1
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Eckardt NA, Avin-Wittenberg T, Bassham DC, Chen P, Chen Q, Fang J, Genschik P, Ghifari AS, Guercio AM, Gibbs DJ, Heese M, Jarvis RP, Michaeli S, Murcha MW, Mursalimov S, Noir S, Palayam M, Peixoto B, Rodriguez PL, Schaller A, Schnittger A, Serino G, Shabek N, Stintzi A, Theodoulou FL, Üstün S, van Wijk KJ, Wei N, Xie Q, Yu F, Zhang H. The lowdown on breakdown: Open questions in plant proteolysis. THE PLANT CELL 2024; 36:2931-2975. [PMID: 38980154 PMCID: PMC11371169 DOI: 10.1093/plcell/koae193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 05/16/2024] [Accepted: 06/19/2024] [Indexed: 07/10/2024]
Abstract
Proteolysis, including post-translational proteolytic processing as well as protein degradation and amino acid recycling, is an essential component of the growth and development of living organisms. In this article, experts in plant proteolysis pose and discuss compelling open questions in their areas of research. Topics covered include the role of proteolysis in the cell cycle, DNA damage response, mitochondrial function, the generation of N-terminal signals (degrons) that mark many proteins for degradation (N-terminal acetylation, the Arg/N-degron pathway, and the chloroplast N-degron pathway), developmental and metabolic signaling (photomorphogenesis, abscisic acid and strigolactone signaling, sugar metabolism, and postharvest regulation), plant responses to environmental signals (endoplasmic-reticulum-associated degradation, chloroplast-associated degradation, drought tolerance, and the growth-defense trade-off), and the functional diversification of peptidases. We hope these thought-provoking discussions help to stimulate further research.
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Affiliation(s)
| | - Tamar Avin-Wittenberg
- Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Diane C Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Poyu Chen
- School of Biological Science and Technology, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Qian Chen
- Ministry of Agriculture and Rural Affairs Key Laboratory for Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Jun Fang
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford OX1 3RB, UK
| | - Pascal Genschik
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, 12, rue du Général Zimmer, Strasbourg 67084, France
| | - Abi S Ghifari
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Angelica M Guercio
- Department of Plant Biology, College of Biological Sciences, University of California-Davis, Davis, CA 95616, USA
| | - Daniel J Gibbs
- School of Biosciences, University of Birmingham, Edgbaston B1 2RU, UK
| | - Maren Heese
- Department of Developmental Biology, University of Hamburg, Ohnhorststr. 18, Hamburg 22609, Germany
| | - R Paul Jarvis
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford OX1 3RB, UK
| | - Simon Michaeli
- Department of Postharvest Sciences, Agricultural Research Organization (ARO), Volcani Institute, Rishon LeZion 7505101, Israel
| | - Monika W Murcha
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Sergey Mursalimov
- Department of Postharvest Sciences, Agricultural Research Organization (ARO), Volcani Institute, Rishon LeZion 7505101, Israel
| | - Sandra Noir
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, 12, rue du Général Zimmer, Strasbourg 67084, France
| | - Malathy Palayam
- Department of Plant Biology, College of Biological Sciences, University of California-Davis, Davis, CA 95616, USA
| | - Bruno Peixoto
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford OX1 3RB, UK
| | - Pedro L Rodriguez
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Cientificas-Universidad Politecnica de Valencia, Valencia ES-46022, Spain
| | - Andreas Schaller
- Department of Plant Physiology and Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart 70599, Germany
| | - Arp Schnittger
- Department of Developmental Biology, University of Hamburg, Ohnhorststr. 18, Hamburg 22609, Germany
| | - Giovanna Serino
- Department of Biology and Biotechnology, Sapienza Universita’ di Roma, p.le A. Moro 5, Rome 00185, Italy
| | - Nitzan Shabek
- Department of Plant Biology, College of Biological Sciences, University of California-Davis, Davis, CA 95616, USA
| | - Annick Stintzi
- Department of Plant Physiology and Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart 70599, Germany
| | | | - Suayib Üstün
- Faculty of Biology and Biotechnology, Ruhr-University of Bochum, Bochum 44780, Germany
| | - Klaas J van Wijk
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, NY 14853, USA
| | - Ning Wei
- School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Qi Xie
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, the Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Feifei Yu
- College of Grassland Science and Technology, China Agricultural University, Beijing 100083, China
| | - Hongtao Zhang
- Plant Sciences and the Bioeconomy, Rothamsted Research, Harpenden AL5 2JQ, UK
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2
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Li N, Jarvis RP. Recruitment of Cdc48 to chloroplasts by a UBX-domain protein in chloroplast-associated protein degradation. NATURE PLANTS 2024; 10:1400-1417. [PMID: 39160348 PMCID: PMC11410653 DOI: 10.1038/s41477-024-01769-x] [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: 08/09/2023] [Accepted: 07/20/2024] [Indexed: 08/21/2024]
Abstract
The translocon at the outer chloroplast membrane (TOC) is the gateway for chloroplast protein import and so is vital for photosynthetic establishment and plant growth. Chloroplast-associated protein degradation (CHLORAD) is a ubiquitin-dependent proteolytic system that regulates TOC. In CHLORAD, cytosolic Cdc48 provides motive force for the retrotranslocation of ubiquitinated TOC proteins to the cytosol but how Cdc48 is recruited is unknown. Here, we identify plant UBX-domain protein PUX10 as a component of the CHLORAD machinery. We show that PUX10 is an integral chloroplast outer membrane protein that projects UBX and ubiquitin-associated domains into the cytosol. It interacts with Cdc48 via its UBX domain, bringing it to the chloroplast surface, and with ubiquitinated TOC proteins via its ubiquitin-associated domain. Genetic analyses in Arabidopsis revealed a requirement for PUX10 during CHLORAD-mediated regulation of TOC function and plant development. Thus, PUX10 coordinates ubiquitination and retrotranslocation activities of CHLORAD to enable efficient TOC turnover.
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Affiliation(s)
- Na Li
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford, UK
| | - R Paul Jarvis
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford, UK.
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3
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Discovery of a component of the chloroplast-associated protein degradation system. NATURE PLANTS 2024; 10:1293-1294. [PMID: 39169262 DOI: 10.1038/s41477-024-01770-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
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4
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Nishio H, Cano-Ramirez DL, Muranaka T, de Barros Dantas LL, Honjo MN, Sugisaka J, Kudoh H, Dodd AN. Circadian and environmental signal integration in a natural population of Arabidopsis. Proc Natl Acad Sci U S A 2024; 121:e2402697121. [PMID: 39172785 PMCID: PMC11363283 DOI: 10.1073/pnas.2402697121] [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: 02/13/2024] [Accepted: 07/29/2024] [Indexed: 08/24/2024] Open
Abstract
Plants sense and respond to environmental cues during 24 h fluctuations in their environment. This requires the integration of internal cues such as circadian timing with environmental cues such as light and temperature to elicit cellular responses through signal transduction. However, the integration and transduction of circadian and environmental signals by plants growing in natural environments remains poorly understood. To gain insights into 24 h dynamics of environmental signaling in nature, we performed a field study of signal transduction from the nucleus to chloroplasts in a natural population of Arabidopsis halleri. Using several modeling approaches to interpret the data, we identified that the circadian clock and temperature are key regulators of this pathway under natural conditions. We identified potential time-delay steps between pathway components, and diel fluctuations in the response of the pathway to temperature cues that are reminiscent of the process of circadian gating. We found that our modeling framework can be extended to other signaling pathways that undergo diel oscillations and respond to environmental cues. This approach of combining studies of gene expression in the field with modeling allowed us to identify the dynamic integration and transduction of environmental cues, in plant cells, under naturally fluctuating diel cycles.
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Affiliation(s)
- Haruki Nishio
- Center for Ecological Research, Kyoto University, Otsu, Shiga520-2113, Japan
- Data Science and AI Innovation Research Promotion Center, Shiga University, Hikone, Shiga522-8522, Japan
| | - Dora L. Cano-Ramirez
- The Sainsbury Laboratory, University of Cambridge, CambridgeCB2 1LR, United Kingdom
- School of Biological Sciences, University of Bristol, BristolBS8 1TQ, United Kingdom
| | - Tomoaki Muranaka
- Center for Ecological Research, Kyoto University, Otsu, Shiga520-2113, Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi464-0814, Japan
| | | | - Mie N. Honjo
- Center for Ecological Research, Kyoto University, Otsu, Shiga520-2113, Japan
| | - Jiro Sugisaka
- Center for Ecological Research, Kyoto University, Otsu, Shiga520-2113, Japan
| | - Hiroshi Kudoh
- Center for Ecological Research, Kyoto University, Otsu, Shiga520-2113, Japan
| | - Antony N. Dodd
- Department of Cell and Developmental Biology, John Innes Centre, NorwichNR4 7RU, United Kingdom
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5
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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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6
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K. Raval P, MacLeod AI, Gould SB. A molecular atlas of plastid and mitochondrial proteins reveals organellar remodeling during plant evolutionary transitions from algae to angiosperms. PLoS Biol 2024; 22:e3002608. [PMID: 38713727 PMCID: PMC11135702 DOI: 10.1371/journal.pbio.3002608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 05/29/2024] [Accepted: 03/28/2024] [Indexed: 05/09/2024] Open
Abstract
Algae and plants carry 2 organelles of endosymbiotic origin that have been co-evolving in their host cells for more than a billion years. The biology of plastids and mitochondria can differ significantly across major lineages and organelle changes likely accompanied the adaptation to new ecological niches such as the terrestrial habitat. Based on organelle proteome data and the genomes of 168 phototrophic (Archaeplastida) versus a broad range of 518 non-phototrophic eukaryotes, we screened for changes in plastid and mitochondrial biology across 1 billion years of evolution. Taking into account 331,571 protein families (or orthogroups), we identify 31,625 protein families that are unique to primary plastid-bearing eukaryotes. The 1,906 and 825 protein families are predicted to operate in plastids and mitochondria, respectively. Tracing the evolutionary history of these protein families through evolutionary time uncovers the significant remodeling the organelles experienced from algae to land plants. The analyses of gained orthogroups identifies molecular changes of organelle biology that connect to the diversification of major lineages and facilitated major transitions from chlorophytes en route to the global greening and origin of angiosperms.
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Affiliation(s)
- Parth K. Raval
- Institute for Molecular Evolution, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Alexander I. MacLeod
- Institute for Molecular Evolution, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Sven B. Gould
- Institute for Molecular Evolution, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
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7
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Núñez-Becerril LF, Hernández-Castellano S, Limones-Briones V, De-la-Peña C. Chloroplast Isolation in Agavaceas. Methods Mol Biol 2024; 2827:377-383. [PMID: 38985283 DOI: 10.1007/978-1-0716-3954-2_25] [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: 07/11/2024]
Abstract
Chloroplast isolation protocols have been extensively developed for various species of plants, particularly model organisms with easily manipulable physical characteristics. However, succulent plants, such as Agave angustifolia Haw., which possess adaptations for arid environments like the Crassulacean acid metabolism (CAM) and a thicker cuticle, have received less attention, resulting in a potential knowledge gap. This chapter presents a specialized protocol focusing on isolating chloroplast from A. angustifolia, a species exhibiting adaptations to arid conditions and holding ecological and economic significance due to its role in producing bacanora and mezcal beverages. By successfully isolating chloroplast from A. angustifolia plant growth in ex vitro and in vitro conditions, this protocol enables comprehensive future analyses to elucidate metabolic processes and explore potential applications in related species. Consequently, this research aims to bridge this knowledge gap in chloroplast isolation for succulent plants, providing new insights for future investigations in the field.
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Affiliation(s)
- Luis F Núñez-Becerril
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Mérida, Yucatán, México
| | | | | | - Clelia De-la-Peña
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Mérida, Yucatán, México.
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8
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Sendra M, Moreno-Garrido I, Blasco J. Single and multispecies microalgae toxicological tests assessing the impact of several BPA analogues used by industry. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 333:122073. [PMID: 37331580 DOI: 10.1016/j.envpol.2023.122073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/15/2023] [Accepted: 06/16/2023] [Indexed: 06/20/2023]
Abstract
BPA is a hazard for human and environmental health and recently BPA was added to the Candidate List of substances of very high concern by European Chemical Agency (ECHA). In accordance with this proposal, the authorities have encouraged the replacement of BPA by BPA analogues; however, little is known about the impact of these compounds on the environment. Due to this situation five BPA analogues (BPS, BPAP, BPAF, BPFL and BPC) were chosen in order to study their effects on marine primary producers. Three marine microalgae species (Phaeodactylum tricornutum, Tetraselmis suecica and Nannochloropsis gaditana) were selected for single and multispecies tests concerning the ecotoxicological effects of these BPA analogues. Microalgae were exposed to BPs over 72 h at different dosages (5, 20, 40, 80, 150 and 300 μM). Responses such as: growth, ROS production, cell complexity, cell size, autofluorescence of chlorophyll a, effective quantum yield of PSII and pigment concentrations were assessed at 24, 48 and 72 h. The results revealed that BPS and BPA showed lower toxicity to microalgae in comparison with BPFL > BPAF > BPAP and >BPC for the endpoints studied. N. gaditana was the least sensitive microalgae in comparison to P. tricornutum and T. suecica. However, a different trend was found in the multispecies tests where T. suecica dominated the microalgae community in relation to N. gaditana and P. tricornutum. The results of this work revealed for first time that present day BPA analogues are a threat and not a safe substitute for BPA in terms of the marine phytoplanktonic community. Therefore, the results of their impact on aquatic organisms should be shared.
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Affiliation(s)
- Marta Sendra
- Department of Biotechnology and Food Science, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos, 09001, Burgos, Spain; International Research Center in Critical Raw Materials for Advanced Industrial Technologies (ICCRAM), R&D Center, Universidad de Burgos, Plaza de Misael Bañuelos s/n, 09001, Burgos, Spain.
| | - Ignacio Moreno-Garrido
- Department of Ecology and Coastal Management, Institute of Marine Sciences of Andalusia (CSIC), Campus Río S. Pedro, 11510, Puerto Real, Cádiz, Spain
| | - Julián Blasco
- Department of Ecology and Coastal Management, Institute of Marine Sciences of Andalusia (CSIC), Campus Río S. Pedro, 11510, Puerto Real, Cádiz, Spain
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9
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Nellaepalli S, Lau AS, Jarvis RP. Chloroplast protein translocation pathways and ubiquitin-dependent regulation at a glance. J Cell Sci 2023; 136:jcs241125. [PMID: 37732520 PMCID: PMC10546890 DOI: 10.1242/jcs.241125] [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] [Indexed: 09/22/2023] Open
Abstract
Chloroplasts conduct photosynthesis and numerous metabolic and signalling processes that enable plant growth and development. Most of the ∼3000 proteins in chloroplasts are nucleus encoded and must be imported from the cytosol. Thus, the protein import machinery of the organelle (the TOC-TIC apparatus) is of fundamental importance for chloroplast biogenesis and operation. Cytosolic factors target chloroplast precursor proteins to the TOC-TIC apparatus, which drives protein import across the envelope membranes into the organelle, before various internal systems mediate downstream routing to different suborganellar compartments. The protein import system is proteolytically regulated by the ubiquitin-proteasome system (UPS), enabling centralized control over the organellar proteome. In addition, the UPS targets a range of chloroplast proteins directly. In this Cell Science at a Glance article and the accompanying poster, we present mechanistic details of these different chloroplast protein targeting and translocation events, and of the UPS systems that regulate chloroplast proteins.
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Affiliation(s)
- Sreedhar Nellaepalli
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford OX1 3RB, UK
| | - Anne Sophie Lau
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford OX1 3RB, UK
- Department of Plant Physiology, Faculty of Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - R. Paul Jarvis
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford OX1 3RB, UK
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10
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Wan C, Zhang H, Cheng H, Sowden RG, Cai W, Jarvis RP, Ling Q. Selective autophagy regulates chloroplast protein import and promotes plant stress tolerance. EMBO J 2023; 42:e112534. [PMID: 37248861 PMCID: PMC10350842 DOI: 10.15252/embj.2022112534] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 03/26/2023] [Accepted: 05/09/2023] [Indexed: 05/31/2023] Open
Abstract
Chloroplasts are plant organelles responsible for photosynthesis and environmental sensing. Most chloroplast proteins are imported from the cytosol through the translocon at the outer envelope membrane of chloroplasts (TOC). Previous work has shown that TOC components are regulated by the ubiquitin-proteasome system (UPS) to control the chloroplast proteome, which is crucial for the organelle's function and plant development. Here, we demonstrate that the TOC apparatus is also subject to K63-linked polyubiquitination and regulation by selective autophagy, potentially promoting plant stress tolerance. We identify NBR1 as a selective autophagy adaptor targeting TOC components, and mediating their relocation into vacuoles for autophagic degradation. Such selective autophagy is shown to control TOC protein levels and chloroplast protein import and to influence photosynthetic activity as well as tolerance to UV-B irradiation and heat stress in Arabidopsis plants. These findings uncover the vital role of selective autophagy in the proteolytic regulation of specific chloroplast proteins, and how dynamic control of chloroplast protein import is critically important for plants to cope with challenging environments.
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Affiliation(s)
- Chen Wan
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Hui Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
| | - Hongying Cheng
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Robert G Sowden
- Department of Plant Sciences and Section of Molecular Plant Biology (Department of Biology)University of OxfordOxfordUK
| | - Wenjuan Cai
- Core Facility Center, CAS Centre for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - R Paul Jarvis
- Department of Plant Sciences and Section of Molecular Plant Biology (Department of Biology)University of OxfordOxfordUK
| | - Qihua Ling
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
- CAS‐JIC Center of Excellence for Plant and Microbial Sciences (CEPAMS), Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
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11
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van Wijk KJ, Leppert T, Sun Z, Deutsch EW. Does the Ubiquitination Degradation Pathway Really Reach inside of the Chloroplast? A Re-Evaluation of Mass Spectrometry-Based Assignments of Ubiquitination. J Proteome Res 2023. [PMID: 37092802 DOI: 10.1021/acs.jproteome.3c00178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
A recent paper in Science Advances by Sun et al. claims that intra-chloroplast proteins in the model plant Arabidopsis can be polyubiquitinated and then extracted into the cytosol for subsequent degradation by the proteasome. Most of this conclusion hinges on several sets of mass spectrometry (MS) data. If the proposed results and conclusion are true, this would be a major change in the proteolysis/proteostasis field, breaking the long-standing dogma that there are no polyubiquitination mechanisms within chloroplast organelles (nor in mitochondria). Given its importance, we reanalyzed their raw MS data using both open and closed sequence database searches and encountered many issues not only with the results but also discrepancies between stated methods (e.g., use of alkylating agent iodoacetamide (IAA)) and observed mass modifications. Although there is likely enrichment of ubiquitination signatures in a subset of the data (probably from ubiquitination in the cytosol), we show that runaway alkylation with IAA caused extensive artifactual modifications of N termini and lysines to the point that a large fraction of the desired ubiquitination signatures is indistinguishable from artifactual acetamide signatures, and thus, no intra-chloroplast polyubiquitination conclusions can be drawn from these data. We provide recommendations on how to avoid such perils in future work.
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Affiliation(s)
- Klaas J van Wijk
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, New York 14853, United States
| | - Tami Leppert
- Institute for Systems Biology (ISB), Seattle, Washington 98109, United States
| | - Zhi Sun
- Institute for Systems Biology (ISB), Seattle, Washington 98109, United States
| | - Eric W Deutsch
- Institute for Systems Biology (ISB), Seattle, Washington 98109, United States
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12
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Christian R, Labbancz J, Usadel B, Dhingra A. Understanding protein import in diverse non-green plastids. Front Genet 2023; 14:969931. [PMID: 37007964 PMCID: PMC10063809 DOI: 10.3389/fgene.2023.969931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 02/24/2023] [Indexed: 03/19/2023] Open
Abstract
The spectacular diversity of plastids in non-green organs such as flowers, fruits, roots, tubers, and senescing leaves represents a Universe of metabolic processes in higher plants that remain to be completely characterized. The endosymbiosis of the plastid and the subsequent export of the ancestral cyanobacterial genome to the nuclear genome, and adaptation of the plants to all types of environments has resulted in the emergence of diverse and a highly orchestrated metabolism across the plant kingdom that is entirely reliant on a complex protein import and translocation system. The TOC and TIC translocons, critical for importing nuclear-encoded proteins into the plastid stroma, remain poorly resolved, especially in the case of TIC. From the stroma, three core pathways (cpTat, cpSec, and cpSRP) may localize imported proteins to the thylakoid. Non-canonical routes only utilizing TOC also exist for the insertion of many inner and outer membrane proteins, or in the case of some modified proteins, a vesicular import route. Understanding this complex protein import system is further compounded by the highly heterogeneous nature of transit peptides, and the varying transit peptide specificity of plastids depending on species and the developmental and trophic stage of the plant organs. Computational tools provide an increasingly sophisticated means of predicting protein import into highly diverse non-green plastids across higher plants, which need to be validated using proteomics and metabolic approaches. The myriad plastid functions enable higher plants to interact and respond to all kinds of environments. Unraveling the diversity of non-green plastid functions across the higher plants has the potential to provide knowledge that will help in developing climate resilient crops.
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Affiliation(s)
- Ryan Christian
- Department of Horticulture, Washington State University, Pullman, WA, United States
| | - June Labbancz
- Department of Horticulture, Washington State University, Pullman, WA, United States
- Department of Horticultural Sciences, Texas A&M University, College Station, TX, United States
| | | | - Amit Dhingra
- Department of Horticulture, Washington State University, Pullman, WA, United States
- Department of Horticultural Sciences, Texas A&M University, College Station, TX, United States
- *Correspondence: Amit Dhingra,
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13
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Sun Y, Li J, Zhang L, Lin R. Regulation of chloroplast protein degradation. J Genet Genomics 2023:S1673-8527(23)00049-8. [PMID: 36863685 DOI: 10.1016/j.jgg.2023.02.010] [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: 12/24/2022] [Revised: 02/02/2023] [Accepted: 02/14/2023] [Indexed: 03/04/2023]
Abstract
Chloroplasts are unique organelles that not only provide sites for photosynthesis and many metabolic processes, but also are sensitive to various environmental stresses. Chloroplast proteins are encoded by genes from both nuclear and chloroplast genomes. During chloroplast development and responses to stresses, the robust protein quality control systems are essential for regulation of protein homeostasis and the integrity of chloroplast proteome. In this review, we summarize the regulatory mechanisms of chloroplast protein degradation refer to protease system, ubiquitin-proteasome system, and the chloroplast autophagy. These mechanisms symbiotically play a vital role in chloroplast development and photosynthesis under both normal or stress conditions.
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Affiliation(s)
- Yang Sun
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, Henan 475001, China
| | - Jialong Li
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Lixin Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, Henan 475001, China.
| | - Rongcheng Lin
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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14
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Research progress on maintaining chloroplast homeostasis under stress conditions: a review. Acta Biochim Biophys Sin (Shanghai) 2023; 55:173-182. [PMID: 36840466 PMCID: PMC10157539 DOI: 10.3724/abbs.2023022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
On a global scale, drought, salinity, extreme temperature, and other abiotic stressors severely limit the quality and yield of crops. Therefore, it is crucial to clarify the adaptation strategies of plants to harsh environments. Chloroplasts are important environmental sensors in plant cells. For plants to thrive in different habitats, chloroplast homeostasis must be strictly regulated, which is necessary to maintain efficient plant photosynthesis and other metabolic reactions under stressful environments. To maintain normal chloroplast physiology, two important biological processes are needed: the import and degradation of chloroplast proteins. The orderly import of chloroplast proteins and the timely degradation of damaged chloroplast components play a key role in adapting plants to their environment. In this review, we briefly described the mechanism of chloroplast TOC-TIC protein transport. The importance and recent progress of chloroplast protein turnover, retrograde signaling, and chloroplast protein degradation under stress are summarized. Furthermore, the potential of targeted regulation of chloroplast homeostasis is emphasized to improve plant adaptation to environmental stresses.
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15
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Mohd Ali S, Li N, Soufi Z, Yao J, Johnson E, Ling Q, Jarvis RP. Multiple ubiquitin E3 ligase genes antagonistically regulate chloroplast-associated protein degradation. Curr Biol 2023; 33:1138-1146.e5. [PMID: 36822201 DOI: 10.1016/j.cub.2023.01.060] [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: 03/30/2021] [Revised: 12/02/2022] [Accepted: 01/26/2023] [Indexed: 02/24/2023]
Abstract
The chloroplast is the most prominent member of a diverse group of plant organelles called the plastids, and it is characterized by its vital role in photosynthesis. 1,2,3 Most of the ∼3,000 different proteins in chloroplasts are synthesized in the cytosol in precursor (preprotein) form, each with a cleavable transit peptide. 4,5,6,7,8 Preproteins are imported via translocons in the outer and inner envelope membranes of the chloroplast, termed TOC and TIC, respectively. 9,10,11,12,13 Discovery of the chloroplast-localized ubiquitin E3 ligase SUPPRESSOR OF PPI1 LOCUS1 (SP1) demonstrated that the nucleocytosolic ubiquitin-proteasome system (UPS) targets the TOC apparatus to dynamically control protein import and chloroplast biogenesis in response to developmental and environmental cues. The relevant UPS pathway is termed chloroplast-associated protein degradation (CHLORAD). 14,15,16 Two homologs of SP1 exist, SP1-like1 (SPL1) and SPL2, but their roles have remained obscure. Here, we show that SP1 is ubiquitous in the Viridiplantae and that SPL2 and SPL1 appeared early during the evolution of the Viridiplantae and land plants, respectively. Through genetic and biochemical analysis, we reveal that SPL1 functions as a negative regulator of SP1, potentially by interfering with its ability to catalyze ubiquitination. In contrast, SPL2, the more distantly related SP1 homolog, displays partial functional redundancy with SP1. Both SPL1 and SPL2 modify the extent of leaf senescence, like SP1, but do so in diametrically opposite ways. Thus, SPL1 and SPL2 are bona fide CHLORAD system components with negative and positive regulatory functions that allow for nuanced control of this vital proteolytic pathway.
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Affiliation(s)
- Sabri Mohd Ali
- Section of Molecular Plant Biology (Department of Biology) and Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Na Li
- Section of Molecular Plant Biology (Department of Biology) and Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Ziad Soufi
- Section of Molecular Plant Biology (Department of Biology) and Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Jinrong Yao
- University of Chinese Academy of Sciences, Beijing 100049, China; National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Errin Johnson
- The Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Qihua Ling
- Section of Molecular Plant Biology (Department of Biology) and Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK; National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - R Paul Jarvis
- Section of Molecular Plant Biology (Department of Biology) and Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
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16
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Kim DB, Na C, Hwang I, Lee DW. Understanding protein translocation across chloroplast membranes: Translocons and motor proteins. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2023; 65:408-416. [PMID: 36223071 DOI: 10.1111/jipb.13385] [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: 08/29/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Subcellular organelles in eukaryotes are surrounded by lipid membranes. In an endomembrane system, vesicle trafficking is the primary mechanism for the delivery of organellar proteins to specific organelles. However, organellar proteins for chloroplasts, mitochondria, the nucleus, and peroxisomes that are translated in the cytosol are directly imported into their target organelles. Chloroplasts are a plant-specific organelle with outer and inner envelope membranes, a dual-membrane structure that is similar to mitochondria. Interior chloroplast proteins translated by cytosolic ribosomes are thus translocated through TOC and TIC complexes (translocons in the outer and inner envelope of chloroplasts, respectively), with stromal ATPase motor proteins playing a critical role in pulling pre-proteins through these import channels. Over the last three decades, the identity and function of TOC/TIC components and stromal motor proteins have been actively investigated, which has shed light on the action mechanisms at a molecular level. However, there remains some disagreement over the exact composition of TIC complexes and genuine stromal motor proteins. In this review, we discuss recent findings on the mechanisms by which proteins are translocated through TOC/TIC complexes and discuss future prospects for this field of research.
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Affiliation(s)
- Da Been Kim
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Korea
| | - Changhee Na
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Korea
| | - Inhwan Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Dong Wook Lee
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Korea
- Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, 61186, Korea
- Kumho Life Science Laboratory, Chonnam National University, Gwangju, 61186, Korea
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17
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Hipsch M, Michael Y, Lampl N, Sapir O, Cohen Y, Helman D, Rosenwasser S. Early detection of late blight in potato by whole-plant redox imaging. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 113:649-664. [PMID: 36534114 DOI: 10.1111/tpj.16071] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 12/06/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
Late blight caused by the oomycete Phytophthora infestans is a most devastating disease of potatoes (Solanum tuberosum). Its early detection is crucial for suppressing disease spread. Necrotic lesions are normally seen in leaves at 4 days post-inoculation (dpi) when colonized cells are dead, but early detection of the initial biotrophic growth stage, when the pathogen feeds on living cells, is challenging. Here, the biotrophic growth phase of P. infestans was detected by whole-plant redox imaging of potato plants expressing chloroplast-targeted reduction-oxidation sensitive green fluorescent protein (chl-roGFP2). Clear spots on potato leaves with a lower chl-roGFP2 oxidation state were detected as early as 2 dpi, before any visual symptoms were recorded. These spots were particularly evident during light-to-dark transitions, and reflected the mislocalization of chl-roGFP2 outside the chloroplasts. Image analysis based on machine learning enabled systematic identification and quantification of spots, and unbiased classification of infected and uninfected leaves in inoculated plants. Comparing redox with chlorophyll fluorescence imaging showed that infected leaf areas that exhibit mislocalized chl-roGFP2 also showed reduced non-photochemical quenching and enhanced quantum PSII yield (ΦPSII) compared with the surrounding leaf areas. The data suggest that mislocalization of chloroplast-targeted proteins is an efficient marker of late blight infection, and demonstrate how it can be utilized for non-destructive monitoring of the disease biotrophic stage using whole-plant redox imaging.
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Affiliation(s)
- Matanel Hipsch
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610000, Israel
| | - Yaron Michael
- Department of Soil & Water Sciences, Institute of Environmental Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Nardy Lampl
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610000, Israel
| | - Omer Sapir
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610000, Israel
| | - Yigal Cohen
- Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290000, Israel
| | - David Helman
- Department of Soil & Water Sciences, Institute of Environmental Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
- The Advanced School for Environmental Studies, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Shilo Rosenwasser
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610000, Israel
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18
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Gao LL, Hong ZH, Wang Y, Wu GZ. Chloroplast proteostasis: A story of birth, life, and death. PLANT COMMUNICATIONS 2023; 4:100424. [PMID: 35964157 PMCID: PMC9860172 DOI: 10.1016/j.xplc.2022.100424] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 08/02/2022] [Accepted: 08/10/2022] [Indexed: 06/02/2023]
Abstract
Protein homeostasis (proteostasis) is a dynamic balance of protein synthesis and degradation. Because of the endosymbiotic origin of chloroplasts and the massive transfer of their genetic information to the nucleus of the host cell, many protein complexes in the chloroplasts are constituted from subunits encoded by both genomes. Hence, the proper function of chloroplasts relies on the coordinated expression of chloroplast- and nucleus-encoded genes. The biogenesis and maintenance of chloroplast proteostasis are dependent on synthesis of chloroplast-encoded proteins, import of nucleus-encoded chloroplast proteins from the cytosol, and clearance of damaged or otherwise undesired "old" proteins. This review focuses on the regulation of chloroplast proteostasis, its interaction with proteostasis of the cytosol, and its retrograde control over nuclear gene expression. We also discuss significant issues and perspectives for future studies and potential applications for improving the photosynthetic performance and stress tolerance of crops.
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Affiliation(s)
- Lin-Lin Gao
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Zheng-Hui Hong
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Yinsong Wang
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Guo-Zhang Wu
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
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19
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He C, Berkowitz O, Hu S, Zhao Y, Qian K, Shou H, Whelan J, Wang Y. Co-regulation of mitochondrial and chloroplast function: Molecular components and mechanisms. PLANT COMMUNICATIONS 2023; 4:100496. [PMID: 36435968 PMCID: PMC9860188 DOI: 10.1016/j.xplc.2022.100496] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/20/2022] [Accepted: 11/23/2022] [Indexed: 06/16/2023]
Abstract
The metabolic interdependence, interactions, and coordination of functions between chloroplasts and mitochondria are established and intensively studied. However, less is known about the regulatory components that control these interactions and their responses to external stimuli. Here, we outline how chloroplastic and mitochondrial activities are coordinated via common components involved in signal transduction pathways, gene regulatory events, and post-transcriptional processes. The endoplasmic reticulum emerges as a point of convergence for both transcriptional and post-transcriptional pathways that coordinate chloroplast and mitochondrial functions. Although the identification of molecular components and mechanisms of chloroplast and mitochondrial signaling increasingly suggests common players, this raises the question of how these allow for distinct organelle-specific downstream pathways. Outstanding questions with respect to the regulation of post-transcriptional pathways and the cell and/or tissue specificity of organelle signaling are crucial for understanding how these pathways are integrated at a whole-plant level to optimize plant growth and its response to changing environmental conditions.
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Affiliation(s)
- Cunman He
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; Department of Animal, Plant and Soil Science, School of Agriculture, Biomedical and Environmental Sciences, La Trobe University, Bundoora, VIC 3086, Australia
| | - Oliver Berkowitz
- Department of Animal, Plant and Soil Science, School of Agriculture, Biomedical and Environmental Sciences, La Trobe University, Bundoora, VIC 3086, Australia
| | - Shanshan Hu
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; International Science and Technology Cooperation Base on Engineering Biology, International Campus of Zhejiang University, Haining, Zhejiang 314400, P.R. China
| | - Yang Zhao
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; Department of Animal, Plant and Soil Science, School of Agriculture, Biomedical and Environmental Sciences, La Trobe University, Bundoora, VIC 3086, Australia
| | - Kun Qian
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; Department of Animal, Plant and Soil Science, School of Agriculture, Biomedical and Environmental Sciences, La Trobe University, Bundoora, VIC 3086, Australia
| | - Huixia Shou
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; International Science and Technology Cooperation Base on Engineering Biology, International Campus of Zhejiang University, Haining, Zhejiang 314400, P.R. China
| | - James Whelan
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; Department of Animal, Plant and Soil Science, School of Agriculture, Biomedical and Environmental Sciences, La Trobe University, Bundoora, VIC 3086, Australia; International Science and Technology Cooperation Base on Engineering Biology, International Campus of Zhejiang University, Haining, Zhejiang 314400, P.R. China
| | - Yan Wang
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, P.R. China; Department of Animal, Plant and Soil Science, School of Agriculture, Biomedical and Environmental Sciences, La Trobe University, Bundoora, VIC 3086, Australia.
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20
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Sun Y, Yao Z, Ye Y, Fang J, Chen H, Lyu Y, Broad W, Fournier M, Chen G, Hu Y, Mohammed S, Ling Q, Jarvis RP. Ubiquitin-based pathway acts inside chloroplasts to regulate photosynthesis. SCIENCE ADVANCES 2022; 8:eabq7352. [PMID: 36383657 PMCID: PMC9668298 DOI: 10.1126/sciadv.abq7352] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Photosynthesis is the energetic basis for most life on Earth, and in plants it operates inside double membrane-bound organelles called chloroplasts. The photosynthetic apparatus comprises numerous proteins encoded by the nuclear and organellar genomes. Maintenance of this apparatus requires the action of internal chloroplast proteases, but a role for the nucleocytosolic ubiquitin-proteasome system (UPS) was not expected, owing to the barrier presented by the double-membrane envelope. Here, we show that photosynthesis proteins (including those encoded internally by chloroplast genes) are ubiquitinated and processed via the CHLORAD pathway: They are degraded by the 26S proteasome following CDC48-dependent retrotranslocation to the cytosol. This demonstrates that the reach of the UPS extends to the interior of endosymbiotically derived chloroplasts, where it acts to regulate photosynthesis, arguably the most fundamental process of life.
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Affiliation(s)
- Yi Sun
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
| | - Zujie Yao
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Yiting Ye
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jun Fang
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
| | - Honglin Chen
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Yuping Lyu
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Shanghai, China
| | - William Broad
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
| | - Marjorie Fournier
- Advanced Proteomics Facility, University of Oxford, Oxford OX1 3QU, UK
| | - Genyun Chen
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Yonghong Hu
- Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Shanghai, China
| | - Shabaz Mohammed
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
- Rosalind Franklin Institute, Oxfordshire OX11 0FA, UK
| | - Qihua Ling
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS-JIC Center of Excellence for Plant and Microbial Sciences (CEPAMS), Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- Corresponding author. (Q.L.); (R.P.J.)
| | - R. Paul Jarvis
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
- Corresponding author. (Q.L.); (R.P.J.)
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21
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Lee HY, Hwang OJ, Back K. Phytomelatonin as a signaling molecule for protein quality control via chaperone, autophagy, and ubiquitin-proteasome systems in plants. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:5863-5873. [PMID: 35246975 DOI: 10.1093/jxb/erac002] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
Physiological effects mediated by melatonin are attributable to its potent antioxidant activity as well as its role as a signaling molecule in inducing a vast array of melatonin-mediated genes. Here, we propose melatonin as a signaling molecule essential for protein quality control (PQC) in plants. PQC occurs by the coordinated activities of three systems: the chaperone network, autophagy, and the ubiquitin-proteasome system. With regard to the melatonin-mediated chaperone pathway, melatonin increases thermotolerance by induction of heat shock proteins and confers endoplasmic reticulum stress tolerance by increasing endoplasmic reticulum chaperone proteins. In chloroplasts, melatonin-induced chaperones, including Clps and CpHSP70s, play key roles in the PQC of chloroplast-localized proteins, such as Lhcb1, Lhcb4, and RBCL, during growth. Melatonin regulates PQC by autophagy processes, in which melatonin induces many autophagy (ATG) genes and autophagosome formation under stress conditions. Finally, melatonin-mediated plant stress tolerance is associated with up-regulation of stress-induced transcription factors, which are regulated by the ubiquitin-proteasome system. In this review, we propose that melatonin plays a pivotal role in PQC and consequently functions as a pleiotropic molecule under non-stress and adverse conditions in plants.
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Affiliation(s)
- Hyoung Yool Lee
- Department of Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, South Korea
| | - Ok Jin Hwang
- Department of Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, South Korea
| | - Kyoungwhan Back
- Department of Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, South Korea
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22
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Hand KA, Shabek N. The Role of E3 Ubiquitin Ligases in Chloroplast Function. Int J Mol Sci 2022; 23:9613. [PMID: 36077009 PMCID: PMC9455731 DOI: 10.3390/ijms23179613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/23/2022] [Accepted: 08/24/2022] [Indexed: 12/14/2022] Open
Abstract
Chloroplasts are ancient organelles responsible for photosynthesis and various biosynthetic functions essential to most life on Earth. Many of these functions require tightly controlled regulatory processes to maintain homeostasis at the protein level. One such regulatory mechanism is the ubiquitin-proteasome system whose fundamental role is increasingly emerging in chloroplasts. In particular, the role of E3 ubiquitin ligases as determinants in the ubiquitination and degradation of specific intra-chloroplast proteins. Here, we highlight recent advances in understanding the roles of plant E3 ubiquitin ligases SP1, COP1, PUB4, CHIP, and TT3.1 as well as the ubiquitin-dependent segregase CDC48 in chloroplast function.
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Affiliation(s)
| | - Nitzan Shabek
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA
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23
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Chloroplasts Protein Quality Control and Turnover: A Multitude of Mechanisms. Int J Mol Sci 2022; 23:ijms23147760. [PMID: 35887108 PMCID: PMC9319218 DOI: 10.3390/ijms23147760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/11/2022] [Accepted: 07/12/2022] [Indexed: 11/16/2022] Open
Abstract
As the organelle of photosynthesis and other important metabolic pathways, chloroplasts contain up to 70% of leaf proteins with uniquely complex processes in synthesis, import, assembly, and turnover. Maintaining functional protein homeostasis in chloroplasts is vitally important for the fitness and survival of plants. Research over the past several decades has revealed a multitude of mechanisms that play important roles in chloroplast protein quality control and turnover under normal and stress conditions. These mechanisms include: (i) endosymbiotically-derived proteases and associated proteins that play a vital role in maintaining protein homeostasis inside the chloroplasts, (ii) the ubiquitin-dependent turnover of unimported chloroplast precursor proteins to prevent their accumulation in the cytosol, (iii) chloroplast-associated degradation of the chloroplast outer-membrane translocon proteins for the regulation of chloroplast protein import, (iv) chloroplast unfolded protein response triggered by accumulated unfolded and misfolded proteins inside the chloroplasts, and (v) vesicle-mediated degradation of chloroplast components in the vacuole. Here, we provide a comprehensive review of these diverse mechanisms of chloroplast protein quality control and turnover and discuss important questions that remain to be addressed in order to better understand and improve important chloroplast functions.
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Yue N, Jiang Z, Zhang X, Li Z, Wang X, Wen Z, Gao Z, Pi Q, Zhang Y, Wang X, Han C, Yu J, Li D. Palmitoylation of γb protein directs a dynamic switch between Barley stripe mosaic virus replication and movement. EMBO J 2022; 41:e110060. [PMID: 35642376 PMCID: PMC9251889 DOI: 10.15252/embj.2021110060] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 04/28/2022] [Accepted: 05/05/2022] [Indexed: 11/09/2022] Open
Abstract
Viral replication and movement are intimately linked; however, the molecular mechanisms regulating the transition between replication and subsequent movement remain largely unknown. We previously demonstrated that the Barley stripe mosaic virus (BSMV) γb protein promotes viral replication and movement by interacting with the αa replicase and TGB1 movement proteins. Here, we found that γb is palmitoylated at Cys-10, Cys-19, and Cys-60 in Nicotiana benthamiana, which supports BSMV infection. Intriguingly, non-palmitoylated γb is anchored to chloroplast replication sites and enhances BSMV replication, whereas palmitoylated γb protein recruits TGB1 to the chloroplasts and forms viral replication-movement intermediate complexes. At the late stages of replication, γb interacts with NbPAT15 and NbPAT21 and is palmitoylated at the chloroplast periphery, thereby shifting viral replication to intracellular and intercellular movement. We also show that palmitoylated γb promotes virus cell-to-cell movement by interacting with NbREM1 to inhibit callose deposition at the plasmodesmata. Altogether, our experiments reveal a model whereby palmitoylation of γb directs a dynamic switch between BSMV replication and movement events during infection.
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Affiliation(s)
- Ning Yue
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Zhihao Jiang
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Xuan Zhang
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Zhenggang Li
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Xueting Wang
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Zhiyan Wen
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Zongyu Gao
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Qinglin Pi
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Yongliang Zhang
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Xian‐Bing Wang
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Chenggui Han
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Jialin Yu
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Dawei Li
- State Key Laboratory of Agro‐Biotechnology, College of Biological SciencesChina Agricultural UniversityBeijingChina
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25
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Barth MA, Soll J, Akbaş Ş. Prokaryotic and eukaryotic traits support the biological role of the chloroplast outer envelope. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119224. [PMID: 35120999 DOI: 10.1016/j.bbamcr.2022.119224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 01/22/2022] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
The plastid outer envelope (OE) is a mixture of components inherited from their prokaryotic ancestor like galactolipids, carotenoids and porin type ion channels supplemented with eukaryotic inventions to make the endosymbiotic process successful as well as to control plastid biogenesis and differentiation. In this review we wanted to highlight the importance of the OE proteins and its evolutionary origin. For a long time, the OE was thought to be a diffusion barrier only, but with the recent discoveries of all kinds of different proteins in the OE it has been shown that the OE can modulate various functions within the cell. The phenotypic changes show that channels like the outer envelope proteins OEP40, OEP16 or JASSY have a pronounced ion selectivity that cannot be replaced by other ion channels present in the OE. Eukaryotic additions, like the GTPase receptors Toc33 and Toc159 or the ubiquitin proteasome system for chloroplast protein quality control, round up the profile of the OE.
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Affiliation(s)
- Melanie Anette Barth
- Department Biologie 1, Botanik, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - Jürgen Soll
- Department Biologie 1, Botanik, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany.
| | - Şebnem Akbaş
- Department Biologie 1, Botanik, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
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Calvanese E, Gu Y. Towards understanding inner nuclear membrane protein degradation in plants. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:2266-2274. [PMID: 35139191 DOI: 10.1093/jxb/erac037] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 01/31/2022] [Indexed: 06/14/2023]
Abstract
The inner nuclear membrane (INM) hosts a unique set of membrane proteins that play essential roles in various aspects of the nuclear function. However, overaccumulation or malfunction of INM protein has been associated with a range of rare genetic diseases; therefore, maintaining the homeostasis and integrity of INM proteins by active removal of aberrantly accumulated proteins and replacing defective molecules through proteolysis is of critical importance. Within the last decade, it has been shown that INM proteins are degraded in yeasts by a process very similar to endoplasmic reticulum-associated degradation (ERAD), which is accomplished by retrotranslocation of membrane substrates followed by proteasome-dependent proteolysis, and this process was named inner nuclear membrane-associated degradation (INMAD). INMAD is distinguished from ERAD by specific INM-localized E3 ubiquitin ligases and proteolysis regulators. While much is yet to be determined about the INMAD pathway in yeasts, virtually no knowledge of it exists for higher eukaryotes, and only very recently have several critical regulators that participate in INM protein degradation been discovered in plants. Here, we review key molecular components of the INMAD pathway and draw parallels between the yeast and plant system to discuss promising directions in the future study of the plant INMAD process.
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Affiliation(s)
- Enrico Calvanese
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
- Innovative Genomics Institute, University of California, Berkeley, CA 94720, USA
| | - Yangnan Gu
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
- Innovative Genomics Institute, University of California, Berkeley, CA 94720, USA
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27
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Woodson JD. Control of chloroplast degradation and cell death in response to stress. Trends Biochem Sci 2022; 47:851-864. [DOI: 10.1016/j.tibs.2022.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/25/2022] [Accepted: 03/14/2022] [Indexed: 12/16/2022]
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Coordination of Chloroplast Activity with Plant Growth: Clues Point to TOR. PLANTS 2022; 11:plants11060803. [PMID: 35336685 PMCID: PMC8953291 DOI: 10.3390/plants11060803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 11/17/2022]
Abstract
Photosynthesis is the defining function of most autotrophic organisms. In the plantae kingdom, chloroplasts host this function and ensure growth. However, these organelles are very sensitive to stressful conditions and the photosynthetic process can cause photooxidative damage if not perfectly regulated. In addition, their function is energivorous in terms of both chemical energy and nutrients. To coordinate chloroplast activity with the cell’s need, continuous signaling is required: from chloroplasts to cytoplasm and from nucleus to chloroplasts. In this opinion article, several mechanisms that ensure this communication are reported and the many clues that point to an important role of the Target of Rapamycin (TOR) kinase in the coordination between the eukaryotic and prokaryotic sides of plants are highlighted.
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TIC236 gain-of-function mutations unveil the link between plastid division and plastid protein import. Proc Natl Acad Sci U S A 2022; 119:e2123353119. [PMID: 35275795 PMCID: PMC8931380 DOI: 10.1073/pnas.2123353119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Although plastid division is critical for plant development, how components of the plastid division machinery (PDM) are imported into plastids remains unexplored. A forward genetic screen to identify suppressors of a crumpled leaf (crl) mutant deficient in plastid division led us to find dominant gain-of-function (GF) mutations in TIC236, which significantly increases the import of PDM components and completely rescues crl phenotypes. The defective plastid division phenotypes in crl and tic236-knockdown mutants and CRL-TIC236 association in a functional complex indicate that the CRL-TIC236 module is vital for plastid division. Hence, we report the first GF translocon mutants and unveil CRL as a novel functional partner of TIC236 for PDM import. TIC236 is an essential component of the translocon for protein import into chloroplasts, as evidenced by the embryonic lethality of the knockout mutant. Here, we unveil a TIC236-allied component, the chloroplast outer membrane protein CRUMPLED LEAF (CRL), absence of which impairs plastid division and induces autoimmune responses in Arabidopsis thaliana. A forward genetic screen exploring CRL function found multiple dominant TIC236 gain-of-function (tic236-gf) mutations that abolished crl-induced phenotypes. Moreover, CRL associates with TIC236, and a tic236-knockdown mutant exhibited multiple lesions similar to the crl mutant, supporting their shared functionality. Consistent with the defective plastid division phenotype of crl, CRL interacts with the transit peptides of proteins essential in plastid division, with tic236-gf mutations reinforcing their import via increased TIC236 stability. Ensuing reverse genetic analyses further revealed genetic interaction between CRL and SP1, a RING-type ubiquitin E3 ligase, as well as with the plastid protease FTSH11, which function in TOC and TIC protein turnover, respectively. Loss of either SP1 or FTSH11 rescued crl mutant phenotypes to varying degrees due to increased translocon levels. Collectively, our data shed light on the links between plastid protein import, plastid division, and plant stress responses.
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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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31
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Song Y, Feng L, Alyafei MAM, Jaleel A, Ren M. Function of Chloroplasts in Plant Stress Responses. Int J Mol Sci 2021; 22:ijms222413464. [PMID: 34948261 PMCID: PMC8705820 DOI: 10.3390/ijms222413464] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/06/2021] [Accepted: 12/13/2021] [Indexed: 12/24/2022] Open
Abstract
The chloroplast has a central position in oxygenic photosynthesis and primary metabolism. In addition to these functions, the chloroplast has recently emerged as a pivotal regulator of plant responses to abiotic and biotic stress conditions. Chloroplasts have their own independent genomes and gene-expression machinery and synthesize phytohormones and a diverse range of secondary metabolites, a significant portion of which contribute the plant response to adverse conditions. Furthermore, chloroplasts communicate with the nucleus through retrograde signaling, for instance, reactive oxygen signaling. All of the above facilitate the chloroplast’s exquisite flexibility in responding to environmental stresses. In this review, we summarize recent findings on the involvement of chloroplasts in plant regulatory responses to various abiotic and biotic stresses including heat, chilling, salinity, drought, high light environmental stress conditions, and pathogen invasions. This review will enrich the better understanding of interactions between chloroplast and environmental stresses, and will lay the foundation for genetically enhancing plant-stress acclimatization.
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Affiliation(s)
- Yun Song
- School of Life Sciences, Liaocheng University, Liaocheng 252000, China;
| | - Li Feng
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu 610213, China;
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou 450001, China
| | - Mohammed Abdul Muhsen Alyafei
- Department of Integrative Agriculture, College of Agriculture and Veterinary Medicine, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (M.A.M.A.); (A.J.)
| | - Abdul Jaleel
- Department of Integrative Agriculture, College of Agriculture and Veterinary Medicine, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (M.A.M.A.); (A.J.)
| | - Maozhi Ren
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu 610213, China;
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou 450001, China
- Correspondence: ; Tel.: +86-(13)-527313471
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32
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Luo S, Kim C. Current Understanding of Temperature Stress-Responsive Chloroplast FtsH Metalloproteases. Int J Mol Sci 2021; 22:ijms222212106. [PMID: 34829988 PMCID: PMC8622299 DOI: 10.3390/ijms222212106] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/07/2021] [Accepted: 11/08/2021] [Indexed: 12/22/2022] Open
Abstract
Low and high temperatures are life-threatening stress factors, diminishing plant productivity. One of the earliest responses of plants to stress is a rapid burst of reactive oxygen species (ROS) in chloroplasts. Widespread efforts over the past decade shed new light on the chloroplast as an environmental sensor, translating the environmental fluctuation into varying physiological responses by utilizing distinct retrograde (chloroplast-to-nucleus) signals. Recent studies have unveiled that chloroplasts mediate a similar unfolded/misfolded/damaged protein response (cpUPR) as observed in the endoplasmic reticulum and mitochondria. Although observing cpUPR is not surprising since the chloroplast is a prime organelle producing harmful ROS, the intertwined relationship among ROS, protein damage, and chloroplast protein quality controls (cpPQCs) with retrograde signaling has recently been reported. This finding also gives rise to critical attention on chloroplast proteins involved in cpPQCs, ROS detoxifiers, transcription/translation, import of precursor proteins, and assembly/maturation, the deficiency of which compromises chloroplast protein homeostasis (proteostasis). Any perturbation in the protein may require readjustment of proteostasis by transmitting retrograde signal(s) to the nucleus, whose genome encodes most of the chloroplast proteins involved in proteostasis. This review focuses on recent findings on cpUPR and chloroplast-targeted FILAMENTOUS TEMPERATURE-SENSITIVE H proteases involved in cpPQC and retrograde signaling and their impacts on plant responses to temperature stress.
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Affiliation(s)
- Shengji Luo
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Chanhong Kim
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
- Correspondence:
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Clavel M, Dagdas Y. Proteasome and selective autophagy: Brothers-in-arms for organelle quality control. CURRENT OPINION IN PLANT BIOLOGY 2021; 63:102106. [PMID: 34487948 DOI: 10.1016/j.pbi.2021.102106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/08/2021] [Accepted: 08/02/2021] [Indexed: 06/13/2023]
Abstract
Maintaining the integrity of organelles despite the cellular disturbances that arise during stress is essential for life. To ensure organelle proteostasis (protein homeostasis), plants have evolved multitiered quality control mechanisms that work together to repair or recycle the damaged organelles. Despite recent advances, our understanding of plant organelle quality control mechanisms is far from complete. Especially, the crosstalk between different quality control pathways remains elusive. Here, we highlight recent advances on organelle quality control, focusing on the targeted protein degradation pathways that maintain the homeostasis of the endoplasmic reticulum (ER), chloroplast, and mitochondria. We discuss how plant cells decide to employ different degradation pathways and propose tools that could be used to discover the missing components in organelle quality control.
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Affiliation(s)
- Marion Clavel
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria.
| | - Yasin Dagdas
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria.
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Jeran N, Rotasperti L, Frabetti G, Calabritto A, Pesaresi P, Tadini L. The PUB4 E3 Ubiquitin Ligase Is Responsible for the Variegated Phenotype Observed upon Alteration of Chloroplast Protein Homeostasis in Arabidopsis Cotyledons. Genes (Basel) 2021; 12:genes12091387. [PMID: 34573369 PMCID: PMC8464772 DOI: 10.3390/genes12091387] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 08/31/2021] [Accepted: 09/03/2021] [Indexed: 12/17/2022] Open
Abstract
During a plant's life cycle, plastids undergo several modifications, from undifferentiated pro-plastids to either photosynthetically-active chloroplasts, ezioplasts, chromoplasts or storage organelles, such as amyloplasts, elaioplasts and proteinoplasts. Plastid proteome rearrangements and protein homeostasis, together with intracellular communication pathways, are key factors for correct plastid differentiation and functioning. When plastid development is affected, aberrant organelles are degraded and recycled in a process that involves plastid protein ubiquitination. In this study, we have analysed the Arabidopsis gun1-102 ftsh5-3 double mutant, lacking both the plastid-located protein GUN1 (Genomes Uncoupled 1), involved in plastid-to-nucleus communication, and the chloroplast-located FTSH5 (Filamentous temperature-sensitive H5), a metalloprotease with a role in photosystem repair and chloroplast biogenesis. gun1-102 ftsh5-3 seedlings show variegated cotyledons and true leaves that we attempted to suppress by introgressing second-site mutations in genes involved in: (i) plastid translation, (ii) plastid folding/import and (iii) cytosolic protein ubiquitination. Different phenotypic effects, ranging from seedling-lethality to partial or complete suppression of the variegated phenotype, were observed in the corresponding triple mutants. Our findings indicate that Plant U-Box 4 (PUB4) E3 ubiquitin ligase plays a major role in the target degradation of damaged chloroplasts and is the main contributor to the variegated phenotype observed in gun1-102 ftsh5-3 seedlings.
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35
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Watson SJ, Li N, Ye Y, Wu F, Ling Q, Jarvis RP. Crosstalk between the chloroplast protein import and SUMO systems revealed through genetic and molecular investigation in Arabidopsis. eLife 2021; 10:60960. [PMID: 34473053 PMCID: PMC8497055 DOI: 10.7554/elife.60960] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 09/01/2021] [Indexed: 11/19/2022] Open
Abstract
The chloroplast proteome contains thousands of different proteins that are encoded by the nuclear genome. These proteins are imported into the chloroplast via the action of the TOC translocase and associated downstream systems. Our recent work has revealed that the stability of the TOC complex is dynamically regulated by the ubiquitin-dependent chloroplast-associated protein degradation pathway. Here, we demonstrate that the TOC complex is also regulated by the small ubiquitin-like modifier (SUMO) system. Arabidopsis mutants representing almost the entire SUMO conjugation pathway can partially suppress the phenotype of ppi1, a pale-yellow mutant lacking the Toc33 protein. This suppression is linked to increased abundance of TOC proteins and improvements in chloroplast development. Moreover, data from molecular and biochemical experiments support a model in which the SUMO system directly regulates TOC protein stability. Thus, we have identified a regulatory link between the SUMO system and the chloroplast protein import machinery. All green plants grow by converting light energy into chemical energy. They do this using a process called photosynthesis, which happens inside compartments in plant cells called chloroplasts. Chloroplasts use thousands of different proteins to make chemical energy. Some of these proteins allow the chloroplasts to absorb light energy using chlorophyll, the pigment that makes leaves green. The vast majority of these proteins are transported into the chloroplasts through a protein machine called the TOC complex. When plants lack parts of the TOC complex, their chloroplasts develop abnormally, and their leaves turn yellow. Photosynthesis can make toxic by-products, so cells need a way to turn it off when they are under stress; for example, by lowering the number of TOC complexes on the chloroplasts. This is achieved by tagging TOC complexes with a molecule called ubiquitin, which will lead to their removal from chloroplasts, slowing photosynthesis down. It is unknown whether another, similar, molecular tag called SUMO aids in this destruction process. To find out, Watson et al. examined a mutant of the plant Arabidopsis thaliana. This mutant had low levels of the TOC complex, turning its leaves pale yellow. A combination of genetic, molecular, and biochemical experiments showed that SUMO molecular tags control the levels of TOC complex on chloroplasts. Increasing the amount of SUMO in the mutant plants made their leaves turn yellower, while interfering with the genes responsible for depositing SUMO tags turned the leaves green. This implies that in plants with less SUMO tags, cells stopped destroying their TOC complexes, allowing the chloroplasts to develop better, and changing the colour of the leaves. The SUMO tagging of TOC complexes shares a lot of genetic similarities with the ubiquitin tag system. It is possible that SUMO tags may help to control the CHLORAD pathway, which destroys TOC complexes marked with ubiquitin. Understanding this relationship, and how to influence it, could help to improve the performance of crops. The next step is to understand exactly how SUMO tags promote the destruction of the TOC complex.
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Affiliation(s)
| | - Na Li
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Yiting Ye
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Feijie Wu
- National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.,Department of Biology, University of Leicester, Leicester, United Kingdom
| | - Qihua Ling
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom.,National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.,Department of Biology, University of Leicester, Leicester, United Kingdom
| | - R Paul Jarvis
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom.,Department of Biology, University of Leicester, Leicester, United Kingdom
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Wang X, Jiang Z, Yue N, Jin X, Zhang X, Li Z, Zhang Y, Wang X, Han C, Yu J, Li D. Barley stripe mosaic virus γb protein disrupts chloroplast antioxidant defenses to optimize viral replication. EMBO J 2021; 40:e107660. [PMID: 34254679 PMCID: PMC8365260 DOI: 10.15252/embj.2021107660] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 06/10/2021] [Accepted: 06/17/2021] [Indexed: 01/21/2023] Open
Abstract
The plant antioxidant system plays important roles in response to diverse abiotic and biotic stresses. However, the effects of virus infection on host redox homeostasis and how antioxidant defense pathway is manipulated by viruses remain poorly understood. We previously demonstrated that the Barley stripe mosaic virus (BSMV) γb protein is recruited to the chloroplast by the viral αa replicase to enhance viral replication. Here, we show that BSMV infection induces chloroplast oxidative stress. The versatile γb protein interacts directly with NADPH-dependent thioredoxin reductase C (NTRC), a core component of chloroplast antioxidant systems. Overexpression of NbNTRC significantly impairs BSMV replication in Nicotiana benthamiana plants, whereas disruption of NbNTRC expression leads to increased viral accumulation and infection severity. To counter NTRC-mediated defenses, BSMV employs the γb protein to competitively interfere with NbNTRC binding to 2-Cys Prx. Altogether, this study indicates that beyond acting as a helicase enhancer, γb also subverts NTRC-mediated chloroplast antioxidant defenses to create an oxidative microenvironment conducive to viral replication.
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Affiliation(s)
- Xueting Wang
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Zhihao Jiang
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Ning Yue
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Xuejiao Jin
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Xuan Zhang
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Zhaolei Li
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Yongliang Zhang
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Xian‐Bing Wang
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Chenggui Han
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Jialin Yu
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Dawei Li
- State Key Laboratory of Agro‐Biotechnology and Ministry of Agriculture Key Laboratory of Soil MicrobiologyCollege of Biological SciencesChina Agricultural UniversityBeijingChina
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Hameed A, Ahmed MZ, Hussain T, Aziz I, Ahmad N, Gul B, Nielsen BL. Effects of Salinity Stress on Chloroplast Structure and Function. Cells 2021; 10:2023. [PMID: 34440792 PMCID: PMC8395010 DOI: 10.3390/cells10082023] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 08/05/2021] [Indexed: 02/07/2023] Open
Abstract
Salinity is a growing problem affecting soils and agriculture in many parts of the world. The presence of salt in plant cells disrupts many basic metabolic processes, contributing to severe negative effects on plant development and growth. This review focuses on the effects of salinity on chloroplasts, including the structures and function of these organelles. Chloroplasts house various important biochemical reactions, including photosynthesis, most of which are considered essential for plant survival. Salinity can affect these reactions in a number of ways, for example, by changing the chloroplast size, number, lamellar organization, lipid and starch accumulation, and interfering with cross-membrane transportation. Research has shown that maintenance of the normal chloroplast physiology is necessary for the survival of the entire plant. Many plant species have evolved different mechanisms to withstand the harmful effects of salt-induced toxicity on their chloroplasts and its machinery. The differences depend on the plant species and growth stage and can be quite different between salt-sensitive (glycophyte) and salt-tolerant (halophyte) plants. Salt stress tolerance is a complex trait, and many aspects of salt tolerance in plants are not entirely clear yet. In this review, we discuss the different mechanisms of salt stress tolerance in plants with a special focus on chloroplast structure and its functions, including the underlying differences between glycophytes and halophytes.
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Affiliation(s)
- Abdul Hameed
- Dr. M. Ajmal Khan Institute for Sustainable Halophyte Utilization, University of Karachi, Sindh 75270, Pakistan; (A.H.); (M.Z.A.); (T.H.); (I.A.); (B.G.)
| | - Muhammad Zaheer Ahmed
- Dr. M. Ajmal Khan Institute for Sustainable Halophyte Utilization, University of Karachi, Sindh 75270, Pakistan; (A.H.); (M.Z.A.); (T.H.); (I.A.); (B.G.)
| | - Tabassum Hussain
- Dr. M. Ajmal Khan Institute for Sustainable Halophyte Utilization, University of Karachi, Sindh 75270, Pakistan; (A.H.); (M.Z.A.); (T.H.); (I.A.); (B.G.)
| | - Irfan Aziz
- Dr. M. Ajmal Khan Institute for Sustainable Halophyte Utilization, University of Karachi, Sindh 75270, Pakistan; (A.H.); (M.Z.A.); (T.H.); (I.A.); (B.G.)
| | - Niaz Ahmad
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad 44000, Pakistan;
- Department of Biotechnology, Pakistan Institute of Engineering and Applied Science (PIEAS), Islamabad 44000, Pakistan
| | - Bilquees Gul
- Dr. M. Ajmal Khan Institute for Sustainable Halophyte Utilization, University of Karachi, Sindh 75270, Pakistan; (A.H.); (M.Z.A.); (T.H.); (I.A.); (B.G.)
| | - Brent L. Nielsen
- Department of Microbiology & Molecular Biology, Brigham Young University, Provo, UT 84602, USA
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Rodríguez-Saavedra C, Morgado-Martínez LE, Burgos-Palacios A, King-Díaz B, López-Coria M, Sánchez-Nieto S. Moonlighting Proteins: The Case of the Hexokinases. Front Mol Biosci 2021; 8:701975. [PMID: 34235183 PMCID: PMC8256278 DOI: 10.3389/fmolb.2021.701975] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 05/24/2021] [Indexed: 12/14/2022] Open
Abstract
Moonlighting proteins are defined as proteins with two or more functions that are unrelated and independent to each other, so that inactivation of one of them should not affect the second one and vice versa. Intriguingly, all the glycolytic enzymes are described as moonlighting proteins in some organisms. Hexokinase (HXK) is a critical enzyme in the glycolytic pathway and displays a wide range of functions in different organisms such as fungi, parasites, mammals, and plants. This review discusses HXKs moonlighting functions in depth since they have a profound impact on the responses to nutritional, environmental, and disease challenges. HXKs’ activities can be as diverse as performing metabolic activities, as a gene repressor complexing with other proteins, as protein kinase, as immune receptor and regulating processes like autophagy, programmed cell death or immune system responses. However, most of those functions are particular for some organisms while the most common moonlighting HXK function in several kingdoms is being a glucose sensor. In this review, we also analyze how different regulation mechanisms cause HXK to change its subcellular localization, oligomeric or conformational state, the response to substrate and product concentration, and its interactions with membrane, proteins, or RNA, all of which might impact the HXK moonlighting functions.
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Affiliation(s)
- Carolina Rodríguez-Saavedra
- Laboratorio de Transporte y Percepción de Azúcares en Plantas, Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Luis Enrique Morgado-Martínez
- Laboratorio de Transporte y Percepción de Azúcares en Plantas, Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Andrés Burgos-Palacios
- Laboratorio de Transporte y Percepción de Azúcares en Plantas, Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Beatriz King-Díaz
- Laboratorio de Transporte y Percepción de Azúcares en Plantas, Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Montserrat López-Coria
- Laboratorio de Transporte y Percepción de Azúcares en Plantas, Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Sobeida Sánchez-Nieto
- Laboratorio de Transporte y Percepción de Azúcares en Plantas, Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Tracz M, Górniak I, Szczepaniak A, Białek W. E3 Ubiquitin Ligase SPL2 Is a Lanthanide-Binding Protein. Int J Mol Sci 2021; 22:5712. [PMID: 34071935 PMCID: PMC8198723 DOI: 10.3390/ijms22115712] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 01/17/2023] Open
Abstract
The SPL2 protein is an E3 ubiquitin ligase of unknown function. It is one of only three types of E3 ligases found in the outer membrane of plant chloroplasts. In this study, we show that the cytosolic fragment of SPL2 binds lanthanide ions, as evidenced by fluorescence measurements and circular dichroism spectroscopy. We also report that SPL2 undergoes conformational changes upon binding of both Ca2+ and La3+, as evidenced by its partial unfolding. However, these structural rearrangements do not interfere with SPL2 enzymatic activity, as the protein retains its ability to auto-ubiquitinate in vitro. The possible applications of lanthanide-based probes to identify protein interactions in vivo are also discussed. Taken together, the results of this study reveal that the SPL2 protein contains a lanthanide-binding site, showing for the first time that at least some E3 ubiquitin ligases are also capable of binding lanthanide ions.
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Affiliation(s)
- Michał Tracz
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland; (M.T.); (I.G.); (A.S.)
| | - Ireneusz Górniak
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland; (M.T.); (I.G.); (A.S.)
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Andrzej Szczepaniak
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland; (M.T.); (I.G.); (A.S.)
| | - Wojciech Białek
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland; (M.T.); (I.G.); (A.S.)
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Guardini Z, Dall’Osto L, Barera S, Jaberi M, Cazzaniga S, Vitulo N, Bassi R. High Carotenoid Mutants of Chlorella vulgaris Show Enhanced Biomass Yield under High Irradiance. PLANTS 2021; 10:plants10050911. [PMID: 34062906 PMCID: PMC8147269 DOI: 10.3390/plants10050911] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/30/2022]
Abstract
Microalgae represent a carbon-neutral source of bulk biomass, for extraction of high-value compounds and production of renewable fuels. Due to their high metabolic activity and reproduction rates, species of the genus Chlorella are highly productive when cultivated in photobioreactors. However, wild-type strains show biological limitations making algal bioproducts expensive compared to those extracted from other feedstocks. Such constraints include inhomogeneous light distribution due to high optical density of the culture, and photoinhibition of the surface-exposed cells. Thus, the domestication of algal strains for industry makes it increasingly important to select traits aimed at enhancing light-use efficiency while withstanding excess light stress. Carotenoids have a crucial role in protecting against photooxidative damage and, thus, represent a promising target for algal domestication. We applied chemical mutagenesis to Chlorella vulgaris and selected for enhanced tolerance to the carotenoid biosynthesis inhibitor norflurazon. The NFR (norflurazon-resistant) strains showed an increased carotenoid pool size and enhanced tolerance towards photooxidative stress. Growth under excess light revealed an improved carbon assimilation rate of NFR strains with respect to WT. We conclude that domestication of Chlorella vulgaris, by optimizing both carotenoid/chlorophyll ratio and resistance to photooxidative stress, boosted light-to-biomass conversion efficiency under high light conditions typical of photobioreactors. Comparison with strains previously reported for enhanced tolerance to singlet oxygen, reveals that ROS resistance in Chlorella is promoted by at least two independent mechanisms, only one of which is carotenoid-dependent.
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Ling Q, Sadali NM, Soufi Z, Zhou Y, Huang B, Zeng Y, Rodriguez-Concepcion M, Jarvis RP. The chloroplast-associated protein degradation pathway controls chromoplast development and fruit ripening in tomato. NATURE PLANTS 2021; 7:655-666. [PMID: 34007040 DOI: 10.1038/s41477-021-00916-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 04/06/2021] [Indexed: 06/12/2023]
Abstract
The maturation of green fleshy fruit to become colourful and flavoursome is an important strategy for plant reproduction and dispersal. In tomato (Solanum lycopersicum) and many other species, fruit ripening is intimately linked to the biogenesis of chromoplasts, the plastids that are abundant in ripe fruit and specialized for the accumulation of carotenoid pigments. Chromoplasts develop from pre-existing chloroplasts in the fruit, but the mechanisms underlying this transition are poorly understood. Here, we reveal a role for the chloroplast-associated protein degradation (CHLORAD) proteolytic pathway in chromoplast differentiation. Knockdown of the plastid ubiquitin E3 ligase SP1, or its homologue SPL2, delays tomato fruit ripening, whereas overexpression of SP1 accelerates ripening, as judged by colour changes. We demonstrate that SP1 triggers broader effects on fruit ripening, including fruit softening, and gene expression and metabolism changes, by promoting the chloroplast-to-chromoplast transition. Moreover, we show that tomato SP1 and SPL2 regulate leaf senescence, revealing conserved functions of CHLORAD in plants. We conclude that SP1 homologues control plastid transitions during fruit ripening and leaf senescence by enabling reconfiguration of the plastid protein import machinery to effect proteome reorganization. The work highlights the critical role of chromoplasts in fruit ripening, and provides a theoretical basis for engineering crop improvements.
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Affiliation(s)
- Qihua Ling
- Department of Plant Sciences, University of Oxford, Oxford, UK
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS-JIC Center of Excellence for Plant and Microbial Sciences (CEPAMS), Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Najiah Mohd Sadali
- Department of Plant Sciences, University of Oxford, Oxford, UK
- Centre for Research in Biotechnology for Agriculture (CEBAR), University of Malaya, Kuala Lumpur, Malaysia
| | - Ziad Soufi
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - Yuan Zhou
- Department of Plant Sciences, University of Oxford, Oxford, UK
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Binquan Huang
- Department of Plant Sciences, University of Oxford, Oxford, UK
- School of Agriculture, Yunnan University, Kunming, China
| | - Yunliu Zeng
- Department of Plant Sciences, University of Oxford, Oxford, UK
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Manuel Rodriguez-Concepcion
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), CSIC-Universitat Politècnica de València, Valencia, Spain
| | - R Paul Jarvis
- Department of Plant Sciences, University of Oxford, Oxford, UK.
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Sharma S, Prasad A, Sharma N, Prasad M. Role of ubiquitination enzymes in abiotic environmental interactions with plants. Int J Biol Macromol 2021; 181:494-507. [PMID: 33798570 DOI: 10.1016/j.ijbiomac.2021.03.185] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/08/2021] [Accepted: 03/27/2021] [Indexed: 12/14/2022]
Abstract
Ubiquitination, a post-translational modification, plays a crucial role in various aspects of plant development and stress responses. Protein degradation by ubiquitination is well established and ubiquitin is the main underlying component directing the turnover of proteins. Recent reports have also revealed the non-proteolytic roles of ubiquitination in plants. In the past decade, ubiquitination has emerged to be one of the most important players in modulating plant's responses to abiotic stresses, which led to identification of specific E3 ligases and their targets involved in the process. Most of the E3 ligases play regulatory roles by modifying the stability and accumulation of stress responsive regulatory proteins, such as transcription factors, thus, modifying the downstream responses, or by degrading the proteins involved in the downstream cascade itself. In this review, we summarize and highlight the recent advances in the field of ubiquitination-mediated regulation of plant's responses to various abiotic stresses including limited nutrient availability and metal toxicity. The non-proteolytic role of ubiquitination in epigenetic regulation of abiotic stress induced response has also been discussed.
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Affiliation(s)
- Shambhavi Sharma
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Ashish Prasad
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Namisha Sharma
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Manoj Prasad
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India.
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Cheng L, Zhang W, Hu J, Zhang Z, Liu Y, Lin Y. Characterization of the key region and putative phosphorylation sites of EcaICE1 in its molecular interaction with the EcaHOS1 protein in Eucalyptus camaldulensis. PLANT BIOLOGY (STUTTGART, GERMANY) 2021; 23:400-406. [PMID: 33107181 DOI: 10.1111/plb.13205] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/22/2020] [Indexed: 06/11/2023]
Abstract
Inducer of CBF expression 1 (ICE1), a MYC-like bHLH transcriptional activator, plays an important role in plants under cold stress. The ubiquitination-proteasome pathway mediated by high expression of osmotically responsive gene1 (HOS1) can effectively induce the degradation of ICE1 and decrease the expression of CBFs and their downstream genes under cold stress response in Arabidopsis, but knowledge of ubiquitination regulation of ICE1 by HOS1 is still limited in woody plants. In this study, a E3 ubiquitin ligase gene EcaHOS1 were amplified from Eucalyptus camaldulensis and the protein interactions between EcaICE1 and EcaHOS1 were analysed. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assay results showed that EcaICE1 can interact with the EcaHOS1 protein in the nucleus and, further, the Y2H assay demonstrated that the 126-185 amino acid region at the N-terminus of the EcaICE1 protein was indispensable for its interaction with EcaHOS1 protein. Moreover, we found that the amino acids at positions 145, 158 and 184 within the key interaction region were the putative phosphorylation sites of EcaICE1, based on bioinformatics analysis, and only the substitution of serine (Ser) 158 by alanine (Ala) blocked the protein-protein interactions between EcaICE1 and EcaHOS1 based on Y2H and β-galactosidase activity assays using site-directed mutagenesis. We identified Ser 158 of EcaICE1 as the key putative phosphorylation site for its interaction with the EcaHOS1 protein.
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Affiliation(s)
- L Cheng
- College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou, China
- Guangzhou Genedenovo Biotechnology Company Limited, Guangzhou, China
| | - W Zhang
- Guangdong Academy of Forestry, Guangzhou, China
| | - J Hu
- College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou, China
| | - Z Zhang
- College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou, China
| | - Y Liu
- College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou, China
| | - Y Lin
- College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou, China
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Doroodian P, Hua Z. The Ubiquitin Switch in Plant Stress Response. PLANTS (BASEL, SWITZERLAND) 2021; 10:246. [PMID: 33514032 PMCID: PMC7911189 DOI: 10.3390/plants10020246] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 01/19/2021] [Accepted: 01/22/2021] [Indexed: 12/20/2022]
Abstract
Ubiquitin is a 76 amino acid polypeptide common to all eukaryotic organisms. It functions as a post-translationally modifying mark covalently linked to a large cohort of yet poorly defined protein substrates. The resulting ubiquitylated proteins can rapidly change their activities, cellular localization, or turnover through the 26S proteasome if they are no longer needed or are abnormal. Such a selective modification is essential to many signal transduction pathways particularly in those related to stress responses by rapidly enhancing or quenching output. Hence, this modification system, the so-called ubiquitin-26S proteasome system (UPS), has caught the attention in the plant research community over the last two decades for its roles in plant abiotic and biotic stress responses. Through direct or indirect mediation of plant hormones, the UPS selectively degrades key components in stress signaling to either negatively or positively regulate plant response to a given stimulus. As a result, a tightly regulated signaling network has become of much interest over the years. The ever-increasing changes of the global climate require both the development of new crops to cope with rapid changing environment and new knowledge to survey the dynamics of ecosystem. This review examines how the ubiquitin can switch and tune plant stress response and poses potential avenues to further explore this system.
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Affiliation(s)
- Paymon Doroodian
- Department of Environment and Plant Biology, Ohio University, Athens, OH 45701, USA;
- Molecular and Cellular Biology Program, Ohio University, Athens, OH 45701, USA
| | - Zhihua Hua
- Department of Environment and Plant Biology, Ohio University, Athens, OH 45701, USA;
- Molecular and Cellular Biology Program, Ohio University, Athens, OH 45701, USA
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The Arabidopsis NOT4A E3 ligase promotes PGR3 expression and regulates chloroplast translation. Nat Commun 2021; 12:251. [PMID: 33431870 PMCID: PMC7801604 DOI: 10.1038/s41467-020-20506-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 11/30/2020] [Indexed: 12/14/2022] Open
Abstract
Chloroplast function requires the coordinated action of nuclear- and chloroplast-derived proteins, including several hundred nuclear-encoded pentatricopeptide repeat (PPR) proteins that regulate plastid mRNA metabolism. Despite their large number and importance, regulatory mechanisms controlling PPR expression are poorly understood. Here we show that the Arabidopsis NOT4A ubiquitin-ligase positively regulates the expression of PROTON GRADIENT REGULATION 3 (PGR3), a PPR protein required for translating several thylakoid-localised photosynthetic components and ribosome subunits within chloroplasts. Loss of NOT4A function leads to a strong depletion of cytochrome b6f and NAD(P)H dehydrogenase (NDH) complexes, as well as plastid 30 S ribosomes, which reduces mRNA translation and photosynthetic capacity, causing pale-yellow and slow-growth phenotypes. Quantitative transcriptome and proteome analysis of the not4a mutant reveal it lacks PGR3 expression, and that its molecular defects resemble those of a pgr3 mutant. Furthermore, we show that normal plastid function is restored to not4a through transgenic PGR3 expression. Our work identifies NOT4A as crucial for ensuring robust photosynthetic function during development and stress-response, through promoting PGR3 production and chloroplast translation.
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Sun JL, Li JY, Wang MJ, Song ZT, Liu JX. Protein Quality Control in Plant Organelles: Current Progress and Future Perspectives. MOLECULAR PLANT 2021; 14:95-114. [PMID: 33137518 DOI: 10.1016/j.molp.2020.10.011] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 10/09/2020] [Accepted: 10/28/2020] [Indexed: 05/20/2023]
Abstract
The endoplasmic reticulum, chloroplasts, and mitochondria are major plant organelles for protein synthesis, photosynthesis, metabolism, and energy production. Protein homeostasis in these organelles, maintained by a balance between protein synthesis and degradation, is essential for cell functions during plant growth, development, and stress resistance. Nucleus-encoded chloroplast- and mitochondrion-targeted proteins and ER-resident proteins are imported from the cytosol and undergo modification and maturation within their respective organelles. Protein folding is an error-prone process that is influenced by both developmental signals and environmental cues; a number of mechanisms have evolved to ensure efficient import and proper folding and maturation of proteins in plant organelles. Misfolded or damaged proteins with nonnative conformations are subject to degradation via complementary or competing pathways: intraorganelle proteases, the organelle-associated ubiquitin-proteasome system, and the selective autophagy of partial or entire organelles. When proteins in nonnative conformations accumulate, the organelle-specific unfolded protein response operates to restore protein homeostasis by reducing protein folding demand, increasing protein folding capacity, and enhancing components involved in proteasome-associated protein degradation and autophagy. This review summarizes recent progress on the understanding of protein quality control in the ER, chloroplasts, and mitochondria in plants, with a focus on common mechanisms shared by these organelles during protein homeostasis.
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Affiliation(s)
- Jing-Liang Sun
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310027, China
| | - Jin-Yu Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310027, China
| | - Mei-Jing Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310027, China
| | - Ze-Ting Song
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310027, China
| | - Jian-Xiang Liu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310027, China.
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Afitlhile M, Worthington R, Banigan E, Jirik J, Hildebrand D. Ozone-induced lipid changes in the wildtype and toc132toc120 heterozygote mutant of Arabidopsis thaliana. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 158:13-20. [PMID: 33291051 DOI: 10.1016/j.plaphy.2020.11.050] [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: 08/09/2020] [Accepted: 11/27/2020] [Indexed: 06/12/2023]
Abstract
We measured the fatty acids and lipid content in the wildtype and toc132toc120 heterozygote mutant of Arabidopsis thaliana that were exposed to elevated levels of ozone. The goal was to assess whether a defective atToc132/120 receptor would alter the mutant's response to ozone-induced stress. Increased malondialdehyde (MDA) levels were measured in wildtype plants that were exposed to ozone for 3 h and left in an ozone-free environment for 21 h. The increased levels of MDA were not positively correlated with changes in the levels of triunsaturated fatty acids from which MDA is derived. In both the wildtype and mutant plants, absolute amounts of the glycerolipids were not altered by ozone treatment. The untreated mutant, however, accumulated decreased levels of chloroplast lipids and triunsaturated fatty acids. In ozone-treated wildtype, the levels of 16:3 were significantly decreased and this was mirrored by decreased levels of TOC132 and FAD5 transcripts, and increased levels of SP1 E3 ligase transcripts. These data suggest a possible increase in protein ubiquitination under ozone-induced stress. In contrast, in ozone-treated mutant, the FAD5 transcripts accumulated at the control level. The untreated mutant, however, accumulated significantly increased levels of CAT1 and FAD7 transcripts, which indicates that a defective chloroplast receptor induced cellular stress. In ozone-treated wildtype, there was a small increase in 34:6-phosphatidic acid, which indicates that a small amount of the chloroplast-derived MGDG was degraded in response to ozone-induced stress. Overall, these data indicate that the wildtype and mutant responded differently in lipid composition and oxidation to ozone-induced stress.
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Affiliation(s)
- Meshack Afitlhile
- Western Illinois University, Department of Biological Sciences, 1 University Circle, Waggoner Hall 311 Macomb, IL, 61455, USA.
| | - Rebecca Worthington
- Western Illinois University, Department of Biological Sciences, 1 University Circle, Waggoner Hall 311 Macomb, IL, 61455, USA
| | - Emily Banigan
- Western Illinois University, Department of Biological Sciences, 1 University Circle, Waggoner Hall 311 Macomb, IL, 61455, USA
| | - Jessica Jirik
- Western Illinois University, Department of Biological Sciences, 1 University Circle, Waggoner Hall 311 Macomb, IL, 61455, USA
| | - David Hildebrand
- University of Kentucky, Department of Plant Sciences, 1405 Veterans Drive, Office 403 PSB, Lexington, KY, 40546, USA
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Mamaeva A, Taliansky M, Filippova A, Love AJ, Golub N, Fesenko I. The role of chloroplast protein remodeling in stress responses and shaping of the plant peptidome. THE NEW PHYTOLOGIST 2020; 227:1326-1334. [PMID: 32320487 DOI: 10.1111/nph.16620] [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: 12/09/2019] [Accepted: 04/15/2020] [Indexed: 06/11/2023]
Abstract
In addition to photosynthesis, chloroplasts perform a variety of important cellular functions in the plant cell, which can, for example, regulate plant responses to abiotic and biotic stress conditions. Under stress, intensive chloroplast protein remodeling and degradation can occur, releasing large numbers of endogenous peptides. These protein-derived peptides can be found intracellularly, but also in the plant secretome. Although the pathways of chloroplast protein degradation and the types of chloroplast proteases implicated in this process have received much attention, the role of the resulting peptides is less well understood. In this review we summarize the data on peptide generation processes during the remodeling of the chloroplast proteome under stress conditions and discuss the mechanisms leading to these changes. We also review the experimental evidence which supports the concept that peptides derived from chloroplast proteins can function as regulators of plant responses to (a)biotic stresses.
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Affiliation(s)
- Anna Mamaeva
- Laboratory of Plant Functional Genomics and Proteomics, Laboratory of Molecular Basis of Plant Stress Resistance, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997, Moscow, Russian Federation
| | - Michael Taliansky
- Laboratory of Plant Functional Genomics and Proteomics, Laboratory of Molecular Basis of Plant Stress Resistance, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997, Moscow, Russian Federation
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Anna Filippova
- Laboratory of Plant Functional Genomics and Proteomics, Laboratory of Molecular Basis of Plant Stress Resistance, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997, Moscow, Russian Federation
| | - Andrew J Love
- The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Nina Golub
- Laboratory of Plant Functional Genomics and Proteomics, Laboratory of Molecular Basis of Plant Stress Resistance, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997, Moscow, Russian Federation
| | - Igor Fesenko
- Laboratory of Plant Functional Genomics and Proteomics, Laboratory of Molecular Basis of Plant Stress Resistance, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997, Moscow, Russian Federation
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Kikuchi Y, Nakamura S, Woodson JD, Ishida H, Ling Q, Hidema J, Jarvis RP, Hagihara S, Izumi M. Chloroplast Autophagy and Ubiquitination Combine to Manage Oxidative Damage and Starvation Responses. PLANT PHYSIOLOGY 2020; 183:1531-1544. [PMID: 32554506 PMCID: PMC7401110 DOI: 10.1104/pp.20.00237] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/04/2020] [Indexed: 05/18/2023]
Abstract
Autophagy and the ubiquitin-proteasome system are the major degradation processes for intracellular components in eukaryotes. Although ubiquitination acts as a signal inducing organelle-targeting autophagy, the interaction between ubiquitination and autophagy in chloroplast turnover has not been addressed. In this study, we found that two chloroplast-associated E3 enzymes, SUPPRESSOR OF PPI1 LOCUS1 and PLANT U-BOX4 (PUB4), are not necessary for the induction of either piecemeal autophagy of chloroplast stroma or chlorophagy of whole damaged chloroplasts in Arabidopsis (Arabidopsis thaliana). Double mutations of an autophagy gene and PUB4 caused synergistic phenotypes relative to single mutations. The double mutants developed accelerated leaf chlorosis linked to the overaccumulation of reactive oxygen species during senescence and had reduced seed production. Biochemical detection of ubiquitinated proteins indicated that both autophagy and PUB4-associated ubiquitination contributed to protein degradation in the senescing leaves. Furthermore, the double mutants had enhanced susceptibility to carbon or nitrogen starvation relative to single mutants. Together, these results indicate that autophagy and chloroplast-associated E3s cooperate for protein turnover, management of reactive oxygen species accumulation, and adaptation to starvation.
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Affiliation(s)
- Yuta Kikuchi
- Graduate School of Life Sciences, Tohoku University, 980-0845 Sendai, Japan
| | - Sakuya Nakamura
- Center for Sustainable Resource Science, RIKEN, 351-0198 Wako, Japan
| | - Jesse D Woodson
- School of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036
| | - Hiroyuki Ishida
- Graduate School of Agricultural Science, Tohoku University, 980-0845 Sendai, Japan
| | - Qihua Ling
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Jun Hidema
- Graduate School of Life Sciences, Tohoku University, 980-0845 Sendai, Japan
| | - R Paul Jarvis
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Shinya Hagihara
- Center for Sustainable Resource Science, RIKEN, 351-0198 Wako, Japan
| | - Masanori Izumi
- Center for Sustainable Resource Science, RIKEN, 351-0198 Wako, Japan
- PRESTO, Japan Science and Technology Agency, 322-0012 Kawaguchi, Japan
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Protein import into chloroplasts and its regulation by the ubiquitin-proteasome system. Biochem Soc Trans 2020; 48:71-82. [PMID: 31922184 PMCID: PMC7054747 DOI: 10.1042/bst20190274] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/19/2019] [Accepted: 12/23/2019] [Indexed: 02/08/2023]
Abstract
Chloroplasts are photosynthetic plant organelles descended from a bacterial ancestor. The vast majority of chloroplast proteins are synthesized in the cytosol and then imported into the chloroplast post-translationally. Translocation complexes exist in the organelle's outer and inner envelope membranes (termed TOC and TIC, respectively) to facilitate protein import. These systems recognize chloroplast precursor proteins and mediate their import in an energy-dependent manner. However, many unanswered questions remain regarding mechanistic details of the import process and the participation and functions of individual components; for example, the cytosolic events that mediate protein delivery to chloroplasts, the composition of the TIC apparatus, and the nature of the protein import motor all require resolution. The flux of proteins through TOC and TIC varies greatly throughout development and in response to specific environmental cues. The import process is, therefore, tightly regulated, and it has emerged that the ubiquitin-proteasome system (UPS) plays a key role in this regard, acting at several different steps in the process. The UPS is involved in: the selective degradation of transcription factors that co-ordinate the expression of chloroplast precursor proteins; the removal of unimported chloroplast precursor proteins in the cytosol; the inhibition of chloroplast biogenesis pre-germination; and the reconfiguration of the TOC apparatus in response to developmental and environmental signals in a process termed chloroplast-associated protein degradation. In this review, we highlight recent advances in our understanding of protein import into chloroplasts and how this process is regulated by the UPS.
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