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Reyes MI, Flores‐Vergara MA, Guerra‐Peraza O, Rajabu C, Desai J, Hiromoto‐Ruiz YH, Ndunguru J, Hanley‐Bowdoin L, Kjemtrup S, Ascencio‐Ibáñez JT, Robertson D. A VIGS screen identifies immunity in the Arabidopsis Pla-1 accession to viruses in two different genera of the Geminiviridae. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:796-807. [PMID: 28901681 PMCID: PMC5725698 DOI: 10.1111/tpj.13716] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 09/01/2017] [Accepted: 09/06/2017] [Indexed: 05/21/2023]
Abstract
Geminiviruses are DNA viruses that cause severe crop losses in different parts of the world, and there is a need for genetic sources of resistance to help combat them. Arabidopsis has been used as a source for virus-resistant genes that derive from alterations in essential host factors. We used a virus-induced gene silencing (VIGS) vector derived from the geminivirus Cabbage leaf curl virus (CaLCuV) to assess natural variation in virus-host interactions in 190 Arabidopsis accessions. Silencing of CH-42, encoding a protein needed to make chlorophyll, was used as a visible marker to discriminate asymptomatic accessions from those showing resistance. There was a wide range in symptom severity and extent of silencing in different accessions, but two correlations could be made. Lines with severe symptoms uniformly lacked extensive VIGS, and lines that showed attenuated symptoms over time (recovery) showed a concomitant increase in the extent of VIGS. One accession, Pla-1, lacked both symptoms and silencing, and was immune to wild-type infectious clones corresponding to CaLCuV or Beet curly top virus (BCTV), which are classified in different genera in the Geminiviridae. It also showed resistance to the agronomically important Tomato yellow leaf curl virus (TYLCV). Quantitative trait locus mapping of a Pla-1 X Col-0 F2 population was used to detect a major peak on chromosome 1, which is designated gip-1 (geminivirus immunity Pla-1-1). The recessive nature of resistance to CaLCuV and the lack of obvious candidate genes near the gip-1 locus suggest that a novel resistance gene(s) confers immunity.
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Affiliation(s)
- Maria Ines Reyes
- Department of Plant and Microbial BiologyNorth Carolina State UniversityRaleighNCUSA
| | - Miguel A. Flores‐Vergara
- Department of Plant and Microbial BiologyNorth Carolina State UniversityRaleighNCUSA
- Paradigm GeneticsResearch Triangle ParkNCUSA
| | - Orlene Guerra‐Peraza
- Department of Plant and Microbial BiologyNorth Carolina State UniversityRaleighNCUSA
- Present address:
Citrus Research and Education CenterUniversity of FloridaLake AlfredFL33850USA
| | - Cyprian Rajabu
- Mikocheni Agricultural Research InstituteDar es SalaamTanzania
| | - Jigar Desai
- Department of Molecular and Structural BiochemistryNorth Carolina State UniversityRaleighNCUSA
| | | | - Joseph Ndunguru
- Mikocheni Agricultural Research InstituteDar es SalaamTanzania
| | - Linda Hanley‐Bowdoin
- Department of Plant and Microbial BiologyNorth Carolina State UniversityRaleighNCUSA
| | - Susanne Kjemtrup
- Paradigm GeneticsResearch Triangle ParkNCUSA
- Present address:
Department of Plant and Microbial BiologyNorth Carolina State UniversityRaleighNCUSA
| | - Jose T. Ascencio‐Ibáñez
- Department of Molecular and Structural BiochemistryNorth Carolina State UniversityRaleighNCUSA
| | - Dominique Robertson
- Department of Plant and Microbial BiologyNorth Carolina State UniversityRaleighNCUSA
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Pimenta MR, Silva PA, Mendes GC, Alves JR, Caetano HDN, Machado JPB, Brustolini OJB, Carpinetti PA, Melo BP, Silva JCF, Rosado GL, Ferreira MFS, Dal-Bianco M, Picoli EADT, Aragao FJL, Ramos HJO, Fontes EPB. The Stress-Induced Soybean NAC Transcription Factor GmNAC81 Plays a Positive Role in Developmentally Programmed Leaf Senescence. PLANT & CELL PHYSIOLOGY 2016; 57:1098-114. [PMID: 27016095 DOI: 10.1093/pcp/pcw059] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 03/15/2016] [Indexed: 05/02/2023]
Abstract
The onset of leaf senescence is a highly regulated developmental change that is controlled by both genetics and the environment. Senescence is triggered by massive transcriptional reprogramming, but functional information about its underlying regulatory mechanisms is limited. In the current investigation, we performed a functional analysis of the soybean (Glycine max) osmotic stress- and endoplasmic reticulum (ER) stress-induced NAC transcription factor GmNAC81 during natural leaf senescence using overexpression studies and reverse genetics. GmNAC81-overexpressing lines displayed accelerated flowering and leaf senescence but otherwise developed normally. The precocious leaf senescence of GmNAC81-overexpressing lines was associated with greater Chl loss, faster photosynthetic decay and higher expression of hydrolytic enzyme-encoding GmNAC81 target genes, including the vacuolar processing enzyme (VPE), an executioner of vacuole-triggered programmed cell death (PCD). Conversely, virus-induced gene silencing-mediated silencing of GmNAC81 delayed leaf senescence and was associated with reductions in Chl loss, lipid peroxidation and the expression of GmNAC81 direct targets. Promoter-reporter studies revealed that the expression pattern of GmNAC81 was associated with senescence in soybean leaves. Our data indicate that GmNAC81 is a positive regulator of age-dependent senescence and may integrate osmotic stress- and ER stress-induced PCD responses with natural leaf senescence through the GmNAC81/VPE regulatory circuit.
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Affiliation(s)
- Maiana Reis Pimenta
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Priscila Alves Silva
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Giselle Camargo Mendes
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Janaína Roberta Alves
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Hanna Durso Neves Caetano
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Joao Paulo Batista Machado
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Otavio José Bernardes Brustolini
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Paola Avelar Carpinetti
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Bruno Paes Melo
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - José Cleydson Ferreira Silva
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Gustavo Leão Rosado
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Márcia Flores Silva Ferreira
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Biologia, Universidade Federal do Espírito Santo, 29500.000, Alegre, ES, Brazil
| | - Maximillir Dal-Bianco
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | | | | | - Humberto Josué Oliveira Ramos
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
| | - Elizabeth Pacheco Batista Fontes
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil Departamento de Bioquímica e Biologia Molecular/Bioagro, Universidade Federal de Viçosa, 36570.000, Viçosa, MG, Brazil
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3
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Zorzatto C, Machado JPB, Lopes KVG, Nascimento KJT, Pereira WA, Brustolini OJB, Reis PAB, Calil IP, Deguchi M, Sachetto-Martins G, Gouveia BC, Loriato VAP, Silva MAC, Silva FF, Santos AA, Chory J, Fontes EPB. NIK1-mediated translation suppression functions as a plant antiviral immunity mechanism. Nature 2015; 520:679-82. [PMID: 25707794 DOI: 10.1038/nature14171] [Citation(s) in RCA: 141] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 12/19/2014] [Indexed: 12/17/2022]
Abstract
Plants and plant pathogens are subject to continuous co-evolutionary pressure for dominance, and the outcomes of these interactions can substantially impact agriculture and food security. In virus-plant interactions, one of the major mechanisms for plant antiviral immunity relies on RNA silencing, which is often suppressed by co-evolving virus suppressors, thus enhancing viral pathogenicity in susceptible hosts. In addition, plants use the nucleotide-binding and leucine-rich repeat (NB-LRR) domain-containing resistance proteins, which recognize viral effectors to activate effector-triggered immunity in a defence mechanism similar to that employed in non-viral infections. Unlike most eukaryotic organisms, plants are not known to activate mechanisms of host global translation suppression to fight viruses. Here we demonstrate in Arabidopsis that the constitutive activation of NIK1, a leucine-rich repeat receptor-like kinase (LRR-RLK) identified as a virulence target of the begomovirus nuclear shuttle protein (NSP), leads to global translation suppression and translocation of the downstream component RPL10 to the nucleus, where it interacts with a newly identified MYB-like protein, L10-INTERACTING MYB DOMAIN-CONTAINING PROTEIN (LIMYB), to downregulate translational machinery genes fully. LIMYB overexpression represses ribosomal protein genes at the transcriptional level, resulting in protein synthesis inhibition, decreased viral messenger RNA association with polysome fractions and enhanced tolerance to begomovirus. By contrast, the loss of LIMYB function releases the repression of translation-related genes and increases susceptibility to virus infection. Therefore, LIMYB links immune receptor LRR-RLK activation to global translation suppression as an antiviral immunity strategy in plants.
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Affiliation(s)
- Cristiane Zorzatto
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - João Paulo B Machado
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Kênia V G Lopes
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Kelly J T Nascimento
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Welison A Pereira
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Otávio J B Brustolini
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Pedro A B Reis
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Iara P Calil
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Michihito Deguchi
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Gilberto Sachetto-Martins
- 1] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] Departamento de Genética, Universidade Federal do Rio de Janeiro, 21944.970 Rio de Janeiro, Brazil
| | - Bianca C Gouveia
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Virgílio A P Loriato
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Marcos A C Silva
- National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Fabyano F Silva
- Departamento de Zootecnia, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Anésia A Santos
- National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
| | - Joanne Chory
- 1] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] Howard Hughes Medical Institute and Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Elizabeth P B Fontes
- 1] Departamento de Bioquímica e Biologia Molecular, National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil [2] National Institute of Science and Technology in Plant-Pest Interactions, Bioagro, Universidade Federal de Viçosa, 36570.000 Viçosa, Minas Gerais, Brazil
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4
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Nash TE, Dallas MB, Reyes MI, Buhrman GK, Ascencio-Ibañez JT, Hanley-Bowdoin L. Functional analysis of a novel motif conserved across geminivirus Rep proteins. J Virol 2011; 85:1182-92. [PMID: 21084480 PMCID: PMC3020519 DOI: 10.1128/jvi.02143-10] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 11/09/2010] [Indexed: 12/28/2022] Open
Abstract
Members of the Geminiviridae have single-stranded DNA genomes that replicate in nuclei of infected plant cells. All geminiviruses encode a conserved protein (Rep) that catalyzes initiation of rolling-circle replication. Earlier studies showed that three conserved motifs-motifs I, II, and III-in the N termini of geminivirus Rep proteins are essential for function. In this study, we identified a fourth sequence, designated GRS (geminivirus Rep sequence), in the Rep N terminus that displays high amino acid sequence conservation across all geminivirus genera. Using the Rep protein of Tomato golden mosaic virus (TGMV AL1), we show that GRS mutants are not infectious in plants and do not support viral genome replication in tobacco protoplasts. GRS mutants are competent for protein-protein interactions and for both double- and single-stranded DNA binding, indicating that the mutations did not impair its global conformation. In contrast, GRS mutants are unable to specifically cleave single-stranded DNA, which is required to initiate rolling-circle replication. Interestingly, the Rep proteins of phytoplasmal and algal plasmids also contain GRS-related sequences. Modeling of the TGMV AL1 N terminus suggested that GRS mutations alter the relative positioning of motif II, which coordinates metal ions, and motif III, which contains the tyrosine involved in DNA cleavage. Together, these results established that the GRS is a conserved, essential motif characteristic of an ancient lineage of rolling-circle initiators and support the idea that geminiviruses may have evolved from plasmids associated with phytoplasma or algae.
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Affiliation(s)
- Tara E. Nash
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
| | - Mary B. Dallas
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
| | - Maria Ines Reyes
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
| | - Gregory K. Buhrman
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
| | - J. Trinidad Ascencio-Ibañez
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
| | - Linda Hanley-Bowdoin
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7688
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Santos AA, Carvalho CM, Florentino LH, Ramos HJO, Fontes EPB. Conserved threonine residues within the A-loop of the receptor NIK differentially regulate the kinase function required for antiviral signaling. PLoS One 2009; 4:e5781. [PMID: 19492062 PMCID: PMC2686266 DOI: 10.1371/journal.pone.0005781] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 05/12/2009] [Indexed: 11/18/2022] Open
Abstract
NSP-interacting kinase (NIK1) is a receptor-like kinase identified as a virulence target of the begomovirus nuclear shuttle protein (NSP). We found that NIK1 undergoes a stepwise pattern of phosphorylation within its activation-loop domain (A-loop) with distinct roles for different threonine residues. Mutations at Thr-474 or Thr-468 impaired autophosphorylation and were defective for kinase activation. In contrast, a mutation at Thr-469 did not impact autophosphorylation and increased substrate phosphorylation, suggesting an inhibitory role for Thr-469 in kinase function. To dissect the functional significance of these results, we used NSP-expressing virus infection as a mechanism to interfere with wild type and mutant NIK1 action in plants. The NIK1 knockout mutant shows enhanced susceptibility to virus infections, a phenotype that could be complemented with ectopic expression of a 35S-NIK1 or 35S-T469A NIK1 transgenes. However, ectopic expression of an inactive kinase or the 35S-T474A NIK1 mutant did not reverse the enhanced susceptibility phenotype of knockout lines, demonstrating that Thr-474 autophosphorylation was needed to transduce a defense response to geminiviruses. Furthermore, mutations at Thr-474 and Thr-469 residues antagonistically affected NIK-mediated nuclear relocation of the downstream effector rpL10. These results establish that NIK1 functions as an authentic defense receptor as it requires activation to elicit a defense response. Our data also suggest a model whereby phosphorylation-dependent activation of a plant receptor-like kinase enables the A-loop to control differentially auto- and substrate phosphorylation.
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Affiliation(s)
- Anésia A. Santos
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Claudine M. Carvalho
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Lilian H. Florentino
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Humberto J. O. Ramos
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Elizabeth P. B. Fontes
- Departamento de Bioquímica e Biologia Molecular/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
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Regulated nuclear trafficking of rpL10A mediated by NIK1 represents a defense strategy of plant cells against virus. PLoS Pathog 2008; 4:e1000247. [PMID: 19112492 PMCID: PMC2597721 DOI: 10.1371/journal.ppat.1000247] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Accepted: 11/25/2008] [Indexed: 11/24/2022] Open
Abstract
The NSP-interacting kinase (NIK) receptor-mediated defense pathway has been identified recently as a virulence target of the geminivirus nuclear shuttle protein (NSP). However, the NIK1–NSP interaction does not fit into the elicitor–receptor model of resistance, and hence the molecular mechanism that links this antiviral response to receptor activation remains obscure. Here, we identified a ribosomal protein, rpL10A, as a specific partner and substrate of NIK1 that functions as an immediate downstream effector of NIK1-mediated response. Phosphorylation of cytosolic rpL10A by NIK1 redirects the protein to the nucleus where it may act to modulate viral infection. While ectopic expression of normal NIK1 or a hyperactive NIK1 mutant promotes the accumulation of phosphorylated rpL10A within the nuclei, an inactive NIK1 mutant fails to redirect the protein to the nuclei of co-transfected cells. Likewise, a mutant rpL10A defective for NIK1 phosphorylation is not redirected to the nucleus. Furthermore, loss of rpL10A function enhances susceptibility to geminivirus infection, resembling the phenotype of nik1 null alleles. We also provide evidence that geminivirus infection directly interferes with NIK1-mediated nuclear relocalization of rpL10A as a counterdefensive measure. However, the NIK1-mediated defense signaling neither activates RNA silencing nor promotes a hypersensitive response but inhibits plant growth and development. Although the virulence function of the particular geminivirus NSP studied here overcomes this layer of defense in Arabidopsis, the NIK1-mediated signaling response may be involved in restricting the host range of other viruses. Plants are constantly exposed to microorganisms and, like animals, developed innate immune systems to prevent infections. Although these immune systems protect plants against most potential pathogens, the molecular mechanisms underlying nonhost immunity remain obscure. Here, we describe a novel strategy of plant defenses identified as a target of the geminivirus nuclear shuttle protein (NSP) that suppresses the activity of the transmembrane receptor NIK (NSP-interacting kinase). In addition, we identified a ribosomal protein, rpL10A, as the immediate downstream component of the pathway. Based on our findings, we propose that this pathway is elicited by activation of the receptor NIK1, which results in phosphorylation and translocation of rpL10A to the nucleus. We also provided genetic and biochemical evidence that this regulated trafficking of rpL10A may effectively mount a defense strategy that negatively impacts geminivirus proliferation or movement. Nevertheless, the virulence function of NSP from the bipartite geminivirus CaLCuV (Cabbage leaf curl virus) is capable of overcoming the NIK1-mediated defense and thereby enhances the pathogenicity of CaLCuV in Arabidopsis. The NIK1-mediated signaling response may be involved in restricting the host range of other viruses.
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The ribosomal protein L10/QM-like protein is a component of the NIK-mediated antiviral signaling. Virology 2008; 380:165-9. [DOI: 10.1016/j.virol.2008.08.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Revised: 07/13/2008] [Accepted: 08/02/2008] [Indexed: 11/18/2022]
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