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Rabeh K, Oubohssaine M, Hnini M. TOR in plants: Multidimensional regulators of plant growth and signaling pathways. JOURNAL OF PLANT PHYSIOLOGY 2024; 294:154186. [PMID: 38330538 DOI: 10.1016/j.jplph.2024.154186] [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: 09/01/2023] [Revised: 01/20/2024] [Accepted: 01/22/2024] [Indexed: 02/10/2024]
Abstract
Target Of Rapamycin (TOR) represents a ubiquitous kinase complex that has emerged as a central regulator of cell growth and metabolism in nearly all eukaryotic organisms. TOR is an evolutionarily conserved protein kinase, functioning as a central signaling hub that integrates diverse internal and external cues to regulate a multitude of biological processes. These processes collectively exert significant influence on plant growth, development, nutrient assimilation, photosynthesis, fruit ripening, and interactions with microorganisms. Within the plant domain, the TOR complex comprises three integral components: TOR, RAPTOR, and LST8. This comprehensive review provides insights into various facets of the TOR protein, encompassing its origin, structure, function, and the regulatory and signaling pathways operative in photosynthetic organisms. Additionally, we explore future perspectives related to this pivotal protein kinase.
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Affiliation(s)
- Karim Rabeh
- Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnologies, Biodiversity and Environment, Faculty of Sciences, Mohammed V University, Rabat, Morocco.
| | - Malika Oubohssaine
- Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnologies, Biodiversity and Environment, Faculty of Sciences, Mohammed V University, Rabat, Morocco
| | - Mohamed Hnini
- Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnologies, Biodiversity and Environment, Faculty of Sciences, Mohammed V University, Rabat, Morocco
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2
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Calderan-Rodrigues MJ, Caldana C. Impact of the TOR pathway on plant growth via cell wall remodeling. JOURNAL OF PLANT PHYSIOLOGY 2024; 294:154202. [PMID: 38422631 DOI: 10.1016/j.jplph.2024.154202] [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: 10/01/2023] [Revised: 02/12/2024] [Accepted: 02/13/2024] [Indexed: 03/02/2024]
Abstract
Plant growth is intimately linked to the availability of carbon and energy status. The Target of rapamycin (TOR) pathway is a highly relevant metabolic sensor and integrator of plant-assimilated C into development and growth. The cell wall accounts for around a third of the cell biomass, and the investment of C into this structure should be finely tuned for optimal growth. The plant C status plays a significant role in controlling the rate of cell wall synthesis. TOR signaling regulates cell growth and expansion, which are fundamental processes for plant development. The availability of nutrients and energy, sensed and integrated by TOR, influences cell division and elongation, ultimately impacting the synthesis and deposition of cell wall components. The plant cell wall is crucial in environmental adaptation and stress responses. TOR senses and internalizes various environmental cues, such as nutrient availability and stresses. These environmental factors influence TOR activity, which modulates cell wall remodeling to cope with changing conditions. Plant hormones, including auxins, gibberellins, and brassinosteroids, also regulate TOR signaling and cell wall-related processes. The connection between nutrients and cell wall pathways modulated by TOR are discussed.
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Affiliation(s)
- Maria Juliana Calderan-Rodrigues
- Max-Planck Institut für Molekulare Pflanzenphysiologie, 14476, Potsdam-Golm, Germany; Universidade de São Paulo, Escola Superior de Agricultura "Luiz de Queiroz", 13418-900, Piracicaba, SP, Brazil.
| | - Camila Caldana
- Max-Planck Institut für Molekulare Pflanzenphysiologie, 14476, Potsdam-Golm, Germany
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3
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Marash I, Gupta R, Anand G, Leibman-Markus M, Lindner N, Israeli A, Nir D, Avni A, Bar M. TOR coordinates cytokinin and gibberellin signals mediating development and defense. PLANT, CELL & ENVIRONMENT 2024; 47:629-650. [PMID: 37904283 DOI: 10.1111/pce.14748] [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: 05/16/2023] [Revised: 09/15/2023] [Accepted: 10/17/2023] [Indexed: 11/01/2023]
Abstract
Plants constantly perceive and process environmental signals and balance between the energetic demands of growth and defense. Growth arrest upon pathogen attack was previously suggested to result from a redirection of the plants' metabolic resources towards the activation of plant defense. The energy sensor Target of Rapamycin (TOR) kinase is a conserved master coordinator of growth and development in all eukaryotes. Although TOR is positioned at the interface between development and defense, little is known about the mechanisms by which TOR may potentially regulate the relationship between these two modalities. The plant hormones cytokinin (CK) and gibberellin (GA) execute various aspects of plant development and defense. The ratio between CK and GA was reported to determine the outcome of developmental programmes. Here, investigating the interplay between TOR-mediated development and TOR-mediated defense in tomato, we found that TOR silencing resulted in rescue of several different aberrant developmental phenotypes, demonstrating that TOR is required for the execution of developmental cues. In parallel, TOR inhibition enhanced immunity in genotypes with a low CK/GA ratio but not in genotypes with a high CK/GA ratio. TOR-inhibition mediated disease resistance was found to depend on developmental status, and was abolished in strongly morphogenetic leaves, while being strongest in mature, differentiated leaves. CK repressed TOR activity, suggesting that CK-mediated immunity may rely on TOR downregulation. At the same time, TOR activity was promoted by GA, and TOR silencing reduced GA sensitivity, indicating that GA signalling requires normal TOR activity. Our results demonstrate that TOR likely acts in concert with CK and GA signalling, executing signalling cues in both defense and development. Thus, differential regulation of TOR or TOR-mediated processes could regulate the required outcome of development-defense prioritisation.
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Affiliation(s)
- Iftah Marash
- Department of Plant Pathology and Weed Research, Agricultural Research Organization, Volcani Institute, Bet Dagan, Israel
- School of Plant Science and Food Security, Tel-Aviv University, Tel-Aviv, Israel
| | - Rupali Gupta
- Department of Plant Pathology and Weed Research, Agricultural Research Organization, Volcani Institute, Bet Dagan, Israel
| | - Gautam Anand
- Department of Plant Pathology and Weed Research, Agricultural Research Organization, Volcani Institute, Bet Dagan, Israel
| | - Meirav Leibman-Markus
- Department of Plant Pathology and Weed Research, Agricultural Research Organization, Volcani Institute, Bet Dagan, Israel
| | - Naomi Lindner
- Department of Plant Pathology and Weed Research, Agricultural Research Organization, Volcani Institute, Bet Dagan, Israel
- Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Alon Israeli
- Institute of Plant Science and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Dov Nir
- Institute of Plant Science and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Adi Avni
- School of Plant Science and Food Security, Tel-Aviv University, Tel-Aviv, Israel
| | - Maya Bar
- Department of Plant Pathology and Weed Research, Agricultural Research Organization, Volcani Institute, Bet Dagan, Israel
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Siodmak A, Martinez-Seidel F, Rayapuram N, Bazin J, Alhoraibi H, Gentry-Torfer D, Tabassum N, Sheikh AH, Kise J, Blilou I, Crespi M, Kopka J, Hirt H. Dynamics of ribosome composition and ribosomal protein phosphorylation in immune signaling in Arabidopsis thaliana. Nucleic Acids Res 2023; 51:11876-11892. [PMID: 37823590 PMCID: PMC10681734 DOI: 10.1093/nar/gkad827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 09/14/2023] [Accepted: 09/20/2023] [Indexed: 10/13/2023] Open
Abstract
In plants, the detection of microbe-associated molecular patterns (MAMPs) induces primary innate immunity by the activation of mitogen-activated protein kinases (MAPKs). We show here that the MAMP-activated MAPK MPK6 not only modulates defense through transcriptional regulation but also via the ribosomal protein translation machinery. To understand the effects of MPK6 on ribosomes and their constituent ribosomal proteins (RPs), polysomes, monosomes and the phosphorylation status of the RPs, MAMP-treated WT and mpk6 mutant plants were analysed. MAMP-activation induced rapid changes in RP composition of monosomes, polysomes and in the 60S ribosomal subunit in an MPK6-specific manner. Phosphoproteome analysis showed that MAMP-activation of MPK6 regulates the phosphorylation status of the P-stalk ribosomal proteins by phosphorylation of RPP0 and the concomitant dephosphorylation of RPP1 and RPP2. These events coincide with a significant decrease in the abundance of ribosome-bound RPP0s, RPP1s and RPP3s in polysomes. The P-stalk is essential in regulating protein translation by recruiting elongation factors. Accordingly, we found that RPP0C mutant plants are compromised in basal resistance to Pseudomonas syringae infection. These data suggest that MAMP-induced defense also involves MPK6-induced regulation of P-stalk proteins, highlighting a new role of ribosomal regulation in plant innate immunity.
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Affiliation(s)
- Anna Siodmak
- Center for Desert Agriculture, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Federico Martinez-Seidel
- Willmitzer Department, Max Planck-Institute of Molecular Plant Physiology, Potsdam, Germany
- School of Biosciences, The University of Melbourne, Parkville, VIC, Australia
| | - Naganand Rayapuram
- Center for Desert Agriculture, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Jeremie Bazin
- CNRS, INRA, Institute of Plant Sciences Paris-Saclay IPS2, Univ Paris Sud, Univ Evry, Univ Paris-Diderot, Sorbonne Paris-Cite, Universite Paris-Saclay, Orsay, France
| | - Hanna Alhoraibi
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, 21551 Jeddah, Saudi Arabia
| | - Dione Gentry-Torfer
- Willmitzer Department, Max Planck-Institute of Molecular Plant Physiology, Potsdam, Germany
- School of Biosciences, The University of Melbourne, Parkville, VIC, Australia
| | - Naheed Tabassum
- Center for Desert Agriculture, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Arsheed H Sheikh
- Center for Desert Agriculture, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - José Kenyi González Kise
- Center for Desert Agriculture, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Ikram Blilou
- Center for Desert Agriculture, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Martin Crespi
- CNRS, INRA, Institute of Plant Sciences Paris-Saclay IPS2, Univ Paris Sud, Univ Evry, Univ Paris-Diderot, Sorbonne Paris-Cite, Universite Paris-Saclay, Orsay, France
| | - Joachim Kopka
- Willmitzer Department, Max Planck-Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Heribert Hirt
- Center for Desert Agriculture, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9, 1030 Vienna, Austria
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5
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Helderman TA, Deurhof L, Bertran A, Richard MMS, Kormelink R, Prins M, Joosten MHAJ, van den Burg HA. Members of the ribosomal protein S6 (RPS6) family act as pro-viral factor for tomato spotted wilt orthotospovirus infectivity in Nicotiana benthamiana. MOLECULAR PLANT PATHOLOGY 2022; 23:431-446. [PMID: 34913556 PMCID: PMC8828452 DOI: 10.1111/mpp.13169] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/16/2021] [Accepted: 11/17/2021] [Indexed: 05/07/2023]
Abstract
To identify host factors for tomato spotted wilt orthotospovirus (TSWV), a virus-induced gene silencing (VIGS) screen using tobacco rattle virus (TRV) was performed on Nicotiana benthamiana for TSWV susceptibility. To rule out any negative effect on the plants' performance due to a double viral infection, the method was optimized to allow screening of hundreds of clones in a standardized fashion. To normalize the results obtained in and between experiments, a set of controls was developed to evaluate in a consist manner both VIGS efficacy and the level of TSWV resistance. Using this method, 4532 random clones of an N. benthamiana cDNA library were tested, resulting in five TRV clones that provided nearly complete resistance against TSWV. Here we report on one of these clones, of which the insert targets a small gene family coding for the ribosomal protein S6 (RPS6) that is part of the 40S ribosomal subunit. This RPS6 family is represented by three gene clades in the genome of Solanaceae family members, which were jointly important for TSWV susceptibility. Interestingly, RPS6 is a known host factor implicated in the replication of different plant RNA viruses, including the negative-stranded TSWV and the positive-stranded potato virus X.
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Affiliation(s)
- Tieme A. Helderman
- Molecular Plant PathologySwammerdam Institute for Life SciencesUniversity of AmsterdamAmsterdamNetherlands
| | - Laurens Deurhof
- Laboratory of PhytopathologyDepartment of Plant SciencesWageningen UniversityWageningenNetherlands
| | - André Bertran
- Laboratory of VirologyDepartment of Plant SciencesWageningen UniversityWageningenNetherlands
| | - Manon M. S. Richard
- Molecular Plant PathologySwammerdam Institute for Life SciencesUniversity of AmsterdamAmsterdamNetherlands
| | - Richard Kormelink
- Laboratory of VirologyDepartment of Plant SciencesWageningen UniversityWageningenNetherlands
| | - Marcel Prins
- Molecular Plant PathologySwammerdam Institute for Life SciencesUniversity of AmsterdamAmsterdamNetherlands
- KeyGene N.V.WageningenNetherlands
| | | | - Harrold A. van den Burg
- Molecular Plant PathologySwammerdam Institute for Life SciencesUniversity of AmsterdamAmsterdamNetherlands
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Salazar-Díaz K, Dong Y, Papdi C, Ferruzca-Rubio EM, Olea-Badillo G, Ryabova LA, Dinkova TD. TOR senses and regulates spermidine metabolism during seedling establishment and growth in maize and Arabidopsis. iScience 2021; 24:103260. [PMID: 34765910 PMCID: PMC8571727 DOI: 10.1016/j.isci.2021.103260] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 04/23/2021] [Accepted: 10/11/2021] [Indexed: 12/14/2022] Open
Abstract
Spermidine (Spd) is a nitrogen sink and signaling molecule that plays pivotal roles in eukaryotic cell growth and must be finetuned to meet various energy demands. In eukaryotes, target of rapamycin (TOR) is a central nutrient sensor, especially N, and a master-regulator of growth and development. Here, we discovered that Spd stimulates the growth of maize and Arabidopsis seedlings through TOR signaling. Inhibition of Spd biosynthesis led to TOR inactivation and growth defects. Furthermore, disruption of a TOR complex partner RAPTOR1B abolished seedling growth stimulation by Spd. Strikingly, TOR activated by Spd promotes translation of key metabolic enzyme upstream open reading frame (uORF)-containing mRNAs, PAO and CuAO, by facilitating translation reinitiation and providing feedback to polyamine metabolism and TOR activation. The Spd-TOR relay protected young-age seedlings of maize from expeditious stress heat shock. Our results demonstrate Spd is an upstream effector of TOR kinase in planta and provide its potential application for crop protection. Spermidine (Spd) stimulates growth of maize and Arabidopsis by activating TOR signaling TOR stimulates translation efficiency of uORF-containing mRNAs involved in Spd catabolism TOR provides feedback to polyamine homeostasis in response to excess of Spd The Spd-TOR signaling axis protects maize seedlings from expeditious heat stress
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Affiliation(s)
- Kenia Salazar-Díaz
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Yihan Dong
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 67084 Strasbourg, France
| | - Csaba Papdi
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 67084 Strasbourg, France
| | - Ernesto Miguel Ferruzca-Rubio
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Grecia Olea-Badillo
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Lyubov A Ryabova
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 67084 Strasbourg, France
| | - Tzvetanka D Dinkova
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
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Mancera-Martínez E, Dong Y, Makarian J, Srour O, Thiébeauld O, Jamsheer M, Chicher J, Hammann P, Schepetilnikov M, Ryabova LA. Phosphorylation of a reinitiation supporting protein, RISP, determines its function in translation reinitiation. Nucleic Acids Res 2021; 49:6908-6924. [PMID: 34133725 PMCID: PMC8266674 DOI: 10.1093/nar/gkab501] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 05/14/2021] [Accepted: 06/14/2021] [Indexed: 12/12/2022] Open
Abstract
Reinitiation supporting protein, RISP, interacts with 60S (60S ribosomal subunit) and eIF3 (eukaryotic initiation factor 3) in plants. TOR (target-of-rapamycin) mediates RISP phosphorylation at residue Ser267, favoring its binding to eL24 (60S ribosomal protein L24). In a viral context, RISP, when phosphorylated, binds the CaMV transactivator/ viroplasmin, TAV, to assist in an exceptional mechanism of reinitiation after long ORF translation. Moreover, we show here that RISP interacts with eIF2 via eIF2β and TOR downstream target 40S ribosomal protein eS6. A RISP phosphorylation knockout, RISP-S267A, binds preferentially eIF2β, and both form a ternary complex with eIF3a in vitro. Accordingly, transient overexpression in plant protoplasts of RISP-S267A, but not a RISP phosphorylation mimic, RISP-S267D, favors translation initiation. In contrast, RISP-S267D preferentially binds eS6, and, when bound to the C-terminus of eS6, can capture 60S in a highly specific manner in vitro, suggesting that it mediates 60S loading during reinitiation. Indeed, eS6-deficient plants are highly resistant to CaMV due to their reduced reinitiation capacity. Strikingly, an eS6 phosphomimic, when stably expressed in eS6-deficient plants, can fully restore the reinitiation deficiency of these plants in cellular and viral contexts. These results suggest that RISP function in translation (re)initiation is regulated by phosphorylation at Ser267.
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Affiliation(s)
- Eder Mancera-Martínez
- Institut de biologie de moléculaire des plantes UPR2357 du CNRS, Université de Strasbourg, Strasbourg, France
| | - Yihan Dong
- Institut de biologie de moléculaire des plantes UPR2357 du CNRS, Université de Strasbourg, Strasbourg, France
| | - Joelle Makarian
- Institut de biologie de moléculaire des plantes UPR2357 du CNRS, Université de Strasbourg, Strasbourg, France
| | - Ola Srour
- Institut de biologie de moléculaire des plantes UPR2357 du CNRS, Université de Strasbourg, Strasbourg, France
| | - Odon Thiébeauld
- Institut de biologie de moléculaire des plantes UPR2357 du CNRS, Université de Strasbourg, Strasbourg, France
| | - Muhammed Jamsheer
- Institut de biologie de moléculaire des plantes UPR2357 du CNRS, Université de Strasbourg, Strasbourg, France
| | - Johana Chicher
- Plateforme protéomique Strasbourg Esplanade FRC1589 du CNRS, Université de Strasbourg, Strasbourg, France
| | - Philippe Hammann
- Plateforme protéomique Strasbourg Esplanade FRC1589 du CNRS, Université de Strasbourg, Strasbourg, France
| | - Mikhail Schepetilnikov
- Institut de biologie de moléculaire des plantes UPR2357 du CNRS, Université de Strasbourg, Strasbourg, France
| | - Lyubov A Ryabova
- Institut de biologie de moléculaire des plantes UPR2357 du CNRS, Université de Strasbourg, Strasbourg, France
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Uzair M, Long H, Zafar SA, Patil SB, Chun Y, Li L, Fang J, Zhao J, Peng L, Yuan S, Li X. Narrow Leaf21, encoding ribosomal protein RPS3A, controls leaf development in rice. PLANT PHYSIOLOGY 2021; 186:497-518. [PMID: 33591317 PMCID: PMC8154097 DOI: 10.1093/plphys/kiab075] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 01/26/2021] [Indexed: 05/19/2023]
Abstract
Leaf morphology influences photosynthesis, transpiration, and ultimately crop yield. However, the molecular mechanism of leaf development is still not fully understood. Here, we identified and characterized the narrow leaf21 (nal21) mutant in rice (Oryza sativa), showing a significant reduction in leaf width, leaf length and plant height, and increased tiller number. Microscopic observation revealed defects in the vascular system and reduced epidermal cell size and number in the nal21 leaf blade. Map-based cloning revealed that NAL21 encodes a ribosomal small subunit protein RPS3A. Ribosome-targeting antibiotics resistance assay and ribosome profiling showed a significant reduction in the free 40S ribosome subunit in the nal21 mutant. The nal21 mutant showed aberrant auxin responses in which multiple auxin response factors (ARFs) harboring upstream open-reading frames (uORFs) in their 5'-untranslated region were repressed at the translational level. The WUSCHEL-related homeobox 3A (OsWOX3A) gene, a key transcription factor involved in leaf blade lateral outgrowth, is also under the translational regulation by RPS3A. Transformation with modified OsARF11, OsARF16, and OsWOX3A genomic DNA (gDNA) lacking uORFs rescued the narrow leaf phenotype of nal21 to a better extent than transformation with their native gDNA, implying that RPS3A could regulate translation of ARFs and WOX3A through uORFs. Our results demonstrate that proper translational regulation of key factors involved in leaf development is essential to maintain normal leaf morphology.
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Affiliation(s)
- Muhammad Uzair
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Haixin Long
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Syed Adeel Zafar
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Suyash B Patil
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Yan Chun
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Lu Li
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Jingjing Fang
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Jinfeng Zhao
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Lixiang Peng
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | | | - Xueyong Li
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
- Author for communication:
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Obomighie I, Lapenas K, Murphy BE, Bowles AMC, Bechtold U, Prischi F. The Role of Ribosomal Protein S6 Kinases in Plant Homeostasis. Front Mol Biosci 2021; 8:636560. [PMID: 33778006 PMCID: PMC7988200 DOI: 10.3389/fmolb.2021.636560] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 01/11/2021] [Indexed: 01/11/2023] Open
Abstract
The p70 ribosomal S6 kinase (S6K) family is a group of highly conserved kinases in eukaryotes that regulates cell growth, cell proliferation, and stress response via modulating protein synthesis and ribosomal biogenesis. S6Ks are downstream effectors of the Target of Rapamycin (TOR) pathway, which connects nutrient and energy signaling to growth and homeostasis, under normal and stress conditions. The plant S6K family includes two isoforms, S6K1 and S6K2, which, despite their high level of sequence similarity, have distinct functions and regulation mechanisms. Significant advances on the characterization of human S6Ks have occurred in the past few years, while studies on plant S6Ks are scarce. In this article, we review expression and activation of the two S6K isoforms in plants and we discuss their roles in mediating responses to stresses and developmental cues.
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Affiliation(s)
| | - Kestutis Lapenas
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Billy E Murphy
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | | | - Ulrike Bechtold
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Filippo Prischi
- School of Life Sciences, University of Essex, Colchester, United Kingdom
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10
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Zhigailov AV, Stanbekova GE, Beisenov DK, Nizkorodova AS, Polimbetova NS, Iskakov BK. Constructing the constitutively active ribosomal protein S6 kinase 2 from Arabidopsis thaliana (AtRPS6K2) and testing its activity in vitro. Vavilovskii Zhurnal Genet Selektsii 2021; 24:233-238. [PMID: 33659803 PMCID: PMC7904244 DOI: 10.18699/vj20.39-o] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Ribosomal protein S6 (RPS6) is the only phosphorylatable protein of the eukaryotic 40S ribosomal subunit. Ribosomes with phosphorylated RPS6 can selectively translate 5'TOP-(5'-terminal oligopyrimidine)-containing mRNAs that encode most proteins of the translation apparatus. The study of translational control of 5'TOP-mRNAs, which are preferentially translated when RPS6 is phosphorylated and cease to be translated when RPS6 is de-phosphorylated, is particularly important. In Arabidopsis thaliana, AtRPS6 is phosphorylated by kinase AtRPS6K2, which should in turn be phosphorylated by upper level kinases (AtPDK1 - at serine (S) 296, AtTOR - at threonine (T) 455 and S437) for full activation. We have cloned AtRPS6K2 cDNA gene and carried out in vitro mutagenesis replacing codons encoding S296, S437 and T455 by triplets of phosphomimetic glutamic acid (E). After the expression of both natural and mutated cDNAs in Escherichia coli cells, two recombinant proteins were isolated: native AtRPS6K2 and presumably constitutively active AtRPS6K2(S296E, S437E, T455E). The activity of these variants was tested in vitro. Both kinases could phosphorylate wheat (Triticum aestivum L.) TaRPS6 as part of 40S ribosomal subunits isolated from wheat embryos, though the non-mutated variant had less activity than phosphomimetic one. The ability of recombinant non-mutated kinase to phosphorylate TaRPS6 can be explained by its phosphorylation by bacterial kinases during the expression and isolation steps. The phosphomimetically mutated AtRPS6K2(S296E, S437E, T455E) can serve as a tool to investigate preferential translation of 5'TOP-mRNAs in wheat germ cell-free system, in which most of 40S ribosomal subunits have phosphorylated TaRPS6. Besides, such an approach has a biotechnological application in producing genetically modified plants with increased biomass and productivity through stimulation of cell growth and division.
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Affiliation(s)
- A V Zhigailov
- M.A. Aitkhozhin Institute of Molecular Biology and Biochemistry, Almaty, Kazakhstan
| | - G E Stanbekova
- M.A. Aitkhozhin Institute of Molecular Biology and Biochemistry, Almaty, Kazakhstan
| | - D K Beisenov
- M.A. Aitkhozhin Institute of Molecular Biology and Biochemistry, Almaty, Kazakhstan Institute of Plant Biology and Biotechnology, Almaty, Kazakhstan
| | - A S Nizkorodova
- M.A. Aitkhozhin Institute of Molecular Biology and Biochemistry, Almaty, Kazakhstan
| | - N S Polimbetova
- M.A. Aitkhozhin Institute of Molecular Biology and Biochemistry, Almaty, Kazakhstan
| | - B K Iskakov
- M.A. Aitkhozhin Institute of Molecular Biology and Biochemistry, Almaty, Kazakhstan Institute of Plant Biology and Biotechnology, Almaty, Kazakhstan
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11
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González-López O, Palacios-Nava BB, Peña-Uribe CA, Campos-García J, López-Bucio J, García-Pineda E, Reyes de la Cruz H. Growth promotion in Arabidopsis thaliana by bacterial cyclodipeptides involves the TOR/S6K pathway activation. JOURNAL OF PLANT PHYSIOLOGY 2021; 257:153343. [PMID: 33387853 DOI: 10.1016/j.jplph.2020.153343] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 06/12/2023]
Abstract
Cyclodipeptides (CDPs) are the smallest peptidic molecules that can be produced by diverse organisms such as bacteria, fungi, and animals. They have multiple biological effects. In this paper, we examined the CDPs produced by the bacteria Pseudomonas aeruginosa PAO1, which are known as opportunistic pathogens of humans and plants on TARGET OF RAPAMYCIN (TOR) signaling pathways, and regulation of root system architecture. This bacterium produces the bioactive CDPs: cyclo(L-Pro-L-Leu), cyclo(L-Pro-L-Phe), cyclo(L-Pro-L-Tyr), and cyclo(L-Pro-L-Val). In a previous report, these molecules were found to modulate basic cellular programs not only via auxin mechanisms but also by promoting the phosphorylation of the S6 ribosomal protein kinase (S6K), a downstream substrate of the TOR kinase. In the present work, we found that the inoculation of Arabidopsis plants with P. aeruginosa PAO1, the non-pathogenic P. aeruginosa ΔlasI/Δrhll strain (JM2), or by direct exposure of plants to CDPs influenced growth and promoted root branching depending upon the treatment imposed, while genetic evidence using Arabidopsis lines with enhanced or decreased TOR levels indicated a critical role of this pathway in the bacterial phytostimulation.
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Affiliation(s)
- Omar González-López
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ed B1, B3, A1', U3, Ciudad Universitaria, Morelia, Michoacán, CP 58030, Mexico
| | - Brenda Berenice Palacios-Nava
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ed B1, B3, A1', U3, Ciudad Universitaria, Morelia, Michoacán, CP 58030, Mexico
| | - César Arturo Peña-Uribe
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ed B1, B3, A1', U3, Ciudad Universitaria, Morelia, Michoacán, CP 58030, Mexico
| | - Jesús Campos-García
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ed B1, B3, A1', U3, Ciudad Universitaria, Morelia, Michoacán, CP 58030, Mexico
| | - José López-Bucio
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ed B1, B3, A1', U3, Ciudad Universitaria, Morelia, Michoacán, CP 58030, Mexico
| | - Ernesto García-Pineda
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ed B1, B3, A1', U3, Ciudad Universitaria, Morelia, Michoacán, CP 58030, Mexico
| | - Homero Reyes de la Cruz
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ed B1, B3, A1', U3, Ciudad Universitaria, Morelia, Michoacán, CP 58030, Mexico.
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12
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Wang P, Wang T, Han J, Li M, Zhao Y, Su T, Ma C. Plant Autophagy: An Intricate Process Controlled by Various Signaling Pathways. FRONTIERS IN PLANT SCIENCE 2021; 12:754982. [PMID: 34630498 PMCID: PMC8495024 DOI: 10.3389/fpls.2021.754982] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 08/31/2021] [Indexed: 05/17/2023]
Abstract
Autophagy is a ubiquitous process used widely across plant cells to degrade cellular material and is an important regulator of plant growth and various environmental stress responses in plants. The initiation and dynamics of autophagy in plant cells are precisely controlled according to the developmental stage of the plant and changes in the environment, which are transduced into intracellular signaling pathways. These signaling pathways often regulate autophagy by mediating TOR (Target of Rapamycin) kinase activity, an important regulator of autophagy initiation; however, some also act via TOR-independent pathways. Under nutrient starvation, TOR activity is suppressed through glucose or ROS (reactive oxygen species) signaling, thereby promoting the initiation of autophagy. Under stresses, autophagy can be regulated by the regulatory networks connecting stresses, ROS and plant hormones, and in turn, autophagy regulates ROS levels and hormone signaling. This review focuses on the latest research progress in the mechanism of different external signals regulating autophagy.
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13
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Kazibwe Z, Soto-Burgos J, MacIntosh GC, Bassham DC. TOR mediates the autophagy response to altered nucleotide homeostasis in an RNase mutant. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:6907-6920. [PMID: 32905584 DOI: 10.1093/jxb/eraa410] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 09/06/2020] [Indexed: 06/11/2023]
Abstract
The Arabidopsis thaliana T2 family endoribonuclease RNS2 localizes to the vacuole and functions in rRNA degradation. Loss of RNS2 activity impairs rRNA turnover and leads to constitutive autophagy, a process for degradation of cellular components. Autophagy is normally activated during environmental stress and is important for stress tolerance and homeostasis. Here we show that restoration of cytosolic purine nucleotide levels rescues the constitutive autophagy phenotype of rns2-2 seedlings, whereas inhibition of purine synthesis induces autophagy in wild-type seedlings. rns2-2 seedlings have reduced activity of the target of rapamycin (TOR) kinase complex, a negative regulator of autophagy, and this phenotype is rescued by addition of inosine to increase purine levels. Activation of TOR in rns2-2 by exogenous auxin blocks the enhanced autophagy, indicating a possible involvement of the TOR signaling pathway in the activation of autophagy in the rns2-2 mutant. Our data suggest a model in which loss of rRNA degradation in rns2-2 leads to a reduction in cytoplasmic nucleotide concentrations, which in turn inhibits TOR activity, leading to activation of autophagy to restore homeostasis.
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Affiliation(s)
- Zakayo Kazibwe
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA
| | - Junmarie Soto-Burgos
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA
| | - Gustavo C MacIntosh
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, USA
| | - Diane C Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA
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14
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Mugume Y, Kazibwe Z, Bassham DC. Target of Rapamycin in Control of Autophagy: Puppet Master and Signal Integrator. Int J Mol Sci 2020; 21:ijms21218259. [PMID: 33158137 PMCID: PMC7672647 DOI: 10.3390/ijms21218259] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/01/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023] Open
Abstract
The target of rapamycin (TOR) is an evolutionarily-conserved serine/threonine kinase that senses and integrates signals from the environment to coordinate developmental and metabolic processes. TOR senses nutrients, hormones, metabolites, and stress signals to promote cell and organ growth when conditions are favorable. However, TOR is inhibited when conditions are unfavorable, promoting catabolic processes such as autophagy. Autophagy is a macromolecular degradation pathway by which cells degrade and recycle cytoplasmic materials. TOR negatively regulates autophagy through phosphorylation of ATG13, preventing activation of the autophagy-initiating ATG1-ATG13 kinase complex. Here we review TOR complex composition and function in photosynthetic and non-photosynthetic organisms. We also review recent developments in the identification of upstream TOR activators and downstream effectors of TOR. Finally, we discuss recent developments in our understanding of the regulation of autophagy by TOR in photosynthetic organisms.
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15
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Urquidi-Camacho RA, Lokdarshi A, von Arnim AG. Translational gene regulation in plants: A green new deal. WILEY INTERDISCIPLINARY REVIEWS. RNA 2020; 11:e1597. [PMID: 32367681 PMCID: PMC9258721 DOI: 10.1002/wrna.1597] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/31/2020] [Accepted: 04/01/2020] [Indexed: 01/09/2023]
Abstract
The molecular machinery for protein synthesis is profoundly similar between plants and other eukaryotes. Mechanisms of translational gene regulation are embedded into the broader network of RNA-level processes including RNA quality control and RNA turnover. However, over eons of their separate history, plants acquired new components, dropped others, and generally evolved an alternate way of making the parts list of protein synthesis work. Research over the past 5 years has unveiled how plants utilize translational control to defend themselves against viruses, regulate translation in response to metabolites, and reversibly adjust translation to a wide variety of environmental parameters. Moreover, during seed and pollen development plants make use of RNA granules and other translational controls to underpin developmental transitions between quiescent and metabolically active stages. The economics of resource allocation over the daily light-dark cycle also include controls over cellular protein synthesis. Important new insights into translational control on cytosolic ribosomes continue to emerge from studies of translational control mechanisms in viruses. Finally, sketches of coherent signaling pathways that connect external stimuli with a translational response are emerging, anchored in part around TOR and GCN2 kinase signaling networks. These again reveal some mechanisms that are familiar and others that are different from other eukaryotes, motivating deeper studies on translational control in plants. This article is categorized under: Translation > Translation Regulation RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Ricardo A. Urquidi-Camacho
- UT-ORNL Graduate School of Genome Science and Technology, The University of Tennessee, Knoxville, TN 37996
| | - Ansul Lokdarshi
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Albrecht G von Arnim
- Department of Biochemistry & Cellular and Molecular Biology and UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996
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16
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Scarpin MR, Leiboff S, Brunkard JO. Parallel global profiling of plant TOR dynamics reveals a conserved role for LARP1 in translation. eLife 2020; 9:e58795. [PMID: 33054972 PMCID: PMC7584452 DOI: 10.7554/elife.58795] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 10/14/2020] [Indexed: 12/15/2022] Open
Abstract
Target of rapamycin (TOR) is a protein kinase that coordinates eukaryotic metabolism. In mammals, TOR specifically promotes translation of ribosomal protein (RP) mRNAs when amino acids are available to support protein synthesis. The mechanisms controlling translation downstream from TOR remain contested, however, and are largely unexplored in plants. To define these mechanisms in plants, we globally profiled the plant TOR-regulated transcriptome, translatome, proteome, and phosphoproteome. We found that TOR regulates ribosome biogenesis in plants at multiple levels, but through mechanisms that do not directly depend on 5' oligopyrimidine tract motifs (5'TOPs) found in mammalian RP mRNAs. We then show that the TOR-LARP1-5'TOP signaling axis is conserved in plants and regulates expression of a core set of eukaryotic 5'TOP mRNAs, as well as new, plant-specific 5'TOP mRNAs. Our study illuminates ancestral roles of the TOR-LARP1-5'TOP metabolic regulatory network and provides evolutionary context for ongoing debates about the molecular function of LARP1.
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Affiliation(s)
- M Regina Scarpin
- Department of Plant and Microbial Biology, University of California at BerkeleyBerkeleyUnited States
- Plant Gene Expression Center, U.S. Department of Agriculture Agricultural Research ServiceAlbanyUnited States
| | - Samuel Leiboff
- Department of Plant and Microbial Biology, University of California at BerkeleyBerkeleyUnited States
- Plant Gene Expression Center, U.S. Department of Agriculture Agricultural Research ServiceAlbanyUnited States
- Department of Botany and Plant Pathology, Oregon State UniversityCorvallisUnited States
| | - Jacob O Brunkard
- Department of Plant and Microbial Biology, University of California at BerkeleyBerkeleyUnited States
- Plant Gene Expression Center, U.S. Department of Agriculture Agricultural Research ServiceAlbanyUnited States
- Laboratory of Genetics, University of Wisconsin—MadisonMadisonUnited States
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17
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Díaz-Granados VH, López-López JM, Flores-Sánchez J, Olguin-Alor R, Bedoya-López A, Dinkova TD, Salazar-Díaz K, Vázquez-Santana S, Vázquez-Ramos JM, Lara-Núñez A. Glucose modulates proliferation in root apical meristems via TOR in maize during germination. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 155:126-135. [PMID: 32745931 DOI: 10.1016/j.plaphy.2020.07.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 07/08/2020] [Accepted: 07/21/2020] [Indexed: 05/25/2023]
Abstract
The Glucose-Target of Rapamycin (Glc-TOR) pathway has been studied in different biological systems, but scarcely during early seed germination. This work examines its importance for cell proliferation, expression of cell cycle key genes, their protein levels, besides morphology and cellularization of the root apical meristem of maize (Zea mays) embryo axes during germination under the influence of two simple sugars, glucose and sucrose, and a specific inhibitor of TOR activity, AZD 8055. The two sugars promote germination similarly and to an extent, independently of TOR activity. However, the Glc-TOR pathway increases the number of cells committed to proliferation, increasing the expression of a cell cycle gene, ZmCycD4;2, a putative G1/S regulator. Also, Glc-TOR may have influence on the protein stability of another G1/S cyclin, ZmCycD3, but had no influence on ZmCDKA;1 or ZmKRP3 or their proteins. Results suggest that the Glc-TOR pathway participates in the regulation of proliferation through different mechanisms that, in the end, modify the timing of seed germination.
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Affiliation(s)
- Víctor Hugo Díaz-Granados
- Facultad de Química, Departamento de Bioquímica, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
| | - Jorge Manuel López-López
- Facultad de Química, Departamento de Bioquímica, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
| | - Jesús Flores-Sánchez
- Facultad de Química, Departamento de Bioquímica, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
| | - Roxana Olguin-Alor
- Laboratorio Nacional de Citometría de Flujo, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
| | - Andrea Bedoya-López
- Laboratorio Nacional de Citometría de Flujo, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
| | - Tzvetanka D Dinkova
- Facultad de Química, Departamento de Bioquímica, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
| | - Kenia Salazar-Díaz
- Facultad de Química, Departamento de Bioquímica, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
| | - Sonia Vázquez-Santana
- Facultad de Ciencias, Departamento de Biología Comparada, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
| | - Jorge Manuel Vázquez-Ramos
- Facultad de Química, Departamento de Bioquímica, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
| | - Aurora Lara-Núñez
- Facultad de Química, Departamento de Bioquímica, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
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18
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Upadhyaya S, Agrawal S, Gorakshakar A, Rao BJ. TOR kinase activity in Chlamydomonas reinhardtii is modulated by cellular metabolic states. FEBS Lett 2020; 594:3122-3141. [PMID: 32677084 DOI: 10.1002/1873-3468.13888] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 11/28/2019] [Accepted: 11/28/2019] [Indexed: 12/25/2022]
Abstract
Target of rapamycin (TOR) kinase is a sensor and a central integrator of internal and external metabolic cues. However, in algae and in higher plants, the components of TOR kinase signaling are yet to be characterized. Here, we establish an assay system to study TOR kinase activity in Chlamydomonas reinhardtii using the phosphorylation status of its putative downstream target, CrS6K. Using this assay, we probe the modulation of cellular TOR kinase activity under various physiological states such as photoautotrophy, heterotrophy, mixotrophy, and nitrogen (N) starvation. Importantly, we uncover that excess acetate in the medium leads to high cellular reactive oxygen species levels, triggering autophagy and a concomitant drop in TOR kinase activity in a dose-dependent manner, thus leading to a N-starvation-like cellular phenotype, even when nitrogen is present.
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Affiliation(s)
- Shivani Upadhyaya
- Department of Biological Sciences, Tata Institute of Fundamental Research (TIFR), Mumbai, India
| | - Shreya Agrawal
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Anmol Gorakshakar
- School of Biosciences and Technology, VIT University, Vellore, India
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19
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Méndez-Gómez M, Castro-Mercado E, Peña-Uribe CA, Reyes-de la Cruz H, López-Bucio J, García-Pineda E. TARGET OF RAPAMYCIN signaling plays a role in Arabidopsis growth promotion by Azospirillum brasilense Sp245. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2020; 293:110416. [PMID: 32081264 DOI: 10.1016/j.plantsci.2020.110416] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 12/16/2019] [Accepted: 12/19/2019] [Indexed: 06/10/2023]
Abstract
Azospirillum brasilense colonizes plant roots and improves productivity, but the molecular mechanisms behind its phytostimulation properties remain mostly unknown. Here, we uncover an important role of TARGET OF RAPAMYCIN (TOR) signaling on the response of Arabidopsis thaliana to A. brasilense Sp245. The effect of the bacterium on TOR expression was analyzed in the transgenic line TOR/tor-1, which carries a translational fusion with the GUS reporter protein, and the activity of TOR was assayed thought the phosphorylation of its downstream signaling target S6K protein. Besides, the role of TOR on plant growth in inoculated plants was assessed using the ATP-competitive inhibitor AZD-8055. A decrease in growth of the primary root correlates with an improved branching and absorptive capacity via lateral root and root hair proliferation 6 days after transplant to different concentrations of the bacterium (103 or 105 CFU/mL). Bacterization increased the expression of TOR in shoot and root apexes and promoted phosphorylation of S6K 3 days after transplant. The TOR inhibitor AZD-8055 (1 μM) inhibited plant growth and cell division in root meristems and in lateral root primordia, interfering with the phytostimulation by A. brasilense. In addition, the role of auxin produced by the bacterium to stimulate TOR expression was explored. Noteworthy, the A. brasilense mutant FAJ009, impaired in auxin production, was unable to elicit TOR signaling to the level observed for the wild-type strain, showing the importance of this phyhormone to stimulate TOR signaling. Together, our findings establish an important role of TOR signaling for the probiotic traits elicited by A. brasilense in A. thaliana.
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Affiliation(s)
- Manuel Méndez-Gómez
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Edif. A1´, Morelia, Michoacán CP 58040, Mexico
| | - Elda Castro-Mercado
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Edif. A1´, Morelia, Michoacán CP 58040, Mexico
| | - César Arturo Peña-Uribe
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Edif. A1´, Morelia, Michoacán CP 58040, Mexico
| | - Homero Reyes-de la Cruz
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Edif. A1´, Morelia, Michoacán CP 58040, Mexico
| | - José López-Bucio
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Edif. A1´, Morelia, Michoacán CP 58040, Mexico
| | - Ernesto García-Pineda
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Edif. A1´, Morelia, Michoacán CP 58040, Mexico.
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20
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Bakshi A, Moin M, Madhav MS, Kirti PB. Target of rapamycin, a master regulator of multiple signalling pathways and a potential candidate gene for crop improvement. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:190-205. [PMID: 30411830 DOI: 10.1111/plb.12935] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 11/05/2018] [Indexed: 06/08/2023]
Abstract
The target of rapamycin (TOR) protein regulates growth and development in photosynthetic and non-photosynthetic eukaryotes. Although the TOR regulatory networks are involved in nutrient and energy signalling, and transcriptional and translational control of multiple signalling pathways, the molecular mechanism of TOR regulation of plant abiotic stress responses is still unclear. The TOR-mediated transcriptional regulation of genes encoding ribosomal proteins (RP) is a necessity under stress conditions for balanced growth and productivity in plants. The activation of SnRKs (sucrose non-fermenting-related kinases) and the inactivation of TOR signalling in abiotic stresses is in line with the accumulation of ABA and transcriptional activation of stress responsive genes. Autophagy is induced under abiotic stress conditions, which results in degradation of proteins and the release of amino acids, which might possibly induce phosphorylation of TOR and, hence, its activation. TOR signalling also has a role in regulating ABA biosynthesis for transcriptional regulation of stress-related genes. The switch between activation and inactivation of TOR by its phosphorylation and de-phosphorylation maintains balanced growth in response to stresses. In the present review, we discuss the important signalling pathways that are regulated by TOR and try to assess the relationship between TOR signalling and tolerance to abiotic stresses in plants. The review also discusses possible cross-talk between TOR and RP genes in response to abiotic stresses.
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Affiliation(s)
- A Bakshi
- Department of Plant Sciences, University of Hyderabad, Hyderabad, India
| | - M Moin
- Department of Biotechnology, Indian Institute of Rice Research, Hyderabad, India
| | - M S Madhav
- Department of Biotechnology, Indian Institute of Rice Research, Hyderabad, India
| | - P B Kirti
- Department of Plant Sciences, University of Hyderabad, Hyderabad, India
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21
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Monte-Bello CC, Araujo EF, Martins MCM, Mafra V, da Silva VCH, Celente V, Caldana C. A Flexible Low Cost Hydroponic System for Assessing Plant Responses to Small Molecules in Sterile Conditions. J Vis Exp 2018:57800. [PMID: 30199012 PMCID: PMC6231878 DOI: 10.3791/57800] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A wide range of studies in plant biology are performed using hydroponic cultures. In this work, an in vitro hydroponic growth system designed for assessing plant responses to chemicals and other substances of interest is presented. This system is highly efficient in obtaining homogeneous and healthy seedlings of the C3 and C4 model species Arabidopsis thaliana and Setaria viridis, respectively. The sterile cultivation avoids algae and microorganism contamination, which are known limiting factors for plant normal growth and development in hydroponics. In addition, this system is scalable, enabling the harvest of plant material on a large scale with minor mechanical damage, as well as the harvest of individual parts of a plant if desired. A detailed protocol demonstrating that this system has an easy and low-cost assembly, as it uses pipette racks as the main platform for growing plants, is provided. The feasibility of this system was validated using Arabidopsis seedlings to assess the effect of the drug AZD-8055, a chemical inhibitor of the target of rapamycin (TOR) kinase. TOR inhibition was efficiently detected as early as 30 min after an AZD-8055 treatment in roots and shoots. Furthermore, AZD-8055-treated plants displayed the expected starch-excess phenotype. We proposed this hydroponic system as an ideal method for plant researchers aiming to monitor the action of plant inducers or inhibitors, as well as to assess metabolic fluxes using isotope-labeling compounds which, in general, requires the use of expensive reagents.
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Affiliation(s)
- Carolina C Monte-Bello
- Brazilian Bioethanol Science and Technology Laboratory (CTBE), Brazilian Center for Research in energy and materials (CNPEM); University of Campinas (UNICAMP)
| | - Elias F Araujo
- Brazilian Bioethanol Science and Technology Laboratory (CTBE), Brazilian Center for Research in energy and materials (CNPEM); University of Viçosa (UFV)
| | - Marina C M Martins
- Brazilian Bioethanol Science and Technology Laboratory (CTBE), Brazilian Center for Research in energy and materials (CNPEM)
| | | | - Viviane C H da Silva
- Brazilian Bioethanol Science and Technology Laboratory (CTBE), Brazilian Center for Research in energy and materials (CNPEM); University of Campinas (UNICAMP)
| | - Viviane Celente
- Brazilian Bioethanol Science and Technology Laboratory (CTBE), Brazilian Center for Research in energy and materials (CNPEM)
| | - Camila Caldana
- Brazilian Bioethanol Science and Technology Laboratory (CTBE), Brazilian Center for Research in energy and materials (CNPEM); Brazilian Bioethanol Science and Technology Laboratory (CTBE/CNPEM), Max Planck Partner Group;
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22
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Punzo P, Ruggiero A, Possenti M, Nurcato R, Costa A, Morelli G, Grillo S, Batelli G. The PP2A-interactor TIP41 modulates ABA responses in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 94:991-1009. [PMID: 29602224 DOI: 10.1111/tpj.13913] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 03/09/2018] [Accepted: 03/13/2018] [Indexed: 05/27/2023]
Abstract
Modulation of growth in response to environmental cues is a fundamental aspect of plant adaptation to abiotic stresses. TIP41 (TAP42 INTERACTING PROTEIN OF 41 kDa) is the Arabidopsis thaliana orthologue of proteins isolated in mammals and yeast that participate in the Target-of-Rapamycin (TOR) pathway, which modifies cell growth in response to nutrient status and environmental conditions. Here, we characterized the function of TIP41 in Arabidopsis. Expression analyses showed that TIP41 is constitutively expressed in vascular tissues, and is induced following long-term exposure to NaCl, polyethylene glycol and abscisic acid (ABA), suggesting a role of TIP41 in adaptation to abiotic stress. Visualization of a fusion protein with yellow fluorescent protein indicated that TIP41 is localized in the cytoplasm and the nucleus. Abolished expression of TIP41 results in smaller plants with a lower number of rosette leaves and lateral roots, and an increased sensitivity to treatments with chemical TOR inhibitors, indicating that TOR signalling is affected in these mutants. In addition, tip41 mutants are hypersensitive to ABA at germination and seedling stage, whereas over-expressing plants show higher tolerance. Several TOR- and ABA-responsive genes are differentially expressed in tip41, including iron homeostasis, senescence and ethylene-associated genes. In yeast and mammals, TIP41 provides a link between the TOR pathway and the protein phosphatase 2A (PP2A), which in plants participates in several ABA-mediated mechanisms. Here, we showed an interaction of TIP41 with the catalytic subunit of PP2A. Taken together, these results offer important insights into the function of Arabidopsis TIP41 in the modulation of plant growth and ABA responses.
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Affiliation(s)
- Paola Punzo
- National Research Council of Italy, Institute of Biosciences and Bioresources (CNR-IBBR), Via Università 133, Portici, NA, Italy
| | - Alessandra Ruggiero
- National Research Council of Italy, Institute of Biosciences and Bioresources (CNR-IBBR), Via Università 133, Portici, NA, Italy
| | - Marco Possenti
- Council for Agricultural Research and Economics, Research Centre for Genomics and Bioinformatics (CREA-GB), Via Ardeatina 546, 00178, Rome, Italy
| | - Roberta Nurcato
- National Research Council of Italy, Institute of Biosciences and Bioresources (CNR-IBBR), Via Università 133, Portici, NA, Italy
| | - Antonello Costa
- National Research Council of Italy, Institute of Biosciences and Bioresources (CNR-IBBR), Via Università 133, Portici, NA, Italy
| | - Giorgio Morelli
- Council for Agricultural Research and Economics, Research Centre for Genomics and Bioinformatics (CREA-GB), Via Ardeatina 546, 00178, Rome, Italy
| | - Stefania Grillo
- National Research Council of Italy, Institute of Biosciences and Bioresources (CNR-IBBR), Via Università 133, Portici, NA, Italy
| | - Giorgia Batelli
- National Research Council of Italy, Institute of Biosciences and Bioresources (CNR-IBBR), Via Università 133, Portici, NA, Italy
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23
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Schepetilnikov M, Ryabova LA. Recent Discoveries on the Role of TOR (Target of Rapamycin) Signaling in Translation in Plants. PLANT PHYSIOLOGY 2018; 176:1095-1105. [PMID: 29122989 PMCID: PMC5813564 DOI: 10.1104/pp.17.01243] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 11/09/2017] [Indexed: 05/18/2023]
Abstract
TOR signaling regulates plant translation via a specific translation initiation mechanism: reinitiation.
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Affiliation(s)
- Mikhail Schepetilnikov
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, 67084 Strasbourg, France
| | - Lyubov A Ryabova
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, 67084 Strasbourg, France
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24
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Meng X, Yu Y, Zhao J, Cui N, Song T, Yang Y, Fan H. The Two Translationally Controlled Tumor Protein Genes, CsTCTP1 and CsTCTP2, Are Negative Modulators in the Cucumis sativus Defense Response to Sphaerotheca fuliginea. FRONTIERS IN PLANT SCIENCE 2018; 9:544. [PMID: 29922303 PMCID: PMC5996911 DOI: 10.3389/fpls.2018.00544] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/09/2018] [Indexed: 05/04/2023]
Abstract
Pathogen stress often significantly decreases cucumber production. However, knowledge regarding the molecular mechanism and signals of cucumber disease resistance is far from complete. Here, we report two translationally controlled tumor protein genes, CsTCTP1 and CsTCTP2, that are both negative modulators in the Cucumis sativus defense response to Sphaerotheca fuliginea. Subcellular localization analysis showed that CsTCTP1 and CsTCTP2 were both localized in the cytoplasm. Expression analysis indicated that the transcript levels of CsTCTP1 and CsTCTP2 were linked to the degree of cucumber resistance to S. fuliginea. Transient overexpression of either CsTCTP1 or CsTCTP2 in cucumber cotyledons impaired resistance to S. fuliginea, whereas silencing of either CsTCTP1 or CsTCTP2 enhanced cucumber resistance to S. fuliginea. The relationship of several defense-related genes and ABA and target of rapamycin (TOR) signaling pathway-related genes to the overexpressing and silencing of CsTCTP1/CsTCTP2 in non-infested cucumber plants was investigated. The results indicated that CsTCTP1 participates in the defense response to S. fuliginea by regulating the expression of certain defense-associated genes and/or ABA signaling pathway-associated genes, and CsTCTP2 participates through regulating the expression of TOR signaling pathway-associated genes. Our findings will guide enhancing the resistance of cucumber to powdery mildew.
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Affiliation(s)
- Xiangnan Meng
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, China
- College of Horticulture, Shenyang Agricultural University, Shenyang, China
| | - Yang Yu
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, China
| | - Junyue Zhao
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, China
| | - Na Cui
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, China
| | - Tiefeng Song
- Vegetable Research Institute, Liaoning Academy of Agricultural Sciences, Shenyang, China
| | - Yun Yang
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, China
| | - Haiyan Fan
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, China
- Key Laboratory of Protected Horticulture of Ministry of Education, Shenyang Agricultural University, Shenyang, China
- *Correspondence: Haiyan Fan,
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25
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Lee DH, Park SJ, Ahn CS, Pai HS. MRF Family Genes Are Involved in Translation Control, Especially under Energy-Deficient Conditions, and Their Expression and Functions Are Modulated by the TOR Signaling Pathway. THE PLANT CELL 2017; 29:2895-2920. [PMID: 29084871 PMCID: PMC5728134 DOI: 10.1105/tpc.17.00563] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/02/2017] [Accepted: 10/27/2017] [Indexed: 05/20/2023]
Abstract
Dynamic control of protein translation in response to the environment is essential for the survival of plant cells. Target of rapamycin (TOR) coordinates protein synthesis with cellular energy/nutrient availability through transcriptional modulation and phosphorylation of the translation machinery. However, mechanisms of TOR-mediated translation control are poorly understood in plants. Here, we report that Arabidopsis thaliana MRF (MA3 DOMAIN-CONTAINING TRANSLATION REGULATORY FACTOR) family genes encode translation regulatory factors under TOR control, and their functions are particularly important in energy-deficient conditions. Four MRF family genes (MRF1-MRF4) are transcriptionally induced by dark and starvation (DS). Silencing of multiple MRFs increases susceptibility to DS and treatment with a TOR inhibitor, while MRF1 overexpression decreases susceptibility. MRF proteins interact with eIF4A and cofractionate with ribosomes. MRF silencing decreases translation activity, while MRF1 overexpression increases it, accompanied by altered ribosome patterns, particularly in DS. Furthermore, MRF deficiency in DS causes altered distribution of mRNAs in sucrose gradient fractions and accelerates rRNA degradation. MRF1 is phosphorylated in vivo and phosphorylated by S6 kinases in vitro. MRF expression and MRF1 ribosome association and phosphorylation are modulated by cellular energy status and TOR activity. We discuss possible mechanisms of the function of MRF family proteins under normal and energy-deficient conditions and their functional link with the TOR pathway.
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Affiliation(s)
- Du-Hwa Lee
- Department of Systems Biology, Yonsei University, Seoul 120-749, Korea
| | - Seung Jun Park
- Department of Systems Biology, Yonsei University, Seoul 120-749, Korea
| | - Chang Sook Ahn
- Department of Systems Biology, Yonsei University, Seoul 120-749, Korea
| | - Hyun-Sook Pai
- Department of Systems Biology, Yonsei University, Seoul 120-749, Korea
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26
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Schepetilnikov M, Ryabova LA. Auxin Signaling in Regulation of Plant Translation Reinitiation. FRONTIERS IN PLANT SCIENCE 2017; 8:1014. [PMID: 28659957 PMCID: PMC5469914 DOI: 10.3389/fpls.2017.01014] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/26/2017] [Indexed: 05/03/2023]
Abstract
The mRNA translation machinery directs protein production, and thus cell growth, according to prevailing cellular and environmental conditions. The target of rapamycin (TOR) signaling pathway-a major growth-related pathway-plays a pivotal role in optimizing protein synthesis in mammals, while its deregulation triggers uncontrolled cell proliferation and the development of severe diseases. In plants, several signaling pathways sensitive to environmental changes, hormones, and pathogens have been implicated in post-transcriptional control, and thus far phytohormones have attracted most attention as TOR upstream regulators in plants. Recent data have suggested that the coordinated actions of the phytohormone auxin, Rho-like small GTPases (ROPs) from plants, and TOR signaling contribute to translation regulation of mRNAs that harbor upstream open reading frames (uORFs) within their 5'-untranslated regions (5'-UTRs). This review will summarize recent advances in translational regulation of a specific set of uORF-containing mRNAs that encode regulatory proteins-transcription factors, protein kinases and other cellular controllers-and how their control can impact plant growth and development.
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Affiliation(s)
- Mikhail Schepetilnikov
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de StrasbourgStrasbourg, France
| | - Lyubov A. Ryabova
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de StrasbourgStrasbourg, France
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27
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Merchante C, Stepanova AN, Alonso JM. Translation regulation in plants: an interesting past, an exciting present and a promising future. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 90:628-653. [PMID: 28244193 DOI: 10.1111/tpj.13520] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 02/17/2017] [Accepted: 02/21/2017] [Indexed: 05/19/2023]
Abstract
Changes in gene expression are at the core of most biological processes, from cell differentiation to organ development, including the adaptation of the whole organism to the ever-changing environment. Although the central role of transcriptional regulation is solidly established and the general mechanisms involved in this type of regulation are relatively well understood, it is clear that regulation at a translational level also plays an essential role in modulating gene expression. Despite the large number of examples illustrating the critical role played by translational regulation in determining the expression levels of a gene, our understanding of the molecular mechanisms behind such types of regulation has been slow to emerge. With the recent development of high-throughput approaches to map and quantify different critical parameters affecting translation, such as RNA structure, protein-RNA interactions and ribosome occupancy at the genome level, a renewed enthusiasm toward studying translation regulation is warranted. The use of these new powerful technologies in well-established and uncharacterized translation-dependent processes holds the promise to decipher the likely complex and diverse, but also fascinating, mechanisms behind the regulation of translation.
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Affiliation(s)
- Catharina Merchante
- Departamento de Biologia Molecular y Bioquimica, Universidad de Malaga-Instituto de Hortofruticultura Subtropical y Mediterranea, IHSM-UMA-CSIC, Malaga, Andalucía, Spain
| | - Anna N Stepanova
- Department of Plant and Microbial Biology, Genetics Graduate Program, North Carolina State University, Raleigh, NC, 27607, USA
| | - Jose M Alonso
- Department of Plant and Microbial Biology, Genetics Graduate Program, North Carolina State University, Raleigh, NC, 27607, USA
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28
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Schepetilnikov M, Makarian J, Srour O, Geldreich A, Yang Z, Chicher J, Hammann P, Ryabova LA. GTPase ROP2 binds and promotes activation of target of rapamycin, TOR, in response to auxin. EMBO J 2017; 36:886-903. [PMID: 28246118 DOI: 10.15252/embj.201694816] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 01/18/2017] [Accepted: 01/27/2017] [Indexed: 01/16/2023] Open
Abstract
Target of rapamycin (TOR) promotes reinitiation at upstream ORFs (uORFs) in genes that play important roles in stem cell regulation and organogenesis in plants. Here, we report that the small GTPase ROP2, if activated by the phytohormone auxin, promotes activation of TOR, and thus translation reinitiation of uORF-containing mRNAs. Plants with high levels of active ROP2, including those expressing constitutively active ROP2 (CA-ROP2), contain high levels of active TOR ROP2 physically interacts with and, when GTP-bound, activates TOR in vitro TOR activation in response to auxin is abolished in ROP-deficient rop2 rop6 ROP4 RNAi plants. GFP-TOR can associate with endosome-like structures in ROP2-overexpressing plants, indicating that endosomes mediate ROP2 effects on TOR activation. CA-ROP2 is efficient in loading uORF-containing mRNAs onto polysomes and stimulates translation in protoplasts, and both processes are sensitive to TOR inhibitor AZD-8055. TOR inactivation abolishes ROP2 regulation of translation reinitiation, but not its effects on cytoskeleton or intracellular trafficking. These findings imply a mode of translation control whereby, as an upstream effector of TOR, ROP2 coordinates TOR function in translation reinitiation pathways in response to auxin.
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Affiliation(s)
- Mikhail Schepetilnikov
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, Strasbourg, France
| | - Joelle Makarian
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, Strasbourg, France
| | - Ola Srour
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, Strasbourg, France
| | - Angèle Geldreich
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, Strasbourg, France
| | - Zhenbiao Yang
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, CA, USA
| | - Johana Chicher
- Plateforme Proteómique Strasbourg-Esplanade, Centre National de la Recherche Scientifique, FRC 1589, Université de Strasbourg, Strasbourg, France
| | - Philippe Hammann
- Plateforme Proteómique Strasbourg-Esplanade, Centre National de la Recherche Scientifique, FRC 1589, Université de Strasbourg, Strasbourg, France
| | - Lyubov A Ryabova
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, Strasbourg, France
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29
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Enganti R, Cho SK, Toperzer JD, Urquidi-Camacho RA, Cakir OS, Ray AP, Abraham PE, Hettich RL, von Arnim AG. Phosphorylation of Ribosomal Protein RPS6 Integrates Light Signals and Circadian Clock Signals. FRONTIERS IN PLANT SCIENCE 2017; 8:2210. [PMID: 29403507 PMCID: PMC5780430 DOI: 10.3389/fpls.2017.02210] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 12/15/2017] [Indexed: 05/20/2023]
Abstract
The translation of mRNA into protein is tightly regulated by the light environment as well as by the circadian clock. Although changes in translational efficiency have been well documented at the level of mRNA-ribosome loading, the underlying mechanisms are unclear. The reversible phosphorylation of RIBOSOMAL PROTEIN OF THE SMALL SUBUNIT 6 (RPS6) has been known for 40 years, but the biochemical significance of this event remains unclear to this day. Here, we confirm using a clock-deficient strain of Arabidopsis thaliana that RPS6 phosphorylation (RPS6-P) is controlled by the diel light-dark cycle with a peak during the day. Strikingly, when wild-type, clock-enabled, seedlings that have been entrained to a light-dark cycle are placed under free-running conditions, the circadian clock drives a cycle of RPS6-P with an opposite phase, peaking during the subjective night. We show that in wild-type seedlings under a light-dark cycle, the incoherent light and clock signals are integrated by the plant to cause an oscillation in RPS6-P with a reduced amplitude with a peak during the day. Sucrose can stimulate RPS6-P, as seen when sucrose in the medium masks the light response of etiolated seedlings. However, the diel cycles of RPS6-P are observed in the presence of 1% sucrose and in its absence. Sucrose at a high concentration of 3% appears to interfere with the robust integration of light and clock signals at the level of RPS6-P. Finally, we addressed whether RPS6-P occurs uniformly in polysomes, non-polysomal ribosomes and their subunits, and non-ribosomal protein. It is the polysomal RPS6 whose phosphorylation is most highly stimulated by light and repressed by darkness. These data exemplify a striking case of contrasting biochemical regulation between clock signals and light signals. Although the physiological significance of RPS6-P remains unknown, our data provide a mechanistic basis for the future understanding of this enigmatic event.
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Affiliation(s)
- Ramya Enganti
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, United States
| | - Sung Ki Cho
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, United States
| | - Jody D. Toperzer
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, United States
| | - Ricardo A. Urquidi-Camacho
- Graduate School of Genome Science and Technology, The University of Tennessee, Knoxville, TN, United States
| | - Ozkan S. Cakir
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, United States
| | - Alexandria P. Ray
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, United States
| | - Paul E. Abraham
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Robert L. Hettich
- Graduate School of Genome Science and Technology, The University of Tennessee, Knoxville, TN, United States
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Albrecht G. von Arnim
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, United States
- Graduate School of Genome Science and Technology, The University of Tennessee, Knoxville, TN, United States
- *Correspondence: Albrecht G. von Arnim,
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30
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Pu Y, Luo X, Bassham DC. TOR-Dependent and -Independent Pathways Regulate Autophagy in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2017; 8:1204. [PMID: 28744293 PMCID: PMC5504165 DOI: 10.3389/fpls.2017.01204] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 06/26/2017] [Indexed: 05/18/2023]
Abstract
Autophagy is a critical process for recycling of cytoplasmic materials during environmental stress, senescence and cellular remodeling. It is upregulated under a wide range of abiotic stress conditions and is important for stress tolerance. Autophagy is repressed by the protein kinase target of rapamycin (TOR), which is activated in response to nutrients and in turn upregulates cell growth and translation and inhibits autophagy. Down-regulation of TOR in Arabidopsis thaliana leads to constitutive autophagy and to decreased growth, but the relationship to stress conditions is unclear. Here, we assess the extent to which TOR controls autophagy activation by abiotic stress. Overexpression of TOR inhibited autophagy activation by nutrient starvation, salt and osmotic stress, indicating that activation of autophagy under these conditions requires down-regulation of TOR activity. In contrast, TOR overexpression had no effect on autophagy induced by oxidative stress or ER stress, suggesting that activation of autophagy by these conditions is independent of TOR function. The plant hormone auxin has been shown previously to up-regulate TOR activity. To confirm the existence of two pathways for activation of autophagy, dependent on the stress conditions, auxin was added exogenously to activate TOR, and the effect on autophagy under different conditions was assessed. Consistent with the effect of TOR overexpression, the addition of the auxin NAA inhibited autophagy during nutrient deficiency, salt and osmotic stress, but not during oxidative or ER stress. NAA treatment was unable to block autophagy induced by a TOR inhibitor or by a mutation in the TOR complex component RAPTOR1B, indicating that auxin is upstream of TOR in the regulation of autophagy. We conclude that repression of auxin-regulated TOR activity is required for autophagy activation in response to a subset of abiotic stress conditions.
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Affiliation(s)
- Yunting Pu
- Department of Genetics, Development and Cell Biology, Iowa State University, AmesIA, United States
- Interdepartmental Genetics Program, Iowa State University, AmesIA, United States
| | - Xinjuan Luo
- Department of Genetics, Development and Cell Biology, Iowa State University, AmesIA, United States
- College of Life Sciences, Northwest A&F UniversityYangling, China
| | - Diane C. Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, AmesIA, United States
- Interdepartmental Genetics Program, Iowa State University, AmesIA, United States
- Plant Sciences Institute, Iowa State University, AmesIA, United States
- *Correspondence: Diane C. Bassham,
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31
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Dobrenel T, Caldana C, Hanson J, Robaglia C, Vincentz M, Veit B, Meyer C. TOR Signaling and Nutrient Sensing. ANNUAL REVIEW OF PLANT BIOLOGY 2016; 67:261-85. [PMID: 26905651 DOI: 10.1146/annurev-arplant-043014-114648] [Citation(s) in RCA: 243] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
All living organisms rely on nutrients to sustain cell metabolism and energy production, which in turn need to be adjusted based on available resources. The evolutionarily conserved target of rapamycin (TOR) protein kinase is a central regulatory hub that connects environmental information about the quantity and quality of nutrients to developmental and metabolic processes in order to maintain cellular homeostasis. TOR is activated by both nitrogen and carbon metabolites and promotes energy-consuming processes such as cell division, mRNA translation, and anabolism in times of abundance while repressing nutrient remobilization through autophagy. In animals and yeasts, TOR acts antagonistically to the starvation-induced AMP-activated kinase (AMPK)/sucrose nonfermenting 1 (Snf1) kinase, called Snf1-related kinase 1 (SnRK1) in plants. This review summarizes the immense knowledge on the relationship between TOR signaling and nutrients in nonphotosynthetic organisms and presents recent findings in plants that illuminate the crucial role of this pathway in conveying nutrient-derived signals and regulating many aspects of metabolism and growth.
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Affiliation(s)
- Thomas Dobrenel
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, ERL CNRS 3559, Saclay Plant Sciences, Versailles 78026, France;
- Umeå Plant Science Center, Department of Plant Physiology, Umeå University, Umeå 90187, Sweden
| | - Camila Caldana
- Molecular Physiology of Plant Biomass Production Group, Max Planck Partner Group, Brazilian Bioethanol Science and Technology Laboratory, CEP 13083-100 Campinas, São Paulo, Brazil
| | - Johannes Hanson
- Umeå Plant Science Center, Department of Plant Physiology, Umeå University, Umeå 90187, Sweden
| | - Christophe Robaglia
- Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, DSV, IBEB, SBVME, CEA, CNRS, Aix Marseille Université, Faculté des Sciences de Luminy, Marseille 13009, France
| | - Michel Vincentz
- Laboratório de Genética de Plantas, Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, CEP 13083-875 Campinas, São Paulo, Brazil
| | - Bruce Veit
- Forage Improvement, AgResearch, Institute of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Christian Meyer
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, ERL CNRS 3559, Saclay Plant Sciences, Versailles 78026, France;
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32
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Wu L, Tian L, Wang S, Zhang J, Liu P, Tian Z, Zhang H, Liu H, Chen Y. Comparative Proteomic Analysis of the Response of Maize (Zea mays L.) Leaves to Long Photoperiod Condition. FRONTIERS IN PLANT SCIENCE 2016; 7:752. [PMID: 27313588 PMCID: PMC4889979 DOI: 10.3389/fpls.2016.00752] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Accepted: 05/17/2016] [Indexed: 05/11/2023]
Abstract
Maize (Zea mays L.), an important industrial material and food source, shows an astonishing environmental adaptation. A remarkable feature of its post-domestication adaptation from tropical to temperate environments is adaptation to a long photoperiod (LP). Many photoperiod-related genes have been identified in previous transcriptomics analysis, but proteomics shows less evidence for this mechanism of photoperiod response. In this study, we sampled newly expanded leaves of maize at the three- and six-leaf stages from an LP-sensitive introgression line H496, the donor CML288, LP-insensitive inbred line, and recurrent parent Huangzao4 (HZ4) grown under long days (15 h light and 9 h dark). To characterize the proteomic changes in response to LP, the iTRAQ-labeling method was used to determine the proteome profiles of plants exposed to LP. A total of 943 proteins differentially expressed at the three- and six-leaf stages in HZ4 and H496 were identified. Functional analysis was performed by which the proteins were classified into stress defense, signal transduction, carbohydrate metabolism, protein metabolism, energy production, and transport functional groups using the WEGO online tool. The enriched gene ontology categories among the identified proteins were identified statistically with the Cytoscape plugin ClueGO + Cluepedia. Twenty Gene Ontology terms showed the highest significance, including those associated with protein processing in the endoplasmic reticulum, splicesome, ribosome, glyoxylate, dicarboxylate metabolism, L-malate dehydrogenase activity, and RNA transport. In addition, for subcellular location, all proteins showed significant enrichment of the mitochondrial outer membrane. The sugars producted by photosynthesis in plants are also a pivotal metabolic output in the circadian regulation. The results permit the prediction of several crucial proteins to photoperiod response and provide a foundation for further study of the influence of LP treatments on the circadian response in short-day plants.
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Affiliation(s)
- Liuji Wu
- Henan Agricultural University and Synergetic Innovation Center of Henan Grain CropsZhengzhou, China
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan ProvinceZhengzhou, China
| | - Lei Tian
- Henan Agricultural University and Synergetic Innovation Center of Henan Grain CropsZhengzhou, China
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan ProvinceZhengzhou, China
| | - Shunxi Wang
- Henan Agricultural University and Synergetic Innovation Center of Henan Grain CropsZhengzhou, China
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan ProvinceZhengzhou, China
| | - Jun Zhang
- Food Crops Research Institute, Henan Academy of Agricultural ScienceZhengzhou, China
| | - Ping Liu
- Henan Agricultural University and Synergetic Innovation Center of Henan Grain CropsZhengzhou, China
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan ProvinceZhengzhou, China
| | - Zhiqiang Tian
- Henan Agricultural University and Synergetic Innovation Center of Henan Grain CropsZhengzhou, China
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan ProvinceZhengzhou, China
| | - Huimin Zhang
- Henan Agricultural University and Synergetic Innovation Center of Henan Grain CropsZhengzhou, China
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan ProvinceZhengzhou, China
| | - Haiping Liu
- Department of Biological Science, Michigan Technological UniversityMichigan, MI, USA
| | - Yanhui Chen
- Henan Agricultural University and Synergetic Innovation Center of Henan Grain CropsZhengzhou, China
- Key Laboratory of Physiological Ecology and Genetic Improvement of Food Crops in Henan ProvinceZhengzhou, China
- *Correspondence: Yanhui Chen
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Dobrenel T, Mancera-Martínez E, Forzani C, Azzopardi M, Davanture M, Moreau M, Schepetilnikov M, Chicher J, Langella O, Zivy M, Robaglia C, Ryabova LA, Hanson J, Meyer C. The Arabidopsis TOR Kinase Specifically Regulates the Expression of Nuclear Genes Coding for Plastidic Ribosomal Proteins and the Phosphorylation of the Cytosolic Ribosomal Protein S6. FRONTIERS IN PLANT SCIENCE 2016; 7:1611. [PMID: 27877176 PMCID: PMC5100631 DOI: 10.3389/fpls.2016.01611] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 10/12/2016] [Indexed: 05/05/2023]
Abstract
Protein translation is an energy consuming process that has to be fine-tuned at both the cell and organism levels to match the availability of resources. The target of rapamycin kinase (TOR) is a key regulator of a large range of biological processes in response to environmental cues. In this study, we have investigated the effects of TOR inactivation on the expression and regulation of Arabidopsis ribosomal proteins at different levels of analysis, namely from transcriptomic to phosphoproteomic. TOR inactivation resulted in a coordinated down-regulation of the transcription and translation of nuclear-encoded mRNAs coding for plastidic ribosomal proteins, which could explain the chlorotic phenotype of the TOR silenced plants. We have identified in the 5' untranslated regions (UTRs) of this set of genes a conserved sequence related to the 5' terminal oligopyrimidine motif, which is known to confer translational regulation by the TOR kinase in other eukaryotes. Furthermore, the phosphoproteomic analysis of the ribosomal fraction following TOR inactivation revealed a lower phosphorylation of the conserved Ser240 residue in the C-terminal region of the 40S ribosomal protein S6 (RPS6). These results were confirmed by Western blot analysis using an antibody that specifically recognizes phosphorylated Ser240 in RPS6. Finally, this antibody was used to follow TOR activity in plants. Our results thus uncover a multi-level regulation of plant ribosomal genes and proteins by the TOR kinase.
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Affiliation(s)
- Thomas Dobrenel
- Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-SaclayVersailles, France
- Université Paris-Sud–Université Paris-SaclayOrsay, France
- Umeå Plant Science Center, Department of Plant Physiology, Umeå UniversityUmeå, Sweden
| | - Eder Mancera-Martínez
- Institut de Biologie Moléculaire des Plantes, UPR 2357 CNRS, Université de StrasbourgStrasbourg, France
| | - Céline Forzani
- Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-SaclayVersailles, France
| | - Marianne Azzopardi
- Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-SaclayVersailles, France
| | | | - Manon Moreau
- Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-SaclayVersailles, France
- Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, DSV, IBEB, SBVME, CEA, CNRS, Aix-Marseille Université, Faculté des Sciences de LuminyMarseille, France
| | - Mikhail Schepetilnikov
- Institut de Biologie Moléculaire des Plantes, UPR 2357 CNRS, Université de StrasbourgStrasbourg, France
| | - Johana Chicher
- Plateforme Protéomique Strasbourg-Esplanade, CNRS FRC1589, Institut de Biologie Moléculaire et CellulaireStrasbourg, France
| | | | - Michel Zivy
- Plateforme PAPPSO, UMR GQE-Le MoulonGif sur Yvette, France
| | - Christophe Robaglia
- Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, DSV, IBEB, SBVME, CEA, CNRS, Aix-Marseille Université, Faculté des Sciences de LuminyMarseille, France
| | - Lyubov A. Ryabova
- Institut de Biologie Moléculaire des Plantes, UPR 2357 CNRS, Université de StrasbourgStrasbourg, France
| | - Johannes Hanson
- Umeå Plant Science Center, Department of Plant Physiology, Umeå UniversityUmeå, Sweden
| | - Christian Meyer
- Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-SaclayVersailles, France
- *Correspondence: Christian Meyer,
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Abstract
Although the eukaryotic TOR (target of rapamycin) kinase signalling pathway has emerged as a key player for integrating nutrient-, energy- and stress-related cues with growth and metabolic outputs, relatively little is known of how this ancient regulatory mechanism has been adapted in higher plants. Drawing comparisons with the substantial knowledge base around TOR kinase signalling in fungal and animal systems, functional aspects of this pathway in plants are reviewed. Both conserved and divergent elements are discussed in relation to unique aspects associated with an autotrophic mode of nutrition and adaptive strategies for multicellular development exhibited by plants.
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35
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Baloglu MC, Ulu F, Altunoglu YC, Pekol S, Alagoz G, Ese O. Identification, molecular characterization and expression analysis ofRPL24genes in three Cucurbitaceae family members: cucumber, melon and watermelon. BIOTECHNOL BIOTEC EQ 2015. [DOI: 10.1080/13102818.2015.1079144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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36
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Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective. Int J Mol Sci 2015; 16:19671-97. [PMID: 26295391 PMCID: PMC4581319 DOI: 10.3390/ijms160819671] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Revised: 07/11/2015] [Accepted: 08/11/2015] [Indexed: 12/30/2022] Open
Abstract
Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin) kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth.
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37
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Identification of nucleosome assembly protein 1 (NAP1) as an interacting partner of plant ribosomal protein S6 (RPS6) and a positive regulator of rDNA transcription. Biochem Biophys Res Commun 2015; 465:200-5. [PMID: 26241676 DOI: 10.1016/j.bbrc.2015.07.150] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 07/29/2015] [Indexed: 11/22/2022]
Abstract
The ribosomal protein S6 (RPS6) is a downstream component of the signaling mediated by the target of rapamycin (TOR) kinase that acts as a central regulator of the key metabolic processes, such as protein translation and ribosome biogenesis, in response to various environmental cues. In our previous study, we identified a novel role of plant RPS6, which negatively regulates rDNA transcription, forming a complex with a plant-specific histone deacetylase, AtHD2B. Here we report that the Arabidopsis RPS6 interacts additionally with a histone chaperone, nucleosome assembly protein 1(AtNAP1;1). The interaction does not appear to preclude the association of RPS6 with AtHD2B, as the AtNAP1 was also able to interact with AtHD2B as well as with an RPS6-AtHD2B fusion protein in the BiFC assay and pulldown experiment. Similar to a positive effect of the ribosomal S6 kinase 1 (AtS6K1) on rDNA transcription observed in this study, overexpression or down regulation of the AtNAP1;1 resulted in concomitant increase and decrease, respectively, in rDNA transcription suggesting a positive regulatory role played by AtNAP1 in plant rDNA transcription, possibly through derepression of the negative effect of the RPS6-AtHD2B complex.
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38
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Choudhary MK, Nomura Y, Wang L, Nakagami H, Somers DE. Quantitative Circadian Phosphoproteomic Analysis of Arabidopsis Reveals Extensive Clock Control of Key Components in Physiological, Metabolic, and Signaling Pathways. Mol Cell Proteomics 2015; 14:2243-60. [PMID: 26091701 DOI: 10.1074/mcp.m114.047183] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Indexed: 01/01/2023] Open
Abstract
The circadian clock provides adaptive advantages to an organism, resulting in increased fitness and survival. The phosphorylation events that regulate circadian-dependent signaling and the processes which post-translationally respond to clock-gated signals are largely unknown. To better elucidate post-translational events tied to the circadian system we carried out a survey of circadian-regulated protein phosphorylation events in Arabidopsis seedlings. A large-scale mass spectrometry-based quantitative phosphoproteomics approach employing TiO2-based phosphopeptide enrichment techniques identified and quantified 1586 phosphopeptides on 1080 protein groups. A total of 102 phosphopeptides displayed significant changes in abundance, enabling the identification of specific patterns of response to circadian rhythms. Our approach was sensitive enough to quantitate oscillations in the phosphorylation of low abundance clock proteins (early flowering4; ELF4 and pseudoresponse regulator3; PRR3) as well as other transcription factors and kinases. During constant light, extensive cyclic changes in phosphorylation status occurred in critical regulators, implicating direct or indirect regulation by the circadian system. These included proteins influencing transcriptional regulation, translation, metabolism, stress and phytohormones-mediated responses. We validated our analysis using the elf4-211 allele, in which an S45L transition removes the phosphorylation herein identified. We show that removal of this phosphorylatable site diminishes interaction with early flowering3 (ELF3), a key partner in a tripartite evening complex required for circadian cycling. elf4-211 lengthens period, which increases with increasing temperature, relative to the wild type, resulting in a more stable temperature compensation of circadian period over a wider temperature range.
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Affiliation(s)
- Mani Kant Choudhary
- From the ‡Division of Integrative Biosciences and Biotechnology, POSTECH, Hyojadong, Pohang, Kyungbuk, 790-784, Republic of Korea
| | - Yuko Nomura
- ¶Plant Proteomics Research Unit, RIKEN Center for Sustainable Resource Science (CSRS), Yokohama, Kanagawa, 230-0045, Japan
| | - Lei Wang
- From the ‡Division of Integrative Biosciences and Biotechnology, POSTECH, Hyojadong, Pohang, Kyungbuk, 790-784, Republic of Korea §Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210; ‖Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Hirofumi Nakagami
- ¶Plant Proteomics Research Unit, RIKEN Center for Sustainable Resource Science (CSRS), Yokohama, Kanagawa, 230-0045, Japan
| | - David E Somers
- From the ‡Division of Integrative Biosciences and Biotechnology, POSTECH, Hyojadong, Pohang, Kyungbuk, 790-784, Republic of Korea §Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210;
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39
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Browning KS, Bailey-Serres J. Mechanism of cytoplasmic mRNA translation. THE ARABIDOPSIS BOOK 2015; 13:e0176. [PMID: 26019692 PMCID: PMC4441251 DOI: 10.1199/tab.0176] [Citation(s) in RCA: 152] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Protein synthesis is a fundamental process in gene expression that depends upon the abundance and accessibility of the mRNA transcript as well as the activity of many protein and RNA-protein complexes. Here we focus on the intricate mechanics of mRNA translation in the cytoplasm of higher plants. This chapter includes an inventory of the plant translational apparatus and a detailed review of the translational processes of initiation, elongation, and termination. The majority of mechanistic studies of cytoplasmic translation have been carried out in yeast and mammalian systems. The factors and mechanisms of translation are for the most part conserved across eukaryotes; however, some distinctions are known to exist in plants. A comprehensive understanding of the complex translational apparatus and its regulation in plants is warranted, as the modulation of protein production is critical to development, environmental plasticity and biomass yield in diverse ecosystems and agricultural settings.
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Affiliation(s)
- Karen S. Browning
- Department of Molecular Biosciences and Institute for Cell and Molecular Biology, University of Texas at Austin, Austin TX 78712-0165
- Both authors contributed equally to this work
| | - Julia Bailey-Serres
- Department of Botany and Plant Sciences and Center for Plant Cell Biology, University of California, Riverside, CA, 92521 USA
- Both authors contributed equally to this work
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40
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Abstract
Plant kinases are one of the largest protein families in Arabidopsis. There are almost 600 membrane-located receptor kinases and almost 400 soluble kinases with distinct functions in signal transduction. In this minireview we discuss phylogeny and functional context of prominent members from major protein kinase subfamilies in plants.
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Affiliation(s)
- Monika Zulawski
- Max Planck Institute of molecular Plant Physiology, 14470, Potsdam, Germany
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41
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Lastdrager J, Hanson J, Smeekens S. Sugar signals and the control of plant growth and development. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:799-807. [PMID: 24453229 DOI: 10.1093/jxb/ert474] [Citation(s) in RCA: 332] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Sugars have a central regulatory function in steering plant growth. This review focuses on information presented in the past 2 years on key players in sugar-mediated plant growth regulation, with emphasis on trehalose 6-phosphate, target of rapamycin kinase, and Snf1-related kinase 1 regulatory systems. The regulation of protein synthesis by sugars is fundamental to plant growth control, and recent advances in our understanding of the regulation of translation by sugars will be discussed.
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Affiliation(s)
- Jeroen Lastdrager
- Molecular Plant Physiology, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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42
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Kim YK, Kim S, Shin YJ, Hur YS, Kim WY, Lee MS, Cheon CI, Verma DPS. Ribosomal protein S6, a target of rapamycin, is involved in the regulation of rRNA genes by possible epigenetic changes in Arabidopsis. J Biol Chem 2014; 289:3901-12. [PMID: 24302738 PMCID: PMC3924259 DOI: 10.1074/jbc.m113.515015] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 11/14/2013] [Indexed: 12/24/2022] Open
Abstract
The target of rapamycin (TOR) kinase pathway regulates various biological processes, including translation, synthesis of ribosomal proteins, and transcription of rRNA. The ribosomal protein S6 (RPS6) is one of the well known downstream components of the TOR pathway. Ribosomal proteins have been known to have diverse functions in regulating cellular metabolism as well as protein synthesis. So far, however, little is known about other possible role(s) of RPS6 in plants, besides being a component of the 40 S ribosomal subunit and acting as a target of TOR. Here, we report that RPS6 may have a novel function via interaction with histone deacetylase 2B (AtHD2B) that belongs to the plant-specific histone deacetylase HD2 family. RPS6 and AtHD2B were localized to the nucleolus. Co-expression of RPS6 and AtHD2B caused a change in the location of both RPS6 and AtHD2B to one or several nucleolar spots. ChIP analysis suggests that RPS6 directly interacts with the rRNA gene promoter. Protoplasts overexpressing both AtHD2B and RPS6 exhibited down-regulation of pre-18 S rRNA synthesis with a concomitant decrease in transcription of some of the ribosomal proteins, suggesting their direct role in ribosome biogenesis and plant development. This is consistent with the mutation in rps6b that results in reduction in 18 S rRNA transcription and decreased root growth. We propose that the interaction between RPS6 and AtHD2B brings about a change in the chromatin structure of rDNA and thus plays an important role in linking TOR signaling to rDNA transcription and ribosome biogenesis in plants.
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MESH Headings
- Arabidopsis/cytology
- Arabidopsis/genetics
- Arabidopsis/metabolism
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Cell Nucleolus/genetics
- Cell Nucleolus/metabolism
- DNA, Plant/genetics
- DNA, Plant/metabolism
- DNA, Ribosomal/genetics
- DNA, Ribosomal/metabolism
- Epigenesis, Genetic/physiology
- Genes, Plant/physiology
- Genes, rRNA/physiology
- Histone Deacetylases/genetics
- Histone Deacetylases/metabolism
- Phosphatidylinositol 3-Kinases/genetics
- Phosphatidylinositol 3-Kinases/metabolism
- Promoter Regions, Genetic/physiology
- Protoplasts/cytology
- Protoplasts/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Ribosomal, 18S/biosynthesis
- RNA, Ribosomal, 18S/genetics
- Transcription, Genetic/physiology
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Affiliation(s)
| | - Sunghan Kim
- the Department of Plant Science, Seoul National University, Seoul 151-742, Korea, and
- the Department of Molecular Genetics and Center for Applied Plant Sciences, Ohio State University, Columbus, Ohio 43210
| | | | | | - Woo-Young Kim
- College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Korea
| | | | | | - Desh Pal S. Verma
- the Department of Molecular Genetics and Center for Applied Plant Sciences, Ohio State University, Columbus, Ohio 43210
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43
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Xiong Y, Sheen J. The role of target of rapamycin signaling networks in plant growth and metabolism. PLANT PHYSIOLOGY 2014; 164:499-512. [PMID: 24385567 PMCID: PMC3912084 DOI: 10.1104/pp.113.229948] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 12/05/2013] [Indexed: 05/18/2023]
Abstract
The target of rapamycin (TOR) kinase, a master regulator that is evolutionarily conserved among yeasts (Saccharomyces cerevisiae), plants, animals, and humans, integrates nutrient and energy signaling to promote cell proliferation and growth. Recent breakthroughs made possible by integrating chemical, genetic, and genomic analyses have greatly increased our understanding of the molecular functions and dynamic regulation of the TOR kinase in photosynthetic plants. TOR signaling plays fundamental roles in embryogenesis, meristem activation, root and leaf growth, flowering, senescence, and life span determination. The molecular mechanisms underlying TOR-mediated ribosomal biogenesis, translation promotion, readjustment of metabolism, and autophagy inhibition are now being uncovered. Moreover, monitoring photosynthesis-derived Glc and bioenergetics relays has revealed that TOR orchestrates unprecedented transcriptional networks that wire central metabolism and biosynthesis for energy and biomass production. In addition, these networks integrate localized stem/progenitor cell proliferation through interorgan nutrient coordination to control developmental transitions and growth.
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44
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Roy B, von Arnim AG. Translational Regulation of Cytoplasmic mRNAs. THE ARABIDOPSIS BOOK 2013; 11:e0165. [PMID: 23908601 PMCID: PMC3727577 DOI: 10.1199/tab.0165] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Translation of the coding potential of a messenger RNA into a protein molecule is a fundamental process in all living cells and consumes a large fraction of metabolites and energy resources in growing cells. Moreover, translation has emerged as an important control point in the regulation of gene expression. At the level of gene regulation, translational control is utilized to support the specific life histories of plants, in particular their responses to the abiotic environment and to metabolites. This review summarizes the diversity of translational control mechanisms in the plant cytoplasm, focusing on specific cases where mechanisms of translational control have evolved to complement or eclipse other levels of gene regulation. We begin by introducing essential features of the translation apparatus. We summarize early evidence for translational control from the pre-Arabidopsis era. Next, we review evidence for translation control in response to stress, to metabolites, and in development. The following section emphasizes RNA sequence elements and biochemical processes that regulate translation. We close with a chapter on the role of signaling pathways that impinge on translation.
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Affiliation(s)
- Bijoyita Roy
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN 37996-0840
- Current address: University of Massachussetts Medical School, Worcester, MA 01655-0122, USA
| | - Albrecht G. von Arnim
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN 37996-0840
- Graduate School of Genome Science and Technology, The University of Tennessee, Knoxville, TN 37996-0840
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45
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Henriques R, Magyar Z, Bögre L. S6K1 and E2FB are in mutually antagonistic regulatory links controlling cell growth and proliferation in Arabidopsis. PLANT SIGNALING & BEHAVIOR 2013; 8:e24367. [PMID: 23531690 PMCID: PMC3909064 DOI: 10.4161/psb.24367] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 03/19/2013] [Indexed: 05/24/2023]
Abstract
Plant development is dependent on the coordination between growth and cell proliferation. The nutrient sensing TOR kinase and its downstream target, the 40S ribosomal S6 Kinase, are central controllers of cell growth that were also shown to determine cell size by inhibiting the onset of mitosis in yeast and animal cells. We have shown that the Arabidopsis S6 Kinase1 inhibits cell proliferation through the RBR-E2FB complex. S6K1 interacts with RBR via its N-terminal RBR binding motif, promotes its nuclear localization and consequent RBR-dependent repression of cell cycle genes through E2FB. Here we show that S6K1 and E2FB are in a mutually antagonistic relationship both in their protein abundance and in their activity. We propose that this double inhibitory regulatory connection between S6K1 and E2FB forms a regulatory switch that might be important to determine whether cells divide or grow.
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Affiliation(s)
- Rossana Henriques
- Royal Holloway; University of London; School of Biological Sciences; Egham, UK
| | - Zoltán Magyar
- Royal Holloway; University of London; School of Biological Sciences; Egham, UK
- Institute of Plant Biology; Biological Research Centre; Szeged, Hungary
| | - László Bögre
- Royal Holloway; University of London; School of Biological Sciences; Egham, UK
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46
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Schepetilnikov M, Dimitrova M, Mancera-Martínez E, Geldreich A, Keller M, Ryabova LA. TOR and S6K1 promote translation reinitiation of uORF-containing mRNAs via phosphorylation of eIF3h. EMBO J 2013; 32:1087-102. [PMID: 23524850 DOI: 10.1038/emboj.2013.61] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 02/15/2013] [Indexed: 11/09/2022] Open
Abstract
Mammalian target-of-rapamycin (mTOR) triggers S6 kinase (S6K) activation to phosphorylate targets linked to translation in response to energy, nutrients, and hormones. Pathways of TOR activation in plants remain unknown. Here, we uncover the role of the phytohormone auxin in TOR signalling activation and reinitiation after upstream open reading frame (uORF) translation, which in plants is dependent on translation initiation factor eIF3h. We show that auxin triggers TOR activation followed by S6K1 phosphorylation at T449 and efficient loading of uORF-mRNAs onto polysomes in a manner sensitive to the TOR inhibitor Torin-1. Torin-1 mediates recruitment of inactive S6K1 to polysomes, while auxin triggers S6K1 dissociation and recruitment of activated TOR instead. A putative target of TOR/S6K1-eIF3h-is phosphorylated and detected in polysomes in response to auxin. In TOR-deficient plants, polysomes were prebound by inactive S6K1, and loading of uORF-mRNAs and eIF3h was impaired. Transient expression of eIF3h-S178D in plant protoplasts specifically upregulates uORF-mRNA translation. We propose that TOR functions in polysomes to maintain the active S6K1 (and thus eIF3h) phosphorylation status that is critical for translation reinitiation.
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Affiliation(s)
- Mikhail Schepetilnikov
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg Cedex 67084, France
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47
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Um JH, Kim S, Kim YK, Song SB, Lee SH, Verma DPS, Cheon CI. RNA interference-mediated repression of S6 kinase 1 impairs root nodule development in soybean. Mol Cells 2013; 35:243-8. [PMID: 23475423 PMCID: PMC3887909 DOI: 10.1007/s10059-013-2315-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 02/04/2013] [Accepted: 02/19/2013] [Indexed: 12/31/2022] Open
Abstract
Symbiotic nodule formation on legume roots is characterized with a series of developmental reprograming in root tissues, including extensive proliferation of cortical cells. We examined a possible involvement of the target of rapamycin (TOR) pathway, a central regulator of cell growth and proliferation in animals and yeasts, during soybean nodule development. Our results show that transcription of both GmTOR and its key downstream effector, GmS6K1, are activated during nodulation, which is paralleled with higher kinase activities of these gene products as well. RNAi-mediated knockdown of GmS6K1 impaired the nodule development with severely reduced nodule weight and numbers. In addition, expression of a few nodulins including leghemoglobin was also decreased, and consequently nitrogen fixation was found to be reduced by half. Proteomic analysis of the GmS6K1-RNAi nodules identified glutamine synthetase (GS), an essential enzyme for nitrogen assimilation in nodules, as one of the proteins that are significantly down regulated. These results appear to provide solid evidence for a functional link between GmS6K1 and nodule development.
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Affiliation(s)
- Ji-Hyun Um
- Department of Biological Science, Sookmyung Women’s University, Seoul 140–742,
Korea
| | - Sunghan Kim
- Department of Biological Science, Sookmyung Women’s University, Seoul 140–742,
Korea
| | - Yun-Kyoung Kim
- Department of Biological Science, Sookmyung Women’s University, Seoul 140–742,
Korea
| | - Seok-Bo Song
- Department of Functional Crop, National Institute of Crop Science, Milyang 627-130,
Korea
| | - Suk-Ha Lee
- Department of Plant Science, Seoul National University, Seoul 151–742,
Korea
| | - Desh Pal S. Verma
- Department of Molecular Genetics and Plant Biotechnology Center, The Ohio State University, Columbus, Ohio 43210,
USA
| | - Choong-Ill Cheon
- Department of Biological Science, Sookmyung Women’s University, Seoul 140–742,
Korea
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48
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Zhang H, Zhou H, Berke L, Heck AJR, Mohammed S, Scheres B, Menke FLH. Quantitative phosphoproteomics after auxin-stimulated lateral root induction identifies an SNX1 protein phosphorylation site required for growth. Mol Cell Proteomics 2013; 12:1158-69. [PMID: 23328941 DOI: 10.1074/mcp.m112.021220] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein phosphorylation is instrumental to early signaling events. Studying system-wide phosphorylation in relation to processes under investigation requires a quantitative proteomics approach. In Arabidopsis, auxin application can induce pericycle cell divisions and lateral root formation. Initiation of lateral root formation requires transcriptional reprogramming following auxin-mediated degradation of transcriptional repressors. The immediate early signaling events prior to this derepression are virtually uncharacterized. To identify the signal molecules responding to auxin application, we used a lateral root-inducible system that was previously developed to trigger synchronous division of pericycle cells. To identify and quantify the early signaling events following this induction, we combined (15)N-based metabolic labeling and phosphopeptide enrichment and applied a mass spectrometry-based approach. In total, 3068 phosphopeptides were identified from auxin-treated root tissue. This root proteome dataset contains largely phosphopeptides not previously reported and represents one of the largest quantitative phosphoprotein datasets from Arabidopsis to date. Key proteins responding to auxin treatment included the multidrug resistance-like and PIN2 auxin carriers, auxin response factor2 (ARF2), suppressor of auxin resistance 3 (SAR3), and sorting nexin1 (SNX1). Mutational analysis of serine 16 of SNX1 showed that overexpression of the mutated forms of SNX1 led to retarded growth and reduction of lateral root formation due to the reduced outgrowth of the primordium, showing proof of principle for our approach.
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Affiliation(s)
- Hongtao Zhang
- Bijvoet Center for Biomolecular Research, and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
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Dobrenel T, Marchive C, Azzopardi M, Clément G, Moreau M, Sormani R, Robaglia C, Meyer C. Sugar metabolism and the plant target of rapamycin kinase: a sweet operaTOR? FRONTIERS IN PLANT SCIENCE 2013; 4:93. [PMID: 23641244 PMCID: PMC3640205 DOI: 10.3389/fpls.2013.00093] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 03/27/2013] [Indexed: 05/18/2023]
Abstract
In eukaryotes, the ubiquitous TOR (target of rapamycin) kinase complexes have emerged as central regulators of cell growth and metabolism. The plant TOR complex 1 (TORC1), that contains evolutionary conserved protein partners, has been shown to be implicated in various aspects of C metabolism. Indeed Arabidopsis lines affected in the expression of TORC1 components show profound perturbations in the metabolism of several sugars, including sucrose, starch, and raffinose. Metabolite profiling experiments coupled to transcriptomic analyses of lines affected in TORC1 expression also reveal a wider deregulation of primary metabolism. Moreover recent data suggest that the kinase activity of TORC1, which controls biological outputs like mRNA translation or autophagy, is directly regulated by soluble sugars.
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Affiliation(s)
- Thomas Dobrenel
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, Saclay Plant SciencesVersailles, France
| | - Chloé Marchive
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, Saclay Plant SciencesVersailles, France
| | - Marianne Azzopardi
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, Saclay Plant SciencesVersailles, France
| | - Gilles Clément
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, Saclay Plant SciencesVersailles, France
| | - Manon Moreau
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, Saclay Plant SciencesVersailles, France
- Laboratoire de Génétique et Biophysique des Plantes, UMR7265, DSV, IBEB, SBVME, CEA, CNRS, Faculté des Sciences de Luminy, Aix Marseille UniversitéMarseille, France
| | - Rodnay Sormani
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, Saclay Plant SciencesVersailles, France
| | - Christophe Robaglia
- Laboratoire de Génétique et Biophysique des Plantes, UMR7265, DSV, IBEB, SBVME, CEA, CNRS, Faculté des Sciences de Luminy, Aix Marseille UniversitéMarseille, France
| | - Christian Meyer
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, Saclay Plant SciencesVersailles, France
- *Correspondence: Christian Meyer, Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, Institut National de la Recherche Agronomique Versailles, 78026 Versailles Cedex, France. e-mail:
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Carroll AJ. The Arabidopsis Cytosolic Ribosomal Proteome: From form to Function. FRONTIERS IN PLANT SCIENCE 2013; 4:32. [PMID: 23459595 PMCID: PMC3585428 DOI: 10.3389/fpls.2013.00032] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 02/10/2013] [Indexed: 05/20/2023]
Abstract
The cytosolic ribosomal proteome of Arabidopsis thaliana has been studied intensively by a range of proteomics approaches and is now one of the most well characterized eukaryotic ribosomal proteomes. Plant cytosolic ribosomes are distinguished from other eukaryotic ribosomes by unique proteins, unique post-translational modifications and an abundance of ribosomal proteins for which multiple divergent paralogs are expressed and incorporated. Study of the A. thaliana ribosome has now progressed well beyond a simple cataloging of protein parts and is focused strongly on elucidating the functions of specific ribosomal proteins, their paralogous isoforms and covalent modifications. This review summarises current knowledge concerning the Arabidopsis cytosolic ribosomal proteome and highlights potentially fruitful areas of future research in this fast moving and important area.
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Affiliation(s)
- Adam J. Carroll
- Australian Research Council Centre of Excellence in Plant Energy Biology, Australian National UniversityCanberra, ACT, Australia
- *Correspondence: Adam J. Carroll, Australian Research Council Centre of Excellence in Plant Energy Biology, Australian National University, ACT 0200, Canberra, Australia. e-mail:
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