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Yang M, Chen S, Lim SL, Yang L, Zhong JY, Chan KC, Zhao Z, Wong KB, Wang J, Lim BL. A converged ubiquitin-proteasome pathway for the degradation of TOC and TOM tail-anchored receptors. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2024; 66:1007-1023. [PMID: 38501483 DOI: 10.1111/jipb.13645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 02/27/2024] [Indexed: 03/20/2024]
Abstract
In plants, thousands of nucleus-encoded proteins translated in the cytosol are sorted to chloroplasts and mitochondria by binding to specific receptors of the TOC (translocon on the outer chloroplast membrane) and the TOM (translocon on the outer mitochondrial membrane) complexes for import into those organelles. The degradation pathways for these receptors are unclear. Here, we discovered a converged ubiquitin-proteasome pathway for the degradation of Arabidopsis thaliana TOC and TOM tail-anchored receptors. The receptors are ubiquitinated by E3 ligase(s) and pulled from the outer membranes by the AAA+ adenosine triphosphatase CDC48, after which a previously uncharacterized cytosolic protein, transmembrane domain (TMD)-binding protein for tail-anchored outer membrane proteins (TTOP), binds to the exposed TMDs at the C termini of the receptors and CDC48, and delivers these complexes to the 26S proteasome.
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Affiliation(s)
- Meijing Yang
- School of Biological Sciences, University of Hong Kong, Pokfulam, 999077, Hong Kong, China
- Department of Biology, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Shuai Chen
- School of Biomedical Engineering, Shenzhen University, Shenzhen, 518060, China
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, 999077, Hong Kong, China
| | - Shey-Li Lim
- School of Biological Sciences, University of Hong Kong, Pokfulam, 999077, Hong Kong, China
| | - Lang Yang
- School of Biological Sciences, University of Hong Kong, Pokfulam, 999077, Hong Kong, China
- Department of Biology, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Jia Yi Zhong
- School of Biological Sciences, University of Hong Kong, Pokfulam, 999077, Hong Kong, China
| | - Koon Chuen Chan
- School of Biological Sciences, University of Hong Kong, Pokfulam, 999077, Hong Kong, China
| | - Zhizhu Zhao
- School of Biological Sciences, University of Hong Kong, Pokfulam, 999077, Hong Kong, China
| | - Kam-Bo Wong
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, 999077, Hong Kong, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, 999077, Hong Kong, China
| | - Junqi Wang
- Department of Biology, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Boon Leong Lim
- School of Biological Sciences, University of Hong Kong, Pokfulam, 999077, Hong Kong, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, 999077, Hong Kong, China
- HKU Shenzhen Institute of Research and Innovation, Shenzhen, 518052, China
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2
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Gill-Hille M, Wang A, Murcha MW. Presequence translocase-associated motor subunits of the mitochondrial protein import apparatus are dual-targeted to mitochondria and plastids. FRONTIERS IN PLANT SCIENCE 2022; 13:981552. [PMID: 36438081 PMCID: PMC9695410 DOI: 10.3389/fpls.2022.981552] [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: 06/29/2022] [Accepted: 10/19/2022] [Indexed: 06/16/2023]
Abstract
The import and assembly of most of the mitochondrial proteome is regulated by protein translocases located within the mitochondrial membranes. The Presequence Translocase-Associated Motor (PAM) complex powers the translocation of proteins across the inner membrane and consists of Hsp70, the J-domain containing co-chaperones, Pam16 and Pam18, and their associated proteins Tim15 and Mge1. In Arabidopsis, multiple orthologues of Pam16, Pam18, Tim15 and Mge1 have been identified and a mitochondrial localization has been confirmed for most. As the localization of Pam18-1 has yet to be determined and a plastid localization has been observed for homologues of Tim15 and Mge1, we carried out a comprehensive targeting analysis of all PAM complex orthologues using multiple in vitro and in vivo methods. We found that, Pam16 was exclusively targeted to the mitochondria, but Pam18 orthologues could be targeted to both the mitochondria and plastids, as observed for the PAM complex interacting partner proteins Tim15 and Mge1.
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Affiliation(s)
- Mabel Gill-Hille
- School of Molecular Sciences, The University of Western Australia, Perth, WA, Australia
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, Australia
| | - Andre Wang
- School of Molecular Sciences, The University of Western Australia, Perth, WA, Australia
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, Australia
| | - Monika W. Murcha
- School of Molecular Sciences, The University of Western Australia, Perth, WA, Australia
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, Australia
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3
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Schneider A. Evolution and diversification of mitochondrial protein import systems. Curr Opin Cell Biol 2022; 75:102077. [PMID: 35390639 DOI: 10.1016/j.ceb.2022.102077] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 11/03/2022]
Abstract
More than 95% of mitochondrial proteins are encoded in the nucleus, synthesised in the cytosol and imported into the organelle. The evolution of mitochondrial protein import systems was therefore a prerequisite for the conversion of the α-proteobacterial mitochondrial ancestor into an organelle. Here, I review that the origin of the mitochondrial outer membrane import receptors can best be understood by convergent evolution. Subsequently, I discuss an evolutionary scenario that was proposed to explain the diversification of the inner membrane carrier protein translocases between yeast and mammals. Finally, I illustrate a scenario that can explain how the two specialised inner membrane protein translocase complexes found in most eukaryotes were reduced to a single multifunctional one in trypanosomes.
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Affiliation(s)
- André Schneider
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, Freiestrasse 3, 3012 Bern, Switzerland.
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4
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New Insights into the Chloroplast Outer Membrane Proteome and Associated Targeting Pathways. Int J Mol Sci 2022; 23:ijms23031571. [PMID: 35163495 PMCID: PMC8836251 DOI: 10.3390/ijms23031571] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/24/2022] [Accepted: 01/27/2022] [Indexed: 12/04/2022] Open
Abstract
Plastids are a dynamic class of organelle in plant cells that arose from an ancient cyanobacterial endosymbiont. Over the course of evolution, most genes encoding plastid proteins were transferred to the nuclear genome. In parallel, eukaryotic cells evolved a series of targeting pathways and complex proteinaceous machinery at the plastid surface to direct these proteins back to their target organelle. Chloroplasts are the most well-characterized plastids, responsible for photosynthesis and other important metabolic functions. The biogenesis and function of chloroplasts rely heavily on the fidelity of intracellular protein trafficking pathways. Therefore, understanding these pathways and their regulation is essential. Furthermore, the chloroplast outer membrane proteome remains relatively uncharted territory in our understanding of protein targeting. Many key players in the cytosol, receptors at the organelle surface, and insertases that facilitate insertion into the chloroplast outer membrane remain elusive for this group of proteins. In this review, we summarize recent advances in the understanding of well-characterized chloroplast outer membrane protein targeting pathways as well as provide new insights into novel targeting signals and pathways more recently identified using a bioinformatic approach. As a result of our analyses, we expand the known number of chloroplast outer membrane proteins from 117 to 138.
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5
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Chaudhuri M, Darden C, Soto Gonzalez F, Singha UK, Quinones L, Tripathi A. Tim17 Updates: A Comprehensive Review of an Ancient Mitochondrial Protein Translocator. Biomolecules 2020; 10:E1643. [PMID: 33297490 PMCID: PMC7762337 DOI: 10.3390/biom10121643] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/02/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023] Open
Abstract
The translocases of the mitochondrial outer and inner membranes, the TOM and TIMs, import hundreds of nucleus-encoded proteins into mitochondria. TOM and TIMs are multi-subunit protein complexes that work in cooperation with other complexes to import proteins in different sub-mitochondrial destinations. The overall architecture of these protein complexes is conserved among yeast/fungi, animals, and plants. Recent studies have revealed unique characteristics of this machinery, particularly in the eukaryotic supergroup Excavata. Despite multiple differences, homologues of Tim17, an essential component of one of the TIM complexes and a member of the Tim17/Tim22/Tim23 family, have been found in all eukaryotes. Here, we review the structure and function of Tim17 and Tim17-containing protein complexes in different eukaryotes, and then compare them to the single homologue of this protein found in Trypanosoma brucei, a unicellular parasitic protozoan.
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Affiliation(s)
- Minu Chaudhuri
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, 1005 Dr. D.B. Todd, Jr., Blvd, Nashville, TN 37208, USA; (C.D.); (F.S.G.); (U.K.S.); (L.Q.); (A.T.)
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6
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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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7
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Tichá T, Samakovli D, Kuchařová A, Vavrdová T, Šamaj J. Multifaceted roles of HEAT SHOCK PROTEIN 90 molecular chaperones in plant development. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3966-3985. [PMID: 32293686 DOI: 10.1093/jxb/eraa177] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 04/06/2020] [Indexed: 05/20/2023]
Abstract
HEAT SHOCK PROTEINS 90 (HSP90s) are molecular chaperones that mediate correct folding and stability of many client proteins. These chaperones act as master molecular hubs involved in multiple aspects of cellular and developmental signalling in diverse organisms. Moreover, environmental and genetic perturbations affect both HSP90s and their clients, leading to alterations of molecular networks determining respectively plant phenotypes and genotypes and contributing to a broad phenotypic plasticity. Although HSP90 interaction networks affecting the genetic basis of phenotypic variation and diversity have been thoroughly studied in animals, such studies are just starting to emerge in plants. Here, we summarize current knowledge and discuss HSP90 network functions in plant development and cellular homeostasis.
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Affiliation(s)
- Tereza Tichá
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
| | - Despina Samakovli
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
| | - Anna Kuchařová
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
| | - Tereza Vavrdová
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
| | - Jozef Šamaj
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
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8
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Nickel C, Horneff R, Heermann R, Neumann B, Jung K, Soll J, Schwenkert S. Phosphorylation of the outer membrane mitochondrial protein OM64 influences protein import into mitochondria. Mitochondrion 2019; 44:93-102. [DOI: 10.1016/j.mito.2018.01.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 12/15/2017] [Accepted: 01/18/2018] [Indexed: 10/18/2022]
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9
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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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10
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Krysztofinska EM, Evans NJ, Thapaliya A, Murray JW, Morgan RML, Martinez-Lumbreras S, Isaacson RL. Structure and Interactions of the TPR Domain of Sgt2 with Yeast Chaperones and Ybr137wp. Front Mol Biosci 2017; 4:68. [PMID: 29075633 PMCID: PMC5641545 DOI: 10.3389/fmolb.2017.00068] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 09/21/2017] [Indexed: 12/11/2022] Open
Abstract
Small glutamine-rich tetratricopeptide repeat-containing protein 2 (Sgt2) is a multi-module co-chaperone involved in several protein quality control pathways. The TPR domain of Sgt2 and several other proteins, including SGTA, Hop, and CHIP, is a highly conserved motif known to form transient complexes with molecular chaperones such as Hsp70 and Hsp90. In this work, we present the first high resolution crystal structures of Sgt2_TPR alone and in complex with a C-terminal peptide PTVEEVD from heat shock protein, Ssa1. Using nuclear magnetic resonance spectroscopy and isothermal titration calorimetry, we demonstrate that Sgt2_TPR interacts with peptides corresponding to the C-termini of Ssa1, Hsc82, and Ybr137wp with similar binding modes and affinities.
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Affiliation(s)
| | - Nicola J Evans
- Department of Chemistry, King's College London, London, United Kingdom
| | - Arjun Thapaliya
- Department of Chemistry, King's College London, London, United Kingdom
| | - James W Murray
- Department of Life Sciences, Imperial College London, South Kensington, United Kingdom
| | - Rhodri M L Morgan
- Department of Life Sciences, Imperial College London, South Kensington, United Kingdom
| | | | - Rivka L Isaacson
- Department of Chemistry, King's College London, London, United Kingdom
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11
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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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12
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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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13
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Xu J, Yuan H, Ran T, Zhang Y, Liu H, Lu S, Xiong X, Xu A, Jiang Y, Lu T, Chen Y. A selectivity study of sodium-dependent glucose cotransporter 2/sodium-dependent glucose cotransporter 1 inhibitors by molecular modeling. J Mol Recognit 2015; 28:467-79. [DOI: 10.1002/jmr.2464] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/15/2015] [Accepted: 01/15/2015] [Indexed: 01/01/2023]
Affiliation(s)
- Jinxing Xu
- Laboratory of Molecular Design and Drug Discovery, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
| | - Haoliang Yuan
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine; Jiangsu Institute of Nuclear Medicine; Wuxi 214063 China
| | - Ting Ran
- Laboratory of Molecular Design and Drug Discovery, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
| | - Yanmin Zhang
- Laboratory of Molecular Design and Drug Discovery, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
| | - Haichun Liu
- Laboratory of Molecular Design and Drug Discovery, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
| | - Shuai Lu
- Laboratory of Molecular Design and Drug Discovery, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
| | - Xiao Xiong
- Laboratory of Molecular Design and Drug Discovery, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
| | - Anyang Xu
- Laboratory of Molecular Design and Drug Discovery, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
| | - Yulei Jiang
- Laboratory of Molecular Design and Drug Discovery, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
| | - Tao Lu
- Laboratory of Molecular Design and Drug Discovery, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
- State Key Laboratory of Natural Medicines, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
| | - Yadong Chen
- Laboratory of Molecular Design and Drug Discovery, School of Science; China Pharmaceutical University; 639 Longmian Avenue Nanjing 211198 China
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14
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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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15
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Paila YD, Richardson LGL, Schnell DJ. New insights into the mechanism of chloroplast protein import and its integration with protein quality control, organelle biogenesis and development. J Mol Biol 2014; 427:1038-1060. [PMID: 25174336 DOI: 10.1016/j.jmb.2014.08.016] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 08/20/2014] [Accepted: 08/23/2014] [Indexed: 01/04/2023]
Abstract
The translocons at the outer (TOC) and the inner (TIC) envelope membranes of chloroplasts mediate the targeting and import of several thousand nucleus-encoded preproteins that are required for organelle biogenesis and homeostasis. The cytosolic events in preprotein targeting remain largely unknown, although cytoplasmic chaperones have been proposed to facilitate delivery to the TOC complex. Preprotein recognition is mediated by the TOC GTPase receptors Toc159 and Toc34. The receptors constitute a GTP-regulated switch, which initiates membrane translocation via Toc75, a member of the Omp85 (outer membrane protein 85)/TpsB (two-partner secretion system B) family of bacterial, plastid and mitochondrial β-barrel outer membrane proteins. The TOC receptor systems have diversified to recognize distinct sets of preproteins, thereby maximizing the efficiency of targeting in response to changes in gene expression during developmental and physiological events that impact organelle function. The TOC complex interacts with the TIC translocon to allow simultaneous translocation of preproteins across the envelope. Both the two inner membrane complexes, the Tic110 and 1 MDa complexes, have been implicated as constituents of the TIC translocon, and it remains to be determined how they interact to form the TIC channel and assemble the import-associated chaperone network in the stroma that drives import across the envelope membranes. This review will focus on recent developments in our understanding of the mechanisms and diversity of the TOC-TIC systems. Our goal is to incorporate these recent studies with previous work and present updated or revised models for the function of TOC-TIC in protein import.
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Affiliation(s)
- Yamuna D Paila
- Department of Biochemistry and Molecular Biology, Life Sciences Laboratories Room N431, 240 Thatcher Rd, University of Massachusetts, Amherst MA 01003-9364, USA
| | - Lynn G L Richardson
- Department of Biochemistry and Molecular Biology, Life Sciences Laboratories Room N431, 240 Thatcher Rd, University of Massachusetts, Amherst MA 01003-9364, USA
| | - Danny J Schnell
- Department of Biochemistry and Molecular Biology, Life Sciences Laboratories Room N431, 240 Thatcher Rd, University of Massachusetts, Amherst MA 01003-9364, USA
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