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Lemke MD, Abate AN, Woodson JD. Investigating the mechanism of chloroplast singlet oxygen signaling in the Arabidopsis thaliana accelerated cell death 2 mutant. PLANT SIGNALING & BEHAVIOR 2024; 19:2347783. [PMID: 38699898 PMCID: PMC11073415 DOI: 10.1080/15592324.2024.2347783] [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: 01/29/2024] [Accepted: 04/19/2024] [Indexed: 05/05/2024]
Abstract
As sessile organisms, plants have evolved complex signaling mechanisms to sense stress and acclimate. This includes the use of reactive oxygen species (ROS) generated during dysfunctional photosynthesis to initiate signaling. One such ROS, singlet oxygen (1O2), can trigger retrograde signaling, chloroplast degradation, and programmed cell death. However, the signaling mechanisms are largely unknown. Several proteins (e.g. PUB4, OXI1, EX1) are proposed to play signaling roles across three Arabidopsis thaliana mutants that conditionally accumulate chloroplast 1O2 (fluorescent in blue light (flu), chlorina 1 (ch1), and plastid ferrochelatase 2 (fc2)). We previously demonstrated that these mutants reveal at least two chloroplast 1O2 signaling pathways (represented by flu and fc2/ch1). Here, we test if the 1O2-accumulating lesion mimic mutant, accelerated cell death 2 (acd2), also utilizes these pathways. The pub4-6 allele delayed lesion formation in acd2 and restored photosynthetic efficiency and biomass. Conversely, an oxi1 mutation had no measurable effect on these phenotypes. acd2 mutants were not sensitive to excess light (EL) stress, yet pub4-6 and oxi1 both conferred EL tolerance within the acd2 background, suggesting that EL-induced 1O2 signaling pathways are independent from spontaneous lesion formation. Thus, 1O2 signaling in acd2 may represent a third (partially overlapping) pathway to control cellular degradation.
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Affiliation(s)
- Matthew D. Lemke
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Alexa N. Abate
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Jesse D. Woodson
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
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2
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Geng R, Li X, Huang J, Zhou W. The chloroplast singlet oxygen-triggered biosynthesis of salicylic acid and jasmonic acid is mediated by EX1 and GUN1 in Arabidopsis. PLANT, CELL & ENVIRONMENT 2024; 47:2852-2864. [PMID: 38600785 DOI: 10.1111/pce.14910] [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: 10/26/2023] [Revised: 02/29/2024] [Accepted: 03/29/2024] [Indexed: 04/12/2024]
Abstract
Reactive oxygen species (ROS) and defence hormones like salicylic acid (SA) and jasmonic acid (JA) play pivotal roles in triggering cell death. However, the precise mechanism governing the interaction between ROS and SA/JA remains elusive. Recently, our research revealed that RNAi mutants with suppressed expression of PROGRAMMED CELL DEATH8 (PCD8) exhibit an overabundance of tetrapyrrole intermediates, particularly uroporphyrinogen III (Uro III), leading to the accumulation of singlet oxygen (1O2) during the transition from darkness to light, thereby instigating leaf necrosis. In this investigation, we uncovered that 1O2 stimulates biosynthesis of SA and JA, activating SA/JA signalling and the expression of responsive genes in PCD8 RNAi (pcd8) mutants. Introducing NahG or knocking out PAD4 or NPR1 significantly alleviates the cell death phenotype of pcd8 mutants, while coi1 partially mitigates the pcd8 phenotype. Further exploration revealed that EX1 and GUN1 can partially rescue the pcd8 phenotype by reducing the levels of Uro III and 1O2. Notably, mutations in EX1 mutations but not GUN1, substantially diminish SA content in pcd8 mutants compared to the wild type, implying that EX1 acts as the primary mediator of 1O2 signalling-mediated SA biosynthesis. Moreover, the triple ex1 gun1 pcd8 displays a phenotype similar to ex1. Overall, our findings underscore that the 1O2-induced cell death phenotype requires EX1/GUN1-mediated retrograde signalling in pcd8 mutants, providing novel insights into the interplay between ROS and SA/JA.
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Affiliation(s)
- Rudan Geng
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Xia Li
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jirong Huang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Wenbin Zhou
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
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3
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Rai S, Lemke MD, Arias AM, Mendez MFG, Dehesh K, Woodson JD. Plant U-Box 4 regulates chloroplast stress signaling and programmed cell death via Salicylic acid modulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.13.593788. [PMID: 38798329 PMCID: PMC11118471 DOI: 10.1101/2024.05.13.593788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
In response to environmental stress, chloroplasts generate reactive oxygen species, including singlet oxygen (1O2), which regulates nuclear gene expression (retrograde signaling), chloroplast turnover, and programmed cell death (PCD). Yet, the central signaling mechanisms and downstream responses remain poorly understood. The Arabidopsis thaliana plastid ferrochelatase two (fc2) mutant conditionally accumulates 1O2 and involves Plant U-Box 4 (PUB4), a cytoplasmic E3 ubiquitin ligase, in propagating these signals. To gain insights into 1O2 signaling pathways, we compared transcriptomes of fc2 and fc2 pub4 mutants. The accumulation of 1O2 in fc2 plants broadly repressed genes involved in chloroplast function and photosynthesis, while 1O2 induced genes and transcription factors involved in abiotic and biotic stress, the biosynthesis of jasmonic acid (JA), and Salicylic acid (SA). Elevated JA and SA levels were observed in stressed fc2 plants, but were not responsible for PCD. pub4 reversed the majority of 1O2-induced gene expression in fc2 and reduced the JA content, but maintained elevated levels of SA even in the absence of 1O2 stress. Reducing SA levels in fc2 pub4 restored 1O2 signaling and light sensitivity. Together, this work demonstrates that SA plays a protective role during photo-oxidative stress and that PUB4 mediates 1O2 signaling by modulating its levels.
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Affiliation(s)
- Snigdha Rai
- The School of Plant Sciences, University of Arizona, Tucson, AZ
| | | | - Anika M. Arias
- The School of Plant Sciences, University of Arizona, Tucson, AZ
| | - Maria F. Gomez Mendez
- Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, University of California, Riverside, CA
| | - Katayoon Dehesh
- Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, University of California, Riverside, CA
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Wittmann DT, Peter FE, Strätker SM, Ortega-Rodés P, Grimm B, Hedtke B. Dual plastid targeting of protoporphyrinogen oxidase 2 in Amaranthaceae promotes herbicide tolerance. PLANT PHYSIOLOGY 2024; 195:713-727. [PMID: 38330186 PMCID: PMC11060682 DOI: 10.1093/plphys/kiae062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 01/02/2024] [Accepted: 01/03/2024] [Indexed: 02/10/2024]
Abstract
Plant tetrapyrrole biosynthesis (TPB) takes place in plastids and provides the chlorophyll and heme required for photosynthesis and many redox processes throughout plant development. TPB is strictly regulated, since accumulation of several intermediates causes photodynamic damage and cell death. Protoporphyrinogen oxidase (PPO) catalyzes the last common step before TPB diverges into chlorophyll and heme branches. Land plants possess two PPO isoforms. PPO1 is encoded as a precursor protein with a transit peptide, but in most dicotyledonous plants PPO2 does not possess a cleavable N-terminal extension. Arabidopsis (Arabidopsis thaliana) PPO1 and PPO2 localize in chloroplast thylakoids and envelope membranes, respectively. Interestingly, PPO2 proteins in Amaranthaceae contain an N-terminal extension that mediates their import into chloroplasts. Here, we present multiple lines of evidence for dual targeting of PPO2 to thylakoid and envelope membranes in this clade and demonstrate that PPO2 is not found in mitochondria. Transcript analyses revealed that dual targeting in chloroplasts involves the use of two transcription start sites and initiation of translation at different AUG codons. Among eudicots, the parallel accumulation of PPO1 and PPO2 in thylakoid membranes is specific for the Amaranthaceae and underlies PPO2-based herbicide resistance in Amaranthus species.
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Affiliation(s)
- Daniel T Wittmann
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstr. 13 (Building 12), 10115 Berlin, Germany
| | - Franziska E Peter
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstr. 13 (Building 12), 10115 Berlin, Germany
| | - Sarah Melissa Strätker
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstr. 13 (Building 12), 10115 Berlin, Germany
| | - Patricia Ortega-Rodés
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstr. 13 (Building 12), 10115 Berlin, Germany
- Lab. Fisiología Vegetal, Dpto. Biología Vegetal, Facultad de Biología, Universidad de La Habana, 10400 La Habana, Cuba
| | - Bernhard Grimm
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstr. 13 (Building 12), 10115 Berlin, Germany
| | - Boris Hedtke
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstr. 13 (Building 12), 10115 Berlin, Germany
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5
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van Wijk KJ, Adam Z. Does the polyubiquitination pathway operate inside intact chloroplasts to remove proteins? THE PLANT CELL 2024:koae104. [PMID: 38683741 DOI: 10.1093/plcell/koae104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 03/19/2024] [Indexed: 05/02/2024]
Affiliation(s)
- Klaas J van Wijk
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, NY 14853, USA
| | - Zach Adam
- Faculty of Agriculture, Institute of Plant Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel
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Mei Y, Hu T, Wang Y, Lozano-Durán R, Yang X, Zhou X. Two viral proteins translated from one open reading frame target different layers of plant defense. PLANT COMMUNICATIONS 2024; 5:100788. [PMID: 38160257 PMCID: PMC11009156 DOI: 10.1016/j.xplc.2023.100788] [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: 09/16/2023] [Revised: 12/22/2023] [Accepted: 12/26/2023] [Indexed: 01/03/2024]
Abstract
Multilayered defense responses are activated upon pathogen attack. Viruses utilize a number of strategies to maximize the coding capacity of their small genomes and produce viral proteins for infection, including suppression of host defense. Here, we reveal translation leakage as one of these strategies: two viral effectors encoded by tomato golden mosaic virus, chloroplast-localized C4 (cC4) and membrane-associated C4 (mC4), are translated from two in-frame start codons and function cooperatively to suppress defense. cC4 localizes in chloroplasts, to which it recruits NbPUB4 to induce ubiquitination of the outer membrane; as a result, this organelle is degraded, and chloroplast-mediated defenses are abrogated. However, chloroplast-localized cC4 induces the production of singlet oxygen (1O2), which in turn promotes translocation of the 1O2 sensor NbMBS1 from the cytosol to the nucleus, where it activates expression of the CERK1 gene. Importantly, an antiviral effect exerted by CERK1 is countered by mC4, localized at the plasma membrane. mC4, like cC4, recruits NbPUB4 and promotes the ubiquitination and subsequent degradation of CERK1, suppressing membrane-based, receptor-like kinase-dependent defenses. Importantly, this translation leakage strategy seems to be conserved in multiple viral species and is related to host range. This finding suggests that stacking of different cellular antiviral responses could be an effective way to abrogate viral infection and engineer sustainable resistance to major crop viral diseases in the field.
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Affiliation(s)
- Yuzhen Mei
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Tao Hu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yaqin Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Rosa Lozano-Durán
- Department of Plant Biochemistry, Center for Plant Molecular Biology (ZMBP), Eberhard Karls University, 72076 Tübingen, Germany
| | - Xiuling Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
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Zhou X, Li Y, Wang J, Zhao Y, Wang H, Han Y, Lin X. Genome-wide identification of U-box gene family and expression analysis in response to saline-alkali stress in foxtail millet ( Setaria italica L. Beauv). Front Genet 2024; 15:1356807. [PMID: 38435060 PMCID: PMC10904469 DOI: 10.3389/fgene.2024.1356807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 01/22/2024] [Indexed: 03/05/2024] Open
Abstract
E3 ubiquitin ligases are central modifiers of plant signaling pathways that regulate protein function, localization, degradation, and other biological processes by linking ubiquitin to target proteins. E3 ubiquitin ligases include proteins with the U-box domain. However, there has been no report about the foxtail millet (Setaria italica L. Beauv) U-box gene family (SiPUB) to date. To explore the function of SiPUBs, this study performed genome-wide identification of SiPUBs and expression analysis of them in response to saline-alkali stress. A total of 70 SiPUBs were identified, which were unevenly distributed on eight chromosomes. Phylogenetic and conserved motif analysis demonstrated that SiPUBs could be clustered into six subfamilies (I-VI), and most SiPUBs were closely related to the homologues in rice. Twenty-eight types of cis-acting elements were identified in SiPUBs, most of which contained many light-responsive elements and plant hormone-responsive elements. Foxtail millet had 19, 78, 85, 18, and 89 collinear U-box gene pairs with Arabidopsis, rice, sorghum, tomato, and maize, respectively. Tissue specific expression analysis revealed great variations in SiPUB expression among different tissues, and most SiPUBs were relatively highly expressed in roots, indicating that SiPUBs may play important roles in root development or other growth and development processes of foxtail millet. Furthermore, the responses of 15 SiPUBs to saline-alkali stress were detected by qRT-PCR. The results showed that saline-alkali stress led to significantly differential expression of these 15 SiPUBs, and SiPUB20/48/70 may play important roles in the response mechanism against saline-alkali stress. Overall, this study provides important information for further exploration of the biological function of U-box genes.
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Affiliation(s)
- Xiaoke Zhou
- Hebei Key Laboratory of Crop Stress Biology, College of Agronomy and Biotechnology, Hebei Normal University of Science and Technology, Qinhuangdao, China
| | - Yun Li
- Research Center of Rural Vitalization, Hebei Normal University of Science and Technology, Qinhuangdao, China
| | - Jian Wang
- Hebei Key Laboratory of Crop Stress Biology, College of Agronomy and Biotechnology, Hebei Normal University of Science and Technology, Qinhuangdao, China
| | - Yuxue Zhao
- Hebei Key Laboratory of Crop Stress Biology, College of Agronomy and Biotechnology, Hebei Normal University of Science and Technology, Qinhuangdao, China
| | - Huimin Wang
- Hebei Key Laboratory of Crop Stress Biology, College of Agronomy and Biotechnology, Hebei Normal University of Science and Technology, Qinhuangdao, China
| | - Yucui Han
- Hebei Key Laboratory of Crop Stress Biology, College of Agronomy and Biotechnology, Hebei Normal University of Science and Technology, Qinhuangdao, China
| | - Xiaohu Lin
- Hebei Key Laboratory of Crop Stress Biology, College of Agronomy and Biotechnology, Hebei Normal University of Science and Technology, Qinhuangdao, China
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Zhu PK, Zeng MY, Lin YH, Tang Y, He TY, Zheng YS, Chen LY. Variability in Leaf Color Induced by Chlorophyll Deficiency: Transcriptional Changes in Bamboo Leaves. Curr Issues Mol Biol 2024; 46:1503-1515. [PMID: 38392215 PMCID: PMC10888276 DOI: 10.3390/cimb46020097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 02/04/2024] [Accepted: 02/06/2024] [Indexed: 02/24/2024] Open
Abstract
The diversity of leaf characteristics, particularly leaf color, underscores a pivotal area of inquiry within plant science. The synthesis and functionality of chlorophyll, crucial for photosynthesis, largely dictate leaf coloration, with varying concentrations imparting different shades of green. Complex gene interactions regulate the synthesis and degradation of chlorophyll, and disruptions in these pathways can result in abnormal chlorophyll production, thereby affecting leaf pigmentation. This study focuses on Bambusa multiplex f. silverstripe, a natural variant distinguished by a spectrum of leaf colors, such as green, white, and green-white, attributed to genetic variations influencing gene expression. By examining the physiological and molecular mechanisms underlying chlorophyll anomalies and genetic factors in Silverstripe, this research sheds light on the intricate gene interactions and regulatory networks that contribute to leaf color diversity. The investigation includes the measurement of photosynthetic pigments and nutrient concentrations across different leaf color types, alongside transcriptomic analyses for identifying differentially expressed genes. The role of key genes in pathways such as ALA biosynthesis, chlorophyll synthesis, photosynthesis, and sugar metabolism is explored, offering critical insights for advancing research and plant breeding practices.
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Affiliation(s)
- Peng-Kai Zhu
- College of Architecture and Art, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Mei-Yin Zeng
- College of Architecture and Art, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yu-Han Lin
- College of Architecture and Art, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yu Tang
- College of Architecture and Art, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Tian-You He
- College of Architecture and Art, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yu-Shan Zheng
- College of Architecture and Art, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Ling-Yan Chen
- College of Architecture and Art, Fujian Agriculture and Forestry University, Fuzhou 350002, China
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Lemke MD, Woodson JD. A genetic screen for dominant chloroplast reactive oxygen species signaling mutants reveals life stage-specific singlet oxygen signaling networks. FRONTIERS IN PLANT SCIENCE 2024; 14:1331346. [PMID: 38273946 PMCID: PMC10809407 DOI: 10.3389/fpls.2023.1331346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 12/18/2023] [Indexed: 01/27/2024]
Abstract
Introduction Plants employ intricate molecular mechanisms to respond to abiotic stresses, which often lead to the accumulation of reactive oxygen species (ROS) within organelles such as chloroplasts. Such ROS can produce stress signals that regulate cellular response mechanisms. One ROS, singlet oxygen (1O2), is predominantly produced in the chloroplast during photosynthesis and can trigger chloroplast degradation, programmed cell death (PCD), and retrograde (organelle-to-nucleus) signaling. However, little is known about the molecular mechanisms involved in these signaling pathways or how many different signaling 1O2 pathways may exist. Methods The Arabidopsis thaliana plastid ferrochelatase two (fc2) mutant conditionally accumulates chloroplast 1O2, making fc2 a valuable genetic system for studying chloroplast 1O2-initiated signaling. Here, we have used activation tagging in a new forward genetic screen to identify eight dominant fc2 activation-tagged (fas) mutations that suppress chloroplast 1O2-initiated PCD. Results While 1O2-triggered PCD is blocked in all fc2 fas mutants in the adult stage, such cellular degradation in the seedling stage is blocked in only two mutants. This differential blocking of PCD suggests that life-stage-specific 1O2-response pathways exist. In addition to PCD, fas mutations generally reduce 1O2-induced retrograde signals. Furthermore, fas mutants have enhanced tolerance to excess light, a natural mechanism to produce chloroplast 1O2. However, general abiotic stress tolerance was only observed in one fc2 fas mutant (fc2 fas2). Together, this suggests that plants can employ general stress tolerance mechanisms to overcome 1O2 production but that this screen was mostly specific to 1O2 signaling. We also observed that salicylic acid (SA) and jasmonate (JA) stress hormone response marker genes were induced in 1O2-stressed fc2 and generally reduced by fas mutations, suggesting that SA and JA signaling is correlated with active 1O2 signaling and PCD. Discussion Together, this work highlights the complexity of 1O2 signaling by demonstrating that multiple pathways may exist and introduces a suite of new 1O2 signaling mutants to investigate the mechanisms controlling chloroplast-initiated degradation, PCD, and retrograde signaling.
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Affiliation(s)
| | - Jesse D. Woodson
- The School of Plant Sciences, University of Arizona, Tucson, AZ, United States
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10
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Cadena-Ramos AI, De-la-Peña C. Picky eaters: selective autophagy in plant cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:364-384. [PMID: 37864806 DOI: 10.1111/tpj.16508] [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: 07/14/2023] [Revised: 09/21/2023] [Accepted: 10/10/2023] [Indexed: 10/23/2023]
Abstract
Autophagy, a fundamental cellular process, plays a vital role in maintaining cellular homeostasis by degrading damaged or unnecessary components. While selective autophagy has been extensively studied in animal cells, its significance in plant cells has only recently gained attention. In this review, we delve into the intriguing realm selective autophagy in plants, with specific focus on its involvement in nutrient recycling, organelle turnover, and stress response. Moreover, recent studies have unveiled the interesting interplay between selective autophagy and epigenetic mechanisms in plants, elucidating the significance of epigenetic regulation in modulating autophagy-related gene expression and finely tuning the selective autophagy process in plants. By synthesizing existing knowledge, this review highlights the emerging field of selective autophagy in plant cells, emphasizing its pivotal role in maintaining nutrient homeostasis, facilitating cellular adaptation, and shedding light on the epigenetic regulation that governs these processes. Our comprehensive study provides the way for a deeper understanding of the dynamic control of cellular responses to nutrient availability and stress conditions, opening new avenues for future research in this field of autophagy in plant physiology.
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Affiliation(s)
- Alexis I Cadena-Ramos
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Calle 43 No. 130 x 32 y 34 Col. Chuburná de Hidalgo, 97205, Mérida, Yucatán, Mexico
| | - Clelia De-la-Peña
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Calle 43 No. 130 x 32 y 34 Col. Chuburná de Hidalgo, 97205, Mérida, Yucatán, Mexico
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11
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Hananya N, Green O, Gutiérrez-Fernández I, Shabat D, Arellano JB. Singlet Oxygen Detection by Chemiluminescence Probes in Living Cells. Methods Mol Biol 2024; 2798:27-43. [PMID: 38587734 DOI: 10.1007/978-1-0716-3826-2_3] [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: 04/09/2024]
Abstract
Singlet oxygen is a reactive oxygen species that causes oxidative damage to plant cells, but intriguingly it can also act as a signalling molecule to reprogram gene expression required to induce plant physiological/cellular responses. Singlet oxygen photosensitization in plants mainly occurs in chloroplasts after the molecular collision of ground-state molecular oxygen with triplet-excited-state chlorophyll. Singlet oxygen direct detection through phosphorescence emission in chloroplasts is a herculean task due to its extremely low luminescence quantum yield. Because of this, indirect alternative methods have been developed for its detection in biological systems, for example, by measuring the changes in the EPR signal or fluorescence intensity of singlet oxygen reaction-based probes. The singlet oxygen chemiluminescence (SOCL) is a chemiluminescence probe with high sensitivity and selectivity towards singlet oxygen and promising use to detect it in living cells without the inconvenience of low stability of the EPR signal of spin probes in the presence of redox compounds, spurious light scattering coming from the light source required for the excitation of fluorescence probes or the light emission of endogenous fluorescent molecules like chlorophyll in chloroplasts. The protocol presented in this chapter describes the first steps to characterizing singlet oxygen production within the biological system under study; this is accomplished through monitoring molecular oxygen consumption by SOCL using a Clark-type oxygen electrode and measuring the chemiluminescence generated by SOCL 1,2-dioxetane using a spectrofluorometer. For singlet oxygen detection within living cells, a version of SOCL with increased membrane permeability (SOCL-CPP) is described.
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Affiliation(s)
- Nir Hananya
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Technion City, Haifa, Israel
| | - Ori Green
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Technion City, Haifa, Israel
| | - Ismael Gutiérrez-Fernández
- Departamento de Estrés Abiótico, Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), Salamanca, Spain
| | - Doron Shabat
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Juan B Arellano
- Departamento de Estrés Abiótico, Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), Salamanca, Spain.
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Llamas E, Koyuncu S, Lee HJ, Wehrmann M, Gutierrez-Garcia R, Dunken N, Charura N, Torres-Montilla S, Schlimgen E, Mandel AM, Theile EB, Grossbach J, Wagle P, Lackmann JW, Schermer B, Benzing T, Beyer A, Pulido P, Rodriguez-Concepcion M, Zuccaro A, Vilchez D. In planta expression of human polyQ-expanded huntingtin fragment reveals mechanisms to prevent disease-related protein aggregation. NATURE AGING 2023; 3:1345-1357. [PMID: 37783816 PMCID: PMC10645592 DOI: 10.1038/s43587-023-00502-1] [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: 02/24/2023] [Accepted: 09/01/2023] [Indexed: 10/04/2023]
Abstract
In humans, aggregation of polyglutamine repeat (polyQ) proteins causes disorders such as Huntington's disease. Although plants express hundreds of polyQ-containing proteins, no pathologies arising from polyQ aggregation have been reported. To investigate this phenomenon, we expressed an aggregation-prone fragment of human huntingtin (HTT) with an expanded polyQ stretch (Q69) in Arabidopsis thaliana plants. In contrast to animal models, we find that Arabidopsis sp. suppresses Q69 aggregation through chloroplast proteostasis. Inhibition of chloroplast proteostasis diminishes the capacity of plants to prevent cytosolic Q69 aggregation. Moreover, endogenous polyQ-containing proteins also aggregate on chloroplast dysfunction. We find that Q69 interacts with the chloroplast stromal processing peptidase (SPP). Synthetic Arabidopsis SPP prevents polyQ-expanded HTT aggregation in human cells. Likewise, ectopic SPP expression in Caenorhabditis elegans reduces neuronal Q67 aggregation and subsequent neurotoxicity. Our findings suggest that synthetic plant proteins, such as SPP, hold therapeutic potential for polyQ disorders and other age-related diseases involving protein aggregation.
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Affiliation(s)
- Ernesto Llamas
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Cluster of Excellence on Plant Sciences, Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - Seda Koyuncu
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Institute for Integrated Stress Response Signaling, Faculty of Medicine, University Hospital Cologne, Cologne, Germany
| | - Hyun Ju Lee
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Institute for Integrated Stress Response Signaling, Faculty of Medicine, University Hospital Cologne, Cologne, Germany
| | - Markus Wehrmann
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Institute for Integrated Stress Response Signaling, Faculty of Medicine, University Hospital Cologne, Cologne, Germany
| | - Ricardo Gutierrez-Garcia
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Institute for Integrated Stress Response Signaling, Faculty of Medicine, University Hospital Cologne, Cologne, Germany
| | - Nick Dunken
- Cluster of Excellence on Plant Sciences, Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - Nyasha Charura
- Cluster of Excellence on Plant Sciences, Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | | | - Elena Schlimgen
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Institute for Integrated Stress Response Signaling, Faculty of Medicine, University Hospital Cologne, Cologne, Germany
| | - Amrei M Mandel
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Department II of Internal Medicine, University Hospital Cologne, Cologne, Germany
| | - Erik Boelen Theile
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Jan Grossbach
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Prerana Wagle
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | - Jan-Wilm Lackmann
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | - Bernhard Schermer
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Department II of Internal Medicine, University Hospital Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Thomas Benzing
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Department II of Internal Medicine, University Hospital Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Andreas Beyer
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
- Institute for Genetics, University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Pablo Pulido
- Department of Plant Molecular Genetics, Centro Nacional de Biotecnologia, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | | | - Alga Zuccaro
- Cluster of Excellence on Plant Sciences, Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - David Vilchez
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany.
- Institute for Integrated Stress Response Signaling, Faculty of Medicine, University Hospital Cologne, Cologne, Germany.
- Institute for Genetics, University of Cologne, Cologne, Germany.
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
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13
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Pan T, Liu Y, Hu X, Li P, Lin C, Tang Y, Tang W, Liu Y, Guo L, Kim C, Fang J, Lin H, Wu Z, Blumwald E, Wang S. Stress-induced endocytosis from chloroplast inner envelope membrane is mediated by CHLOROPLAST VESICULATION but inhibited by GAPC. Cell Rep 2023; 42:113208. [PMID: 37792531 DOI: 10.1016/j.celrep.2023.113208] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 06/16/2023] [Accepted: 09/18/2023] [Indexed: 10/06/2023] Open
Abstract
Clathrin-mediated vesicular formation and trafficking are responsible for molecular cargo transport and signal transduction among organelles. Our previous study shows that CHLOROPLAST VESICULATION (CV)-containing vesicles (CVVs) are generated from chloroplasts for chloroplast degradation under abiotic stress. Here, we show that CV interacts with the clathrin heavy chain (CHC) and induces vesicle budding toward the cytosol from the chloroplast inner envelope membrane. In the defective mutants of CHC2 and the dynamin-encoding DRP1A, CVV budding and releasing from chloroplast are impeded. The mutations of CHC2 inhibit CV-induced chloroplast degradation and hypersensitivity to water stress. Moreover, CV-CHC2 interaction is impaired by the oxidized GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE (GAPC). GAPC1 overexpression suppresses CV-mediated chloroplast degradation and hypersensitivity to water stress, while CV silencing alleviates the hypersensitivity of the gapc1gapc2 plant to water stress. Together, our work identifies a pathway of clathrin-assisted CVV budding outward from chloroplast, which is involved in chloroplast degradation and stress response.
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Affiliation(s)
- Ting Pan
- Anhui Province Key Laboratory of Horticultural Crop Quality Biology, School of Horticulture, Anhui Agricultural University, Hefei 230036, China; Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China; College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yangxuan Liu
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Xufan Hu
- Anhui Province Key Laboratory of Horticultural Crop Quality Biology, School of Horticulture, Anhui Agricultural University, Hefei 230036, China
| | - Pengwei Li
- Anhui Province Key Laboratory of Horticultural Crop Quality Biology, School of Horticulture, Anhui Agricultural University, Hefei 230036, China
| | - Chengcheng Lin
- Anhui Province Key Laboratory of Horticultural Crop Quality Biology, School of Horticulture, Anhui Agricultural University, Hefei 230036, China
| | - Yuying Tang
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Wei Tang
- Anhui Province Key Laboratory of Horticultural Crop Quality Biology, School of Horticulture, Anhui Agricultural University, Hefei 230036, China
| | - Yongsheng Liu
- Anhui Province Key Laboratory of Horticultural Crop Quality Biology, School of Horticulture, Anhui Agricultural University, Hefei 230036, China
| | - Liang Guo
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Chanhong Kim
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jun Fang
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Honghui Lin
- Ministry of Education, Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Zhihua Wu
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Eduardo Blumwald
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Songhu Wang
- Anhui Province Key Laboratory of Horticultural Crop Quality Biology, School of Horticulture, Anhui Agricultural University, Hefei 230036, China; Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
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14
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Schwenkert S, Lo WT, Szulc B, Yip CK, Pratt AI, Cusack SA, Brandt B, Leister D, Kunz HH. Probing the physiological role of the plastid outer-envelope membrane using the oemiR plasmid collection. G3 (BETHESDA, MD.) 2023; 13:jkad187. [PMID: 37572358 PMCID: PMC10542568 DOI: 10.1093/g3journal/jkad187] [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: 07/20/2023] [Revised: 07/20/2023] [Accepted: 08/04/2023] [Indexed: 08/14/2023]
Abstract
Plastids are the site of complex biochemical pathways, most prominently photosynthesis. The organelle evolved through endosymbiosis with a cyanobacterium, which is exemplified by the outer envelope membrane that harbors more than 40 proteins in Arabidopsis. Their evolutionary conservation indicates high significance for plant cell function. While a few proteins are well-studied as part of the protein translocon complex the majority of outer envelope protein functions is unclear. Gaining a deeper functional understanding has been complicated by the lack of observable loss-of-function mutant phenotypes, which is often rooted in functional genetic redundancy. Therefore, we designed outer envelope-specific artificial micro RNAs (oemiRs) capable of downregulating transcripts from several loci simultaneously. We successfully tested oemiR function by performing a proof-of-concept screen for pale and cold-sensitive mutants. An in-depth analysis of pale mutant alleles deficient in the translocon component TOC75 using proteomics provided new insights into putative compensatory import pathways. The cold stress screen not only recapitulated 3 previously known phenotypes of cold-sensitive mutants but also identified 4 mutants of additional oemiR outer envelope loci. Altogether our study revealed a role of the outer envelope to tolerate cold conditions and showcasts the power of the oemiR collection to research the significance of outer envelope proteins.
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Affiliation(s)
- Serena Schwenkert
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-Universität Munich, 82152 Planegg-Martinsried, Germany
| | - Wing Tung Lo
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-Universität Munich, 82152 Planegg-Martinsried, Germany
| | - Beata Szulc
- Plant Biochemistry, Faculty of Biology, Ludwig-Maximilians-Universität Munich, 82152 Planegg-Martinsried, Germany
| | - Chun Kwan Yip
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-Universität Munich, 82152 Planegg-Martinsried, Germany
| | - Anna I Pratt
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA
| | | | - Benjamin Brandt
- Plant Biochemistry, Faculty of Biology, Ludwig-Maximilians-Universität Munich, 82152 Planegg-Martinsried, Germany
| | - Dario Leister
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-Universität Munich, 82152 Planegg-Martinsried, Germany
| | - Hans-Henning Kunz
- Plant Biochemistry, Faculty of Biology, Ludwig-Maximilians-Universität Munich, 82152 Planegg-Martinsried, Germany
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA
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15
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Lei P, Yu F, Liu X. Recent advances in cellular degradation and nuclear control of leaf senescence. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:5472-5486. [PMID: 37453102 DOI: 10.1093/jxb/erad273] [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: 04/11/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
Senescence is the final stage of plant growth and development, and is a highly regulated process at the molecular, cellular, and organismal levels. When triggered by age, hormonal, or environmental cues, plants actively adjust their metabolism and gene expression to execute the progression of senescence. Regulation of senescence is vital for the reallocation of nutrients to sink organs, to ensure reproductive success and adaptations to stresses. Identification and characterization of hallmarks of leaf senescence are of great importance for understanding the molecular regulatory mechanisms of plant senescence, and breeding future crops with more desirable senescence traits. Tremendous progress has been made in elucidating the genetic network underpinning the metabolic and cellular changes in leaf senescence. In this review, we focus on three hallmarks of leaf senescence - chlorophyll and chloroplast degradation, loss of proteostasis, and activation of senescence-associated genes (SAGs), and discuss recent findings of the molecular players and the crosstalk of senescence pathways.
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Affiliation(s)
- Pei Lei
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Fei Yu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
- Institute of Future Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xiayan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
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16
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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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17
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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: 0] [Impact Index Per Article: 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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18
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Fan T, Roling L, Hedtke B, Grimm B. FC2 stabilizes POR and suppresses ALA formation in the tetrapyrrole biosynthesis pathway. THE NEW PHYTOLOGIST 2023; 239:624-638. [PMID: 37161708 DOI: 10.1111/nph.18952] [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: 01/04/2023] [Accepted: 04/08/2023] [Indexed: 05/11/2023]
Abstract
During photoperiodic growth, the light-dependent nature of chlorophyll synthesis in angiosperms necessitates robust control of the production of 5-aminolevulinic acid (ALA), the rate-limiting step in the initial stage of tetrapyrrole biosynthesis (TBS). We are interested in dissecting the post-translational control of this process, which suppresses ALA synthesis for chlorophyll synthesis in dark-grown plants. Using biochemical approaches for analysis of Arabidopsis wild-type (WT) and mutant lines as well as complementation lines, we show that the heme-synthesizing ferrochelatase 2 (FC2) interacts with protochlorophyllide oxidoreductase and the regulator FLU which both promote the feedback-controlled suppression of ALA synthesis by inactivation of glutamyl-tRNA reductase, thus preventing excessive accumulation of potentially deleterious tetrapyrrole intermediates. Thereby, FC2 stabilizes POR by physical interaction. When the interaction between FC2 and POR is perturbed, suppression of ALA synthesis is attenuated and photoreactive protochlorophyllide accumulates. FC2 is anchored in the thylakoid membrane via its membrane-spanning CAB (chlorophyll-a-binding) domain. FC2 is one of the two isoforms of ferrochelatase catalyzing the last step of heme synthesis. Although FC2 belongs to the heme-synthesizing branch of TBS, its interaction with POR potentiates the effects of the GluTR-inactivation complex on the chlorophyll-synthesizing branch and ensures reciprocal control of chlorophyll and heme synthesis.
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Affiliation(s)
- Tingting Fan
- Humboldt-Universität zu Berlin, Institute of Biology/Plant Physiology, Philippstraße 13, Building 12,, D-10115, Berlin, Germany
- College of Forestry, Central South University of Forestry and Technology, Changsha, Hunan, 410004, China
| | - Lena Roling
- Humboldt-Universität zu Berlin, Institute of Biology/Plant Physiology, Philippstraße 13, Building 12,, D-10115, Berlin, Germany
| | - Boris Hedtke
- Humboldt-Universität zu Berlin, Institute of Biology/Plant Physiology, Philippstraße 13, Building 12,, D-10115, Berlin, Germany
| | - Bernhard Grimm
- Humboldt-Universität zu Berlin, Institute of Biology/Plant Physiology, Philippstraße 13, Building 12,, D-10115, Berlin, Germany
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19
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Geng R, Pang X, Li X, Shi S, Hedtke B, Grimm B, Bock R, Huang J, Zhou W. PROGRAMMED CELL DEATH8 interacts with tetrapyrrole biosynthesis enzymes and ClpC1 to maintain homeostasis of tetrapyrrole metabolites in Arabidopsis. THE NEW PHYTOLOGIST 2023; 238:2545-2560. [PMID: 36967598 DOI: 10.1111/nph.18906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 03/19/2023] [Indexed: 05/19/2023]
Abstract
Tetrapyrrole biosynthesis (TBS) is a dynamically and strictly regulated process. Disruptions in tetrapyrrole metabolism influence many aspects of plant physiology, including photosynthesis, programmed cell death (PCD), and retrograde signaling, thus affecting plant growth and development at multiple levels. However, the genetic and molecular basis of TBS is not fully understood. We report here PCD8, a newly identified thylakoid-localized protein encoded by an essential gene in Arabidopsis. PCD8 knockdown causes a necrotic phenotype due to excessive chloroplast damage. A burst of singlet oxygen that results from overaccumulated tetrapyrrole intermediates upon illumination is suggested to be responsible for cell death in the knockdown mutants. Genetic and biochemical analyses revealed that PCD8 interacts with ClpC1 and a number of TBS enzymes, such as HEMC, CHLD, and PORC of TBS. Taken together, our findings uncover the function of chloroplast-localized PCD8 and provide a new perspective to elucidate molecular mechanism of how TBS is finely regulated in plants.
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Affiliation(s)
- Rudan Geng
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Xiaoqing Pang
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstraße 13, Berlin, 10115, Germany
| | - Xia Li
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Shanshan Shi
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Boris Hedtke
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstraße 13, Berlin, 10115, Germany
| | - Bernhard Grimm
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstraße 13, Berlin, 10115, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476, Potsdam-Golm, Germany
| | - Jirong Huang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Wenbin Zhou
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
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20
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Hedtke B, Strätker SM, Pulido ACC, Grimm B. Two isoforms of Arabidopsis protoporphyrinogen oxidase localize in different plastidal membranes. PLANT PHYSIOLOGY 2023; 192:871-885. [PMID: 36806676 PMCID: PMC10231370 DOI: 10.1093/plphys/kiad107] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 12/22/2022] [Accepted: 01/24/2023] [Indexed: 06/01/2023]
Abstract
All land plants encode 2 isoforms of protoporphyrinogen oxidase (PPO). While PPO1 is predominantly expressed in green tissues and its loss is seedling-lethal in Arabidopsis (Arabidopsis thaliana), the effects of PPO2 deficiency have not been investigated in detail. We identified 2 ppo2 T-DNA insertion mutants from publicly available collections, one of which (ppo2-2) is a knock-out mutant. While the loss of PPO2 did not result in any obvious phenotype, substantial changes in PPO activity were measured in etiolated and root tissues. However, ppo1 ppo2 double mutants were embryo-lethal. To shed light on possible functional differences between the 2 isoforms, PPO2 was overexpressed in the ppo1 background. Although the ppo1 phenotype was partially complemented, even strong overexpression of PPO2 was unable to fully compensate for the loss of PPO1. Analysis of subcellular localization revealed that PPO2 is found exclusively in chloroplast envelopes, while PPO1 accumulates in thylakoid membranes. Mitochondrial localization of PPO2 in Arabidopsis was ruled out. Since Arabidopsis PPO2 does not encode a cleavable transit peptide, integration of the protein into the chloroplast envelope must make use of a noncanonical import route. However, when a chloroplast transit peptide was fused to the N-terminus of PPO2, the enzyme was detected predominantly in thylakoid membranes and was able to fully complement ppo1. Thus, the 2 PPO isoforms in Arabidopsis are functionally equivalent but spatially separated. Their distinctive localizations within plastids thus enable the synthesis of discrete subpools of the PPO product protoporphyrin IX, which may serve different cellular needs.
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Affiliation(s)
- Boris Hedtke
- Humboldt-Universität zu Berlin, Institute of Biology/Plant Physiology, Philippstraße 13 (Building 12), Berlin 10115, Germany
| | - Sarah Melissa Strätker
- Humboldt-Universität zu Berlin, Institute of Biology/Plant Physiology, Philippstraße 13 (Building 12), Berlin 10115, Germany
| | - Andrea C Chiappe Pulido
- Humboldt-Universität zu Berlin, Institute of Biology/Plant Physiology, Philippstraße 13 (Building 12), Berlin 10115, Germany
| | - Bernhard Grimm
- Humboldt-Universität zu Berlin, Institute of Biology/Plant Physiology, Philippstraße 13 (Building 12), Berlin 10115, Germany
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21
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UPL5 modulates WHY2 protein distribution in a Kub-site dependent ubiquitination in response to [Ca2+]cyt-induced leaf senescence. iScience 2023; 26:106216. [PMID: 36994183 PMCID: PMC10040967 DOI: 10.1016/j.isci.2023.106216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 01/08/2023] [Accepted: 02/13/2023] [Indexed: 03/08/2023] Open
Abstract
The translocation of proteins between various compartments of cells is the simplest and most direct way of an/retrograde communication. However, the mechanism of protein trafficking is far understood. In this study, we showed that the alteration of WHY2 protein abundance in various compartments of cells was dependent on a HECT-type ubiquitin E3 ligase UPL5 interacting with WHY2 in the cytoplasm, plastid, and nucleus, as well as mitochondrion to selectively ubiquitinate various Kub-sites (Kub 45 and Kub 227) of WHY2. Plastid genome stability can be maintained by the UPL5-WHY2 module, accompany by the alteration of photosystem activity and senescence-associated gene expression. In addition, the specificity of UPL5 ubiquitinating various Kub-sites of WHY2 was responded to cold or CaCl2 stress, in a dose [Ca2+]cyt-dependent manner. This demonstrates the integration of the UPL5 ubiquitination with the regulation of WHY2 distribution and retrograde communication between organelle and nuclear events of leaf senescence.
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22
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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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23
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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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Li Y, Liu H, Ma T, Li J, Yuan J, Xu YC, Sun R, Zhang X, Jing Y, Guo YL, Lin R. Arabidopsis EXECUTER1 interacts with WRKY transcription factors to mediate plastid-to-nucleus singlet oxygen signaling. THE PLANT CELL 2023; 35:827-851. [PMID: 36423342 PMCID: PMC9940883 DOI: 10.1093/plcell/koac330] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 10/10/2022] [Accepted: 11/16/2022] [Indexed: 06/01/2023]
Abstract
Chloroplasts produce singlet oxygen (1O2), which causes changes in nuclear gene expression through plastid-to-nucleus retrograde signaling to increase plant fitness. However, the identity of this 1O2-triggered pathway remains unclear. Here, we identify mutations in GENOMES UNCOUPLED4 (GUN4) and GUN5 as suppressors of phytochrome-interacting factor1 (pif1) pif3 in regulating the photo-oxidative response in Arabidopsis thaliana. GUN4 and GUN5 specifically interact with EXECUTER1 (EX1) and EX2 in plastids, and this interaction is alleviated by treatment with Rose Bengal (RB) or white light. Impaired expression of GUN4, GUN5, EX1, or EX2 leads to insensitivity to excess light and overexpression of EX1 triggers photo-oxidative responses. Strikingly, upon light irradiation or RB treatment, EX1 transiently accumulates in the nucleus and the nuclear fraction of EX1 shows a similar molecular weight as the plastid-located protein. Point mutagenesis analysis indicated that nuclear localization of EX1 is required for its function. EX1 acts as a transcriptional co-activator and interacts with the transcription factors WRKY18 and WRKY40 to promote the expression of 1O2-responsive genes. This study suggests that EX1 may act in plastid-to-nucleus signaling and establishes a 1O2-triggered retrograde signaling pathway that allows plants adapt to changing light environments during chloroplast development.
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Affiliation(s)
- Yuhong Li
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hanhong Liu
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tingting Ma
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jialong Li
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jiarui Yuan
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yong-Chao Xu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Ran Sun
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xinyu Zhang
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Yanjun Jing
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Ya-Long Guo
- University of Chinese Academy of Sciences, Beijing 100049, China
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Rongcheng Lin
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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25
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Autophagic degradation of membrane-bound organelles in plants. Biosci Rep 2023; 43:232379. [PMID: 36562332 PMCID: PMC9842949 DOI: 10.1042/bsr20221204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/19/2022] [Accepted: 12/22/2022] [Indexed: 12/24/2022] Open
Abstract
Eukaryotic cells have evolved membrane-bound organelles, including the endoplasmic reticulum (ER), Golgi, mitochondria, peroxisomes, chloroplasts (in plants and green algae) and lysosomes/vacuoles, for specialized functions. Organelle quality control and their proper interactions are crucial both for normal cell homeostasis and function and for environmental adaption. Dynamic turnover of organelles is tightly controlled, with autophagy playing an essential role. Autophagy is a programmed process for efficient clearing of unwanted or damaged macromolecules or organelles, transporting them to vacuoles for degradation and recycling and thereby enhancing plant environmental plasticity. The specific autophagic engulfment of organelles requires activation of a selective autophagy pathway, recognition of the organelle by a receptor, and selective incorporation of the organelle into autophagosomes. While some of the autophagy machinery and mechanisms for autophagic removal of organelles is conserved across eukaryotes, plants have also developed unique mechanisms and machinery for these pathways. In this review, we discuss recent progress in understanding autophagy regulation in plants, with a focus on autophagic degradation of membrane-bound organelles. We also raise some important outstanding questions to be addressed in the future.
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26
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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: 6] [Impact Index Per Article: 6.0] [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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27
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Tano DW, Kozlowska MA, Easter RA, Woodson JD. Multiple pathways mediate chloroplast singlet oxygen stress signaling. PLANT MOLECULAR BIOLOGY 2023; 111:167-187. [PMID: 36266500 DOI: 10.1007/s11103-022-01319-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Chloroplast singlet oxygen initiates multiple pathways to control chloroplast degradation, cell death, and nuclear gene expression. Chloroplasts can respond to stress and changes in the environment by producing reactive oxygen species (ROS). Aside from being cytotoxic, ROS also have signaling capabilities. For example, the ROS singlet oxygen (1O2) can initiate nuclear gene expression, chloroplast degradation, and cell death. To unveil the signaling mechanisms involved, researchers have used several 1O2-producing Arabidopsis thaliana mutants as genetic model systems, including plastid ferrochelatase two (fc2), fluorescent in blue light (flu), chlorina 1 (ch1), and accelerated cell death 2 (acd2). Here, we compare these 1O2-producing mutants to elucidate if they utilize one or more signaling pathways to control cell death and nuclear gene expression. Using publicly available transcriptomic data, we demonstrate fc2, flu, and ch1 share a core response to 1O2 accumulation, but maintain unique responses, potentially tailored to respond to their specific stresses. Subsequently, we used a genetic approach to determine if these mutants share 1O2 signaling pathways by testing the ability of genetic suppressors of one 1O2 producing mutant to suppress signaling in a different 1O2 producing mutant. Our genetic analyses revealed at least two different chloroplast 1O2 signaling pathways control cellular degradation: one specific to the flu mutant and one shared by fc2, ch1, and acd2 mutants, but with life-stage-specific (seedling vs. adult) features. Overall, this work reveals chloroplast stress signaling involving 1O2 is complex and may allow cells to finely tune their physiology to environmental inputs.
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Affiliation(s)
- David W Tano
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA
| | - Marta A Kozlowska
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA
| | - Robert A Easter
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA
| | - Jesse D Woodson
- The School of Plant Sciences, University of Arizona, 1140 E, South Campus Drive, 303 Forbes Hall, Tucson, AZ, 85721-0036, USA.
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28
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Lemke MD, Woodson JD. Targeted for destruction: degradation of singlet oxygen-damaged chloroplasts. PLANT SIGNALING & BEHAVIOR 2022; 17:2084955. [PMID: 35676885 PMCID: PMC9196835 DOI: 10.1080/15592324.2022.2084955] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 05/26/2022] [Accepted: 05/29/2022] [Indexed: 06/15/2023]
Abstract
Photosynthesis is an essential process that plants must regulate to survive in dynamic environments. Thus, chloroplasts (the sites of photosynthesis in plant and algae cells) use multiple signaling mechanisms to report their health to the cell. Such signals are poorly understood but often involve reactive oxygen species (ROS) produced from the photosynthetic light reactions. One ROS, singlet oxygen (1O2), can signal to initiate chloroplast degradation, but the cellular machinery involved in identifying and degrading damaged chloroplasts (i.e., chloroplast quality control pathways) is unknown. To provide mechanistic insight into these pathways, two recent studies have investigated degrading chloroplasts in the Arabidopsis thaliana1O2 over-producing plastid ferrochelatase two (fc2) mutant. First, a structural analysis of degrading chloroplasts was performed with electron microscopy, which demonstrated that damaged chloroplasts can protrude into the central vacuole compartment with structures reminiscent of fission-type microautophagy. 1O2-stressed chloroplasts swelled before these interactions, which may be a mechanism for their selective degradation. Second, the roles of autophagosomes and canonical autophagy (macroautophagy) were shown to be dispensable for 1O2-initiated chloroplast degradation. Instead, putative fission-type microautophagy genes were induced by chloroplast 1O2. Here, we discuss how these studies implicate this poorly understood cellular degradation pathway in the dismantling of 1O2-damaged chloroplasts.
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Affiliation(s)
- Matthew D. Lemke
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Jesse D. Woodson
- The School of Plant Sciences, University of Arizona, Tucson, AZ, USA
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29
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Manoj KM, Bazhin NM, Jacob VD, Parashar A, Gideon DA, Manekkathodi A. Structure-function correlations and system dynamics in oxygenic photosynthesis: classical perspectives and murburn precepts. J Biomol Struct Dyn 2022; 40:10997-11023. [PMID: 34323659 DOI: 10.1080/07391102.2021.1953606] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
HIGHLIGHTS Contemporary beliefs on oxygenic photosynthesis are critiqued.Murburn model is suggested as an alternative explanation.In the new model, diffusible reactive species are the main protagonists.All pigments are deemed photo-redox active in the new stochastic mechanism.NADPH synthesis occurs via simple electron transfers, not via elaborate ETC.Oxygenesis is delocalized and not just centered at Mn-Complex.Energetics of murburn proposal for photophosphorylation is provided.The proposal ushers in a paradigm shift in photosynthesis research.
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Affiliation(s)
| | | | - Vivian David Jacob
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Kerala, India
| | - Abhinav Parashar
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Kerala, India
| | | | - Afsal Manekkathodi
- Satyamjayatu: The Science & Ethics Foundation, Kulappully, Kerala, India
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30
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Liu M, Ma W, Su X, Zhang X, Lu Y, Zhang S, Yan J, Feng D, Ma L, Taylor A, Ge Y, Cheng Q, Xu K, Wang Y, Li N, Gu A, Zhang J, Luo S, Xuan S, Chen X, Scrutton NS, Li C, Zhao J, Shen S. Mutation in a chlorophyll-binding motif of Brassica ferrochelatase enhances both heme and chlorophyll biosynthesis. Cell Rep 2022; 41:111758. [PMID: 36476857 DOI: 10.1016/j.celrep.2022.111758] [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: 03/01/2022] [Revised: 09/06/2022] [Accepted: 11/09/2022] [Indexed: 12/12/2022] Open
Abstract
The heme branch of tetrapyrrole biosynthesis contributes to the regulation of chlorophyll levels. However, the mechanism underlying the balance between chlorophyll and heme synthesis remains elusive. Here, we identify a dark green leaf mutant, dg, from an ethyl methanesulfonate (EMS)-induced mutant library of Chinese cabbage. The dg phenotype is caused by an amino acid substitution in the conserved chlorophyll a/b-binding motif (CAB) of ferrochelatase 2 (BrFC2). This mutation increases the formation of BrFC2 homodimer to promote heme production. Moreover, wild-type BrFC2 and dBrFC2 interact with protochlorophyllide (Pchlide) oxidoreductase B1 and B2 (BrPORB1 and BrPORB2), and dBrFC2 exhibits higher binding ability to substrate Pchlide, thereby promoting BrPORBs-catalyzed production of chlorophyllide (Chlide), which can be directly converted into chlorophyll. Our results show that dBrFC2 is a gain-of-function mutation contributing to balancing heme and chlorophyll synthesis via a regulatory mechanism in which dBrFC2 promotes BrPORB enzymatic reaction to enhance chlorophyll synthesis.
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Affiliation(s)
- Mengyang Liu
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Wei Ma
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Xiangjie Su
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Xiaomeng Zhang
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Yin Lu
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Shaowei Zhang
- Manchester Institute of Biotechnology, Department of Chemistry, School of Natural Sciences, The University of Manchester, Manchester, UK
| | - Jinghui Yan
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Daling Feng
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Lisong Ma
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Aoife Taylor
- Manchester Institute of Biotechnology, Department of Chemistry, School of Natural Sciences, The University of Manchester, Manchester, UK
| | - Yunjia Ge
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Qi Cheng
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Kedong Xu
- Henan Key Laboratory of Crop Molecular Breeding & Bioreactor, Key Laboratory of Plant Genetics and Molecular Breeding, Zhoukou Normal University, Zhoukou 466001, China
| | - Yanhua Wang
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Na Li
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Aixia Gu
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Ju Zhang
- Henan Key Laboratory of Crop Molecular Breeding & Bioreactor, Key Laboratory of Plant Genetics and Molecular Breeding, Zhoukou Normal University, Zhoukou 466001, China
| | - Shuangxia Luo
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Shuxin Xuan
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Xueping Chen
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China
| | - Nigel S Scrutton
- Manchester Institute of Biotechnology, Department of Chemistry, School of Natural Sciences, The University of Manchester, Manchester, UK
| | - Chengwei Li
- Henan Key Laboratory of Crop Molecular Breeding & Bioreactor, Key Laboratory of Plant Genetics and Molecular Breeding, Zhoukou Normal University, Zhoukou 466001, China; College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China.
| | - Jianjun Zhao
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China.
| | - Shuxing Shen
- State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Vegetable Germplasm Innovation and Utilization of Hebei, Collaborative Innovation Center of Vegetable Industry in Hebei, College of Horticulture, Hebei Agricultural University, Baoding 071000, China.
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31
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Yu G, Derkacheva M, Rufian JS, Brillada C, Kowarschik K, Jiang S, Derbyshire P, Ma M, DeFalco TA, Morcillo RJL, Stransfeld L, Wei Y, Zhou J, Menke FLH, Trujillo M, Zipfel C, Macho AP. The Arabidopsis E3 ubiquitin ligase PUB4 regulates BIK1 and is targeted by a bacterial type-III effector. EMBO J 2022; 41:e107257. [PMID: 36314733 PMCID: PMC9713774 DOI: 10.15252/embj.2020107257] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 09/26/2022] [Accepted: 10/07/2022] [Indexed: 12/03/2022] Open
Abstract
Plant immunity is tightly controlled by a complex and dynamic regulatory network, which ensures optimal activation upon detection of potential pathogens. Accordingly, each component of this network is a potential target for manipulation by pathogens. Here, we report that RipAC, a type III-secreted effector from the bacterial pathogen Ralstonia solanacearum, targets the plant E3 ubiquitin ligase PUB4 to inhibit pattern-triggered immunity (PTI). PUB4 plays a positive role in PTI by regulating the homeostasis of the central immune kinase BIK1. Before PAMP perception, PUB4 promotes the degradation of non-activated BIK1, while after PAMP perception, PUB4 contributes to the accumulation of activated BIK1. RipAC leads to BIK1 degradation, which correlates with its PTI-inhibitory activity. RipAC causes a reduction in pathogen-associated molecular pattern (PAMP)-induced PUB4 accumulation and phosphorylation. Our results shed light on the role played by PUB4 in immune regulation, and illustrate an indirect targeting of the immune signalling hub BIK1 by a bacterial effector.
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Affiliation(s)
- Gang Yu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Maria Derkacheva
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Present address:
The Earlham InstituteNorwich Research ParkNorwichUK
| | - Jose S Rufian
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Carla Brillada
- Faculty of Biology, Institute of Biology IIAlbert‐Ludwigs‐University FreiburgFreiburgGermany
| | | | - Shushu Jiang
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Present address:
Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell ScienceChinese Academy of SciencesShanghaiChina
| | - Paul Derbyshire
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
| | - Miaomiao Ma
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
| | - Thomas A DeFalco
- Institute of Plant and Microbial Biology, Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
| | - Rafael J L Morcillo
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Lena Stransfeld
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Institute of Plant and Microbial Biology, Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
| | - Yali Wei
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Jian‐Min Zhou
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
| | - Frank L H Menke
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
| | - Marco Trujillo
- Faculty of Biology, Institute of Biology IIAlbert‐Ludwigs‐University FreiburgFreiburgGermany
- Leibniz Institute for Plant BiochemistryHalle (Saale)Germany
| | - Cyril Zipfel
- The Sainsbury LaboratoryUniversity of East Anglia, Norwich Research ParkNorwichUK
- Institute of Plant and Microbial Biology, Zurich‐Basel Plant Science CenterUniversity of ZurichZurichSwitzerland
| | - Alberto P Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
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32
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Koh E, Brandis A, Fluhr R. Plastid and cytoplasmic origins of 1O 2-mediated transcriptomic responses. FRONTIERS IN PLANT SCIENCE 2022; 13:982610. [PMID: 36420020 PMCID: PMC9676463 DOI: 10.3389/fpls.2022.982610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
The reactive oxygen species singlet oxygen, 1O2, has an extremely short half-life, yet is intimately involved with stress signalling in the cell. We previously showed that the effects of 1O2 on the transcriptome are highly correlated with 80S ribosomal arrest due to oxidation of guanosine residues in mRNA. Here, we show that dysregulation of chlorophyll biosynthesis in the flu mutant or through feeding by δ-aminolevulinic acid can lead to accumulation of photoactive chlorophyll intermediates in the cytoplasm, which generates 1O2 upon exposure to light and causes the oxidation of RNA, eliciting 1O2-responsive genes. In contrast, transcriptomes derived from DCMU treatment, or the Ch1 mutant under moderate light conditions display commonalties with each other but do not induce 1O2 gene signatures. Comparing 1O2 related transcriptomes to an index transcriptome induced by cycloheximide inhibition enables distinction between 1O2 of cytosolic or of plastid origin. These comparisons provide biological insight to cases of mutants or environmental conditions that produce 1O2.
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Affiliation(s)
- Eugene Koh
- Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Alexander Brandis
- Life Sciences Core Facility, Weizmann Institute of Science, Rehovot, Israel
| | - Robert Fluhr
- Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
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Rochaix J. Chloroplast protein import machinery and quality control. FEBS J 2022; 289:6908-6918. [PMID: 35472255 PMCID: PMC9790281 DOI: 10.1111/febs.16464] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 03/20/2022] [Accepted: 04/25/2022] [Indexed: 01/13/2023]
Abstract
Most chloroplast proteins are nucleus-encoded, translated on cytoplasmic ribosomes as precursor proteins, and imported into chloroplasts through TOC and TIC, the translocons of the outer and inner chloroplast envelope membranes. While the composition of the TOC complex is well established, there is still some controversy about the importance of a recently identified TIC complex consisting of Tic20, Tic214, Tic100, and Tic56. TOC and TIC form a supercomplex with a protein channel at the junction of the outer and inner envelope membranes through which preproteins are pulled into the stroma by the ATP-powered Ycf2 complex consisting of several FtsH-like ATPases and/or by chloroplast Hsp proteins. Several components of the TOC/TIC system are moonlighting proteins with additional roles in chloroplast gene expression and metabolism. Chaperones and co-chaperones, associated with TOC and TIC on the cytoplasmic and stromal side of the chloroplast envelope, participate in the unfolding and folding of the precursor proteins and act together with the ubiquitin-proteasome system in protein quality control. Chloroplast protein import is also intimately linked with retrograde signaling, revealing altogether an unsuspected complexity in the regulation of this process.
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Affiliation(s)
- Jean‐David Rochaix
- Departments of Molecular Biology and Plant BiologyUniversity of GenevaSwitzerland
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34
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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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35
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Wan C, Ling Q. Functions of autophagy in chloroplast protein degradation and homeostasis. FRONTIERS IN PLANT SCIENCE 2022; 13:993215. [PMID: 36247630 PMCID: PMC9557084 DOI: 10.3389/fpls.2022.993215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/05/2022] [Indexed: 06/16/2023]
Abstract
Chloroplasts are defining organelles in plant and algae, which carried out various critical metabolic processes, including photosynthesis. Roles of chloroplast protein homeostasis in plant development and stress adaptation were clearly demonstrated in previous studies, and its maintenance requires internal proteases originated from the prokaryotic ancestor. Recently, increasing evidence revealed that eukaryotic proteolytic pathways, ubiquitin-proteasome system (UPS) and autophagy, are also involved in the turnover of chloroplast proteins, in response to developmental and environmental cues. Notably, chloroplasts can be regulated via the selective degradation of chloroplast materials in a process called chlorophagy. Yet, understandings of the mechanism of chlorophagy are still rudimentary, particularly regarding its initiation and operation. Here we provide an updated overview of autophagy pathways for chloroplast protein degradation and discuss their importance for plant physiology. In addition, recent advance in analogous mitophagy in yeast and mammals will also be discussed, which provides clues for further elucidating the mechanism of chlorophagy.
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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 Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - 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
- University of Chinese Academy of Sciences, Beijing, China
- Chinese Academy of Sciences (CAS) and John Innes Centre, Center of Excellence for Plant and Microbial Sciences (CEPAMS), Shanghai, China
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36
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Hand KA, Shabek N. The Role of E3 Ubiquitin Ligases in Chloroplast Function. Int J Mol Sci 2022; 23:ijms23179613. [PMID: 36077009 PMCID: PMC9455731 DOI: 10.3390/ijms23179613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [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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Xing J, Pan J, Yi H, Lv K, Gan Q, Wang M, Ge H, Huang X, Huang F, Wang Y, Rochaix JD, Yang W. The plastid-encoded protein Orf2971 is required for protein translocation and chloroplast quality control. THE PLANT CELL 2022; 34:3383-3399. [PMID: 35708659 PMCID: PMC9421593 DOI: 10.1093/plcell/koac180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
Photosynthesis and the biosynthesis of many important metabolites occur in chloroplasts. In these semi-autonomous organelles, the chloroplast genome encodes approximately 100 proteins. The remaining chloroplast proteins, close to 3,000, are encoded by nuclear genes whose products are translated in the cytosol and imported into chloroplasts. However, there is still no consensus on the composition of the protein import machinery including its motor proteins and on how newly imported chloroplast proteins are refolded. In this study, we have examined the function of orf2971, the largest chloroplast gene of Chlamydomonas reinhardtii. The depletion of Orf2971 causes the accumulation of protein precursors, partial proteolysis and aggregation of proteins, increased expression of chaperones and proteases, and autophagy. Orf2971 interacts with the TIC (translocon at the inner chloroplast envelope) complex, catalyzes ATP (adenosine triphosphate) hydrolysis, and associates with chaperones and chaperonins. We propose that Orf2971 is intimately connected to the protein import machinery and plays an important role in chloroplast protein quality control.
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Affiliation(s)
| | | | - Heng Yi
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Kang Lv
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Qiuliang Gan
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Meimei Wang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Haitao Ge
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Xiahe Huang
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Fang Huang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Yingchun Wang
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Jean-David Rochaix
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland
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Lan W, Ma W, Zheng S, Qiu Y, Zhang H, Lu H, Zhang Y, Miao Y. Ubiquitome profiling reveals a regulatory pattern of UPL3 with UBP12 on metabolic-leaf senescence. Life Sci Alliance 2022; 5:e202201492. [PMID: 35926874 PMCID: PMC9354775 DOI: 10.26508/lsa.202201492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/19/2022] [Accepted: 07/19/2022] [Indexed: 12/03/2022] Open
Abstract
The HECT-type UPL3 ligase plays critical roles in plant development and stress protection, but understanding of its regulation remains limited. Here, the multi-omics analyses of ubiquitinated proteins in <i>upl3</i> mutants were performed. A landscape of UPL3-dependent ubiquitinated proteins is constructed: Preferential ubiquitination of proteins related to carbon fixation represented the largest set of proteins with increased ubiquitination in the <i>upl3</i> plant, including most of carbohydrate metabolic enzymes, BRM, and variant histone, whereas a small set of proteins with reduced ubiquitination caused by the <i>upl3</i> mutation were linked to cysteine/methionine synthesis, as well as hexokinase 1 (HXK1) and phosphoenolpyruvate carboxylase 2 (PPC2). Notably, ubiquitin hydrolase 12 (UBP12), BRM, HXK1, and PPC2 were identified as the UPL3-interacting partners in vivo and in vitro. Characterization of <i>brm</i>, <i>upl3</i>, <i>ppc2</i>, <i>gin2</i>, and <i>ubp12</i> mutant plants and proteomic and transcriptomic analysis suggested that UPL3 fine-tunes carbohydrate metabolism, mediating cellular senescence by interacting with UBP12, BRM, HXK1, and PPC2. Our results highlight a regulatory pattern of UPL3 with UBP12 as a hub of regulator on proteolysis-independent regulation and proteolysis-dependent degradation.
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Affiliation(s)
- Wei Lan
- Fujian Provincial Key Laboratory of Plant Functional Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Weibo Ma
- Fujian Provincial Key Laboratory of Plant Functional Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Shuai Zheng
- Fujian Provincial Key Laboratory of Plant Functional Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yuhao Qiu
- Fujian Provincial Key Laboratory of Plant Functional Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Han Zhang
- Fujian Provincial Key Laboratory of Plant Functional Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Haisen Lu
- Fujian Provincial Key Laboratory of Plant Functional Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yu Zhang
- Fujian Provincial Key Laboratory of Plant Functional Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Ying Miao
- Fujian Provincial Key Laboratory of Plant Functional Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
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Transcriptome Analysis of Air Space-Type Variegation Formation in Trifolium pratense. Int J Mol Sci 2022; 23:ijms23147794. [PMID: 35887138 PMCID: PMC9322087 DOI: 10.3390/ijms23147794] [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: 05/16/2022] [Revised: 07/12/2022] [Accepted: 07/13/2022] [Indexed: 02/04/2023] Open
Abstract
Air space-type variegation is the most diverse among the species of known variegated leaf plants and is caused by conspicuous intercellular spaces between the epidermal and palisade cells and among the palisade cells at non-green areas. Trifolium pratense, a species in Fabaceae with V-shaped air space-type variegation, was selected to explore the application potential of variegated leaf plants and accumulate basic data on the molecular regulatory mechanism and evolutionary history of leaf variegation. We performed comparative transcriptome analysis on young and adult leaflets of variegated and green plants and identified 43 candidate genes related to air space-type variegation formation. Most of the genes were related to cell-wall structure modification (CESA, CSL, EXP, FLA, PG, PGIP, PLL, PME, RGP, SKS, and XTH family genes), followed by photosynthesis (LHCB subfamily, RBCS, GOX, and AGT family genes), redox (2OG and GSH family genes), and nitrogen metabolism (NodGS family genes). Other genes were related to photooxidation, protein interaction, and protease degradation systems. The downregulated expression of light-responsive LHCB subfamily genes and the upregulated expression of the genes involved in cell-wall structure modification were important conditions for air space-type variegation formation in T. pratense. The upregulated expression of the ubiquitin-protein ligase enzyme (E3)-related genes in the protease degradation systems were conducive to air space-type variegation formation. Because these family genes are necessary for plant growth and development, the mechanism of the leaf variegation formation in T. pratense might be a widely existing regulation in air space-type variegation in nature.
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40
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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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41
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Luong AM, Koestel J, Bhati KK, Batoko H. Cargo receptors and adaptors for selective autophagy in plant cells. FEBS Lett 2022; 596:2104-2132. [PMID: 35638898 DOI: 10.1002/1873-3468.14412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 05/08/2022] [Accepted: 05/23/2022] [Indexed: 11/06/2022]
Abstract
Plant selective (macro)autophagy is a highly regulated process whereby eukaryotic cells spatiotemporally degrade some of their constituents that have become superfluous or harmful. The identification and characterization of the factors determining this selectivity make it possible to integrate selective (macro)autophagy into plant cell physiology and homeostasis. The specific cargo receptors and/or scaffold proteins involved in this pathway are generally not structurally conserved, as are the biochemical mechanisms underlying recognition and integration of a given cargo into the autophagosome in different cell types. This review discusses the few specific cargo receptors described in plant cells to highlight key features of selective autophagy in the plant kingdom and its integration with plant physiology, so as to identify evolutionary convergence and knowledge gaps to be filled by future research.
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Affiliation(s)
- Ai My Luong
- Louvain Institute of Biomolecular Science and Technology, University of Louvain Croix du Sud 4, L7.07.14, 1348, Louvain-la-Neuve, Belgium
| | - Jérôme Koestel
- Louvain Institute of Biomolecular Science and Technology, University of Louvain Croix du Sud 4, L7.07.14, 1348, Louvain-la-Neuve, Belgium
| | - Kaushal Kumar Bhati
- Louvain Institute of Biomolecular Science and Technology, University of Louvain Croix du Sud 4, L7.07.14, 1348, Louvain-la-Neuve, Belgium
| | - Henri Batoko
- Louvain Institute of Biomolecular Science and Technology, University of Louvain Croix du Sud 4, L7.07.14, 1348, Louvain-la-Neuve, Belgium
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42
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Enzymes degraded under high light maintain proteostasis by transcriptional regulation in Arabidopsis. Proc Natl Acad Sci U S A 2022; 119:e2121362119. [PMID: 35549553 PMCID: PMC9171785 DOI: 10.1073/pnas.2121362119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Photoinhibitory high light stress in plants leads to increases in markers of protein degradation and transcriptional up-regulation of proteases and proteolytic machinery, but protein homeostasis (proteostasis) of most enzymes is largely maintained under high light, so we know little about the metabolic consequences of it beyond photosystem damage. We developed a technique to look for rapid protein turnover events in response to high light through 13C partial labeling and detailed peptide mass spectrometry. This analysis reveals a light-induced transcriptional program for nuclear-encoded genes, beyond the regulation of photosystem II, to replace key protein degradation targets in plants and ensure proteostasis under high light stress. Photoinhibitory high light stress in Arabidopsis leads to increases in markers of protein degradation and transcriptional up-regulation of proteases and proteolytic machinery, but proteostasis is largely maintained. We find significant increases in the in vivo degradation rate for specific molecular chaperones, nitrate reductase, glyceraldehyde-3 phosphate dehydrogenase, and phosphoglycerate kinase and other plastid, mitochondrial, peroxisomal, and cytosolic enzymes involved in redox shuttles. Coupled analysis of protein degradation rates, mRNA levels, and protein abundance reveal that 57% of the nuclear-encoded enzymes with higher degradation rates also had high light–induced transcriptional responses to maintain proteostasis. In contrast, plastid-encoded proteins with enhanced degradation rates showed decreased transcript abundances and must maintain protein abundance by other processes. This analysis reveals a light-induced transcriptional program for nuclear-encoded genes, beyond the regulation of the photosystem II (PSII) D1 subunit and the function of PSII, to replace key protein degradation targets in plants and ensure proteostasis under high light stress.
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43
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Li J, Yuan J, Li Y, Sun H, Ma T, Huai J, Yang W, Zhang W, Lin R. The CDC48 complex mediates ubiquitin-dependent degradation of intra-chloroplast proteins in plants. Cell Rep 2022; 39:110664. [PMID: 35417702 DOI: 10.1016/j.celrep.2022.110664] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 01/19/2022] [Accepted: 03/20/2022] [Indexed: 11/03/2022] Open
Abstract
Chloroplasts are the site of numerous biochemical reactions including photosynthesis, but they also produce reactive oxygen species (ROS) that negatively affect chloroplast integrity. The chaperone-like CDC48 complex plays critical roles in ubiquitin-dependent protein degradation in yeast and mammals, but its function in plants is largely unknown. Here, we show that defects in CDC48A and its cofactors UFD1 and NPL4 lead to the accumulation of ubiquitinated chloroplast proteins in Arabidopsis thaliana. We reveal that two plastid genome-encoded proteins, RbcL and AtpB, associate with the CDC48 complex. Strikingly, RbcL and AtpB are ubiquitinated and degraded by the 26S proteasome pathway upon ROS stress, and these processes are impaired by defects of the CDC48 complex. Functional analysis demonstrates that the CDC48 complex is required for plant tolerance to ROS. This study reveals a role for the plant CDC48 complex in modulating ubiquitin-dependent degradation of intra-chloroplast proteins in response to oxidative stress.
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Affiliation(s)
- Jialong Li
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jiarui Yuan
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuhong Li
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huilun Sun
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tingting Ma
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Junling Huai
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Wenqiang Yang
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenhao Zhang
- University of Chinese Academy of Sciences, Beijing 100049, China; State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Rongcheng Lin
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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Talloji P, Nehlin L, Hüttel B, Winter N, Černý M, Dufková H, Hamali B, Hanczaryk K, Novák J, Hermanns M, Drexler N, Eifler K, Schlaich N, Brzobohatý B, Bachmair A. Transcriptome, metabolome and suppressor analysis reveal an essential role for the ubiquitin-proteasome system in seedling chloroplast development. BMC PLANT BIOLOGY 2022; 22:183. [PMID: 35395773 PMCID: PMC8991883 DOI: 10.1186/s12870-022-03536-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 03/15/2022] [Indexed: 05/25/2023]
Abstract
BACKGROUND Many regulatory circuits in plants contain steps of targeted proteolysis, with the ubiquitin proteasome system (UPS) as the mediator of these proteolytic events. In order to decrease ubiquitin-dependent proteolysis, we inducibly expressed a ubiquitin variant with Arg at position 48 instead of Lys (ubK48R). This variant acts as an inhibitor of proteolysis via the UPS, and allowed us to uncover processes that are particularly sensitive to UPS perturbation. RESULTS Expression of ubK48R during germination leads to seedling death. We analyzed the seedling transcriptome, proteome and metabolome 24 h post ubK48R induction and confirmed defects in chloroplast development. We found that mutations in single genes can suppress seedling lethality, indicating that a single process in seedlings is critically sensitive to decreased performance of the UPS. Suppressor mutations in phototropin 2 (PHOT2) suggest that a contribution of PHOT2 to chloroplast protection is compromised by proteolysis inhibition. CONCLUSIONS Overall, the results reveal protein turnover as an integral part of a signal transduction chain that protects chloroplasts during development.
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Affiliation(s)
- Prabhavathi Talloji
- Department of Biochemistry and Cell Biology, Max Perutz Labs/Center for Molecular Biology, University of Vienna, A-1030, Vienna, Austria
| | - Lilian Nehlin
- Department of Biochemistry and Cell Biology, Max Perutz Labs/Center for Molecular Biology, University of Vienna, A-1030, Vienna, Austria
| | - Bruno Hüttel
- Max Planck Genome Centre Cologne, Max Planck Institute for Plant Breeding Research, 50829, Cologne, Germany
| | - Nikola Winter
- Department of Biochemistry and Cell Biology, Max Perutz Labs/Center for Molecular Biology, University of Vienna, A-1030, Vienna, Austria
| | - Martin Černý
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, CZ-613 00, Brno, Czech Republic
| | - Hana Dufková
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, CZ-613 00, Brno, Czech Republic
| | - Bulut Hamali
- Department of Biochemistry and Cell Biology, Max Perutz Labs/Center for Molecular Biology, University of Vienna, A-1030, Vienna, Austria
- Present address: Department of Integrative Biology, Oregon State University, 3029 Cordley Hall, Corvallis, OR, 97331, USA
| | - Katarzyna Hanczaryk
- Department of Biochemistry and Cell Biology, Max Perutz Labs/Center for Molecular Biology, University of Vienna, A-1030, Vienna, Austria
| | - Jan Novák
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, CZ-613 00, Brno, Czech Republic
| | - Monika Hermanns
- Institute of Plant Physiology (Bio III), RWTH-Aachen, 52056, Aachen, Germany
| | - Nicole Drexler
- Vienna Biocenter Core Facilities, Electron Microscopy, A-1030, Vienna, Austria
| | - Karolin Eifler
- Department of Biochemistry and Cell Biology, Max Perutz Labs/Center for Molecular Biology, University of Vienna, A-1030, Vienna, Austria
| | - Nikolaus Schlaich
- Institute of Plant Physiology (Bio III), RWTH-Aachen, 52056, Aachen, Germany
| | - Břetislav Brzobohatý
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, CZ-613 00, Brno, Czech Republic
- CEITEC - Central European Institute of Technology, Mendel University in Brno, CZ-61300, Brno, Czech Republic
| | - Andreas Bachmair
- Department of Biochemistry and Cell Biology, Max Perutz Labs/Center for Molecular Biology, University of Vienna, A-1030, Vienna, Austria.
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45
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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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46
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Barczak-Brzyżek A, Brzyżek G, Koter M, Siedlecka E, Gawroński P, Filipecki M. Plastid retrograde regulation of miRNA expression in response to light stress. BMC PLANT BIOLOGY 2022; 22:150. [PMID: 35346032 PMCID: PMC8962581 DOI: 10.1186/s12870-022-03525-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 03/10/2022] [Indexed: 05/03/2023]
Abstract
BACKGROUND MicroRNAs (miRNAs) are a class of endogenous noncoding RNAs that play a pivotal role in the regulation of plant development and responses to the surrounding environment. Despite the efforts made to elucidate their function in the adaptation of plants to many abiotic and biotic stresses, their role in high light (HL) stress is still vague. HL stress often arises upon plant exposure to full sunlight. Subsequent changes in nuclear gene expression are triggered by chloroplast-derived retrograde signals. RESULTS In this study, we show that HL is involved in miRNA-dependent regulation in Arabidopsis thaliana rosettes. Microtranscriptomic screening revealed a limited number of miRNAs reacting to HL. To explain the miRNA regulation mechanisms at the different biogenesis stages, chemical and genetic approaches were applied. First, we tested the possible role of plastoquinone (PQ) redox changes using photosynthetic electron transport chain inhibitors. The results suggest that increased primary transcript abundance (pri-miRNAs) of HL-regulated miRNAs is dependent on signals upstream of PQ. This indicates that such signals may originate from photosystem II, which is the main singlet oxygen (1O2) source. Nevertheless, no changes in pri-miRNA expression upon a dark-light shift in the conditional fluorescent (flu) mutant producing 1O2 were observed when compared to wild-type plants. Thus, we explored the 1O2 signaling pathway, which is initiated independently in HL and is related to β-carotene oxidation and production of volatile derivatives, such as β-cyclocitral (β-CC). Pri-miRNA induction by β-CC, which is a component of this 1O2 pathway, as well as an altered response in the methylene blue sensitivity 1 (mbs1) mutant support the role of 1O2 signaling in miRNA regulation. CONCLUSIONS We show that light stress triggers changes in miRNA expression. This stress response may be regulated by reactive oxygen species (ROS)-related signaling. In conclusion, our results link ROS action to miRNA biogenesis, suggesting its contribution to inconsistent pri- and mature miRNA dynamics.
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Affiliation(s)
- Anna Barczak-Brzyżek
- Department of Plant Genetics, Breeding and Biotechnology, Institute of Biology, Warsaw University of Life Sciences-SGGW, 02-776, Warsaw, Poland
| | - Grzegorz Brzyżek
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106, Warsaw, Poland
| | - Marek Koter
- Department of Plant Genetics, Breeding and Biotechnology, Institute of Biology, Warsaw University of Life Sciences-SGGW, 02-776, Warsaw, Poland
| | - Ewa Siedlecka
- Department of Plant Genetics, Breeding and Biotechnology, Institute of Biology, Warsaw University of Life Sciences-SGGW, 02-776, Warsaw, Poland
| | - Piotr Gawroński
- Department of Plant Genetics, Breeding and Biotechnology, Institute of Biology, Warsaw University of Life Sciences-SGGW, 02-776, Warsaw, Poland
| | - Marcin Filipecki
- Department of Plant Genetics, Breeding and Biotechnology, Institute of Biology, Warsaw University of Life Sciences-SGGW, 02-776, Warsaw, Poland.
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Tano DW, Woodson JD. Putting the brakes on chloroplast stress signaling. MOLECULAR PLANT 2022; 15:388-390. [PMID: 35183786 DOI: 10.1016/j.molp.2022.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 02/11/2022] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Affiliation(s)
- David W Tano
- The School of Plant Sciences, University of Arizona, 303 Forbes Hall, 1140 E. South Campus Drive, Tucson, AZ, USA
| | - Jesse D Woodson
- The School of Plant Sciences, University of Arizona, 303 Forbes Hall, 1140 E. South Campus Drive, Tucson, AZ, USA.
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48
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Wang Y, Wu Y, Zhong H, Chen S, Wong KB, Xia Y. Arabidopsis PUB2 and PUB4 connect signaling components of pattern-triggered immunity. THE NEW PHYTOLOGIST 2022; 233:2249-2265. [PMID: 34918346 DOI: 10.1111/nph.17922] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 12/04/2021] [Indexed: 06/14/2023]
Abstract
Plants use pattern recognition receptors (PRRs) to detect pathogen-associated molecular patterns (PAMPs) and activate pattern-triggered immunity (PTI). Precise regulation of information from PRRs to downstream signaling components is vital to mounting an appropriate immune response and requires dynamic interactions of these PTI components. We used transcriptome profiling, phenotypic analysis, molecular genetics, and protein-protein interaction analysis to understand the roles of the Arabidopsis plant U-box (PUB) proteins PUB2 and PUB4 in disease resistance and PTI signaling. Loss of function of both PUB2 and PUB4 diminishes the PAMP-triggered oxidative bursts and dampens mitogen-activated protein kinase signaling, resulting in a severe compromise in resistance to not only pathogenic but also nonpathogenic strains of Pseudomonas syringae. Within PUB4, the E3 ligase activity is dispensable, but the armadillo repeat region is essential and sufficient for its function in immunity. PUB2 and PUB4 interact with PTI signaling components, including FLS2, BIK1, PBL27, and RbohD, and enhance FLS2-BIK1 and BIK1-RbohD interactions. Our study reveals that PUB2 and PUB4 are critical components of plant immunity and connect PTI components to positively regulate defense responses.
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Affiliation(s)
- Yiping Wang
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
- Institute for Research and Continuing Education, Hong Kong Baptist University, Shen Zhen, 518057, China
| | - Yingying Wu
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Huan Zhong
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Shuai Chen
- School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, 999077, China
| | - Kam-Bo Wong
- School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, 999077, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, 999077, China
| | - Yiji Xia
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, 999077, China
- State Key Laboratory of Biological and Environmental Analysis, Hong Kong Baptist University, Hong Kong, 999077, China
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Fisher KE, Krishnamoorthy P, Joens MS, Chory J, Fitzpatrick JAJ, Woodson JD. Singlet Oxygen Leads to Structural Changes to Chloroplasts during their Degradation in the Arabidopsis thaliana plastid ferrochelatase two Mutant. PLANT & CELL PHYSIOLOGY 2022; 63:248-264. [PMID: 34850209 DOI: 10.1093/pcp/pcab167] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/01/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
During stress, chloroplasts produce large amounts of reactive oxygen species (ROS). Chloroplasts also contain many nutrients, including 80% of a leaf's nitrogen supply. Therefore, to protect cells from photo-oxidative damage and to redistribute nutrients to sink tissues, chloroplasts are prime targets for degradation. Multiple chloroplast degradation pathways are induced by photo-oxidative stress or nutrient starvation, but the mechanisms by which damaged or senescing chloroplasts are identified, transported to the central vacuole and degraded are poorly defined. Here, we investigated the structures involved with degrading chloroplasts induced by the ROS singlet oxygen (1O2) in the Arabidopsis thaliana plastid ferrochelatase two (fc2) mutant. Under mild 1O2 stress, most fc2 chloroplasts appeared normal, but had reduced starch content. A subset of chloroplasts was degrading, and some protruded into the central vacuole via 'blebbing' structures. A 3D electron microscopy analysis demonstrated that up to 35% of degrading chloroplasts contained such structures. While the location of a chloroplast within a cell did not affect the likelihood of its degradation, chloroplasts in spongy mesophyll cells were degraded at a higher rate than those in palisade mesophyll cells. To determine if degrading chloroplasts have unique structural characteristics, allowing them to be distinguished from healthy chloroplasts, we analyzed fc2 seedlings grown under different levels of photo-oxidative stress. A correlation was observed among chloroplast swelling, 1O2 signaling and the state of degradation. Finally, plastoglobule (PG) enzymes involved in chloroplast disassembly were upregulated while PGs increased their association with the thylakoid grana, implicating an interaction between 1O2-induced chloroplast degradation and senescence pathways.
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Affiliation(s)
- Karen E Fisher
- The School of Plant Sciences, University of Arizona, 1140 E South Campus Dr., Tucson, AZ 85721, USA
| | - Praveen Krishnamoorthy
- Washington University Center for Cellular Imaging, Washington University School of Medicine, 660 W. Euclid Avenue, St. Louis, MO 63110, USA
| | | | - Joanne Chory
- Plant Biology Laboratory and the Howard Hughes Medical Institute, The Salk Institute, 10010 N Torrey Pines Rd., La Jolla, CA 92037, USA
| | - James A J Fitzpatrick
- Washington University Center for Cellular Imaging, Washington University School of Medicine, 660 W. Euclid Avenue, St. Louis, MO 63110, USA
- Departments of Cell Biology & Physiology and Neuroscience, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
- Department of Biomedical Engineering, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA
| | - Jesse D Woodson
- The School of Plant Sciences, University of Arizona, 1140 E South Campus Dr., Tucson, AZ 85721, USA
- Washington University Center for Cellular Imaging, Washington University School of Medicine, 660 W. Euclid Avenue, St. Louis, MO 63110, USA
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50
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Li M, Kim C. Chloroplast ROS and stress signaling. PLANT COMMUNICATIONS 2022; 3:100264. [PMID: 35059631 PMCID: PMC8760138 DOI: 10.1016/j.xplc.2021.100264] [Citation(s) in RCA: 78] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/25/2021] [Accepted: 11/05/2021] [Indexed: 05/23/2023]
Abstract
Chloroplasts overproduce reactive oxygen species (ROS) under unfavorable environmental conditions, and these ROS are implicated in both signaling and oxidative damage. There is mounting evidence for their roles in translating environmental fluctuations into distinct physiological responses, but their targets, signaling cascades, and mutualism and antagonism with other stress signaling cascades and within ROS signaling remain poorly understood. Great efforts made in recent years have shed new light on chloroplast ROS-directed plant stress responses, from ROS perception to plant responses, in conditional mutants of Arabidopsis thaliana or under various stress conditions. Some articles have also reported the mechanisms underlying the complexity of ROS signaling pathways, with an emphasis on spatiotemporal regulation. ROS and oxidative modification of affected target proteins appear to induce retrograde signaling pathways to maintain chloroplast protein quality control and signaling at a whole-cell level using stress hormones. This review focuses on these seemingly interconnected chloroplast-to-nucleus retrograde signaling pathways initiated by ROS and ROS-modified target molecules. We also discuss future directions in chloroplast stress research to pave the way for discovering new signaling molecules and identifying intersectional signaling components that interact in multiple chloroplast signaling pathways.
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