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Freytes SN, Gobbini ML, Cerdán PD. The Plant Mediator Complex in the Initiation of Transcription by RNA Polymerase II. ANNUAL REVIEW OF PLANT BIOLOGY 2024; 75:211-237. [PMID: 38277699 DOI: 10.1146/annurev-arplant-070623-114005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2024]
Abstract
Thirty years have passed since the discovery of the Mediator complex in yeast. We are witnessing breakthroughs and advances that have led to high-resolution structural models of yeast and mammalian Mediators in the preinitiation complex, showing how it is assembled and how it positions the RNA polymerase II and its C-terminal domain (CTD) to facilitate the CTD phosphorylation that initiates transcription. This information may be also used to guide future plant research on the mechanisms of Mediator transcriptional control. Here, we review what we know about the subunit composition and structure of plant Mediators, the roles of the individual subunits and the genetic analyses that pioneered Mediator research, and how transcription factors recruit Mediators to regulatory regions adjoining promoters. What emerges from the research is a Mediator that regulates transcription activity and recruits hormonal signaling modules and histone-modifying activities to set up an off or on transcriptional state that recruits general transcription factors for preinitiation complex assembly.
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Affiliation(s)
| | | | - Pablo D Cerdán
- Fundación Instituto Leloir, IIBBA-CONICET, Buenos Aires, Argentina; , ,
- Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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Zhao H, Liu Y, Zhu Z, Feng Q, Ye Y, Zhang J, Han J, Zhou C, Xu J, Yan X, Li X. Mediator subunit MED8 interacts with heat shock transcription factor HSF3 to promote fucoxanthin synthesis in the diatom Phaeodactylum tricornutum. THE NEW PHYTOLOGIST 2024; 241:1574-1591. [PMID: 38062856 DOI: 10.1111/nph.19467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Accepted: 11/18/2023] [Indexed: 01/26/2024]
Abstract
Fucoxanthin, a natural carotenoid that has substantial pharmaceutical value due to its anticancer, antioxidant, antiobesity, and antidiabetic properties, is biosynthesized from glyceraldehyde-3-phosphate (G3P) via a series of enzymatic reactions. However, our understanding of the transcriptional mechanisms involved in fucoxanthin biosynthesis remains limited. Using reverse genetics, the med8 mutant was identified based on its phenotype of reduced fucoxanthin content, and the biological functions of MED8 in fucoxanthin synthesis were characterized using approaches such as gene expression, protein subcellular localization, protein-protein interaction and chromatin immunoprecipitation assay. Gene-editing mutants of MED8 exhibited decreased fucoxanthin content as well as reduced expression levels of six key genes involved in fucoxanthin synthesis, namely DXS, PSY1, ZDS-like, CRTISO5, ZEP1, and ZEP3, when compared to the wild-type (WT) strain. Furthermore, we showed that MED8 interacts with HSF3, and genetic analysis revealed their shared involvement in the genetic pathway governing fucoxanthin synthesis. Additionally, HSF3 was required for MED8 association with the promoters of the six fucoxanthin synthesis genes. In conclusion, MED8 and HSF3 are involved in fucoxanthin synthesis by modulating the expression of the fucoxanthin synthesis genes. Our results increase the understanding of the molecular regulation mechanisms underlying fucoxanthin synthesis in the diatom P. tricornutum.
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Affiliation(s)
- Hejing Zhao
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315211, China
| | - Yan Liu
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315211, China
| | - Zhengjiang Zhu
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315211, China
| | - Qingkai Feng
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315211, China
| | - Yuemei Ye
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315211, China
| | - Jinrong Zhang
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315211, China
| | - Jichang Han
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315211, China
| | - Chengxu Zhou
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315211, China
| | - Jilin Xu
- School of Marine Sciences, Ningbo University, Ningbo, 315211, China
| | - Xiaojun Yan
- School of Marine Sciences, Ningbo University, Ningbo, 315211, China
| | - Xiaohui Li
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, 315211, China
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Singh G, Ambreen H, Jain P, Chakraborty A, Singh B, Manivannan A, Bhatia S. Comparative transcriptomic and metabolite profiling reveals genotype-specific responses to Fe starvation in chickpea. PHYSIOLOGIA PLANTARUM 2023; 175:e13897. [PMID: 36960640 DOI: 10.1111/ppl.13897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 03/13/2023] [Indexed: 06/18/2023]
Abstract
Iron deficiency is a major nutritional stress that severely impacts crop productivity worldwide. However, molecular intricacies and subsequent physiological and metabolic changes in response to Fe starvation, especially in leguminous crops like chickpea, remain elusive. In the present study, we investigated physiological, transcriptional, and metabolic reprogramming in two chickpea genotypes (H6013 and L4958) with contrasting seed iron concentrations upon Fe deficiency. Our findings revealed that iron starvation affected growth and physiological parameters of both chickpea genotypes. Comparative transcriptome analysis led to the identification of differentially expressed genes between the genotypes related to strategy I uptake, metal ions transporters, reactive oxygen species-associated genes, transcription factors, and protein kinases that could mitigate Fe deficiency. Our gene correlation network discovered several putative candidate genes like CIPK25, CKX3, WRKY50, NAC29, MYB4, and PAP18, which could facilitate the investigation of the molecular rationale underlying Fe tolerance in chickpea. Furthermore, the metabolite analysis also illustrated the differential accumulation of organic acids, amino acids and other metabolites associated with Fe mobilization in chickpea genotypes. Overall, our study demonstrated the comparative transcriptional dynamics upon Fe starvation. The outcomes of the current endeavor will enable the development of Fe deficiency tolerant chickpea cultivars.
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Affiliation(s)
- Gourav Singh
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, PO Box No. 10531, New Delhi, 110067, India
| | - Heena Ambreen
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, PO Box No. 10531, New Delhi, 110067, India
| | - Priyanka Jain
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, PO Box No. 10531, New Delhi, 110067, India
| | - Anirban Chakraborty
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, PO Box No. 10531, New Delhi, 110067, India
| | - Baljinder Singh
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, PO Box No. 10531, New Delhi, 110067, India
| | - Abinaya Manivannan
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, PO Box No. 10531, New Delhi, 110067, India
| | - Sabhyata Bhatia
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, PO Box No. 10531, New Delhi, 110067, India
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Ohama N, Moo TL, Chua NH. Differential requirement of MED14/17 recruitment for activation of heat inducible genes. THE NEW PHYTOLOGIST 2021; 229:3360-3376. [PMID: 33251584 DOI: 10.1111/nph.17119] [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: 07/23/2020] [Accepted: 11/09/2020] [Indexed: 05/06/2023]
Abstract
The mechanism of heat stress response in plants has been studied, focusing on the function of transcription factors (TFs). Generally, TFs recruit coactivators, such as Mediator, are needed to assemble the transcriptional machinery. However, despite the close relationship with TFs, how coactivators are involved in transcriptional regulation under heat stress conditions is largely unclear. We found a severe thermosensitive phenotype of Arabidopsis mutants of MED14 and MED17. Transcriptomic analysis revealed that a quarter of the heat stress (HS)-inducible genes were commonly downregulated in these mutants. Furthermore, chromatin immunoprecipitation assay showed that the recruitment of Mediator by HsfA1s, the master regulators of heat stress response, is an important step for the expression of HS-inducible genes. There was a differential requirement of Mediator among genes; TF genes have a high requirement whereas heat shock proteins (HSPs) have a low requirement. Furthermore, artificial activation of HsfA1d mimicking perturbation of protein homeostasis induced HSP gene expression without MED14 recruitment but not TF gene expression. Considering the essential role of MED14 in Mediator function, other coactivators may play major roles in HSP activation depending on the cellular conditions. Our findings highlight the importance of differential recruitment of Mediator for the precise control of HS responses in plants.
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Affiliation(s)
- Naohiko Ohama
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, 117604, Singapore
| | - Teck Lim Moo
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, 117604, Singapore
| | - Nam-Hai Chua
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, 117604, Singapore
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Zhang Y, Shi C, Fu W, Gu X, Qi Z, Xu W, Xia G. Arabidopsis MED18 Interaction With RNA Pol IV and V Subunit NRPD2a in Transcriptional Regulation of Plant Immune Responses. FRONTIERS IN PLANT SCIENCE 2021; 12:692036. [PMID: 34691090 PMCID: PMC8527527 DOI: 10.3389/fpls.2021.692036] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 09/10/2021] [Indexed: 05/02/2023]
Abstract
Mediator is a conserved multiprotein complex important for transcription by RNA polymerase II (Pol II). Arabidopsis Mediator subunit MED18 regulates flowering, hormone signaling and plant immunity. Here we report that Arabidopsis MED18 interacted with NUCLEAR RNA POLYMERASE D2a (NRPD2a), the second largest subunit of the nuclear Pol IV and V, which function in RNA-directed DNA methylation and epigenetic regulation of gene expression. Mutants for both MED18 and NRPD2a were compromised in resistance to necrotrophic fungal pathogen Botrytis cinerea. Mutants for NRPD1a, the largest subunit of Pol IV, were also compromised in resistance to Botrytis, supporting a critical role of Pol IV and V in plant defense against Botrytis. Increased Botrytis susceptibility of both the med18 and nrpd2a mutants were associated with reduced accumulation of reactive oxygen species, which are known to promote resistance to Botrytis. Both the basal and pathogen-induced levels of salicylic acid and jasmonic acid were also significantly altered in the med18 and nrpd2a mutants. Transcriptome profiling found that MED18 and NRPD2a affected both unique and overlapping sets of genes in a broad spectrum of biological processes and pathways that influence plant-pathogen interaction. The genes altered in expression in the med18 and nrpd2a mutants include disease resistance proteins, salicylic acid and jasmonic acid signaling and responses, which are known to affect resistance to necrotrophic pathogens. The novel interaction between subunits of Mediator and plant-specific RNA polymerases provides a new mechanism for epigenetic regulation of resistance and expression of defense-related genes in plant immunity.
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Affiliation(s)
- Yan Zhang
- Department of Landscape and Horticulture, Ecology College, Lishui University, Lishui, China
- *Correspondence: Yan Zhang,
| | - Chengchen Shi
- Department of Landscape and Horticulture, Ecology College, Lishui University, Lishui, China
| | - Weihong Fu
- Department of Landscape and Horticulture, Ecology College, Lishui University, Lishui, China
| | - Xiaojing Gu
- Department of Landscape and Horticulture, Ecology College, Lishui University, Lishui, China
| | - Ziyang Qi
- Department of Landscape and Horticulture, Ecology College, Lishui University, Lishui, China
| | - Weizhong Xu
- Lishui Academy of Agricultural and Forestry Sciences, Lishui, China
| | - Gengshou Xia
- Department of Landscape and Horticulture, Ecology College, Lishui University, Lishui, China
- Gengshou Xia,
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The Important Function of Mediator Complex in Controlling the Developmental Transitions in Plants. Int J Mol Sci 2020; 21:ijms21082733. [PMID: 32326439 PMCID: PMC7215822 DOI: 10.3390/ijms21082733] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/09/2020] [Accepted: 04/11/2020] [Indexed: 12/24/2022] Open
Abstract
Developmental transitions in plants are tightly associated with changes in the transcriptional regulation of gene expression. One of the most important regulations is conferred by cofactors of RNA polymerase II including the mediator complex, a large complex with a modular organization. The mediator complex recruits transcription factors to bind to the specific sites of genes including protein-coding genes and non-coding RNA genes to promote or repress the transcription initiation and elongation using a protein-protein interaction module. Mediator complex subunits have been isolated and identified in plants and the function of most mediator subunits in whole life cycle plants have been revealed. Studies have shown that the Mediator complex is indispensable for the regulation of plant developmental transitions by recruiting age-, flowering-, or hormone-related transcription factors. Here, we first overviewed the Mediator subunits in plants, and then we summarized the specific Mediator subunits involved in developmental transitions, including vegetative phase change and floral transition. Finally, we proposed the future directions to further explore their roles in plants. The link between Mediator subunits and developmental transitions implies the necessity to explore targets of this complex as a potential application in developing high quality crop varieties.
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Xue D, Guo N, Zhang XL, Zhao JM, Bu YP, Jiang DL, Wang XT, Wang HT, Guan RZ, Xing H. Genome-Wide Analysis Reveals the Role of Mediator Complex in the Soybean- Phytophthora sojae Interaction. Int J Mol Sci 2019; 20:E4570. [PMID: 31540158 PMCID: PMC6770253 DOI: 10.3390/ijms20184570] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/07/2019] [Accepted: 09/09/2019] [Indexed: 02/06/2023] Open
Abstract
The mediator complex is an essential link between transcription factors and RNA polymerase II, and mainly functions in the transduction of diverse signals to genes involved in different pathways. Limited information is available on the role of soybean mediator subunits in growth and development, and their participation in defense response regulation. Here, we performed genome-wide identification of the 95 soybean mediator subunits, which were unevenly localized on the 20 chromosomes and only segmental duplication events were detected. We focused on GmMED16-1, which is highly expressed in the roots, for further functional analysis. Transcription of GmMED16-1 was induced in response to Phytophthora sojae infection. Agrobacterium rhizogenes mediated soybean hairy root transformation was performed for the silencing of the GmMED16-1 gene. Silencing of GmMED16-1 led to an enhanced susceptibility phenotype and increased accumulation of P. sojae biomass in hairy roots of transformants. The transcript levels of NPR1, PR1a, and PR5 in the salicylic acid defense pathway in roots of GmMED16-1-silenced transformants were lower than those of empty-vector transformants. The results provide evidence that GmMED16-1 may participate in the soybean-P. sojae interaction via a salicylic acid-dependent process.
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Affiliation(s)
- Dong Xue
- National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Na Guo
- National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiao-Li Zhang
- National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Jin-Ming Zhao
- National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Yuan-Peng Bu
- National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Dian-Liang Jiang
- National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Xiao-Ting Wang
- National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Hai-Tang Wang
- National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Rong-Zhan Guan
- National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
| | - Han Xing
- National Center for Soybean Improvement, Key Laboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
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