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Yuan S, Zhou G, Xu G. Translation machinery: the basis of translational control. J Genet Genomics 2024; 51:367-378. [PMID: 37536497 DOI: 10.1016/j.jgg.2023.07.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 07/23/2023] [Accepted: 07/23/2023] [Indexed: 08/05/2023]
Abstract
Messenger RNA (mRNA) translation consists of initiation, elongation, termination, and ribosome recycling, carried out by the translation machinery, primarily including tRNAs, ribosomes, and translation factors (TrFs). Translational regulators transduce signals of growth and development, as well as biotic and abiotic stresses, to the translation machinery, where global or selective translational control occurs to modulate mRNA translation efficiency (TrE). As the basis of translational control, the translation machinery directly determines the quality and quantity of newly synthesized peptides and, ultimately, the cellular adaption. Thus, regulating the availability of diverse machinery components is reviewed as the central strategy of translational control. We provide classical signaling pathways (e.g., integrated stress responses) and cellular behaviors (e.g., liquid-liquid phase separation) to exemplify this strategy within different physiological contexts, particularly during host-microbe interactions. With new technologies developed, further understanding this strategy will speed up translational medicine and translational agriculture.
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Affiliation(s)
- Shu Yuan
- State Key Laboratory of Hybrid Rice, Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072, China
| | - Guilong Zhou
- State Key Laboratory of Hybrid Rice, Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072, China
| | - Guoyong Xu
- State Key Laboratory of Hybrid Rice, Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072, China; Hubei Hongshan Laboratory, Wuhan, Hubei 430070, China.
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2
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Li N, Duan Y, Ye Q, Ma Y, Ma R, Zhao L, Zhu S, Yu F, Qi S, Wang Y. The Arabidopsis eIF4E1 regulates NRT1.1-mediated nitrate signaling at both translational and transcriptional levels. THE NEW PHYTOLOGIST 2023; 240:338-353. [PMID: 37424317 DOI: 10.1111/nph.19129] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 06/18/2023] [Indexed: 07/11/2023]
Abstract
Identifying new nitrate regulatory genes and illustrating their mechanisms in modulating nitrate signaling are of great significance for achieving the high yield and nitrogen use efficiency (NUE) of crops. Here, we screened a mutant with defects in nitrate response and mapped the mutation to the gene eIF4E1 in Arabidopsis. Our results showed that eIF4E1 regulated nitrate signaling and metabolism. Ribo-seq and polysome profiling analysis revealed that eIF4E1 modulated the amount of some nitrogen (N)-related mRNAs being translated, especially the mRNA of NRT1.1 was reduced in the eif4e1 mutant. RNA-Seq results enriched some N-related genes, supporting that eIF4E1 is involved in nitrate regulation. The genetic analysis indicated that eIF4E1 worked upstream of NRT1.1 in nitrate signaling. In addition, an eIF4E1-interacting protein GEMIN2 was identified and found to be involved in nitrate signaling. Further investigation showed that overexpression of eIF4E1 promoted plant growth and enhanced yield and NUE. These results demonstrate that eIF4E1 regulates nitrate signaling by modulating NRT1.1 at both translational and transcriptional levels, laying the foundation for future research on the regulation of mineral nutrition at the translational level.
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Affiliation(s)
- Na Li
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Yawen Duan
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Qing Ye
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Yuhan Ma
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Rongjie Ma
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Lufei Zhao
- Agricultural Science and Engineering School, Liaocheng University, Liaocheng, Shandong, 252000, China
| | - Sirui Zhu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha, Hunan, 410082, China
| | - Feng Yu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha, Hunan, 410082, China
| | - Shengdong Qi
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Yong Wang
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
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Pechar GS, Donaire L, Gosalvez B, García‐Almodovar C, Sánchez‐Pina MA, Truniger V, Aranda MA. Editing melon eIF4E associates with virus resistance and male sterility. PLANT BIOTECHNOLOGY JOURNAL 2022; 20:2006-2022. [PMID: 35778883 PMCID: PMC9491454 DOI: 10.1111/pbi.13885] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/19/2022] [Accepted: 06/23/2022] [Indexed: 05/20/2023]
Abstract
The cap-binding protein eIF4E, through its interaction with eIF4G, constitutes the core of the eIF4F complex, which plays a key role in the circularization of mRNAs and their subsequent cap-dependent translation. In addition to its fundamental role in mRNA translation initiation, other functions have been described or suggested for eIF4E, including acting as a proviral factor and participating in sexual development. We used CRISPR/Cas9 genome editing to generate melon eif4e knockout mutant lines. Editing worked efficiently in melon, as we obtained transformed plants with a single-nucleotide deletion in homozygosis in the first eIF4E exon already in a T0 generation. Edited and non-transgenic plants of a segregating F2 generation were inoculated with Moroccan watermelon mosaic virus (MWMV); homozygous mutant plants showed virus resistance, while heterozygous and non-mutant plants were infected, in agreement with our previous results with plants silenced in eIF4E. Interestingly, all homozygous edited plants of the T0 and F2 generations showed a male sterility phenotype, while crossing with wild-type plants restored fertility, displaying a perfect correlation between the segregation of the male sterility phenotype and the segregation of the eif4e mutation. Morphological comparative analysis of melon male flowers along consecutive developmental stages showed postmeiotic abnormal development for both microsporocytes and tapetum, with clear differences in the timing of tapetum degradation in the mutant versus wild-type. An RNA-Seq analysis identified critical genes in pollen development that were down-regulated in flowers of eif4e/eif4e plants, and suggested that eIF4E-specific mRNA translation initiation is a limiting factor for male gametes formation in melon.
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Affiliation(s)
- Giuliano S. Pechar
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - Livia Donaire
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - Blanca Gosalvez
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - Carlos García‐Almodovar
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - María Amelia Sánchez‐Pina
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - Verónica Truniger
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - Miguel A. Aranda
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
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Palukaitis P, Kim S. Resistance to Turnip Mosaic Virus in the Family Brassicaceae. THE PLANT PATHOLOGY JOURNAL 2021; 37:1-23. [PMID: 33551693 PMCID: PMC7847761 DOI: 10.5423/ppj.rw.09.2020.0178] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/30/2020] [Accepted: 11/30/2020] [Indexed: 05/21/2023]
Abstract
Resistance to diseases caused by turnip mosaic virus (TuMV) in crop species of the family Brassicaceae has been studied extensively, especially in members of the genus Brassica. The variation in response observed on resistant and susceptible plants inoculated with different isolates of TuMV is due to a combination of the variation in the plant resistome and the variation in the virus genome. Here, we review the breadth of this variation, both at the level of variation in TuMV sequences, with one eye towards the phylogeny and evolution of the virus, and another eye towards the nature of the various responses observed in susceptible vs. different types of resistance responses. The analyses of the viral genomes allowed comparisons of pathotyped viruses on particular indicator hosts to produce clusters of host types, while the inclusion of phylogeny data and geographic location allowed the formation of the host/geographic cluster groups, the derivation of both of which are presented here. Various studies on resistance determination in particular brassica crops sometimes led to further genetic studies, in many cases to include the mapping of genes, and in some cases to the actual identification of the genes. In addition to summarizing the results from such studies done in brassica crops, as well as in radish and Arabidopsis (the latter as a potential source of candidate genes for brassica and radish), we also summarize work done using nonconventional approaches to obtaining resistance to TuMV.
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Affiliation(s)
- Peter Palukaitis
- Department of Horticultural Sciences, Seoul Women’s University, Seoul 0797, Korea
- Co-corresponding authors P. Palukaitis, Phone) +82-2-970-5614, FAX) +82-2-970-5610, E-mail) , S. Kim, Phone) +82-31-5182-8112, FAX) +82-31-5182-8113, E-mail) , ORCID, Peter Palukaitis https://orcid.org/0000-0001-8735-1273
| | - Su Kim
- Institute of Plant Analysis Technology Development, The Saeron Co., Suwon 16648, Korea
- Co-corresponding authors P. Palukaitis, Phone) +82-2-970-5614, FAX) +82-2-970-5610, E-mail) , S. Kim, Phone) +82-31-5182-8112, FAX) +82-31-5182-8113, E-mail) , ORCID, Peter Palukaitis https://orcid.org/0000-0001-8735-1273
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5
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Saha S, Mäkinen K. Insights into the Functions of eIF4E-Biding Motif of VPg in Potato Virus A Infection. Viruses 2020; 12:E197. [PMID: 32053987 PMCID: PMC7077193 DOI: 10.3390/v12020197] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 02/05/2020] [Accepted: 02/07/2020] [Indexed: 12/14/2022] Open
Abstract
The interaction between the viral protein genome-linked (VPg) and eukaryotic initiation factor 4E (eIF4E) or eIF(iso)4E of the host plays a crucial role in potyvirus infection. The VPg of potato virus A (PVA) contains the Tyr-X-X-X-X-Leu-phi (YXXXLΦ) binding motif for eIF(iso)4E. In order to investigate its role in PVA infection, we substituted the conserved tyrosine and leucine residues of the motif with alanine residues in the infectious cDNA of PVA (PVAVPgmut). PVAVPgmut RNA replicated in infiltrated leaves, but RNA accumulation remained low. Systemic infection occurred only if a reversion to wild type PVA occurred. VPg was able to stabilize PVA RNA and enhance the expression of Renilla luciferase (3'RLUC) from the 3' end of the PVA genome. VPgmut could not support either PVA RNA stabilization or enhanced 3'RLUC expression. The RNA silencing suppressor helper-component proteinase (HCPro) is responsible for the formation of PVA-induced RNA granules (PGs) during infection. While VPgmut increased the number of PG-like foci, the percentage of PVA RNA co-localization with PGs was reduced from 86% to 20%. A testable hypothesis for future studies based on these results is that the binding of eIF(iso)4E to PVA VPg via the YXXXLΦ motif is required for PVA RNA stabilization, as well as the transfer to the RNA silencing suppression pathway and, further, to polysomes for viral protein synthesis.
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Affiliation(s)
| | - Kristiina Mäkinen
- Department of Microbiology and Viikki Plant Science Centre, University of Helsinki, 00014 Helsinki, Finland;
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6
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Miller WA, Dinesh-Kumar SP. A new mechanism for translational control in plants. FEBS J 2019; 286:3775-3777. [PMID: 31400078 PMCID: PMC6779488 DOI: 10.1111/febs.15022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 07/27/2019] [Indexed: 12/16/2022]
Abstract
In unstressed conditions, the cap-binding protein, eIF4E, binds the 5' cap structure (m7G) on mRNA and recruits other translation initiation factors to bring the ribosome to the mRNA. Bruns et al. show that, in plants, phosphorylation of eIF4E by the master metabolic regulatory protein, sucrose nonfermenting-related kinase 1 (SnRK1), reduces translation globally. This negative regulation of translation inhibits geminivirus infection and is speculated to be a response to various abiotic stresses.
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Affiliation(s)
- W. Allen Miller
- Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA, USA
| | - Savithramma P. Dinesh-Kumar
- Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California Davis, Davis, CA, USA
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7
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Long YP, Xie DJ, Zhao YY, Shi DQ, Yang WC. BICELLULAR POLLEN 1 is a modulator of DNA replication and pollen development in Arabidopsis. THE NEW PHYTOLOGIST 2019; 222:588-603. [PMID: 30484867 DOI: 10.1111/nph.15610] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 11/19/2018] [Indexed: 06/09/2023]
Abstract
During male gametogenesis in Arabidopsis, the haploid microspore undergoes an asymmetric division to produce a vegetative and a generative cell, the latter of which continues to divide symmetrically to form two sperms. This simple system couples cell cycle with cell fate specification. Here we addressed the role of DNA replication in male gametogenesis using a mutant bicellular pollen 1 (bice1), which produces bicellular, rather than tricellular, pollen grains as in the wild-type plant at anthesis. The mutation prolonged DNA synthesis of the generative cell, which resulted in c. 40% of pollen grains arrested at the two-nucleate stage. The extended S phase did not impact the cell fate of the generative cell as shown by cell-specific markers. BICE1 encodes a plant homolog of human D123 protein that is required for G1 progression, but the underlying mechanism is unknown. Here we showed that BICE1 interacts with MCM4 and MCM7 of the pre-replication complex. Consistently, double mutations in BICE1 and MCM4, or MCM7, also led to bicellular pollen and condensed chromosomes. These suggest that BICE1 plays a role in modulating DNA replication via interaction with MCM4 and MCM7.
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Affiliation(s)
- Yan-Ping Long
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, East Lincui Road, Beijing, 100101, China
- College of Advanced Agricultural Sciences, University of the Chinese Academy of Sciences, Yuquan Road, Beijing, 100049, China
| | - Dong-Jiang Xie
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, East Lincui Road, Beijing, 100101, China
- College of Advanced Agricultural Sciences, University of the Chinese Academy of Sciences, Yuquan Road, Beijing, 100049, China
| | - Yan-Yan Zhao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, East Lincui Road, Beijing, 100101, China
| | - Dong-Qiao Shi
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, East Lincui Road, Beijing, 100101, China
- College of Advanced Agricultural Sciences, University of the Chinese Academy of Sciences, Yuquan Road, Beijing, 100049, China
| | - Wei-Cai Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, East Lincui Road, Beijing, 100101, China
- College of Advanced Agricultural Sciences, University of the Chinese Academy of Sciences, Yuquan Road, Beijing, 100049, China
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8
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Takakura Y, Udagawa H, Shinjo A, Koga K. Mutation of a Nicotiana tabacum L. eukaryotic translation-initiation factor gene reduces susceptibility to a resistance-breaking strain of Potato virus Y. MOLECULAR PLANT PATHOLOGY 2018; 19:2124-2133. [PMID: 29633509 PMCID: PMC6638035 DOI: 10.1111/mpp.12686] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 03/08/2018] [Accepted: 04/03/2018] [Indexed: 05/23/2023]
Abstract
Eukaryotic translation-initiation factors eIF4E and eIF(iso)4E in plants play key roles in infection by potyviruses and other plant RNA viruses. Mutations in the genes encoding these factors reduce susceptibility to the viruses, and are the basis of several recessive virus resistance genes widely used in plant breeding. Because virus variants occasionally break such resistance, the molecular basis for this process must be elucidated. Although deletion mutants of eIF4E1-S of tobacco (Nicotiana tabacum L.) resist Potato virus Y (PVY; the type member of the genus Potyvirus), resistance-breaking strains of PVY threaten tobacco production worldwide. Here, we used RNA interference technology to knock down tobacco eIF4E2-S and eIF4E2-T genes or eIF(iso)4E-S and eIF(iso)4E-T genes. Transgenic plants with reduced transcript levels of both eIF(iso)4E-S and eIF(iso)4E-T showed reduced susceptibility to a resistance-breaking PVY strain with a K105E mutation in the viral genome-associated protein (VPg). By screening a population of chemically induced mutants of eIF(iso)4E-S and eIF(iso)4E-T, we showed that plants with a nonsense mutation in eIF(iso)4E-T, but not eIF(iso)4E-S, showed reduced susceptibility to the resistance-breaking PVY strain. In a yeast two-hybrid assay, VPg of the resistance-breaking strain, but not wild-type PVY, physically interacted with the eIF(iso)4E-T protein. Thus, eIF4E1-S is required for infection by PVY, but eIF(iso)4E-T is required for infection by the resistance-breaking strain. Our study provides the first evidence for the involvement of a host eukaryotic translation-initiation factor in the infection cycle of a resistance-breaking virus strain. The eIF(iso)4E-T mutants will be useful in tobacco breeding to introduce resistance against resistance-breaking PVY strains.
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Affiliation(s)
- Yoshimitsu Takakura
- Leaf Tobacco Research Center, Japan Tobacco, Inc.1900 Idei, OyamaTochigi 323‐0808Japan
| | - Hisashi Udagawa
- Leaf Tobacco Research Center, Japan Tobacco, Inc.1900 Idei, OyamaTochigi 323‐0808Japan
| | - Akira Shinjo
- Leaf Tobacco Research Center, Japan Tobacco, Inc.1900 Idei, OyamaTochigi 323‐0808Japan
| | - Kazuharu Koga
- Leaf Tobacco Research Center, Japan Tobacco, Inc.1900 Idei, OyamaTochigi 323‐0808Japan
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Xu M, Xie H, Wu J, Xie L, Yang J, Chi Y. Translation Initiation Factor eIF4E and eIFiso4E Are Both Required for Peanut stripe virus Infection in Peanut ( Arachis hypogaea L.). Front Microbiol 2017; 8:338. [PMID: 28344571 PMCID: PMC5344889 DOI: 10.3389/fmicb.2017.00338] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 02/17/2017] [Indexed: 01/03/2023] Open
Abstract
Peanut stripe virus (PStV) belongs to the genus Potyvirus and is the most important viral pathogen of cultivated peanut (Arachis hypogaea L.). The eukaryotic translation initiation factor, eIF4E, and its isoform, eIF(iso)4E, play key roles during virus infection in plants, particularly Potyvirus. In the present study, we cloned the eIF4E and eIF(iso)4E homologs in peanut and named these as PeaeIF4E and PeaeIF(iso)4E, respectively. Quantitative real-time PCR (qRT-PCR) analysis showed that these two genes were expressed during all growth periods and in all peanut organs, but were especially abundant in young leaves and roots. These also had similar expression levels. Yeast two-hybrid analysis showed that PStV multifunctional helper component proteinase (HC-Pro) and viral protein genome-linked (VPg) both interacted with PeaeIF4E and PeaeIF(iso)4E. Bimolecular fluorescence complementation assay showed that there was an interaction between HC-Pro and PeaeIF4E/PeaeIF(iso)4E in the cytoplasm and between VPg and PeaeIF4E/PeaeIF(iso)4E in the nucleus. Silencing either PeaeIF4E or PeaeIF(iso)4E using a virus-induced gene silencing system did not significantly affect PStV accumulation. However, silencing both PeaeIF4E and PeaeIF(iso)4E genes significantly weakened PStV accumulation. The findings of the present study suggest that PeaeIF4E and PeaeIF(iso)4E play important roles in the PStV infection cycle and may potentially contribute to PStV resistance.
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Affiliation(s)
- Manlin Xu
- Shandong Peanut Research InstituteQingdao, China
- Fujian Agriculture and Forestry UniversityFuzhou, China
| | - Hongfeng Xie
- Shandong Peanut Research InstituteQingdao, China
| | - Juxiang Wu
- Shandong Peanut Research InstituteQingdao, China
| | - Lianhui Xie
- Fujian Agriculture and Forestry UniversityFuzhou, China
| | - Jinguang Yang
- Open Project Program of Key Laboratory of Tobacco Pest Monitoring Controlling and Integrated Management, Tobacco Research Institute of Chinese Academy of Agricultural SciencesQingdao, China
| | - Yucheng Chi
- Shandong Peanut Research InstituteQingdao, China
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Plant Translation Factors and Virus Resistance. Viruses 2015; 7:3392-419. [PMID: 26114476 PMCID: PMC4517107 DOI: 10.3390/v7072778] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/18/2015] [Accepted: 06/19/2015] [Indexed: 02/06/2023] Open
Abstract
Plant viruses recruit cellular translation factors not only to translate their viral RNAs but also to regulate their replication and potentiate their local and systemic movement. Because of the virus dependence on cellular translation factors, it is perhaps not surprising that many natural plant recessive resistance genes have been mapped to mutations of translation initiation factors eIF4E and eIF4G or their isoforms, eIFiso4E and eIFiso4G. The partial functional redundancy of these isoforms allows specific mutation or knock-down of one isoform to provide virus resistance without hindering the general health of the plant. New possible targets for antiviral strategies have also been identified following the characterization of other plant translation factors (eIF4A-like helicases, eIF3, eEF1A and eEF1B) that specifically interact with viral RNAs and proteins and regulate various aspects of the infection cycle. Emerging evidence that translation repression operates as an alternative antiviral RNA silencing mechanism is also discussed. Understanding the mechanisms that control the development of natural viral resistance and the emergence of virulent isolates in response to these plant defense responses will provide the basis for the selection of new sources of resistance and for the intelligent design of engineered resistance that is broad-spectrum and durable.
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11
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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: 144] [Impact Index Per Article: 16.0] [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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12
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Wang G, Zhang J, Wang G, Fan X, Sun X, Qin H, Xu N, Zhong M, Qiao Z, Tang Y, Song R. Proline responding1 Plays a Critical Role in Regulating General Protein Synthesis and the Cell Cycle in Maize. THE PLANT CELL 2014; 26:2582-2600. [PMID: 24951479 PMCID: PMC4114953 DOI: 10.1105/tpc.114.125559] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 05/19/2014] [Accepted: 05/29/2014] [Indexed: 05/18/2023]
Abstract
Proline, an important amino acid, accumulates in many plant species. Besides its role in plant cell responses to environmental stresses, the potential biological functions of proline in growth and development are unclear. Here, we report cloning and functional characterization of the maize (Zea mays) classic mutant proline responding1 (pro1) gene. This gene encodes a Δ1-pyrroline-5- carboxylate synthetase that catalyzes the biosynthesis of proline from glutamic acid. Loss of function of Pro1 significantly inhibits proline biosynthesis and decreases its accumulation in the pro1 mutant. Proline deficiency results in an increased level of uncharged tRNApro AGG accumulation and triggers the phosphorylation of eukaryotic initiation factor 2α (eIF2α) in the pro1 mutant, leading to a general reduction in protein synthesis in this mutant. Proline deficiency also downregulates major cyclin genes at the transcriptional level, causing cell cycle arrest and suppression of cell proliferation. These processes are reversible when external proline is supplied to the mutant, suggesting that proline plays a regulatory role in the cell cycle transition. Together, the results demonstrate that proline plays an important role in the regulation of general protein synthesis and the cell cycle transition in plants.
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Affiliation(s)
- Gang Wang
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China Coordinated Crop Biology Research Center, Beijing 100193, P.R. China
| | - Jushan Zhang
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Guifeng Wang
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China Coordinated Crop Biology Research Center, Beijing 100193, P.R. China
| | - Xiangyu Fan
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Xin Sun
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Hongli Qin
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Nan Xu
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Mingyu Zhong
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Zhenyi Qiao
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Yuanping Tang
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Rentao Song
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China Coordinated Crop Biology Research Center, Beijing 100193, P.R. China
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13
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Browning KS. Plant Translational Machinery. Mol Biol 2014. [DOI: 10.1007/978-1-4614-7570-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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14
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Cytoplasm: Translational Apparatus. Mol Biol 2014. [DOI: 10.1007/978-1-4939-0263-7_8-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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15
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Moury B, Charron C, Janzac B, Simon V, Gallois JL, Palloix A, Caranta C. Evolution of plant eukaryotic initiation factor 4E (eIF4E) and potyvirus genome-linked protein (VPg): a game of mirrors impacting resistance spectrum and durability. INFECTION GENETICS AND EVOLUTION 2013; 27:472-80. [PMID: 24309680 DOI: 10.1016/j.meegid.2013.11.024] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 11/18/2013] [Accepted: 11/25/2013] [Indexed: 11/29/2022]
Abstract
Polymorphism in the plant eukaryotic translation initiation factor 4E (eIF4E) and potyvirus genome-linked protein (VPg) determine, in many cases, the outcome of the confrontation between these two organisms: compatibility (i.e. infection of the plant by the virus) or incompatibility (i.e. resistance of the plant to the virus). The two interacting proteins eIF4E and VPg show strikingly similar evolution patterns. Most codon positions in their coding sequences are highly constrained for nonsynonymous substitutions but a small number shows evidence for positive selection. Several of these latter positions were shown to be functionally important, conferring resistance to the host or pathogenicity to the virus. Determining the mutational pathways involved in pepper eIF4E diversification revealed a link between an increase of the pepper resistance spectrum towards a panel of potyvirus species and an increase of durability of the resistance towards Potato virus Y. This relationship questions the interest of using more generally the spectrum of action of a plant resistance gene as a predictor of its durability potential.
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Affiliation(s)
- B Moury
- INRA, UR407 Pathologie Végétale, Domaine Saint Maurice, CS 60094, F-84143 Montfavet Cedex, France.
| | - C Charron
- INRA, UR1052, Génétique et Amélioration des Fruits et Légumes, Domaine Saint Maurice, CS 60094, F-84143 Montfavet Cedex, France
| | - B Janzac
- INRA, UR407 Pathologie Végétale, Domaine Saint Maurice, CS 60094, F-84143 Montfavet Cedex, France; INRA, UR1052, Génétique et Amélioration des Fruits et Légumes, Domaine Saint Maurice, CS 60094, F-84143 Montfavet Cedex, France
| | - V Simon
- INRA, UR407 Pathologie Végétale, Domaine Saint Maurice, CS 60094, F-84143 Montfavet Cedex, France
| | - J L Gallois
- INRA, UR1052, Génétique et Amélioration des Fruits et Légumes, Domaine Saint Maurice, CS 60094, F-84143 Montfavet Cedex, France
| | - A Palloix
- INRA, UR1052, Génétique et Amélioration des Fruits et Légumes, Domaine Saint Maurice, CS 60094, F-84143 Montfavet Cedex, France
| | - C Caranta
- INRA, UR1052, Génétique et Amélioration des Fruits et Légumes, Domaine Saint Maurice, CS 60094, F-84143 Montfavet Cedex, France
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16
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Boex-Fontvieille E, Daventure M, Jossier M, Zivy M, Hodges M, Tcherkez G. Photosynthetic control of Arabidopsis leaf cytoplasmic translation initiation by protein phosphorylation. PLoS One 2013; 8:e70692. [PMID: 23894680 PMCID: PMC3722150 DOI: 10.1371/journal.pone.0070692] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 06/20/2013] [Indexed: 01/26/2023] Open
Abstract
Photosynthetic CO2 assimilation is the carbon source for plant anabolism, including amino acid production and protein synthesis. The biosynthesis of leaf proteins is known for decades to correlate with photosynthetic activity but the mechanisms controlling this effect are not documented. The cornerstone of the regulation of protein synthesis is believed to be translation initiation, which involves multiple phosphorylation events in Eukaryotes. We took advantage of phosphoproteomic methods applied to Arabidopsis thaliana rosettes harvested under controlled photosynthetic gas-exchange conditions to characterize the phosphorylation pattern of ribosomal proteins (RPs) and eukaryotic initiation factors (eIFs). The analyses detected 14 and 11 new RP and eIF phosphorylation sites, respectively, revealed significant CO2-dependent and/or light/dark phosphorylation patterns and showed concerted changes in 13 eIF phosphorylation sites and 9 ribosomal phosphorylation sites. In addition to the well-recognized role of the ribosomal small subunit protein RPS6, our data indicate the involvement of eIF3, eIF4A, eIF4B, eIF4G and eIF5 phosphorylation in controlling translation initiation when photosynthesis varies. The response of protein biosynthesis to the photosynthetic input thus appears to be the result of a complex regulation network involving both stimulating (e.g. RPS6, eIF4B phosphorylation) and inhibiting (e.g. eIF4G phosphorylation) molecular events.
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Affiliation(s)
- Edouard Boex-Fontvieille
- Institut de Biologie des Plantes, CNRS UMR 8618, Saclay Plant Sciences, Université Paris-Sud, Orsay, France
| | - Marlène Daventure
- Plateforme PAPPSO, UMR de Génétique Végétale, Ferme du Moulon, Gif sur Yvette, France
| | - Mathieu Jossier
- Institut de Biologie des Plantes, CNRS UMR 8618, Saclay Plant Sciences, Université Paris-Sud, Orsay, France
| | - Michel Zivy
- Plateforme PAPPSO, UMR de Génétique Végétale, Ferme du Moulon, Gif sur Yvette, France
| | - Michael Hodges
- Institut de Biologie des Plantes, CNRS UMR 8618, Saclay Plant Sciences, Université Paris-Sud, Orsay, France
| | - Guillaume Tcherkez
- Institut de Biologie des Plantes, CNRS UMR 8618, Saclay Plant Sciences, Université Paris-Sud, Orsay, France
- Institut Universitaire de France, Paris, France
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17
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Contreras-Paredes CA, Silva-Rosales L, Daròs JA, Alejandri-Ramírez ND, Dinkova TD. The absence of eukaryotic initiation factor eIF(iso)4E affects the systemic spread of a Tobacco etch virus isolate in Arabidopsis thaliana. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:461-70. [PMID: 23252462 DOI: 10.1094/mpmi-09-12-0225-r] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Translation initiation factor eIF4E exerts an important role during infection of viral species in the family Potyviridae. Particularly, a eIF(iso)4E family member is required for Arabidopsis thaliana susceptibility to Turnip mosaic virus, Lettuce mosaic virus, and Tobacco etch virus (TEV). In addition, a resistance mechanism named restriction of TEV movement (RTM) in A. thaliana controls the systemic spread of TEV in Col-0 ecotype. Here, we describe that TEV-TAMPS, a Mexican isolate, overcomes the RTM resistance mechanism reported for TEV-7DA infection of the Col-0 ecotype but depends on eIF(iso)4E for its systemic spread. To understand at which level eIF(iso)4E participates in A. thaliana TEV-TAMPS infection, the viral RNA replication and translation were measured. The absence or overexpression of eIF(iso)4E did not affect viral translation, and replication was still observed in the absence of eIF(iso)4E. However, the TEV-TAMPS systemic spread was completely abolished in the null mutant. The viral protein genome-linked (VPg) precursor NIa was found in coimmunoprecipitated complexes with both, eIF(iso)4E and eIF4E. However, the viral coat protein (CP) was only present in the eIF(iso)4E complexes. Since both the VPg and the CP proteins are needed for systemic spread, we propose a role of A. thaliana eIF(iso)4E in the movement of TEV-TAMPS within this host.
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18
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Song A, Lou W, Jiang J, Chen S, Sun Z, Guan Z, Fang W, Teng N, Chen F. An isoform of eukaryotic initiation factor 4E from Chrysanthemum morifolium interacts with Chrysanthemum virus B coat protein. PLoS One 2013; 8:e57229. [PMID: 23505421 PMCID: PMC3591383 DOI: 10.1371/journal.pone.0057229] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 01/18/2013] [Indexed: 12/24/2022] Open
Abstract
Background Eukaryotic translation initiation factor 4E (eIF4E) plays an important role in plant virus infection as well as the regulation of gene translation. Methodology/Principal Findings Here, we describe the isolation of a cDNA encoding CmeIF(iso)4E (GenBank accession no. JQ904592), an isoform of eIF4E from chrysanthemum, using RACE PCR. We used the CmeIF(iso)4E cDNA for expression profiling and to analyze the interaction between CmeIF(iso)4E and the Chrysanthemum virus B coat protein (CVBCP). Multiple sequence alignment and phylogenetic tree analysis showed that the sequence similarity of CmeIF(iso)4E with other reported plant eIF(iso)4E sequences varied between 69.12% and 89.18%, indicating that CmeIF(iso)4E belongs to the eIF(iso)4E subfamily of the eIF4E family. CmeIF(iso)4E was present in all chrysanthemum organs, but was particularly abundant in the roots and flowers. Confocal microscopy showed that a transiently transfected CmeIF(iso)4E-GFP fusion protein distributed throughout the whole cell in onion epidermis cells. A yeast two hybrid assay showed CVBCP interacted with CmeIF(iso)4E but not with CmeIF4E. BiFC assay further demonstrated the interaction between CmeIF(iso)4E and CVBCP. Luminescence assay showed that CVBCP increased the RLU of Luc-CVB, suggesting CVBCP might participate in the translation of viral proteins. Conclusions/Significance These results inferred that CmeIF(iso)4E as the cap-binding subunit eIF(iso)4F may be involved in Chrysanthemum Virus B infection in chrysanthemum through its interaction with CVBCP in spatial.
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Affiliation(s)
- Aiping Song
- College of Horticulture, Nanjing Agricultural University, Nanjing, China
| | - Wanghuai Lou
- College of Horticulture, Nanjing Agricultural University, Nanjing, China
| | - Jiafu Jiang
- College of Horticulture, Nanjing Agricultural University, Nanjing, China
| | - Sumei Chen
- College of Horticulture, Nanjing Agricultural University, Nanjing, China
| | - Zuxia Sun
- College of Horticulture, Nanjing Agricultural University, Nanjing, China
| | - Zhiyong Guan
- College of Horticulture, Nanjing Agricultural University, Nanjing, China
| | - Weimin Fang
- College of Horticulture, Nanjing Agricultural University, Nanjing, China
| | - Nianjun Teng
- College of Horticulture, Nanjing Agricultural University, Nanjing, China
| | - Fadi Chen
- College of Horticulture, Nanjing Agricultural University, Nanjing, China
- * E-mail:
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19
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Wang X, Kohalmi SE, Svircev A, Wang A, Sanfaçon H, Tian L. Silencing of the host factor eIF(iso)4E gene confers plum pox virus resistance in plum. PLoS One 2013; 8:e50627. [PMID: 23382802 PMCID: PMC3557289 DOI: 10.1371/journal.pone.0050627] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 10/23/2012] [Indexed: 01/29/2023] Open
Abstract
Plum pox virus (PPV) causes the most economically-devastating viral disease in Prunus species. Unfortunately, few natural resistance genes are available for the control of PPV. Recessive resistance to some potyviruses is associated with mutations of eukaryotic translation initiation factor 4E (eIF4E) or its isoform eIF(iso)4E. In this study, we used an RNA silencing approach to manipulate the expression of eIF4E and eIF(iso)4E towards the development of PPV resistance in Prunus species. The eIF4E and eIF(iso)4E genes were cloned from plum (Prunus domestica L.). The sequence identity between plum eIF4E and eIF(iso)4E coding sequences is 60.4% at the nucleotide level and 52.1% at the amino acid level. Quantitative real-time RT-PCR analysis showed that these two genes have a similar expression pattern in different tissues. Transgenes allowing the production of hairpin RNAs of plum eIF4E or eIF(iso)4E were introduced into plum via Agrobacterium-mediated transformation. Gene expression analysis confirmed specific reduced expression of eIF4E or eIF(iso)4E in the transgenic lines and this was associated with the accumulation of siRNAs. Transgenic plants were challenged with PPV-D strain and resistance was evaluated by measuring the concentration of viral RNA. Eighty-two percent of the eIF(iso)4E silenced transgenic plants were resistant to PPV, while eIF4E silenced transgenic plants did not show PPV resistance. Physical interaction between PPV-VPg and plum eIF(iso)4E was confirmed. In contrast, no PPV-VPg/eIF4E interaction was observed. These results indicate that eIF(iso)4E is involved in PPV infection in plum, and that silencing of eIF(iso)4E expression can lead to PPV resistance in Prunus species.
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Affiliation(s)
- Xinhua Wang
- Department of Biology, University of Western Ontario, London, Ontario, Canada
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Susanne E. Kohalmi
- Department of Biology, University of Western Ontario, London, Ontario, Canada
| | - Antonet Svircev
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Aiming Wang
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Hélène Sanfaçon
- Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Summerland, British Columbia, Canada
| | - Lining Tian
- Department of Biology, University of Western Ontario, London, Ontario, Canada
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
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20
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Perez K, Yeam I, Kang BC, Ripoll DR, Kim J, Murphy JF, Jahn MM. Tobacco etch virus infectivity in Capsicum spp. is determined by a maximum of three amino acids in the viral virulence determinant VPg. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:1562-73. [PMID: 23134519 DOI: 10.1094/mpmi-04-12-0091-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Potyvirus resistance in Capsicum spp. has been attributed to amino acid substitutions at the pvr1 locus that cause conformational shifts in eukaryotic translation initiation factor eIF4E. The viral genome-linked protein (VPg) sequence was isolated and compared from three Tobacco etch virus (TEV) strains, highly aphid-transmissible (HAT), Mex21, and N, which differentially infect Capsicum genotypes encoding Pvr1(+), pvr1, and pvr1(2). Viral chimeras were synthesized using the TEV-HAT genome, replacing HAT VPg with Mex21 or N VPg. TEV HAT did not infect pepper plants homozygous for either the pvr1 or pvr1(2) allele. However, the novel chimeric TEV strains, TEVHAT(Mex21-VPg) and TEV-HAT(N-VPg), infected pvr1 and pvr1(2) pepper plants, respectively, demonstrating that VPg is the virulence determinant in this pathosystem. Three dimensional structural models predicted interaction between VPg and the susceptible eIF4E genotype in every case, while resistant genotypes were never predicted to interact. To determine whether there is a correlation between physical interaction of VPg with eIF4E and infectivity, the effects of amino acid variation within VPg were assessed. Interaction between pvr1(2) eIF4E and N VPg was detected in planta, implying that the six amino acid differences in N VPg relative to HAT VPg are responsible for restoring the physical interaction and infectivity.
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Affiliation(s)
- Kari Perez
- Department of Plant Breeding and Genetics, Cornell University, Ithaca, NY, USA
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21
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Sensitivity of translation initiation factor eIF1 as a molecular target of salt toxicity to sodic-alkaline stress in the halophytic grass Leymus chinensis. Biochem Genet 2012; 51:101-18. [PMID: 23112090 DOI: 10.1007/s10528-012-9546-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 07/27/2012] [Indexed: 10/27/2022]
Abstract
Eukaryotic translation initiation factors (eIFs) have been shown to be critical in the initiation of protein synthesis. Here, we report the cloning and characterization of a novel gene, LceIF1, from a potentially interesting forage grass, Leymus chinensis (Trin.). The expression results show that LceIF1 is expressed in most organisms under normal conditions, but the transcription patterns differ under sodic-saline and sodic-alkaline stresses. Sodic-saline stress induced a persistent decrease, and sodic-alkaline stress induced overexpression of LceIF1. Potassic-saline and alkaline stresses did not cause any changes in expression of eIF1. These results indicate that not only pH but also Na(+) concentration affects overtranscription of LceIF1. The eIF1 transgenic lines showed relatively high eIF1 expression, resulting in potentially higher stress resistance. Combined with eIF1 transcription in transgenic lines, LceIF1 as a molecular target of salt toxicity is believed to help enhance salt tolerance.
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22
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Immanuel TM, Greenwood DR, MacDiarmid RM. A critical review of translation initiation factor eIF2α kinases in plants - regulating protein synthesis during stress. FUNCTIONAL PLANT BIOLOGY : FPB 2012; 39:717-735. [PMID: 32480823 DOI: 10.1071/fp12116] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 07/10/2012] [Indexed: 05/10/2023]
Abstract
Eukaryotic cells must cope with environmental stress. One type of general stress response is the downregulation of protein synthesis in order to conserve cellular resources. Protein synthesis is mainly regulated at the level of mRNA translation initiation and when the α subunit of eukaryotic translation initiation factor 2 (eIF2) is phosphorylated, protein synthesis is downregulated. Although eIF2 has the same translation initiation function in all eukaryotes, it is not known whether plants downregulate protein synthesis via eIF2α phosphorylation. Similarly, although there is evidence that plants possess eIF2α kinases, it is not known whether they operate in a similar manner to the well characterised mammalian and yeast eIF2α kinases. Two types of eIF2α kinases have been reported in plants, yet the full understanding of the plant eIF2α phosphorylation mechanism is still lacking. Here we review the current knowledge of the eIF2α phosphorylation mechanism within plants and discuss plant eIF2α, plant eIF2α kinase GCN2 and the data supporting and contradicting the hypothesis that a functional orthologue for the eIF2α kinase PKR, is present and functional in plants.
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Affiliation(s)
- Tracey M Immanuel
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland, 1142, New Zealand
| | - David R Greenwood
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland, 1142, New Zealand
| | - Robin M MacDiarmid
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland, 1142, New Zealand
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23
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Rodríguez-Hernández AM, Gosalvez B, Sempere RN, Burgos L, Aranda MA, Truniger V. Melon RNA interference (RNAi) lines silenced for Cm-eIF4E show broad virus resistance. MOLECULAR PLANT PATHOLOGY 2012; 13:755-63. [PMID: 22309030 PMCID: PMC6638723 DOI: 10.1111/j.1364-3703.2012.00785.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Efficient and sustainable control of plant viruses may be achieved using genetically resistant crop varieties, although resistance genes are not always available for each pathogen; in this regard, the identification of new genes that are able to confer broad-spectrum and durable resistance is highly desirable. Recently, the cloning and characterization of recessive resistance genes from different plant species has pointed towards eukaryotic translation initiation factors (eIF) of the 4E family as factors required for the multiplication of many different viruses. Thus, we hypothesized that eIF4E may control the susceptibility of melon (Cucumis melo L.) to a broad range of viruses. To test this hypothesis, Cm-eIF4E knockdown melon plants were generated by the transformation of explants with a construct that was designed to induce the silencing of this gene, and the plants from T2 generations were genetically and phenotypically characterized. In transformed plants, Cm-eIF4E was specifically silenced, as identified by the decreased accumulation of Cm-eIF4E mRNA and the appearance of small interfering RNAs derived from the transgene, whereas the Cm-eIF(iso)4E mRNA levels remained unaffected. We challenged these transgenic melon plants with eight agronomically important melon-infecting viruses, and identified that they were resistant to Cucumber vein yellowing virus (CVYV), Melon necrotic spot virus (MNSV), Moroccan watermelon mosaic virus (MWMV) and Zucchini yellow mosaic virus (ZYMV), indicating that Cm-eIF4E controls melon susceptibility to these four viruses. Therefore, Cm-eIF4E is an efficient target for the identification of new resistance alleles able to confer broad-spectrum virus resistance in melon.
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Affiliation(s)
- Ana M Rodríguez-Hernández
- Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas, Apdo, Correos 164, 30100 Espinardo (Murcia), Spain
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24
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Ueda K, Matsuura H, Yamaguchi M, Demura T, Kato K. Genome-wide analyses of changes in translation state caused by elevated temperature in Oryza sativa. PLANT & CELL PHYSIOLOGY 2012; 53:1481-91. [PMID: 22722767 DOI: 10.1093/pcp/pcs092] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
It has been reported that the translational status of mRNAs responds dramatically to abiotic stresses. While many useful results have demonstrated translational control in dicotyledonous model plants, little is known about changes in the translation state in response to abiotic stresses in monocotyledonous plants. To understand global changes in translation of mRNAs, we performed genome-wide analyses using Oryza sativa treated with heat stress (HS). These analyses showed that most mRNAs were translationally repressed, while the translation of some mRNAs was maintained. In addition to other regulatory steps in gene expression, including transcription and processing, it is thought that translational regulation is a critical step in adaptation to new conditions because of the functional tendencies of proteins that are either translationally maintained or highly repressed upon HS. When we compared the functional tendencies of translationally regulated proteins in rice with those in Arabidopsis thaliana cells exposed to HS, some showed similar regulation, arguing for both common and different features of translational regulation in the two plants.
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Affiliation(s)
- Kiyotaka Ueda
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192 Japan
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25
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Hernández G, Proud CG, Preiss T, Parsyan A. On the Diversification of the Translation Apparatus across Eukaryotes. Comp Funct Genomics 2012; 2012:256848. [PMID: 22666084 PMCID: PMC3359775 DOI: 10.1155/2012/256848] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Accepted: 03/07/2012] [Indexed: 11/21/2022] Open
Abstract
Diversity is one of the most remarkable features of living organisms. Current assessments of eukaryote biodiversity reaches 1.5 million species, but the true figure could be several times that number. Diversity is ingrained in all stages and echelons of life, namely, the occupancy of ecological niches, behavioral patterns, body plans and organismal complexity, as well as metabolic needs and genetics. In this review, we will discuss that diversity also exists in a key biochemical process, translation, across eukaryotes. Translation is a fundamental process for all forms of life, and the basic components and mechanisms of translation in eukaryotes have been largely established upon the study of traditional, so-called model organisms. By using modern genome-wide, high-throughput technologies, recent studies of many nonmodel eukaryotes have unveiled a surprising diversity in the configuration of the translation apparatus across eukaryotes, showing that this apparatus is far from being evolutionarily static. For some of the components of this machinery, functional differences between different species have also been found. The recent research reviewed in this article highlights the molecular and functional diversification the translational machinery has undergone during eukaryotic evolution. A better understanding of all aspects of organismal diversity is key to a more profound knowledge of life.
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Affiliation(s)
- Greco Hernández
- Division of Basic Research, National Institute for Cancer (INCan), Avenida San Fernando No. 22, Col. Sección XVI, Tlalpan, 14080 Mexico City, Mexico
| | - Christopher G. Proud
- Centre for Biological Sciences, University of Southampton, Life Sciences Building (B85), Southampton SO17 1BJ, UK
| | - Thomas Preiss
- Genome Biology Department, The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Acton, Canberra, ACT 0200, Australia
| | - Armen Parsyan
- Goodman Cancer Centre and Department of Biochemistry, Faculty of Medicine, McGill University, 1160 Pine Avenue West, Montreal, QC, Canada H3A 1A3
- Division of General Surgery, Department of Surgery, Faculty of Medicine, McGill University Health Centre, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, QC, Canada H3A 1A1
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26
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Lázaro-Mixteco PE, Nieto-Sotelo J, Swatek KN, Houston NL, Mendoza-Hernández G, Thelen JJ, Dinkova TD. The absence of heat shock protein HSP101 affects the proteome of mature and germinating maize embryos. J Proteome Res 2012; 11:3246-58. [PMID: 22545728 DOI: 10.1021/pr3000046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Maize heat shock protein HSP101 accumulates during embryo maturation and desiccation and persists at high levels during the first 24 h following kernel imbibition in the absence of heat stress. This protein has a known function in disaggregation of high molecular weight complexes and has been proposed to be a translational regulator of specific mRNAs. Here, a global proteomic approach was used to identify changes in the maize proteome due to the absence of HSP101 in embryos from mature-dry or 24 h-imbibed kernels. A total of 26 protein spots from the mature dry embryo exhibited statistically significant expression changes in the L10 inbred hsp101 mutant (hsp101-m5::Mu1/hsp101-m5::Mu1) line as compared to the corresponding wild type (Hsp101/Hsp101). Additional six spots reproducibly showed qualitative changes between the mutant and wild-type mature and germinating embryos. Several chaperones, translation-related proteins, actin, and enzymes participating in cytokinin metabolism were identified in these spots by tandem mass-spectrometry (MS). The proteomic changes partially explain the altered root growth and architecture observed in young hsp101 mutant seedlings. In addition, specific protein de novo synthesis was altered in the 24 h-imbibed mutant embryos indicating that maize HSP101 functions as both chaperone and translational regulator during germination. Supporting this, HSP101 was found as part of Cap-binding and translation initiation complexes during early kernel imbibition. Overall, these findings expose the relevance of maize HSP101 for protein synthesis and balance mechanisms during germination.
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Affiliation(s)
- Pedro E Lázaro-Mixteco
- Departamento de Bioquímica, Facultad de Química, ‡Jardín Botánico, Instituto de Biología, and #Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México , 04510, México, D.F., Mexico
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The eIF4F and eIFiso4F Complexes of Plants: An Evolutionary Perspective. Comp Funct Genomics 2012; 2012:287814. [PMID: 22611336 PMCID: PMC3352336 DOI: 10.1155/2012/287814] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 02/16/2012] [Indexed: 12/22/2022] Open
Abstract
Translation initiation in eukaryotes requires a number of initiation factors to recruit the assembled ribosome to mRNA. The eIF4F complex plays a key role in initiation and is a common target point for regulation of protein synthesis. Most work on the translation machinery of plants to date has focused on flowering plants, which have both the eIF4F complex (eIF4E and eIF4G) as well as the plant-specific eIFiso4F complex (eIFiso4E and eIFiso4G). The increasing availability of plant genome sequence data has made it possible to trace the evolutionary history of these two complexes in plants, leading to several interesting discoveries. eIFiso4G is conserved throughout plants, while eIFiso4E only appears with the evolution of flowering plants. The eIF4G N-terminus, which has been difficult to annotate, appears to be well conserved throughout the plant lineage and contains two motifs of unknown function. Comparison of eIFiso4G and eIF4G sequence data suggests conserved features unique to eIFiso4G and eIF4G proteins. These findings have answered some questions about the evolutionary history of the two eIF4F complexes of plants, while raising new ones.
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Fan Q, Treder K, Miller WA. Untranslated regions of diverse plant viral RNAs vary greatly in translation enhancement efficiency. BMC Biotechnol 2012; 12:22. [PMID: 22559081 PMCID: PMC3416697 DOI: 10.1186/1472-6750-12-22] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 05/06/2012] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Whole plants or plant cell cultures can serve as low cost bioreactors to produce massive amounts of a specific protein for pharmacological or industrial use. To maximize protein expression, translation of mRNA must be optimized. Many plant viral RNAs harbor extremely efficient translation enhancers. However, few of these different translation elements have been compared side-by-side. Thus, it is unclear which are the most efficient translation enhancers. Here, we compare the effects of untranslated regions (UTRs) containing translation elements from six plant viruses on translation in wheat germ extract and in monocotyledenous and dicotyledenous plant cells. RESULTS The highest expressing uncapped mRNAs contained viral UTRs harboring Barley yellow dwarf virus (BYDV)-like cap-independent translation elements (BTEs). The BYDV BTE conferred the most efficient translation of a luciferase reporter in wheat germ extract and oat protoplasts, while uncapped mRNA containing the BTE from Tobacco necrosis virus-D translated most efficiently in tobacco cells. Capped mRNA containing the Tobacco mosaic virus omega sequence was the most efficient mRNA in tobacco cells. UTRs from Satellite tobacco necrosis virus, Tomato bushy stunt virus, and Crucifer-infecting tobamovirus (crTMV) did not stimulate translation efficiently. mRNA with the crTMV 5' UTR was unstable in tobacco protoplasts. CONCLUSIONS BTEs confer the highest levels of translation of uncapped mRNAs in vitro and in vivo, while the capped omega sequence is most efficient in tobacco cells. These results provide a basis for understanding mechanisms of translation enhancement, and for maximizing protein synthesis in cell-free systems, transgenic plants, or in viral expression vectors.
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Affiliation(s)
- Qiuling Fan
- Department of Plant Pathology & Microbiology, and Center for Plant Responses to Environmental Stresses, Iowa State University, Ames, IA, 50011, USA
- 1615 E 8th St, #6, Davis, CA, 95616, USA
| | - Krzysztof Treder
- Department of Plant Pathology & Microbiology, and Center for Plant Responses to Environmental Stresses, Iowa State University, Ames, IA, 50011, USA
| | - W Allen Miller
- Department of Plant Pathology & Microbiology, and Center for Plant Responses to Environmental Stresses, Iowa State University, Ames, IA, 50011, USA
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29
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Translation initiation factor AteIF(iso)4E is involved in selective mRNA translation in Arabidopsis thaliana seedlings. PLoS One 2012; 7:e31606. [PMID: 22363683 PMCID: PMC3282757 DOI: 10.1371/journal.pone.0031606] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 01/10/2012] [Indexed: 12/28/2022] Open
Abstract
One of the most regulated steps of translation initiation is the recruitment of mRNA by the translation machinery. In eukaryotes, this step is mediated by the 5′end cap-binding factor eIF4E bound to the bridge protein eIF4G and forming the eIF4F complex. In plants, different isoforms of eIF4E and eIF4G form the antigenically distinct eIF4F and eIF(iso)4F complexes proposed to mediate selective translation. Using a microarray analysis of polyribosome- and non-polyribosome-purified mRNAs from 15 day-old Arabidopsis thaliana wild type [WT] and eIF(iso)4E knockout mutant [(iso)4E-1] seedlings we found 79 transcripts shifted from polyribosomes toward non-polyribosomes, and 47 mRNAs with the opposite behavior in the knockout mutant. The translationally decreased mRNAs were overrepresented in root-preferentially expressed genes and proteins from the endomembrane system, including several transporters such as the phosphate transporter PHOSPHATE1 (PHO1), Sucrose transporter 3 (SUC3), ABC transporter-like with ATPase activity (MRP11) and five electron transporters, as well as signal transduction-, protein modification- and transcription-related proteins. Under normal growth conditions, eIF(iso)4E expression under the constitutive promoter 35 S enhanced the polyribosomal recruitment of PHO1 supporting its translational preference for eIF(iso)4E. Furthermore, under phosphate deficiency, the PHO1 protein increased in the eIF(iso)4E overexpressing plants and decreased in the knockout mutant as compared to wild type. In addition, the knockout mutant had larger root, whereas the 35 S directed expression of eIF(iso)4E caused shorter root under normal growth conditions, but not under phosphate deficiency. These results indicate that selective translation mediated by eIF(iso)4E is relevant for Arabidopsis root development under normal growth conditions.
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30
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Muench DG, Zhang C, Dahodwala M. Control of cytoplasmic translation in plants. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 3:178-94. [DOI: 10.1002/wrna.1104] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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31
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Cavatorta J, Perez KW, Gray SM, Van Eck J, Yeam I, Jahn M. Engineering virus resistance using a modified potato gene. PLANT BIOTECHNOLOGY JOURNAL 2011; 9:1014-21. [PMID: 21668622 DOI: 10.1111/j.1467-7652.2011.00622.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Natural mutations in translation initiation factor eIF4E confer resistance to potyviruses in many plant species. Potato is a staple food crop plagued by several potyviruses, yet to date no known eIF4E-mediated resistance genes have been identified. In this study, we demonstrate that transgenic expression of the pvr1(2) gene from pepper confers resistance to Potato virus Y (PVY) in potato. We then use this information to convert the susceptible potato ortholog of this allele into a de novo allele for resistance to PVY using site-directed mutagenesis. Potato plants overexpressing the mutated potato allele are resistant to virus infection. Resistant lines expressed high levels of eIF4E mRNA and protein. The resistant plants showed growth similar to untransformed controls and produced phenotypically similar tubers. This technique disrupts a key step in the viral infection process and may potentially be used to engineer virus resistance in a number of economically important plant-viral pathosystems. Furthermore, the general public may be more amenable to the 'intragenic' nature of this approach because the transferred coding region is modified from a gene in the target crop rather than from a distant species.
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Affiliation(s)
- Jason Cavatorta
- Department of Plant Breeding, Cornell University, Ithaca, NY, USA
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32
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Wang Z, Parisien M, Scheets K, Miller WA. The cap-binding translation initiation factor, eIF4E, binds a pseudoknot in a viral cap-independent translation element. Structure 2011; 19:868-80. [PMID: 21645857 DOI: 10.1016/j.str.2011.03.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2011] [Revised: 03/11/2011] [Accepted: 03/13/2011] [Indexed: 01/15/2023]
Abstract
Eukaryotic initiation factor eIF4E performs a key early step in translation by specifically recognizing the m⁷GpppN cap structure at the 5' end of cellular mRNAs. Many viral mRNAs lack a 5' cap and thus bypass eIF4E. In contrast, we reported a cap-independent translation element (PTE) in Pea enation mosaic virus RNA2 that binds and requires eIF4E for translation initiation. To understand how this uncapped RNA is bound tightly by eIF4E, we employ SHAPE probing, phylogenetic comparisons with new PTEs discovered in panico- and carmoviruses, footprinting of the eIF4E binding site, and 3D RNA modeling using NAST, MC-Fold, and MC-Sym to predict a compact, 3D structure of the RNA. We propose that the cap-binding pocket of eIF4E clamps around a pseudoknot, placing a highly SHAPE-reactive guanosine in the pocket in place of the normal m⁷GpppN cap. This reveals a new mechanism of mRNA recognition by eIF4E.
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Affiliation(s)
- Zhaohui Wang
- Plant Pathology Department, and Biochemistry, Biophysics, and Molecular Biology Department, Iowa State University, Ames, IA 50011, USA
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33
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Kraft JJ, Hoy JA, Miller WA. Crystallization and preliminary X-ray diffraction analysis of the barley yellow dwarf virus cap-independent translation element. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:561-4. [PMID: 21543861 DOI: 10.1107/s1744309111007196] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 02/25/2011] [Indexed: 11/11/2022]
Abstract
Barley yellow dwarf virus (BYDV) RNA lacks a 5' m(7)GTP cap, yet it is translated efficiently because it contains a 105-base BYDV-like cap-independent translation element (BTE) in the 3' untranslated region (UTR). To understand how the BTE outcompetes the host mRNA for protein-synthesis machinery, its three-dimensional structure is being determined at high resolution. The purification using transcription from DNA containing 2'-O-methyl nucleotides and preliminary crystallographic analyses of the BTE RNA are presented here. After varying the BTE sequence and crystallization-condition optimization, crystals were obtained that diffracted to below 5 Å resolution, with a complete data set being collected to 6.9 Å resolution. This crystal form indexes with an R(merge) of 0.094 in the monoclinic space group C2, with unit-cell parameters a = 316.6, b = 54.2, c = 114.5 Å, α = γ = 90, β = 105.1°.
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Affiliation(s)
- Jelena J Kraft
- Biochemistry, Biophysics and Molecular Biology Department, Iowa State University, 351 Bessey Hall, Ames, IA 50011, USA
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34
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Hébrard E, Poulicard N, Gérard C, Traoré O, Wu HC, Albar L, Fargette D, Bessin Y, Vignols F. Direct interaction between the Rice yellow mottle virus (RYMV) VPg and the central domain of the rice eIF(iso)4G1 factor correlates with rice susceptibility and RYMV virulence. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1506-13. [PMID: 20653414 DOI: 10.1094/mpmi-03-10-0073] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The adaptation of Rice yellow mottle virus (RYMV) to recessive resistance mediated by the rymv1-2 allele has been reported as a model to study the emergence and evolution of virulent variants. The resistance and virulence factors have been identified as eukaryotic translation initiation factor eIF(iso)4G1 and viral genome-linked protein (VPg), respectively, but the molecular mechanisms involved in their interaction are still unknown. In this study, we demonstrated a direct interaction between RYMV VPg and the central domain of rice eIF(iso)4G1 both in vitro, using recombinant proteins, and in vivo, using a yeast two-hybrid assay. Insertion of the E309K mutation in eIF(iso)4G1, conferring resistance in planta, strongly diminished the interaction with avirulent VPg. The efficiency of the major virulence mutations at restoring the interaction with the resistance protein was assessed. Our results explain the prevalence of virulence mutations fixed during experimental evolution studies and are consistent with the respective viral RNA accumulation levels of avirulent and virulent isolates. Our results also explain the origin of the residual multiplication of wild-type isolates in rymv1-2-resistant plants and the role of genetic context in the poor adaptability of the S2/S3 strain. Finally, the strategies of RYMV and members of family Potyviridae to overcome recessive resistance were compared.
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Affiliation(s)
- Eugénie Hébrard
- UMR186 Résistance des Plantes aux Bio-agresseurs, Institut de Recherche pour le Développement BP 64501, 34394 Montpellier cedex 5, France.
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35
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Castelló MJ, Carrasco JL, Vera P. DNA-binding protein phosphatase AtDBP1 mediates susceptibility to two potyviruses in Arabidopsis. PLANT PHYSIOLOGY 2010; 153:1521-5. [PMID: 20508138 PMCID: PMC2923898 DOI: 10.1104/pp.110.158923] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
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36
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Hernández G, Altmann M, Lasko P. Origins and evolution of the mechanisms regulating translation initiation in eukaryotes. Trends Biochem Sci 2010; 35:63-73. [DOI: 10.1016/j.tibs.2009.10.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 10/27/2009] [Accepted: 10/28/2009] [Indexed: 02/08/2023]
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37
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Abstract
About half of the approximately 200 known virus resistance genes in plants are recessively inherited, suggesting that this form of resistance is more common for viruses than for other plant pathogens. The use of such genes is therefore a very important tool in breeding programs to control plant diseases caused by pathogenic viruses. Over the last few years, the detailed analysis of many host/virus combinations has substantially advanced basic research on recessive resistance mechanisms in crop species. This type of resistance is preferentially expressed in protoplasts and inoculated leaves, influencing virus multiplication at the single-cell level as well as cell-to-cell movement. Importantly, a growing number of recessive resistance genes have been cloned from crop species, and further analysis has shown them all to encode translation initiation factors of the 4E (eIF4E) and 4G (eIF4G) families. However, not all of the loss-of-susceptibility mutants identified in collections of mutagenized hosts correspond to mutations in eIF4E and eIF4G. This, together with other supporting data, suggests that more extensive characterization of the natural variability of resistance genes may identify new host factors conferring recessive resistance. In this chapter, we discuss the recent work carried out to characterize loss-of-susceptibility and recessive resistance genes in crop and model species. We review actual and probable recessive resistance mechanisms, and bring the chapter to a close by summarizing the current state-of-the-art and offering perspectives on potential future developments.
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Affiliation(s)
- V Truniger
- Centro de Edafología y Biología Aplicada del Segura (CEBAS), Consejo Superior de Investigaciones Científicas (CSIC), Apdo Correos 164, 30100 Espinardo (Murcia), Spain
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38
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Ali Z, Schumacher HM, Heine-Dobbernack E, El-Banna A, Hafeez FY, Jacobsen HJ, Kiesecker H. Dicistronic binary vector system-A versatile tool for gene expression studies in cell cultures and plants. J Biotechnol 2010; 145:9-16. [PMID: 19835918 DOI: 10.1016/j.jbiotec.2009.10.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 08/28/2009] [Accepted: 10/04/2009] [Indexed: 10/20/2022]
Abstract
Dicistronic binary vector constructs based on pGreenII vectors for Agrobacterium mediated gene transfer alleviate the translational expression monitoring of a target gene in plants. The functionality of the transformation vectors was proven by marker gene constructs containing a mannopine synthase promoter (p-MAS) fused to a beta-glucuronidase (gus) gene followed by an internal ribosome entry site and a firefly luciferase (luc) gene. The cap-dependent translation of a physically independent target protein can be monitored by the cap-independently co-translated luciferase, because both mRNAs are located on the same strand. Among three different IRES elements, the tobamo IRES element showed highest activity in transient expression. As a proof of principle for physiological studies the gus gene was replaced by a sodium antiporter gene (Atnhx1). Comparative studies with Atnhx1 transgenic luc expressing tobacco cell cultures and pea plants (Pisum sativum L.) showed improved salt tolerance in relation to their wild type counterparts grown under corresponding conditions. A coincidence of the luc gene expression and increased sodium chloride tolerance is demonstrated by measurement of luminescence and cell growth.
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Affiliation(s)
- Zahid Ali
- German Collection of Microorganisms and Cell Cultures DSMZ GmbH, Braunschweig, Germany
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39
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Abstract
This review focuses on the extensive membrane and organelle rearrangements that have been observed in plant cells infected with RNA viruses. The modifications generally involve the formation of spherules, vesicles, and/or multivesicular bodies associated with various organelles such as the endoplasmic reticulum and peroxisomes. These virus-induced organelles house the viral RNA replication complex and are known as virus factories or viroplasms. Membrane and organelle alterations are attributed to the action of one or two viral proteins, which additionally act as a scaffold for the assembly of a large complex of proteins of both viral and host origin and viral RNA. Some virus factories have been shown to align with and traffic along microfilaments. In addition to viral RNA replication, the factories may be involved in other processes such as viral RNA translation and cell-to-cell virus transport. Confining the process of RNA replication to a specific location may also prevent the activation of certain host defense functions.
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Affiliation(s)
- Jean-François Laliberté
- INRS-Institut Armand-Frappier, Institut National de la Recherche Scientifique, Laval, Québec, Canada H7V 1B7.
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40
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Gallois JL, Charron C, Sanchez F, Pagny G, Houvenaghel MC, Moretti A, Ponz F, Revers F, Caranta C, German-Retana S. Single amino acid changes in the turnip mosaic virus viral genome-linked protein (VPg) confer virulence towards Arabidopsis thaliana mutants knocked out for eukaryotic initiation factors eIF(iso)4E and eIF(iso)4G. J Gen Virol 2009; 91:288-93. [DOI: 10.1099/vir.0.015321-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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41
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Bush MS, Hutchins AP, Jones AME, Naldrett MJ, Jarmolowski A, Lloyd CW, Doonan JH. Selective recruitment of proteins to 5' cap complexes during the growth cycle in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 59:400-12. [PMID: 19453450 DOI: 10.1111/j.1365-313x.2009.03882.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Translation of most mRNAs is performed in a cap-dependent manner, requiring a protein complex, the cap complex, to regulate the accessibility of the message to the 40S ribosome. The cap complex initiates protein translation by binding to the 5' cap of an mRNA and recruiting ribosomes to begin translation. Compared to animals and yeast, there are significant plant-specific differences in the regulation of cap-dependent mRNA translation, but these are poorly understood. Here, we purified proteins that bind to the 5' cap during the Arabidopsis growth cycle. The protein profile of the cap-binding complexes varies during the various stages of the growth cycle in suspension culture cells. Using Western blotting, the cap complexes of quiescent cells were found to be composed of only three major proteins: eIF4isoE, which is primarily a cytoplasmic protein, and eIF4E and CBP80, which accumulate in the nucleus. However, when cells proliferate, at least 10 major proteins bind directly or indirectly to the 5' cap. Proteomic, Western blotting and immunoprecipitation data establish that the spectrum of RNA helicases in the cap complexes also changes during the growth cycle. Cap complexes from proliferating cultures mainly contain eIF4A, which associates with at least four cap complexes, but eIF4A is replaced by additional helicases in quiescent cells. These findings suggest that the dynamic and selective recruitment of various proteins to mRNA 5' cap complexes could play an important role in the regulation of gene expression.
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Affiliation(s)
- Maxwell S Bush
- Department of Cell and Developmental Biology, John Innes Centre, Norwich, UK
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42
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Dennis MD, Browning KS. Differential phosphorylation of plant translation initiation factors by Arabidopsis thaliana CK2 holoenzymes. J Biol Chem 2009; 284:20602-14. [PMID: 19509278 DOI: 10.1074/jbc.m109.006692] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A previously described wheat germ protein kinase (Yan, T. F., and Tao, M. (1982) J. Biol. Chem. 257, 7037-7043) was identified unambiguously as CK2 using mass spectrometry. CK2 is a ubiquitous eukaryotic protein kinase that phosphorylates a wide range of substrates. In previous studies, this wheat germ kinase was shown to phosphorylate eIF2alpha, eIF3c, and three large subunit (60 S) ribosomal proteins (Browning, K. S., Yan, T. F., Lauer, S. J., Aquino, L. A., Tao, M., and Ravel, J. M. (1985) Plant Physiol. 77, 370-373). To further characterize the role of CK2 in the regulation of translation initiation, Arabidopsis thaliana catalytic (alpha1 and alpha2) and regulatory (beta1, beta2, beta3, and beta4) subunits of CK2 were cloned and expressed in Escherichia coli. Recombinant A. thaliana CK2beta subunits spontaneously dimerize and assemble into holoenzymes in the presence of either CK2alpha1 or CK2alpha2 and exhibit autophosphorylation. The purified CK2 subunits were used to characterize the properties of the individual subunits and their ability to phosphorylate various plant protein substrates. CK2 was shown to phosphorylate eIF2alpha, eIF2beta, eIF3c, eIF4B, eIF5, and histone deacetylase 2B but did not phosphorylate eIF1, eIF1A, eIF4A, eIF4E, eIF4G, eIFiso4E, or eIFiso4G. Differential phosphorylation was exhibited by CK2 in the presence of various regulatory beta-subunits. Analysis of A. thaliana mutants either lacking or overexpressing CK2 subunits showed that the amount of eIF2beta protein present in extracts was affected, which suggests that CK2 phosphorylation may play a role in eIF2beta stability. These results provide evidence for a potential mechanism through which the expression and/or subcellular distribution of CK2 beta-subunits could participate in the regulation of the initiation of translation and other physiological processes in plants.
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Affiliation(s)
- Michael D Dennis
- Department of Chemistry and Biochemistry and the Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, USA
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43
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Wang Z, Treder K, Miller WA. Structure of a viral cap-independent translation element that functions via high affinity binding to the eIF4E subunit of eIF4F. J Biol Chem 2009; 284:14189-202. [PMID: 19276085 PMCID: PMC2682867 DOI: 10.1074/jbc.m808841200] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 03/09/2009] [Indexed: 11/06/2022] Open
Abstract
RNAs of many positive strand RNA viruses lack a 5' cap structure and instead rely on cap-independent translation elements (CITEs) to facilitate efficient translation initiation. The mechanisms by which these RNAs recruit ribosomes are poorly understood, and for many viruses the CITE is unknown. Here we identify the first CITE of an umbravirus in the 3'-untranslated region of pea enation mosaic virus RNA 2. Chemical and enzymatic probing of the approximately 100-nucleotide PEMV RNA 2 CITE (PTE), and mutagenesis revealed that it forms a long, bulged helix that branches into two short stem-loops, with a possible pseudoknot interaction between a C-rich bulge at the branch point and a G-rich bulge in the main helix. The PTE inhibited translation in trans, and addition of eIF4F, but not eIFiso4F, restored translation. Filter binding assays revealed that the PTE binds eIF4F and its eIF4E subunit with high affinity. Tight binding required an intact cap-binding pocket in eIF4E. Among many PTE mutants, there was a strong correlation between PTE-eIF4E binding affinity and ability to stimulate cap-independent translation. We conclude that the PTE recruits eIF4F by binding eIF4E. The PTE represents a different class of translation enhancer element, as defined by its structure and ability to bind eIF4E in the absence of an m(7)G cap.
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Affiliation(s)
- Zhaohui Wang
- Department of Plant Pathology and Biochemistry, Iowa State University, Ames, Iowa 50011, USA
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44
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Functional Evolution of Cyclin-Dependent Kinases. Mol Biotechnol 2009; 42:14-29. [DOI: 10.1007/s12033-008-9126-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Accepted: 11/01/2008] [Indexed: 10/21/2022]
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45
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Mustroph A, Juntawong P, Bailey-Serres J. Isolation of plant polysomal mRNA by differential centrifugation and ribosome immunopurification methods. Methods Mol Biol 2009; 553:109-26. [PMID: 19588103 DOI: 10.1007/978-1-60327-563-7_6] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Polyribosomes (polysomes) form as multiple ribosomes engage in translation on a single mRNA. This process is regulated for individual mRNAs by both development and the environment. To evaluate the translation state of an mRNA, ribosomal subunits, ribosomes, and polysomes can be isolated from detergent-treated cell extracts by high-speed differential centrifugation. These ribonucleoprotein complexes can be further purified by centrifugation through sucrose density gradients. By fractionation of the gradient the amount of an individual mRNA in a sub-population of polysomes can be quantitatively determined. Here, we describe methods for the isolation and quantification of polysome complexes from plant tissues. The mRNA obtained can be further analyzed by methods that evaluate polysomal mRNA abundance at the individual transcript or global level. A modification of the conventional polysome isolation procedure is described for transgenic Arabidopsis thaliana that express an epitope-tagged version of ribosomal protein L18 (RPL18) that facilitates capture of ribosomes from crude cell extracts by a one-step immunoprecipitation method.
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Affiliation(s)
- Angelika Mustroph
- Center for Plant Cell Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA, USA
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46
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German-Retana S, Walter J, Doublet B, Roudet-Tavert G, Nicaise V, Lecampion C, Houvenaghel MC, Robaglia C, Michon T, Le Gall O. Mutational analysis of plant cap-binding protein eIF4E reveals key amino acids involved in biochemical functions and potyvirus infection. J Virol 2008; 82:7601-12. [PMID: 18480444 PMCID: PMC2493313 DOI: 10.1128/jvi.00209-08] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Accepted: 05/06/2008] [Indexed: 12/16/2022] Open
Abstract
The eukaryotic translation initiation factor 4E (eIF4E) (the cap-binding protein) is involved in natural resistance against several potyviruses in plants. In lettuce, the recessive resistance genes mo1(1) and mo1(2) against Lettuce mosaic virus (LMV) are alleles coding for forms of eIF4E unable, or less effective, to support virus accumulation. A recombinant LMV expressing the eIF4E of a susceptible lettuce variety from its genome was able to produce symptoms in mo1(1) or mo1(2) varieties. In order to identify the eIF4E amino acid residues necessary for viral infection, we constructed recombinant LMV expressing eIF4E with point mutations affecting various amino acids and compared the abilities of these eIF4E mutants to complement LMV infection in resistant plants. Three types of mutations were produced in order to affect different biochemical functions of eIF4E: cap binding, eIF4G binding, and putative interaction with other virus or host proteins. Several mutations severely reduced the ability of eIF4E to complement LMV accumulation in a resistant host and impeded essential eIF4E functions in yeast. However, the ability of eIF4E to bind a cap analogue or to fully interact with eIF4G appeared unlinked to LMV infection. In addition to providing a functional mutational map of a plant eIF4E, this suggests that the role of eIF4E in the LMV cycle might be distinct from its physiological function in cellular mRNA translation.
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Affiliation(s)
- Sylvie German-Retana
- Interactions Plante-Virus, UMR GDPP 1090, INRA Université de Bordeaux 2, BP 81, F-33883 Villenave d'Ornon Cedex, France.
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Diédhiou CJ, Popova OV, Dietz KJ, Golldack D. The SUI-homologous translation initiation factor eIF-1 is involved in regulation of ion homeostasis in rice. PLANT BIOLOGY (STUTTGART, GERMANY) 2008; 10:298-309. [PMID: 18426477 DOI: 10.1111/j.1438-8677.2008.00037.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Halophytes survive high salinity by using complex adaptive mechanisms. In a search for novel molecular mechanisms involved in salt acclimation, transcript analyses revealed increased expression of a SUI-homologous translation initiation factor eIF-1 in the salt-tolerant grass species Festuca rubra ssp. littoralis but not in rice. Upon analysis of the cell specificity of eIF-1 transcription by in situ polymerase chain reaction (PCR), predominant signals were detected in rice leaf mesophyll. To further examine the role of eIF-1 in salt tolerance, transgenic rice plants were generated that over-express this factor under the control of the CaMV-35S promoter. The eIF-1 over-expressing lines showed improved growth under salt stress that was correlated with maintenance of photosynthetic activity and reduced Na(+) and Cl(-) accumulation in leaves. The transgenic rice lines also activated expression of the vacuolar H(+)-ATPase. In addition, an oxidoreductase that belongs to the aldo/keto reductase family was identified as a gene with modified expression in the eIF-1 over-expressing lines, compared with wild-type rice. Our data suggest that eIF-1 has a central function in salt-stress adaptation in rice by regulating ion accumulation and the intracellular redox status.
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Affiliation(s)
- C J Diédhiou
- Department of Physiology and Biochemistry of Plants, Faculty of Biology, University of Bielefeld, Bielefeld, Germany
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Charron C, Nicolaï M, Gallois JL, Robaglia C, Moury B, Palloix A, Caranta C. Natural variation and functional analyses provide evidence for co-evolution between plant eIF4E and potyviral VPg. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 54:56-68. [PMID: 18182024 DOI: 10.1111/j.1365-313x.2008.03407.x] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Amino acid substitutions in the eukaryotic translation initiation factor 4E (eIF4E) result in recessive resistance to potyviruses in a range of plant species, including Capsicum spp. Correspondingly, amino acid changes in the central part of the viral genome-linked protein (VPg) are responsible for the potyvirus's ability to overcome eIF4E-mediated resistance. A key observation was that physical interaction between eIF4E and the VPg is required for viral infection, and eIF4E mutations that cause resistance prevent VPg binding and inhibit the viral cycle. In this study, polymorphism analysis of the pvr2-eIF4E coding sequence in a worldwide sample of 25 C. annuum accessions identified 10 allelic variants with exclusively non-synonymous variations clustered in two surface loops of eIF4E. Resistance and genetic complementation assays demonstrated that pvr2 variants, each with signature amino acid changes, corresponded to potyvirus resistance alleles. Systematic analysis of the interactions between eIF4E proteins encoded by the 10 pvr2 alleles and VPgs of virulent and avirulent potato virus Y (PVY) and tobacco etch virus (TEV) strains demonstrated that resistance phenotypes arose from disruption of the interaction between eIF4E and VPg, and that viral adaptation to eIF4E-mediated resistance resulted from restored interaction with the resistance protein. Complementation of an eIF4E knockout yeast strain by C. annuum eIF4E proteins further shows that amino acid changes did not impede essential eIF4E functions. Altogether, these results argue in favour of a co-evolutionary 'arms race' between Capsicum eIF4E and potyviral VPg.
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Affiliation(s)
- Carine Charron
- INRA-UR1052, Genetics and Breeding of Fruits and Vegetables, Domaine St Maurice, BP94, F-84143 Montfavet, France
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The amazing diversity of cap-independent translation elements in the 3'-untranslated regions of plant viral RNAs. Biochem Soc Trans 2008; 35:1629-33. [PMID: 18031280 DOI: 10.1042/bst0351629] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Many plant viral RNAs lack the 5'-cap structure that is required on all host mRNAs for interacting with essential translation initiation factors. Instead, uncapped viral RNAs take over the host translation machinery by harbouring sequences that functionally replace the 5'-cap. Recent reports reveal at least eight different classes of CITE (cap-independent translation element) located in the 3'-UTRs (untranslated regions) of various viruses. We describe how the structure and behaviour of each class of element differs from the other classes, suggesting that they recruit translation factors and, ultimately, the ribosome by diverse mechanisms. These results greatly expand our understanding of ways in which mRNAs can recruit ribosomes, and they provide insight into the regulation of virus gene expression.
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Mayberry LK, Dennis MD, Leah Allen M, Ruud Nitka K, Murphy PA, Campbell L, Browning KS. Expression and purification of recombinant wheat translation initiation factors eIF1, eIF1A, eIF4A, eIF4B, eIF4F, eIF(iso)4F, and eIF5. Methods Enzymol 2008; 430:397-408. [PMID: 17913646 DOI: 10.1016/s0076-6879(07)30015-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Protein synthesis initiation factors from wheat germ were cloned into E. coli expression vectors for expression and purification. The ability to obtain large amounts of functional initiation factors and mutants of the factors will facilitate the biophysical and biochemical analysis of the process of initiation in plants. The initiation factors, eIF1, eIF1A, eIF4A, eIF4B, eIF4F, eIF(iso)4F, and eIF5, were successfully expressed and purified from E. coli. In most cases, the use of 6X-histidine tags was avoided to prevent any possible artifacts of folding or activity because of the presence of the tag. The amounts of highly purified wheat initiation factors obtained ranged from 0.5 to 24mg of protein per liter of culture, depending on the particular initiation factor. The initiation factors were of very high purity, and the activities of the wheat recombinant factors purified from E. coli were found to be comparable to or better than those purified from wheat germ.
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Affiliation(s)
- Laura K Mayberry
- Department of Chemistry and Biochemistry and the Institute for Cell and Molecular Biology, University of Texas at Austin, USA
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