1 nSiO2. CONCLUSIONS The 'Kashan' genotype displayed greater tolerance to salinity by enhancing water balance, maintaining membrane integrity, and augmenting the activity of antioxidant enzymes compared to 'Chaharfasl'. The utilization of nSiO2 and AnE biostimulants demonstrated potential benefits for R. damascena, both under salinity and control conditions. These findings hold substantial importance for researchers, policymakers, and farmers, offering valuable insights into the development of salinity-tolerant crop varieties.
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Affiliation(s)
- Hanifeh Seyed Hajizadeh
- Department of Horticulture, Faculty of Agriculture, University of Maragheh, Maragheh, 55136-553, Iran.
| | - Sahar Azizi
- Department of Horticulture, Faculty of Agriculture, University of Maragheh, Maragheh, 55136-553, Iran
| | - Ahmad Aghaee
- Department of Biology, Faculty of Science, University of Maragheh, Maragheh, Iran
| | - Sinem Karakus
- Çölemerik Vocational School, Hakkari University, Hakkari, 30000, Turkey
- Republic of Turkey Ministry of Agriculture and Forestry, Erzincan Horticultural Research Institute, Erzincan, 24060, Turkey
| | - Ozkan Kaya
- Republic of Turkey Ministry of Agriculture and Forestry, Erzincan Horticultural Research Institute, Erzincan, 24060, Turkey
- Department of Plant Sciences, North Dakota State University, Fargo, ND, 58102, USA
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Sáiz-Bonilla M, Martín Merchán A, Pallás V, Navarro JA. Molecular characterization, targeting and expression analysis of chloroplast and mitochondrion protein import components in Nicotiana benthamiana. FRONTIERS IN PLANT SCIENCE 2022; 13:1040688. [PMID: 36388587 PMCID: PMC9643744 DOI: 10.3389/fpls.2022.1040688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Improved bioinformatics tools for annotating gene function are becoming increasingly available, but such information must be considered theoretical until further experimental evidence proves it. In the work reported here, the genes for the main components of the translocons of the outer membrane of chloroplasts (Toc) and mitochondria (Tom), including preprotein receptors and protein-conducting channels of N. benthamiana, were identified. Sequence identity searches and phylogenetic relationships with functionally annotated sequences such as those of A. thaliana revealed that N. benthamiana orthologs mainly exist as recently duplicated loci. Only a Toc34 ortholog was found (NbToc34), while Toc159 receptor family was composed of four orthologs but somewhat different from those of A. thaliana. Except for NbToc90, the rest (NbToc120, NbToc159A and NbToc159B) had a molecular weight of about 150 kDa and an acidic domain similar in length. Only two orthologs of the Tom20 receptors, NbTom20-1 and NbTom20-2, were found. The number of the Toc and Tom receptor isoforms in N. benthamiana was comparable to that previously reported in tomato and what we found in BLAST searches in other species in the genera Nicotiana and Solanum. After cloning, the subcellular localization of N. benthamiana orthologs was studied, resulting to be identical to that of A. thaliana receptors. Phenotype analysis after silencing together with relative expression analysis in roots, stems and leaves revealed that, except for the Toc and Tom channel-forming components (NbToc75 and NbTom40) and NbToc34, functional redundancy could be observed either among Toc159 or mitochondrial receptors. Finally, heterodimer formation between NbToc34 and the NbToc159 family receptors was confirmed by two alternative techniques indicating that different Toc complexes could be assembled. Additional work needs to be addressed to know if this results in a functional specialization of each Toc complex.
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Affiliation(s)
| | | | - Vicente Pallás
- *Correspondence: Vicente Pallas, ; Jose Antonio Navarro,
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Grüttner S, Nguyen TT, Bruhs A, Mireau H, Kempken F. The P-type pentatricopeptide repeat protein DWEORG1 is a non-previously reported rPPR protein of Arabidopsis mitochondria. Sci Rep 2022; 12:12492. [PMID: 35864185 PMCID: PMC9304396 DOI: 10.1038/s41598-022-16812-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 07/15/2022] [Indexed: 11/17/2022] Open
Abstract
Gene expression in plant mitochondria is mainly regulated by nuclear-encoded proteins on a post-transcriptional level. Pentatricopeptide repeat (PPR) proteins play a major role by participating in mRNA stability, splicing, RNA editing, and translation initiation. PPR proteins were also shown to be part of the mitochondrial ribosome (rPPR proteins), which may act as regulators of gene expression in plants. In this study, we focus on a mitochondrial-located P-type PPR protein—DWEORG1—from Arabidopsis thaliana. Its abundance in mitochondria is high, and it has a similar expression pattern as rPPR proteins. Mutant dweorg1 plants exhibit a slow-growth phenotype. Using ribosome profiling, a decrease in translation efficiency for cox2, rps4, rpl5, and ccmFN2 was observed in dweorg1 mutants, correlating with a reduced accumulation of the Cox2 protein in these plants. In addition, the mitochondrial rRNA levels are significantly reduced in dweorg1 compared with the wild type. DWEORG1 co-migrates with the ribosomal proteins Rps4 and Rpl16 in sucrose gradients, suggesting an association of DWEORG1 with the mitoribosome. Collectively, this data suggests that DWEORG1 encodes a novel rPPR protein that is needed for the translation of cox2, rps4, rpl5, and ccmFN2 and provides a stabilizing function for mitochondrial ribosomes.
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Affiliation(s)
- Stefanie Grüttner
- Abteilung Botanische Genetik und Molekularbiologie, Botanisches Institut und Botanischer Garten, Christian-Albrechts-Universität zu Kiel, Olshausenstraße 40, 24098, Kiel, Germany
| | - Tan-Trung Nguyen
- Institut Jean-Pierre Bourgin INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Anika Bruhs
- Abteilung Botanische Genetik und Molekularbiologie, Botanisches Institut und Botanischer Garten, Christian-Albrechts-Universität zu Kiel, Olshausenstraße 40, 24098, Kiel, Germany
| | - Hakim Mireau
- Institut Jean-Pierre Bourgin INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France.
| | - Frank Kempken
- Abteilung Botanische Genetik und Molekularbiologie, Botanisches Institut und Botanischer Garten, Christian-Albrechts-Universität zu Kiel, Olshausenstraße 40, 24098, Kiel, Germany.
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Schäfer K, Engstler C, Dischinger K, Carrie C. Assessment of Mitochondrial Protein Topology and Membrane Insertion. Methods Mol Biol 2022; 2363:165-181. [PMID: 34545493 DOI: 10.1007/978-1-0716-1653-6_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Analyzing the membrane integrity and topology of a mitochondrial protein is essential for truly understanding its function. In this chapter, we demonstrate how to analyze mitochondrial membrane proteins using both an immunological-based assay and an in vivo self-assembling GFP approach. First, immunological approaches to investigate the solubility or membrane association of a protein within mitochondria are described. With this method, we demonstrate how the topology of soluble domains of a membrane-integrated protein can be determined. Using protein-specific antibodies, the localization of the soluble domains of a protein are analyzed by a proteolytic-cleavage approach using proteinase K in mitochondria, outer membrane-ruptured mitochondria, and solubilized mitochondrial membranes. In a second approach, we determine the topology of plant mitochondrial proteins using an in vivo self-assembling GFP localization approach.
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Affiliation(s)
- Kerstin Schäfer
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Carina Engstler
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Korbinian Dischinger
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Chris Carrie
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.
- Department of Biotechnology, University of Verona, Verona, Italy.
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PRAT Proteins Operate in Organellar Protein Import and Export in Arabidopsis thaliana. PLANTS 2021; 10:plants10050958. [PMID: 34064964 PMCID: PMC8151980 DOI: 10.3390/plants10050958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 04/25/2021] [Accepted: 04/29/2021] [Indexed: 11/17/2022]
Abstract
Chloroplasts need to import preproteins and amino acids from the cytosol during their light-induced differentiation. Similarly, chloroplasts have to export organic matter including proteins and amino acids during leaf senescence. Members of the PRAT (preprotein and amino acid transporter) family are candidate transporters for both processes. Here, we defined the role of two small PRAT gene families, At4g26670 and At5g55510 (HP20 subfamily) versus At3g49560 and At5g24650 (HP30 subfamily) during greening of etiolated plants and during leaf senescence. Using a combination of reverse genetics, protein biochemistry and physiological tools, evidence was obtained for a role of chloroplast HP20, HP30 and HP30-2 in protein, but not amino acid, import into chloroplasts. HP20, HP30 and HP30-2 form larger complexes involved in the uptake of transit sequence-less cytosolic precursors. In addition, we identified a fraction of HP30-2 in mitochondria where it served a similar function as found for chloroplasts and operated in the uptake of transit sequence-less cytosolic precursor proteins. By contrast, HP22 was found to act in the export of proteins from chloroplasts during leaf senescence, and thus its role is entirely different from that of its orthologue, HP20. HP22 is part of a unique protein complex in the envelope of senescing chloroplasts that comprises at least 11 proteins and contains with HP65b (At5g55220) a protein that is related to the bacterial trigger factor chaperone. An ortholog of HP65b exists in the cyanobacterium Synechocystis and has previously been implicated in protein secretion. Whereas plants depleted of either HP22 or HP65b or even both were increasingly delayed in leaf senescence and retained much longer stromal chloroplast constituents than wild-type plants, HP22 overexpressors showed premature leaf senescence that was associated with accelerated losses of stromal chloroplast proteins. Together, our results identify the PRAT protein family as a unique system for importing and exporting proteins from chloroplasts.
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tRNA-Dependent Import of a Transit Sequence-Less Aminoacyl-tRNA Synthetase (LeuRS2) into the Mitochondria of Arabidopsis. Int J Mol Sci 2021; 22:ijms22083808. [PMID: 33916944 PMCID: PMC8067559 DOI: 10.3390/ijms22083808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/30/2021] [Accepted: 04/02/2021] [Indexed: 11/17/2022] Open
Abstract
Aminoacyl-tRNA synthetases (AaRS) charge tRNAs with amino acids for protein translation. In plants, cytoplasmic, mitochondrial, and chloroplast AaRS exist that are all coded for by nuclear genes and must be imported from the cytosol. In addition, only a few of the mitochondrial tRNAs needed for translation are encoded in mitochondrial DNA. Despite considerable progress made over the last few years, still little is known how the bulk of cytosolic AaRS and respective tRNAs are transported into mitochondria. Here, we report the identification of a protein complex that ties AaRS and tRNA import into the mitochondria of Arabidopsis thaliana. Using leucyl-tRNA synthetase 2 (LeuRS2) as a model for a mitochondrial signal peptide (MSP)-less precursor, a ≈30 kDa protein was identified that interacts with LeuRS2 during import. The protein identified is identical with a previously characterized mitochondrial protein designated HP30-2 (encoded by At3g49560) that contains a sterile alpha motif (SAM) similar to that found in RNA binding proteins. HP30-2 is part of a larger protein complex that contains with TIM22, TIM8, TIM9 and TIM10 four previously identified components of the translocase for MSP-less precursors. Lack of HP30-2 perturbed mitochondrial biogenesis and function and caused seedling lethality during greening, suggesting an essential role of HP30-2 in planta.
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Cainzos M, Marchetti F, Popovich C, Leonardi P, Pagnussat G, Zabaleta E. Gamma carbonic anhydrases are subunits of the mitochondrial complex I of diatoms. Mol Microbiol 2021; 116:109-125. [PMID: 33550595 DOI: 10.1111/mmi.14694] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 01/12/2021] [Accepted: 02/04/2021] [Indexed: 12/21/2022]
Abstract
Diatoms are unicellular organisms containing red algal-derived plastids that probably originated as result of serial endosymbioses between an ancestral heterotrophic organism and a red alga or cryptophyta algae from which has only the chloroplast left. Diatom mitochondria are thus believed to derive from the exosymbiont. Unlike animals and fungi, diatoms seem to contain ancestral respiratory chains. In support of this, genes encoding gamma type carbonic anhydrases (CAs) whose products were shown to be intrinsic complex I subunits in plants, Euglena and Acanthamoeba were found in diatoms, a representative of Stramenopiles. In this work, we experimentally show that mitochondrial complex I in diatoms is a large complex containing gamma type CA subunits, supporting an ancestral origin. By using a bioinformatic approach, a complex I integrated CA domain with heterotrimeric subunit composition is proposed.
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Affiliation(s)
- Maximiliano Cainzos
- IIB-CONICET-Universidad Nacional de Mar del Plata, Instituto de Investigaciones Biológicas, Mar del Plata, Argentina
| | - Fernanda Marchetti
- IIB-CONICET-Universidad Nacional de Mar del Plata, Instituto de Investigaciones Biológicas, Mar del Plata, Argentina
| | - Cecilia Popovich
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS), Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS) CONICET-UNS, Bahía Blanca, Argentina.,Centro de Emprendedorismo y Desarrollo Territorial Sostenible (CEDETS) CIC-UPSO, Bahía Blanca, Argentina
| | - Patricia Leonardi
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS), Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS) CONICET-UNS, Bahía Blanca, Argentina
| | - Gabriela Pagnussat
- IIB-CONICET-Universidad Nacional de Mar del Plata, Instituto de Investigaciones Biológicas, Mar del Plata, Argentina
| | - Eduardo Zabaleta
- IIB-CONICET-Universidad Nacional de Mar del Plata, Instituto de Investigaciones Biológicas, Mar del Plata, Argentina
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Guo HM, Li HC, Zhou SR, Xue HW, Miao XX. Deficiency of mitochondrial outer membrane protein 64 confers rice resistance to both piercing-sucking and chewing insects in rice. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2020; 62:1967-1982. [PMID: 32542992 DOI: 10.1111/jipb.12983] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 06/13/2020] [Indexed: 06/11/2023]
Abstract
The brown planthopper (BPH) and striped stem borer (SSB) are the most devastating insect pests in rice (Oryza sativa) producing areas. Screening for endogenous resistant genes is the most practical strategy for rice insect-resistance breeding. Forty-five mutants showing high resistance against BPH were identified in a rice T-DNA insertion population (11,000 putative homozygous lines) after 4 years of large-scale field BPH-resistance phenotype screening. Detailed analysis showed that deficiency of rice mitochondrial outer membrane protein 64 (OM64) gene resulted in increased resistance to BPH. Mitochondrial outer membrane protein 64 protein is located in the outer mitochondrial membrane by subcellular localization and its deficiency constitutively activated hydrogen peroxide (H2 O2 ) signaling, which stimulated antibiosis and tolerance to BPH. The om64 mutant also showed enhanced resistance to SSB, a chewing insect, which was due to promotion of Jasmonic acid biosynthesis and related responses. Importantly, om64 plants presented no significant changes in rice yield-related characters. This study confirmed OM64 as a negative regulator of rice herbivore resistance through regulating H2 O2 production. Mitochondrial outer membrane protein 64 is a potentially efficient candidate to improve BPH and SSB resistance through gene deletion. Why the om64 mutant was resistant to both piercing-sucking and chewing insects via a gene deficiency in mitochondria is discussed.
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Affiliation(s)
- Hui-Min Guo
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Hai-Chao Li
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Shi-Rong Zhou
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Hong-Wei Xue
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Xue-Xia Miao
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Shanghai, 200032, China
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Meyer AJ, Riemer J, Rouhier N. Oxidative protein folding: state-of-the-art and current avenues of research in plants. THE NEW PHYTOLOGIST 2019; 221:1230-1246. [PMID: 30230547 DOI: 10.1111/nph.15436] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 08/01/2018] [Indexed: 06/08/2023]
Abstract
Contents Summary 1230 I. Introduction 1230 II. Formation and isomerization of disulfides in the ER and the Golgi apparatus 1231 III. The disulfide relay in the mitochondrial intermembrane space: why are plants different? 1236 IV. Disulfide bond formation on luminal proteins in thylakoids 1240 V. Conclusion 1242 Acknowledgements 1242 References 1242 SUMMARY: Disulfide bonds are post-translational modifications crucial for the structure and function of thousands of proteins. Their formation and isomerization, referred to as oxidative folding, require specific protein machineries found in oxidizing subcellular compartments, namely the endoplasmic reticulum and the associated endomembrane system, the intermembrane space of mitochondria and the thylakoid lumen of chloroplasts. At least one protein component is required for transferring electrons from substrate proteins to an acceptor that is usually molecular oxygen. For oxidation reactions, incoming reduced substrates are oxidized by thiol-oxidoreductase proteins (or domains in case of chimeric proteins), which are usually themselves oxidized by a single thiol oxidase, the enzyme generating disulfide bonds de novo. By contrast, the description of the molecular actors and pathways involved in proofreading and isomerization of misfolded proteins, which require a tightly controlled redox balance, lags behind. Herein we provide a general overview of the knowledge acquired on the systems responsible for oxidative protein folding in photosynthetic organisms, highlighting their particularities compared to other eukaryotes. Current research challenges are discussed including the importance and specificity of these oxidation systems in the context of the existence of reducing systems in the same compartments.
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Affiliation(s)
- Andreas J Meyer
- INRES-Chemical Signalling, University of Bonn, 53113, Bonn, Germany
| | - Jan Riemer
- Institute of Biochemistry, University of Cologne, 50674, Cologne, Germany
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Plant mitochondrial protein import: the ins and outs. Biochem J 2018; 475:2191-2208. [PMID: 30018142 DOI: 10.1042/bcj20170521] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 06/19/2018] [Accepted: 06/21/2018] [Indexed: 01/29/2023]
Abstract
The majority of the mitochondrial proteome, required to fulfil its diverse range of functions, is cytosolically synthesised and translocated via specialised machinery. The dedicated translocases, receptors, and associated proteins have been characterised in great detail in yeast over the last several decades, yet many of the mechanisms that regulate these processes in higher eukaryotes are still unknown. In this review, we highlight the current knowledge of mitochondrial protein import in plants. Despite the fact that the mechanisms of mitochondrial protein import have remained conserved across species, many unique features have arisen in plants to encompass the developmental, tissue-specific, and stress-responsive regulation in planta. An understanding of unique features and mechanisms in plants provides us with a unique insight into the regulation of mitochondrial biogenesis in higher eukaryotes.
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Kolli R, Soll J, Carrie C. Plant Mitochondrial Inner Membrane Protein Insertion. Int J Mol Sci 2018; 19:E641. [PMID: 29495281 PMCID: PMC5855863 DOI: 10.3390/ijms19020641] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 02/20/2018] [Accepted: 02/22/2018] [Indexed: 02/06/2023] Open
Abstract
During the biogenesis of the mitochondrial inner membrane, most nuclear-encoded inner membrane proteins are laterally released into the membrane by the TIM23 and the TIM22 machinery during their import into mitochondria. A subset of nuclear-encoded mitochondrial inner membrane proteins and all the mitochondrial-encoded inner membrane proteins use the Oxa machinery-which is evolutionarily conserved from the endosymbiotic bacterial ancestor of mitochondria-for membrane insertion. Compared to the mitochondria from other eukaryotes, plant mitochondria have several unique features, such as a larger genome and a branched electron transport pathway, and are also involved in additional cellular functions such as photorespiration and stress perception. This review focuses on the unique aspects of plant mitochondrial inner membrane protein insertion machinery, which differs from that in yeast and humans, and includes a case study on the biogenesis of Cox2 in yeast, humans, two plant species, and an algal species to highlight lineage-specific similarities and differences. Interestingly, unlike mitochondria of other eukaryotes but similar to bacteria and chloroplasts, plant mitochondria appear to use the Tat machinery for membrane insertion of the Rieske Fe/S protein.
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Affiliation(s)
- Renuka Kolli
- Department of Biology I, Botany, Ludwig-Maximilians-Universität München, Großhaderner Strasse 2-4, D-82152 Planegg-Martinsried, Germany.
| | - Jürgen Soll
- Department of Biology I, Botany, Ludwig-Maximilians-Universität München, Großhaderner Strasse 2-4, D-82152 Planegg-Martinsried, Germany.
- Munich Center for Integrated Protein Science, CiPSM, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany.
| | - Chris Carrie
- Department of Biology I, Botany, Ludwig-Maximilians-Universität München, Großhaderner Strasse 2-4, D-82152 Planegg-Martinsried, Germany.
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Wojtkowska M, Buczek D, Suzuki Y, Shabardina V, Makałowski W, Kmita H. The emerging picture of the mitochondrial protein import complexes of Amoebozoa supergroup. BMC Genomics 2017; 18:997. [PMID: 29284403 PMCID: PMC5747110 DOI: 10.1186/s12864-017-4383-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 12/14/2017] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND The existence of mitochondria-related organelles (MROs) is proposed for eukaryotic organisms. The Amoebozoa includes some organisms that are known to have mitosomes but also organisms that have aerobic mitochondria. However, the mitochondrial protein apparatus of this supergroup remains largely unsampled, except for the mitochondrial outer membrane import complexes studied recently. Therefore, in this study we investigated the mitochondrial inner membrane and intermembrane space complexes, using the available genome and transcriptome sequences. RESULTS When compared with the canonical cognate complexes described for the yeast Saccharomyces cerevisiae, amoebozoans with aerobic mitochondria, display lower differences in the number of subunits predicted for these complexes than the mitochondrial outer membrane complexes, although the predicted subunits appear to display different levels of diversity in regard to phylogenetic position and isoform numbers. For the putative mitosome-bearing amoebozoans, the number of predicted subunits suggests the complex elimination distinctly more pronounced than in the case of the outer membrane ones. CONCLUSION The results concern the problem of mitochondrial and mitosome protein import machinery structural variability and the reduction of their complexity within the currently defined supergroup of Amoebozoa. This results are crucial for better understanding of the Amoebozoa taxa of both biomedical and evolutionary importance.
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Affiliation(s)
- Małgorzata Wojtkowska
- Laboratory of Bioenergetics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Dorota Buczek
- Laboratory of Bioenergetics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
- Institute of Bioinformatics, Faculty of Medicine, University of Muenster, Niels Stensen Strasse 14, 48149 Muenster, Germany
| | - Yutaka Suzuki
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562 Japan
| | - Victoria Shabardina
- Institute of Bioinformatics, Faculty of Medicine, University of Muenster, Niels Stensen Strasse 14, 48149 Muenster, Germany
| | - Wojciech Makałowski
- Institute of Bioinformatics, Faculty of Medicine, University of Muenster, Niels Stensen Strasse 14, 48149 Muenster, Germany
| | - Hanna Kmita
- Laboratory of Bioenergetics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
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14
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Che-Othman MH, Millar AH, Taylor NL. Connecting salt stress signalling pathways with salinity-induced changes in mitochondrial metabolic processes in C3 plants. PLANT, CELL & ENVIRONMENT 2017; 40:2875-2905. [PMID: 28741669 DOI: 10.1111/pce.13034] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 06/26/2017] [Accepted: 07/09/2017] [Indexed: 05/12/2023]
Abstract
Salinity exerts a severe detrimental effect on crop yields globally. Growth of plants in saline soils results in physiological stress, which disrupts the essential biochemical processes of respiration, photosynthesis, and transpiration. Understanding the molecular responses of plants exposed to salinity stress can inform future strategies to reduce agricultural losses due to salinity; however, it is imperative that signalling and functional response processes are connected to tailor these strategies. Previous research has revealed the important role that plant mitochondria play in the salinity response of plants. Review of this literature shows that 2 biochemical processes required for respiratory function are affected under salinity stress: the tricarboxylic acid cycle and the transport of metabolites across the inner mitochondrial membrane. However, the mechanisms by which components of these processes are affected or react to salinity stress are still far from understood. Here, we examine recent findings on the signal transduction pathways that lead to adaptive responses of plants to salinity and discuss how they can be involved in and be affected by modulation of the machinery of energy metabolism with attention to the role of the tricarboxylic acid cycle enzymes and mitochondrial membrane transporters in this process.
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Affiliation(s)
- M Hafiz Che-Othman
- ARC Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia, WA 6009, Australia
- School of Bioscience and Biotechnology, Faculty of Science and Technology, National University of Malaysia, Bangi, Selangor, 43600, Malaysia
| | - A Harvey Millar
- ARC Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia, WA 6009, Australia
| | - Nicolas L Taylor
- ARC Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia, WA 6009, Australia
- Institute of Agriculture, The University of Western Australia, Crawley, Western Australia, WA 6009, Australia
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15
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Fukasawa Y, Oda T, Tomii K, Imai K. Origin and Evolutionary Alteration of the Mitochondrial Import System in Eukaryotic Lineages. Mol Biol Evol 2017; 34:1574-1586. [PMID: 28369657 PMCID: PMC5455965 DOI: 10.1093/molbev/msx096] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Protein transport systems are fundamentally important for maintaining mitochondrial function. Nevertheless, mitochondrial protein translocases such as the kinetoplastid ATOM complex have recently been shown to vary in eukaryotic lineages. Various evolutionary hypotheses have been formulated to explain this diversity. To resolve any contradiction, estimating the primitive state and clarifying changes from that state are necessary. Here, we present more likely primitive models of mitochondrial translocases, specifically the translocase of the outer membrane (TOM) and translocase of the inner membrane (TIM) complexes, using scrutinized phylogenetic profiles. We then analyzed the translocases’ evolution in eukaryotic lineages. Based on those results, we propose a novel evolutionary scenario for diversification of the mitochondrial transport system. Our results indicate that presequence transport machinery was mostly established in the last eukaryotic common ancestor, and that primitive translocases already had a pathway for transporting presequence-containing proteins. Moreover, secondary changes including convergent and migrational gains of a presequence receptor in TOM and TIM complexes, respectively, likely resulted from constrained evolution. The nature of a targeting signal can constrain alteration to the protein transport complex.
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Affiliation(s)
- Yoshinori Fukasawa
- Artificial Intelligence Research Center, National Institute of Advanced Science and Technology (AIST), Tokyo, Japan
| | - Toshiyuki Oda
- Artificial Intelligence Research Center, National Institute of Advanced Science and Technology (AIST), Tokyo, Japan
| | - Kentaro Tomii
- Artificial Intelligence Research Center, National Institute of Advanced Science and Technology (AIST), Tokyo, Japan.,Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Science and Technology (AIST), Tokyo, Japan
| | - Kenichiro Imai
- Artificial Intelligence Research Center, National Institute of Advanced Science and Technology (AIST), Tokyo, Japan.,Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Science and Technology (AIST), Tokyo, Japan
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16
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Rossig C, Gray J, Valdes O, Rustgi S, von Wettstein D, Reinbothe C, Reinbothe S. HP30-2, a mitochondrial PRAT protein for import of signal sequence-less precursor proteins in Arabidopsis thaliana. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2017; 59:535-551. [PMID: 28544763 DOI: 10.1111/jipb.12555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 05/19/2017] [Indexed: 06/07/2023]
Abstract
Chloroplasts and mitochondria contain a family of putative preprotein and amino acid transporters designated PRAT. Here, we analyzed the role of two previously characterized PRAT protein family members, encoded by At3g49560 (HP30) and At5g24650 (HP30-2), in planta using a combination of genetic, cell biological and biochemical approaches. Expression studies and green fluorescent protein tagging identified HP30-2 both in chloroplasts and mitochondria, whereas HP30 was located exclusively in chloroplasts. Biochemical evidence was obtained for an association of mitochondrial HP30-2 with two distinct protein complexes, one containing the inner membrane translocase TIM22 and the other containing an alternative NAD(P)H dehydrogenase subunit (NDC1) implicated in a respiratory complex 1-like electron transport chain. Through its association with TIM22, HP30-2 is involved in the uptake of carrier proteins and other, hydrophobic membrane proteins lacking cleavable NH2 -terminal presequences, whereas HP30-2's interaction with NDC1 may permit controlling mitochondrial biogenesis and activity.
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Affiliation(s)
- Claudia Rossig
- Laboratory of Plant Molecular Genetics and Laboratory of Environmental and Systems Biology, Grenoble-Alpes-University, Grenoble, France
| | - John Gray
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606, USA
| | - Oscar Valdes
- Laboratory of Plant Molecular Genetics and Laboratory of Environmental and Systems Biology, Grenoble-Alpes-University, Grenoble, France
| | - Sachin Rustgi
- Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Clemson University, Florence, SC 29506, USA
- Department of Crop and Soil Sciences, Washington State University, Pullman WA 99164-6420, USA
| | - Diter von Wettstein
- Department of Crop and Soil Sciences, Washington State University, Pullman WA 99164-6420, USA
| | - Christiane Reinbothe
- Laboratory of Plant Molecular Genetics and Laboratory of Environmental and Systems Biology, Grenoble-Alpes-University, Grenoble, France
| | - Steffen Reinbothe
- Laboratory of Plant Molecular Genetics and Laboratory of Environmental and Systems Biology, Grenoble-Alpes-University, Grenoble, France
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17
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Harsman A, Schneider A. Mitochondrial protein import in trypanosomes: Expect the unexpected. Traffic 2017; 18:96-109. [PMID: 27976830 DOI: 10.1111/tra.12463] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/01/2016] [Accepted: 12/06/2016] [Indexed: 12/11/2022]
Abstract
Mitochondria have many different functions, the most important one of which is oxidative phosphorylation. They originated from an endosymbiotic event between a bacterium and an archaeal host cell. It was the evolution of a protein import system that marked the boundary between the endosymbiotic ancestor of the mitochondrion and a true organelle that is under the control of the nucleus. In present day mitochondria more than 95% of all proteins are imported from the cytosol in a proces mediated by hetero-oligomeric protein complexes in the outer and inner mitochondrial membranes. In this review we compare mitochondrial protein import in the best studied model system yeast and the parasitic protozoan Trypanosoma brucei. The 2 organisms are phylogenetically only remotely related. Despite the fact that mitochondrial protein import has the same function in both species, only very few subunits of their import machineries are conserved. Moreover, while yeast has 2 inner membrane protein translocases, one specialized for presequence-containing and one for mitochondrial carrier proteins, T. brucei has a single inner membrane translocase only, that mediates import of both types of substrates. The evolutionary implications of these findings are discussed.
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Affiliation(s)
- Anke Harsman
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
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18
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Li L, Kubiszewski-Jakubiak S, Radomiljac J, Wang Y, Law SR, Keech O, Narsai R, Berkowitz O, Duncan O, Murcha MW, Whelan J. Characterization of a novel β-barrel protein (AtOM47) from the mitochondrial outer membrane of Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:6061-6075. [PMID: 27811077 PMCID: PMC5100019 DOI: 10.1093/jxb/erw366] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In plant cells, mitochondria are major providers of energy and building blocks for growth and development as well as abiotic and biotic stress responses. They are encircled by two lipid membranes containing proteins that control mitochondrial function through the import of macromolecules and metabolites. Characterization of a novel β-barrel protein, OUTER MEMBRANE PROTEIN 47 (OM47), unique to the green lineage and related to the voltage-dependent anion channel (VDAC) protein family, showed that OM47 can complement a VDAC mutant in yeast. Mutation of OM47 in Arabidopsis thaliana by T-DNA insertion had no effect on the import of proteins, such as the β-barrel proteins translocase of the outer membrane 40 (TOM40) or sorting and assembly machinery 50 (SAM50), into mitochondria. Molecular and physiological analyses revealed a delay in chlorophyll breakdown, higher levels of starch, and a delay in the induction of senescence marker genes in the mutant lines. While there was a reduction of >90% in OM47 protein in mitochondria isolated from 3-week-old om47 mutants, in mitochondria isolated from 8-week-old plants OM47 levels were similar to that of the wild type. This recovery was achieved by an up-regulation of OM47 transcript abundance in the mutants. Combined, these results highlight a role in leaf senescence for this plant-specific β-barrel protein, probably mediating the recovery and recycling of chloroplast breakdown products by transporting metabolic intermediates into and out of mitochondria.
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Affiliation(s)
- Lu Li
- Australian Research Council Centre of Excellence in Plant Energy Biology, Department of Animal, Plant and Soil Science, School of Life Science, La Trobe University, Bundoora, Victoria, 3086, Australia
| | - Szymon Kubiszewski-Jakubiak
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009 Australia
| | - Jordan Radomiljac
- Australian Research Council Centre of Excellence in Plant Energy Biology, Department of Animal, Plant and Soil Science, School of Life Science, La Trobe University, Bundoora, Victoria, 3086, Australia
| | - Yan Wang
- Australian Research Council Centre of Excellence in Plant Energy Biology, Department of Animal, Plant and Soil Science, School of Life Science, La Trobe University, Bundoora, Victoria, 3086, Australia
| | - Simon R Law
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, S-90187 Umeå, Sweden
| | - Olivier Keech
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, S-90187 Umeå, Sweden
| | - Reena Narsai
- Australian Research Council Centre of Excellence in Plant Energy Biology, Department of Animal, Plant and Soil Science, School of Life Science, La Trobe University, Bundoora, Victoria, 3086, Australia
| | - Oliver Berkowitz
- Australian Research Council Centre of Excellence in Plant Energy Biology, Department of Animal, Plant and Soil Science, School of Life Science, La Trobe University, Bundoora, Victoria, 3086, Australia
| | - Owen Duncan
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009 Australia
| | - Monika W Murcha
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009 Australia
| | - James Whelan
- Australian Research Council Centre of Excellence in Plant Energy Biology, Department of Animal, Plant and Soil Science, School of Life Science, La Trobe University, Bundoora, Victoria, 3086, Australia
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19
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Carraretto L, Teardo E, Checchetto V, Finazzi G, Uozumi N, Szabo I. Ion Channels in Plant Bioenergetic Organelles, Chloroplasts and Mitochondria: From Molecular Identification to Function. MOLECULAR PLANT 2016; 9:371-395. [PMID: 26751960 DOI: 10.1016/j.molp.2015.12.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/22/2015] [Accepted: 12/01/2015] [Indexed: 06/05/2023]
Abstract
Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioenergetic organelles, chloroplasts and mitochondria, leading to the molecular identification and functional characterization of several ion transport systems in recent years. Here we focus on channels that mediate relatively high-rate ion and water flux and summarize the current knowledge in this field, focusing on targeting mechanisms, proteomics, electrophysiology, and physiological function. In addition, since chloroplasts evolved from a cyanobacterial ancestor, we give an overview of the information available about cyanobacterial ion channels and discuss the evolutionary origin of chloroplast channels. The recent molecular identification of some of these ion channels allowed their physiological functions to be studied using genetically modified Arabidopsis plants and cyanobacteria. The view is emerging that alteration of chloroplast and mitochondrial ion homeostasis leads to organelle dysfunction, which in turn significantly affects the energy metabolism of the whole organism. Clear-cut identification of genes encoding for channels in these organelles, however, remains a major challenge in this rapidly developing field. Multiple strategies including bioinformatics, cell biology, electrophysiology, use of organelle-targeted ion-sensitive probes, genetics, and identification of signals eliciting specific ion fluxes across organelle membranes should provide a better understanding of the physiological role of organellar channels and their contribution to signaling pathways in plants in the future.
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Affiliation(s)
- Luca Carraretto
- Department of Biology, University of Padova, Padova 35121, Italy
| | - Enrico Teardo
- Department of Biology, University of Padova, Padova 35121, Italy; CNR Institute of Neuroscience, University of Padova, Padova 35121, Italy
| | | | - Giovanni Finazzi
- UMR 5168 Laboratoire de Physiologie Cellulaire Végétale (LPCV) CNRS/ UJF / INRA / CEA, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), CEA Grenoble, 38054 Grenoble, France.
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan.
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padova 35121, Italy; CNR Institute of Neuroscience, University of Padova, Padova 35121, Italy.
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20
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Mani J, Meisinger C, Schneider A. Peeping at TOMs-Diverse Entry Gates to Mitochondria Provide Insights into the Evolution of Eukaryotes. Mol Biol Evol 2015; 33:337-51. [PMID: 26474847 DOI: 10.1093/molbev/msv219] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mitochondria are essential for eukaryotic life and more than 95% of their proteins are imported as precursors from the cytosol. The targeting signals for this posttranslational import are conserved in all eukaryotes. However, this conservation does not hold true for the protein translocase of the mitochondrial outer membrane that serves as entry gate for essentially all precursor proteins. Only two of its subunits, Tom40 and Tom22, are conserved and thus likely were present in the last eukaryotic common ancestor. Tom7 is found in representatives of all supergroups except the Excavates. This suggests that it was added to the core of the translocase after the Excavates segregated from all other eukaryotes. A comparative analysis of the biochemically and functionally characterized outer membrane translocases of yeast, plants, and trypanosomes, which represent three eukaryotic supergroups, shows that the receptors that recognize the conserved import signals differ strongly between the different systems. They present a remarkable example of convergent evolution at the molecular level. The structural diversity of the functionally conserved import receptors therefore provides insight into the early evolutionary history of mitochondria.
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Affiliation(s)
- Jan Mani
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Chris Meisinger
- Institut für Biochemie und Molekularbiologie, ZBMZ and BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg, Germany
| | - André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
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21
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The Design and Structure of Outer Membrane Receptors from Peroxisomes, Mitochondria, and Chloroplasts. Structure 2015; 23:1783-1800. [DOI: 10.1016/j.str.2015.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 07/20/2015] [Accepted: 08/10/2015] [Indexed: 01/03/2023]
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22
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Bölter B, Soll J, Schwenkert S. Redox meets protein trafficking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:949-56. [PMID: 25626173 DOI: 10.1016/j.bbabio.2015.01.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 01/16/2015] [Accepted: 01/19/2015] [Indexed: 11/15/2022]
Abstract
After the engulfment of two prokaryotic organisms, the thus emerged eukaryotic cell needed to establish means of communication and signaling to properly integrate the acquired organelles into its metabolism. Regulatory mechanisms had to evolve to ensure that chloroplasts and mitochondria smoothly function in accordance with all other cellular processes. One essential process is the post-translational import of nuclear encoded organellar proteins, which needs to be adapted according to the requirements of the plant. The demand for protein import is constantly changing depending on varying environmental conditions, as well as external and internal stimuli or different developmental stages. Apart from long-term regulatory mechanisms such as transcriptional/translation control, possibilities for short-term acclimation are mandatory. To this end, protein import is integrated into the cellular redox network, utilizing the recognition of signals from within the organelles and modifying the efficiency of the translocon complexes. Thereby, cellular requirements can be communicated throughout the whole organism. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Affiliation(s)
- Bettina Bölter
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany
| | - Jürgen Soll
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany.
| | - Serena Schwenkert
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany
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23
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Murcha MW, Narsai R, Devenish J, Kubiszewski-Jakubiak S, Whelan J. MPIC: a mitochondrial protein import components database for plant and non-plant species. PLANT & CELL PHYSIOLOGY 2015; 56:e10. [PMID: 25435547 DOI: 10.1093/pcp/pcu186] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In the 2 billion years since the endosymbiotic event that gave rise to mitochondria, variations in mitochondrial protein import have evolved across different species. With the genomes of an increasing number of plant species sequenced, it is possible to gain novel insights into mitochondrial protein import pathways. We have generated the Mitochondrial Protein Import Components (MPIC) Database (DB; http://www.plantenergy.uwa.edu.au/applications/mpic) providing searchable information on the protein import apparatus of plant and non-plant mitochondria. An in silico analysis was carried out, comparing the mitochondrial protein import apparatus from 24 species representing various lineages from Saccharomyces cerevisiae (yeast) and algae to Homo sapiens (human) and higher plants, including Arabidopsis thaliana (Arabidopsis), Oryza sativa (rice) and other more recently sequenced plant species. Each of these species was extensively searched and manually assembled for analysis in the MPIC DB. The database presents an interactive diagram in a user-friendly manner, allowing users to select their import component of interest. The MPIC DB presents an extensive resource facilitating detailed investigation of the mitochondrial protein import machinery and allowing patterns of conservation and divergence to be recognized that would otherwise have been missed. To demonstrate the usefulness of the MPIC DB, we present a comparative analysis of the mitochondrial protein import machinery in plants and non-plant species, revealing plant-specific features that have evolved.
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Affiliation(s)
- Monika W Murcha
- Australian Research Council Centre of Excellence in Plant Energy Biology, Bayliss Building M316, University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
| | - Reena Narsai
- Department of Botany, Australian Research Council Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University, Bundoora 3083, Victoria, Australia
| | - James Devenish
- Australian Research Council Centre of Excellence in Plant Energy Biology, Bayliss Building M316, University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
| | - Szymon Kubiszewski-Jakubiak
- Australian Research Council Centre of Excellence in Plant Energy Biology, Bayliss Building M316, University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
| | - James Whelan
- Department of Botany, Australian Research Council Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University, Bundoora 3083, Victoria, Australia
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24
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Murcha MW, Kmiec B, Kubiszewski-Jakubiak S, Teixeira PF, Glaser E, Whelan J. Protein import into plant mitochondria: signals, machinery, processing, and regulation. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:6301-35. [PMID: 25324401 DOI: 10.1093/jxb/eru399] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The majority of more than 1000 proteins present in mitochondria are imported from nuclear-encoded, cytosolically synthesized precursor proteins. This impressive feat of transport and sorting is achieved by the combined action of targeting signals on mitochondrial proteins and the mitochondrial protein import apparatus. The mitochondrial protein import apparatus is composed of a number of multi-subunit protein complexes that recognize, translocate, and assemble mitochondrial proteins into functional complexes. While the core subunits involved in mitochondrial protein import are well conserved across wide phylogenetic gaps, the accessory subunits of these complexes differ in identity and/or function when plants are compared with Saccharomyces cerevisiae (yeast), the model system for mitochondrial protein import. These differences include distinct protein import receptors in plants, different mechanistic operation of the intermembrane protein import system, the location and activity of peptidases, the function of inner-membrane translocases in linking the outer and inner membrane, and the association/regulation of mitochondrial protein import complexes with components of the respiratory chain. Additionally, plant mitochondria share proteins with plastids, i.e. dual-targeted proteins. Also, the developmental and cell-specific nature of mitochondrial biogenesis is an aspect not observed in single-celled systems that is readily apparent in studies in plants. This means that plants provide a valuable model system to study the various regulatory processes associated with protein import and mitochondrial biogenesis.
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Affiliation(s)
- Monika W Murcha
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Beata Kmiec
- Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, SE-10691 Stockholm, Sweden
| | - Szymon Kubiszewski-Jakubiak
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Pedro F Teixeira
- Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, SE-10691 Stockholm, Sweden
| | - Elzbieta Glaser
- Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, SE-10691 Stockholm, Sweden
| | - James Whelan
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University, Bundoora, Victoria, 3086, Australia
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25
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Deng Y, Zou W, Li G, Zhao J. TRANSLOCASE OF THE INNER MEMBRANE9 and 10 are essential for maintaining mitochondrial function during early embryo cell and endosperm free nucleus divisions in Arabidopsis. PLANT PHYSIOLOGY 2014; 166:853-68. [PMID: 25104724 PMCID: PMC4213113 DOI: 10.1104/pp.114.242560] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
In the life cycle of flowering plants, the sporophytic generation takes up most of the time and plays a dominant role in influencing plant growth and development. The embryo cell and endosperm free nucleus divisions establish the critical initiation phase of early sporophyte development, which forms mature seeds through a series of cell growth and differentiation events. Here, we report on the biological functions of two Arabidopsis (Arabidopsis thaliana) mitochondrial proteins, TRANSLOCASE OF THE INNER MEMBRANE9 (TIM9) and TIM10. We found that dysfunction of either AtTIM9 or AtTIM10 led to an early sporophyte-lethal phenotype; the embryo and endosperm both arrest division when the embryo proper developed to 16 to 32 cells. The abortion of tim9-1 and tim10 embryos at the 16/32-cell stage was caused by the loss of cell viability and the cessation of division in the embryo proper region, and this inactivation was due to the collapse of the mitochondrial structure and activity. Our characterization of tim9-1 and tim10 showed that mitochondrial membrane permeability increased and that cytochrome c was released from mitochondria into the cytoplasm in the 16/32-cell embryo proper, indicating that mitochondrial dysfunction occurred in the early sporophytic cells, and thus caused the initiation of a necrosis-like programmed cell death, which was further proved by the evidence of reactive oxygen species and DNA fragmentation tests. Consequently, we verified that AtTIM9 and AtTIM10 are nonredundantly essential for maintaining the mitochondrial function of early embryo proper cells and endosperm-free nuclei; these proteins play critically important roles during sporophyte initiation and development in Arabidopsis.
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Affiliation(s)
- Yingtian Deng
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Wenxuan Zou
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Gang Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jie Zhao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
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Panigrahi R, Whelan J, Vrielink A. Exploring ligand recognition, selectivity and dynamics of TPR domains of chloroplast Toc64 and mitochondria Om64 fromArabidopsis thaliana. J Mol Recognit 2014; 27:402-14. [DOI: 10.1002/jmr.2360] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Revised: 01/14/2014] [Accepted: 01/15/2014] [Indexed: 01/31/2023]
Affiliation(s)
- Rashmi Panigrahi
- School of Chemistry and Biochemistry; University of Western Australia; 35 Stirling Highway Crawley WA 6009 Australia
| | - James Whelan
- ARC Centre of Excellence in Plant Energy Biology; University of Western Australia; 35 Stirling Highway Crawley WA 6009 Australia
- Department of Botany, School of Life Science; La Trobe University; Bundoora Victoria 3086 Australia
| | - Alice Vrielink
- School of Chemistry and Biochemistry; University of Western Australia; 35 Stirling Highway Crawley WA 6009 Australia
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Vázquez-Acevedo M, Rubalcava-Gracia D, González-Halphen D. In vitro import and assembly of the nucleus-encoded mitochondrial subunit III of cytochrome c oxidase (Cox3). Mitochondrion 2014; 19 Pt B:314-22. [PMID: 24561572 DOI: 10.1016/j.mito.2014.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/24/2014] [Accepted: 02/12/2014] [Indexed: 11/17/2022]
Abstract
The cox3 gene, encoding subunit III of cytochrome c oxidase (Cox3) is in mitochondrial genomes except in chlorophycean algae, where it is localized in the nucleus. Therefore, algae like Chlamydomonas reinhardtii, Polytomella sp. and Volvox carteri, synthesize the Cox3 polypeptide in the cytosol, import it into mitochondria, and integrate it into the cytochrome c oxidase complex. In this work, we followed the in vitro internalization of the Cox3 precursor by isolated, import-competent mitochondria of Polytomella sp. In this colorless alga, the precursor Cox3 protein is synthesized with a long, cleavable, N-terminal mitochondrial targeting sequence (MTS) of 98 residues. In an import time course, a transient Cox3 intermediate was identified, suggesting that the long MTS is processed more than once. The first processing step is sensitive to the metalo-protease inhibitor 1,10-ortophenantroline, suggesting that it is probably carried out by the matrix-located Mitochondrial Processing Protease. Cox3 is readily imported through an energy-dependent import pathway and integrated into the inner mitochondrial membrane, becoming resistant to carbonate extraction. Furthermore, the imported Cox3 protein was assembled into cytochrome c oxidase, as judged by the presence of a labeled band co-migrating with complex IV in Blue Native Electrophoresis. A model for the biogenesis of Cox3 in chlorophycean algae is proposed. This is the first time that the in vitro mitochondrial import of a cytosol-synthesized Cox3 subunit is described.
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Affiliation(s)
- Miriam Vázquez-Acevedo
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-243, México 04510, D.F., Mexico
| | - Diana Rubalcava-Gracia
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-243, México 04510, D.F., Mexico
| | - Diego González-Halphen
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-243, México 04510, D.F., Mexico.
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Murcha MW, Kubiszewski-Jakubiak S, Wang Y, Whelan J. Evidence for interactions between the mitochondrial import apparatus and respiratory chain complexes via Tim21-like proteins in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2014; 5:82. [PMID: 24653731 PMCID: PMC3949100 DOI: 10.3389/fpls.2014.00082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 02/21/2014] [Indexed: 05/06/2023]
Abstract
The mitochondrial import machinery and the respiratory chain complexes of the inner membrane are highly interdependent for the efficient import and assembly of nuclear encoded respiratory chain components and for the generation of a proton motive force essential for protein translocation into or across the inner membrane. In plant and non-plant systems functional, physical, and evolutionary associations have been observed between proteins of the respiratory chain and protein import apparatus. Here we identify two novel Tim21-like proteins encoded by At2g40800 and At3g56430 that are imported into the mitochondrial inner membrane. We propose that Tim21-like proteins may associate with respiratory chain Complex I, III, in addition to the TIM17:23 translocase of the inner membrane. These results are discussed further with regards to the regulation of mitochondrial activity and biogenesis.
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Affiliation(s)
- Monika W. Murcha
- ARC Centre of Excellence in Plant Energy Biology, The University of Western AustraliaPerth, WA, Australia
- *Correspondence: Monika W. Murcha, ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, MCS Building M316, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia e-mail:
| | | | - Yan Wang
- ARC Centre of Excellence in Plant Energy Biology, The University of Western AustraliaPerth, WA, Australia
| | - James Whelan
- Department of Botany, ARC Centre of Excellence in Plant Energy Biology, School of Life Sciences, La Trobe UniversityBundoora, VIC, Australia
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Marty NJ, Teresinski HJ, Hwang YT, Clendening EA, Gidda SK, Sliwinska E, Zhang D, Miernyk JA, Brito GC, Andrews DW, Dyer JM, Mullen RT. New insights into the targeting of a subset of tail-anchored proteins to the outer mitochondrial membrane. FRONTIERS IN PLANT SCIENCE 2014; 5:426. [PMID: 25237314 PMCID: PMC4154396 DOI: 10.3389/fpls.2014.00426] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 08/12/2014] [Indexed: 05/21/2023]
Abstract
Tail-anchored (TA) proteins are a unique class of functionally diverse membrane proteins defined by their single C-terminal membrane-spanning domain and their ability to insert post-translationally into specific organelles with an Ncytoplasm-Corganelle interior orientation. The molecular mechanisms by which TA proteins are sorted to the proper organelles are not well-understood. Herein we present results indicating that a dibasic targeting motif (i.e., -R-R/K/H-X({X≠E})) identified previously in the C terminus of the mitochondrial isoform of the TA protein cytochrome b 5, also exists in many other A. thaliana outer mitochondrial membrane (OMM)-TA proteins. This motif is conspicuously absent, however, in all but one of the TA protein subunits of the translocon at the outer membrane of mitochondria (TOM), suggesting that these two groups of proteins utilize distinct biogenetic pathways. Consistent with this premise, we show that the TA sequences of the dibasic-containing proteins are both necessary and sufficient for targeting to mitochondria, and are interchangeable, while the TA regions of TOM proteins lacking a dibasic motif are necessary, but not sufficient for localization, and cannot be functionally exchanged. We also present results from a comprehensive mutational analysis of the dibasic motif and surrounding sequences that not only greatly expands the functional definition and context-dependent properties of this targeting signal, but also led to the identification of other novel putative OMM-TA proteins. Collectively, these results provide important insight to the complexity of the targeting pathways involved in the biogenesis of OMM-TA proteins and help define a consensus targeting motif that is utilized by at least a subset of these proteins.
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Affiliation(s)
- Naomi J. Marty
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Howard J. Teresinski
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Yeen Ting Hwang
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Eric A. Clendening
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Elwira Sliwinska
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
- Department of Plant Genetics, Physiology and Biotechnology, University of Technology and Life Sciences in BydgoszczBydgoszcz, Poland
| | - Daiyuan Zhang
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research CenterMaricopa, AZ, USA
| | - Ján A. Miernyk
- United States Department of Agriculture, Agricultural Research Service, Plant Genetics Research Unit, University of MissouriColumbia, MO, USA
| | - Glauber C. Brito
- Instituto do Cancer do Estado de Sao Paulo, Fundacao Faculdade de Medicina, Universidade de Sao PauloSao Paulo, Brazil
| | - David W. Andrews
- Sunnybrook Research Institute and Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - John M. Dyer
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research CenterMaricopa, AZ, USA
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
- *Correspondence: Robert T. Mullen, Department of Molecular and Cellular, Biology, University of Guelph, Room 4470 Science Complex, 488 Gordon Street, Guelph, ON N1G 2W1, Canada e-mail:
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Fuss J, Liegmann O, Krause K, Rensing SA. Green targeting predictor and ambiguous targeting predictor 2: the pitfalls of plant protein targeting prediction and of transient protein expression in heterologous systems. THE NEW PHYTOLOGIST 2013; 200:1022-33. [PMID: 23915300 DOI: 10.1111/nph.12433] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 07/01/2013] [Indexed: 05/08/2023]
Abstract
The challenges of plant protein targeting prediction are the existence of dual subcellular targets and the bias of experimentally confirmed data towards few and mostly nonplant model species. To assess whether training with proteins from evolutionarily distant species has a negative impact on prediction accuracy, we developed the Green Targeting Predictor tool, which was trained with a species-specific data set for Physcomitrella patens. Its performance was compared with that of the same tool trained with a mixed data set. In addition, we updated the Ambiguous Targeting Predictor. We found that predictions deviated from in vivo observations predominantly for proteins diverging within the green lineage, as well as for dual targeted proteins. To evaluate the usefulness of heterologous expression systems, selected proteins were subjected to localization studies in P. patens, Arabidopsis thaliana and Nicotiana tabacum. Four out of six proteins that show dual targeting in the original plant system were located only in a single compartment in one or both heterologous systems. We conclude that targeting signals of divergent plant species exhibit differences, calling for custom in silico and in vivo approaches when aiming to unravel the actual distribution patterns of proteins within a plant cell.
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Affiliation(s)
- Janina Fuss
- Department of Arctic and Marine Biology, University of Tromsø, Dramsvegen 201, N-9037, Tromsø, Norway
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31
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Murcha MW, Wang Y, Narsai R, Whelan J. The plant mitochondrial protein import apparatus - the differences make it interesting. Biochim Biophys Acta Gen Subj 2013; 1840:1233-45. [PMID: 24080405 DOI: 10.1016/j.bbagen.2013.09.026] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 09/17/2013] [Accepted: 09/18/2013] [Indexed: 12/25/2022]
Abstract
BACKGROUND Mitochondria play essential roles in the life and death of almost all eukaryotic cells, ranging from single-celled to multi-cellular organisms that display tissue and developmental differentiation. As mitochondria only arose once in evolution, much can be learned from studying single celled model systems such as yeast and applying this knowledge to other organisms. However, two billion years of evolution have also resulted in substantial divergence in mitochondrial function between eukaryotic organisms. SCOPE OF REVIEW Here we review our current understanding of the mechanisms of mitochondrial protein import between plants and yeast (Saccharomyces cerevisiae) and identify a high level of conservation for the essential subunits of plant mitochondrial import apparatus. Furthermore, we investigate examples whereby divergence and acquisition of functions have arisen and highlight the emerging examples of interactions between the import apparatus and components of the respiratory chain. MAJOR CONCLUSIONS After more than three decades of research into the components and mechanisms of mitochondrial protein import of plants and yeast, the differences between these systems are examined. Specifically, expansions of the small gene families that encode the mitochondrial protein import apparatus in plants are detailed, and their essential role in seed viability is revealed. GENERAL SIGNIFICANCE These findings point to the essential role of the inner mitochondrial protein translocases in Arabidopsis, establishing their necessity for seed viability and the crucial role of mitochondrial biogenesis during germination. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.
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Affiliation(s)
- Monika W Murcha
- ARC Centre of Excellence in Plant Energy Biology, Bayliss Building M316, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia.
| | - Yan Wang
- ARC Centre of Excellence in Plant Energy Biology, Bayliss Building M316, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
| | - Reena Narsai
- ARC Centre of Excellence in Plant Energy Biology, Bayliss Building M316, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia; Computational Systems Biology, Bayliss Building M316, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
| | - James Whelan
- ARC Centre of Excellence in Plant Energy Biology, Bayliss Building M316, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia; Department of Botany, School of Life Science, La Trobe University, Bundoora 3086, Victoria, Australia
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32
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Schweiger R, Soll J, Jung K, Heermann R, Schwenkert S. Quantification of interaction strengths between chaperones and tetratricopeptide repeat domain-containing membrane proteins. J Biol Chem 2013; 288:30614-30625. [PMID: 24036116 DOI: 10.1074/jbc.m113.493015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The three tetratricopeptide repeat domain-containing docking proteins Toc64, OM64, and AtTPR7 reside in the chloroplast, mitochondrion, and endoplasmic reticulum of Arabidopsis thaliana, respectively. They are suggested to act during post-translational protein import by association with chaperone-bound preprotein complexes. Here, we performed a detailed biochemical, biophysical, and computational analysis of the interaction between Toc64, OM64, and AtTPR7 and the five cytosolic chaperones HSP70.1, HSP90.1, HSP90.2, HSP90.3, and HSP90.4. We used surface plasmon resonance spectroscopy in combination with Interaction Map® analysis to distinguish between chaperone oligomerization and docking protein-chaperone interactions and to calculate binding affinities for all tested interactions. Complementary to this, we applied pulldown assays as well as microscale thermophoresis as surface immobilization independent techniques. The data revealed that OM64 prefers HSP70 over HSP90, whereas Toc64 binds all chaperones with comparable affinities. We could further show that AtTPR7 is able to bind HSP90 in addition to HSP70. Moreover, differences between the HSP90 isoforms were detected and revealed a weaker binding for HSP90.1 to AtTPR7 and OM64, showing that slight differences in the amino acid composition or structure of the chaperones influence binding to the tetratricopeptide repeat domain. The combinatory approach of several methods provided a powerful toolkit to determine binding affinities of similar interaction partners in a highly quantitative manner.
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Affiliation(s)
| | - Jürgen Soll
- From the Departments of Biology I, Botany, and
| | - Kirsten Jung
- Biology I, Microbiology, Munich Center for Integrated Protein Science, Ludwig-Maximilians-Universität München, Grosshaderner Strasse 2-4, D-82152 Planegg-Martinsried, Germany
| | - Ralf Heermann
- Biology I, Microbiology, Munich Center for Integrated Protein Science, Ludwig-Maximilians-Universität München, Grosshaderner Strasse 2-4, D-82152 Planegg-Martinsried, Germany.
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Paul P, Simm S, Blaumeiser A, Scharf KD, Fragkostefanakis S, Mirus O, Schleiff E. The protein translocation systems in plants - composition and variability on the example of Solanum lycopersicum. BMC Genomics 2013; 14:189. [PMID: 23506162 PMCID: PMC3610429 DOI: 10.1186/1471-2164-14-189] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 02/25/2013] [Indexed: 11/22/2022] Open
Abstract
Background Protein translocation across membranes is a central process in all cells. In the past decades the molecular composition of the translocation systems in the membranes of the endoplasmic reticulum, peroxisomes, mitochondria and chloroplasts have been established based on the analysis of model organisms. Today, these results have to be transferred to other plant species. We bioinformatically determined the inventory of putative translocation factors in tomato (Solanum lycopersicum) by orthologue search and domain architecture analyses. In addition, we investigated the diversity of such systems by comparing our findings to the model organisms Saccharomyces cerevisiae, Arabidopsis thaliana and 12 other plant species. Results The literature search end up in a total of 130 translocation components in yeast and A. thaliana, which are either experimentally confirmed or homologous to experimentally confirmed factors. From our bioinformatic analysis (PGAP and OrthoMCL), we identified (co-)orthologues in plants, which in combination yielded 148 and 143 orthologues in A. thaliana and S. lycopersicum, respectively. Interestingly, we traced 82% overlap in findings from both approaches though we did not find any orthologues for 27% of the factors by either procedure. In turn, 29% of the factors displayed the presence of more than one (co-)orthologue in tomato. Moreover, our analysis revealed that the genomic composition of the translocation machineries in the bryophyte Physcomitrella patens resemble more to higher plants than to single celled green algae. The monocots (Z. mays and O. sativa) follow more or less a similar conservation pattern for encoding the translocon components. In contrast, a diverse pattern was observed in different eudicots. Conclusions The orthologue search shows in most cases a clear conservation of components of the translocation pathways/machineries. Only the Get-dependent integration of tail-anchored proteins seems to be distinct. Further, the complexity of the translocation pathway in terms of existing orthologues seems to vary among plant species. This might be the consequence of palaeoploidisation during evolution in plants; lineage specific whole genome duplications in Arabidopsis thaliana and triplications in Solanum lycopersicum.
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Affiliation(s)
- Puneet Paul
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, Frankfurt/Main, 60438, Germany
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Carrie C, Murcha MW, Giraud E, Ng S, Zhang MF, Narsai R, Whelan J. How do plants make mitochondria? PLANTA 2013; 237:429-439. [PMID: 22976451 DOI: 10.1007/s00425-012-1762-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 09/04/2012] [Indexed: 05/28/2023]
Abstract
Plant mitochondria can differ in size, shape, number and protein content across different tissue types and over development. These differences are a result of signaling and regulatory processes that ensure mitochondrial function is tuned in a cell-specific manner to support proper plant growth and development. In the last decade, the processes involved in mitochondrial biogenesis are becoming clearer, including; how dormant seeds transition from empty promitochondria to fully functional mitochondria with extensive cristae structures and various biochemical activities, the regulation of nuclear genes encoding mitochondrial proteins via regulators of the diurnal cycle in plants, the mitochondrial stress response, the targeting of proteins to mitochondria and other organelles and connections between the respiratory chain and protein import complexes. All these findings indicate that mitochondrial function is a part of an integrated cellular network, and communication between mitochondria and other cellular processes extends beyond the known exchange or transport of metabolites. Our current knowledge now needs to be used to gain more insight into the molecular components at various levels of this hierarchical and complex regulatory and communication network, so that mitochondrial function can be predicted and modified in a rational manner.
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Affiliation(s)
- Chris Carrie
- Department of Biology I, Botany, Ludwig-Maximilians Universität München, Großhaderner Strasse 2-4, Planegg-Martinsried, Germany.
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Benz M, Soll J, Ankele E. Arabidopsis thaliana Oxa proteins locate to mitochondria and fulfill essential roles during embryo development. PLANTA 2013; 237:573-88. [PMID: 23179441 DOI: 10.1007/s00425-012-1793-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 10/19/2012] [Indexed: 05/12/2023]
Abstract
Members of the Alb3/Oxa1/YidC protein family function as insertases in chloroplasts, mitochondria, and bacteria. Due to independent gene duplications, all organisms possess two isoforms, Oxa1 and Oxa2 except gram-negative bacteria, which encode only for one YidC-like protein. The genome of Arabidopsis thaliana however, encodes for eight different isoforms. The localization of three of these isoforms has been identified earlier: Alb3 and Alb4 located in thylakoid membranes of chloroplasts while AtOxa1 was found in the inner membrane of mitochondria. Here, we show that the second Oxa1 protein, Oxa1b as well as two Oxa2 proteins are also localized in mitochondria. The last two isoforms most likely encode truncated versions of Oxa-like proteins, which might be inoperable pseudogenes. Homozygous mutant lines were only obtained for Oxa1b, which did not reveal any significant phenotypes, while T-DNA insertion lines of Oxa1a, Oxa2a and Oxa2b resulted only in heterozygous plants indicating that these genes are indispensable for plant development. Phenotyping heterozygous lines showed that embryos are either retarded in growth, display an albino phenotype or embryo formation was entirely abolished suggesting that Oxa1a and both Oxa2 proteins function in embryo formation although at different developmental stages as indicated by the various phenotypes observed.
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Affiliation(s)
- Monique Benz
- Energy Biosciences Institute, University of California, 2151 Berkeley Way, Berkeley, CA 94720-5230, USA.
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36
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Xu L, Carrie C, Law SR, Murcha MW, Whelan J. Acquisition, conservation, and loss of dual-targeted proteins in land plants. PLANT PHYSIOLOGY 2013; 161:644-62. [PMID: 23257241 PMCID: PMC3561010 DOI: 10.1104/pp.112.210997] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The dual-targeting ability of a variety of proteins from Physcomitrella patens, rice (Oryza sativa), and Arabidopsis (Arabidopsis thaliana) was tested to determine when dual targeting arose and to what extent it was conserved in land plants. Overall, the targeting ability of over 80 different proteins from rice and P. patens, representing 42 dual-targeted proteins in Arabidopsis, was tested. We found that dual targeting arose early in land plant evolution, as it was evident in many cases with P. patens proteins that were conserved in rice and Arabidopsis. Furthermore, we found that the acquisition of dual-targeting ability is still occurring, evident in P. patens as well as rice and Arabidopsis. The loss of dual-targeting ability appears to be rare, but does occur. Ascorbate peroxidase represents such an example. After gene duplication in rice, individual genes encode proteins that are targeted to a single organelle. Although we found that dual targeting was generally conserved, the ability to detect dual-targeted proteins differed depending on the cell types used. Furthermore, it appears that small changes in the targeting signal can result in a loss (or gain) of dual-targeting ability. Overall, examination of the targeting signals within this study did not reveal any clear patterns that would predict dual-targeting ability. The acquisition of dual-targeting ability also appears to be coordinated between proteins. Mitochondrial intermembrane space import and assembly protein40, a protein involved in oxidative folding in mitochondria and peroxisomes, provides an example where acquisition of dual targeting is accompanied by the dual targeting of substrate proteins.
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Divergence of Erv1-associated mitochondrial import and export pathways in trypanosomes and anaerobic protists. EUKARYOTIC CELL 2012; 12:343-55. [PMID: 23264646 DOI: 10.1128/ec.00304-12] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In yeast (Saccharomyces cerevisiae) and animals, the sulfhydryl oxidase Erv1 functions with Mia40 in the import and oxidative folding of numerous cysteine-rich proteins in the mitochondrial intermembrane space (IMS). Erv1 is also required for Fe-S cluster assembly in the cytosol, which uses at least one mitochondrially derived precursor. Here, we characterize an essential Erv1 orthologue from the protist Trypanosoma brucei (TbERV1), which naturally lacks a Mia40 homolog. We report kinetic parameters for physiologically relevant oxidants cytochrome c and O(2), unexpectedly find O(2) and cytochrome c are reduced simultaneously, and demonstrate that efficient reduction of O(2) by TbERV1 is not dependent upon a simple O(2) channel defined by conserved histidine and tyrosine residues. Massive mitochondrial swelling following TbERV1 RNA interference (RNAi) provides evidence that trypanosome Erv1 functions in IMS protein import despite the natural absence of the key player in the yeast and animal import pathways, Mia40. This suggests significant evolutionary divergence from a recently established paradigm in mitochondrial cell biology. Phylogenomic profiling of genes also points to a conserved role for TbERV1 in cytosolic Fe-S cluster assembly. Conversely, loss of genes implicated in precursor delivery for cytosolic Fe-S assembly in Entamoeba, Trichomonas, and Giardia suggests fundamental differences in intracellular trafficking pathways for activated iron or sulfur species in anaerobic versus aerobic eukaryotes.
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Butterfield ER, Howe CJ, Nisbet RER. An analysis of dinoflagellate metabolism using EST data. Protist 2012; 164:218-36. [PMID: 23085481 DOI: 10.1016/j.protis.2012.09.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 09/10/2012] [Accepted: 09/10/2012] [Indexed: 01/03/2023]
Abstract
The dinoflagellates are an important group of eukaryotic, single celled algae. They are the sister group of the Apicomplexa, a group of intracellular parasites and photosynthetic algae including the malaria parasite Plasmodium. Many apicomplexan mitochondria have a number of unusual features, including the lack of a pyruvate dehydrogenase and the existence of a branched TCA cycle. Here, we analyse dinoflagellate EST (expressed sequence tag) data to determine whether these features are apicomplexan-specific, or if they are more widespread. We show that dinoflagellates have replaced a key subunit (E1) of pyruvate dehydrogenase with a subunit of bacterial origin and that transcripts encoding many of the proteins that are essential in a conventional ATP synthase/Complex V are absent, as is the case in Apicomplexa. There is a pathway for synthesis of starch or glycogen as a storage carbohydrate. Transcripts encoding isocitrate lyase and malate synthase are present, consistent with ultrastructural reports of a glyoxysome. Finally, evidence for a conventional haem biosynthesis pathway is found, in contrast to the Apicomplexa, Chromera and early branching dinoflagellates (Perkinsus, Oxyrrhis).
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Affiliation(s)
- Erin R Butterfield
- Sansom Institute for Health Research, University of South Australia, North Terrace, Adelaide, SA 5000, Australia
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A new arsenate reductase involved in arsenic detoxification in Anabaena sp. PCC7120. Funct Integr Genomics 2012; 13:43-55. [DOI: 10.1007/s10142-012-0296-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 09/10/2012] [Accepted: 09/21/2012] [Indexed: 10/27/2022]
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Wang Y, Carrie C, Giraud E, Elhafez D, Narsai R, Duncan O, Whelan J, Murcha MW. Dual location of the mitochondrial preprotein transporters B14.7 and Tim23-2 in complex I and the TIM17:23 complex in Arabidopsis links mitochondrial activity and biogenesis. THE PLANT CELL 2012; 24:2675-95. [PMID: 22730406 PMCID: PMC3406907 DOI: 10.1105/tpc.112.098731] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Interactions between the respiratory chain and protein import complexes have been previously reported in Saccharomyces cerevisiae, but the biological significance of such interactions remains unknown. Characterization of two mitochondrial preprotein and amino acid transport proteins from Arabidopsis thaliana, NADH dehydrogenase B14.7 like (B14.7 [encoded by At2g42210]) and Translocase of the inner membrane subunit 23-2 (Tim23-2 [encoded by At1g72750]), revealed both proteins are present in respiratory chain complex I and the Translocase of the Inner Membrane 17:23. Whereas depletion of B14.7 by T-DNA insertion is lethal, Tim23-2 can be depleted without lethality. Subtle overexpression of Tim23-2 results in a severe delayed growth phenotype and revealed an unexpected, inverse correlation between the abundance of Tim23-2 and the abundance of respiratory complex I. This newly discovered relationship between protein import and respiratory function was confirmed through the investigation of independent complex I knockout mutants, which were found to have correspondingly increased levels of Tim23-2. This increase in Tim23-2 was also associated with delayed growth phenotypes, increased abundance of other import components, and an increased capacity for mitochondrial protein import. Analysis of the Tim23-2-overexpressing plants through global quantitation of transcript abundance and in-organelle protein synthesis assays revealed widespread alterations in transcript abundance of genes encoding mitochondrial proteins and altered rates of mitochondrial protein translation, indicating a pivotal relationship between the machinery of mitochondrial biogenesis and mitochondrial function.
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Affiliation(s)
- Yan Wang
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009, Western Australia, Australia
| | - Chris Carrie
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009, Western Australia, Australia
| | - Estelle Giraud
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009, Western Australia, Australia
| | - Dina Elhafez
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009, Western Australia, Australia
| | - Reena Narsai
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009, Western Australia, Australia
- Centre for Computational Systems Biology, University of Western Australia, Crawley 6009, Western Australia, Australia
| | - Owen Duncan
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009, Western Australia, Australia
| | - James Whelan
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009, Western Australia, Australia
| | - Monika W. Murcha
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009, Western Australia, Australia
- Address correspondence to
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Tan YF, Millar AH, Taylor NL. Components of mitochondrial oxidative phosphorylation vary in abundance following exposure to cold and chemical stresses. J Proteome Res 2012; 11:3860-79. [PMID: 22574745 DOI: 10.1021/pr3003535] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Plant mitochondria are highly responsive organelles that vary their metabolism in response to a wide range of chemical and environmental conditions. Quantitative proteomics studies have begun to allow the analysis of these large-scale protein changes in mitochondria. However studies of the integral membrane proteome of plant mitochondria, arguably the site responsible for the most fundamental mitochondrial processes of oxidative phosphorylation, protein import and metabolite transport, remain a technical challenge. Here we have investigated the changes in protein abundance in response to a number of chemical stresses and cold. In addition to refining the subcellular localization of 66 proteins, we have been able to characterize 596 protein × treatment combinations following a range of stresses. To date it has been assumed that the main mitochondrial response to stress involved the induction of alternative respiratory proteins such as AOX, UCPs, and alternative NAD(P)H dehydrogenases; we now provide evidence for a number of very specific protein abundance changes that have not been highlighted previously by transcript studies. This includes both previously characterized stress responsive proteins as well as major components of oxidative phosphorylation, protein import/export, and metabolite transport.
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Affiliation(s)
- Yew-Foon Tan
- ARC Centre of Excellence in Plant Energy Biology, MCS Building M316, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Western Australia, Australia
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In Polytomella sp. mitochondria, biogenesis of the heterodimeric COX2 subunit of cytochrome c oxidase requires two different import pathways. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:819-27. [DOI: 10.1016/j.bbabio.2012.02.038] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 02/28/2012] [Accepted: 02/28/2012] [Indexed: 11/22/2022]
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Duncan O, Murcha MW, Whelan J. Unique components of the plant mitochondrial protein import apparatus. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:304-13. [PMID: 22406071 DOI: 10.1016/j.bbamcr.2012.02.015] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 02/21/2012] [Accepted: 02/23/2012] [Indexed: 10/28/2022]
Abstract
The basic mitochondrial protein import apparatus was established in the earliest eukaryotes. Over the subsequent course of evolution and the divergence of the plant, animal and fungal lineages, this basic import apparatus has been modified and expanded in order to meet the specific needs of protein import in each kingdom. In the plant kingdom, the arrival of the plastid complicated the process of protein trafficking and is thought to have given rise to the evolution of a number of unique components that allow specific and efficient targeting of mitochondrial proteins from their site of synthesis in the cytosol, to their final location in the organelle. This includes the evolution of two unique outer membrane import receptors, plant Translocase of outer membrane 20 kDa subunit (TOM20) and Outer membrane protein of 64 kDa (OM64), the loss of a receptor domain from an ancestral import component, Translocase of outer membrane 22 kDa subunit (TOM22), evolution of unique features in the disulfide relay system of the inter membrane space, and the addition of an extra membrane spanning domain to another ancestral component of the inner membrane, Translocase of inner membrane 17 kDa subunit (TIM17). Notably, many of these components are encoded by multi-gene families and exhibit differential sub-cellular localisation and functional specialisation. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
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Affiliation(s)
- Owen Duncan
- ARC Centre of Excellence in Plant Energy Biology, Bayliss Building M316, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
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Abstract
Depending on the organism, mitochondria consist approximately of 500-1,400 different proteins. By far most of these proteins are encoded by nuclear genes and synthesized on cytosolic ribosomes. Targeting signals direct these proteins into mitochondria and there to their respective subcompartment: the outer membrane, the intermembrane space (IMS), the inner membrane, and the matrix. Membrane-embedded translocation complexes allow the translocation of proteins across and, in the case of membrane proteins, the insertion into mitochondrial membranes. A small number of proteins are encoded by the mitochondrial genome: Most mitochondrial translation products represent hydrophobic proteins of the inner membrane which-together with many nuclear-encoded proteins-form the respiratory chain complexes. This chapter gives an overview on the mitochondrial protein translocases and the mechanisms by which they drive the transport and assembly of mitochondrial proteins.
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The mitochondrial proteome of the model legume Medicago truncatula. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:1658-68. [DOI: 10.1016/j.bbapap.2011.08.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 08/08/2011] [Accepted: 08/15/2011] [Indexed: 11/23/2022]
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Rada P, Doležal P, Jedelský PL, Bursac D, Perry AJ, Šedinová M, Smíšková K, Novotný M, Beltrán NC, Hrdý I, Lithgow T, Tachezy J. The core components of organelle biogenesis and membrane transport in the hydrogenosomes of Trichomonas vaginalis. PLoS One 2011; 6:e24428. [PMID: 21935410 PMCID: PMC3174187 DOI: 10.1371/journal.pone.0024428] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 08/09/2011] [Indexed: 12/02/2022] Open
Abstract
Trichomonas vaginalis is a parasitic protist of the Excavata group. It contains an anaerobic form of mitochondria called hydrogenosomes, which produce hydrogen and ATP; the majority of mitochondrial pathways and the organellar genome were lost during the mitochondrion-to-hydrogenosome transition. Consequently, all hydrogenosomal proteins are encoded in the nucleus and imported into the organelles. However, little is known about the membrane machineries required for biogenesis of the organelle and metabolite exchange. Using a combination of mass spectrometry, immunofluorescence microscopy, in vitro import assays and reverse genetics, we characterized the membrane proteins of the hydrogenosome. We identified components of the outer membrane (TOM) and inner membrane (TIM) protein translocases include multiple paralogs of the core Tom40-type porins and Tim17/22/23 channel proteins, respectively, and uniquely modified small Tim chaperones. The inner membrane proteins TvTim17/22/23-1 and Pam18 were shown to possess conserved information for targeting to mitochondrial inner membranes, but too divergent in sequence to support the growth of yeast strains lacking Tim17, Tim22, Tim23 or Pam18. Full complementation was seen only when the J-domain of hydrogenosomal Pam18 was fused with N-terminal region and transmembrane segment of the yeast homolog. Candidates for metabolite exchange across the outer membrane were identified including multiple isoforms of the β-barrel proteins, Hmp35 and Hmp36; inner membrane MCF-type metabolite carriers were limited to five homologs of the ATP/ADP carrier, Hmp31. Lastly, hydrogenosomes possess a pathway for the assembly of C-tail-anchored proteins into their outer membrane with several new tail-anchored proteins being identified. These results show that hydrogenosomes and mitochondria share common core membrane components required for protein import and metabolite exchange; however, they also reveal remarkable differences that reflect the functional adaptation of hydrogenosomes to anaerobic conditions and the peculiar evolutionary history of the Excavata group.
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Affiliation(s)
- Petr Rada
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Pavel Doležal
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Petr L. Jedelský
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
- Laboratory of Mass Spectrometry, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Dejan Bursac
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Australia
| | - Andrew J. Perry
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Australia
| | - Miroslava Šedinová
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Kateřina Smíšková
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Marian Novotný
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Neritza Campo Beltrán
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Ivan Hrdý
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Trevor Lithgow
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Australia
| | - Jan Tachezy
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
- * E-mail:
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Abstract
The majority of outer membrane proteins (OMPs) from gram-negative bacteria and many of mitochondria and chloroplasts are β-barrels. Insertion and assembly of these proteins are catalyzed by the Omp85 protein family in a seemingly conserved process. All members of this family exhibit a characteristic N-terminal polypeptide-transport-associated (POTRA) and a C-terminal 16-stranded β-barrel domain. In plants, two phylogenetically distinct and essential Omp85's exist in the chloroplast outer membrane, namely Toc75-III and Toc75-V. Whereas Toc75-V, similar to the mitochondrial Sam50, is thought to possess the original bacterial function, its homolog, Toc75-III, evolved to the pore-forming unit of the TOC translocon for preprotein import. In all current models of OMP biogenesis and preprotein translocation, a topology of Omp85 with the POTRA domain in the periplasm or intermembrane space is assumed. Using self-assembly GFP-based in vivo experiments and in situ topology studies by electron cryotomography, we show that the POTRA domains of both Toc75-III and Toc75-V are exposed to the cytoplasm. This unexpected finding explains many experimental observations and requires a reevaluation of current models of OMP biogenesis and TOC complex function.
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