Conserved Threonine Residues within the A-Loop of the Receptor NIK Differentially Regulate the Kinase Function Required for Antiviral Signaling
| Autor: | Elizabeth P. B. Fontes, Lilian H. Florentino, Humberto J.O. Ramos, Claudine M. Carvalho, Anésia A. Santos |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
Ribosomal Proteins
Threonine Ribosomal Protein L10 Receptor NIK Science Molecular Sequence Data Arabidopsis Plant Biology Mitogen-activated protein kinase kinase Antiviral Agents MAP2K7 Tobacco Point Mutation ASK1 Amino Acid Sequence Phosphorylation Cell Nucleus Multidisciplinary Alanine MAP kinase kinase kinase biology Sequence Homology Amino Acid Arabidopsis Proteins Cyclin-dependent kinase 2 Autophosphorylation Molecular biology Protein kinase R Protein Structure Tertiary Geminiviridae Spectrometry Mass Matrix-Assisted Laser Desorption-Ionization Mutation Viruses biology.protein Medicine Cyclin-dependent kinase 9 Virology/Host Antiviral Responses Antiviral signaling Research Article Plant Biology/Plant-Biotic Interactions Signal Transduction |
| Zdroj: | PLoS ONE PLoS ONE, Vol 4, Iss 6, p e5781 (2009) LOCUS Repositório Institucional da UFV Universidade Federal de Viçosa (UFV) instacron:UFV |
| ISSN: | 1932-6203 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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