Plant A20/AN1 protein serves as the important hub to mediate antiviral immunity
Journal
PLoS Pathogens
Journal Volume
14
Journal Issue
9
Date Issued
2018
Abstract
Salicylic acid (SA) is a key phytohormone that mediates a broad spectrum of resistance against a diverse range of viruses; however, the downstream pathway of SA governed antiviral immune response remains largely to be explored. Here, we identified an orchid protein containing A20 and AN1 zinc finger domains, designated Pha13. Pha13 is up-regulated upon virus infection, and the transgenic monocot orchid and dicot Arabidopsis overexpressing orchid Pha13 conferred greater resistance to different viruses. In addition, our data showed that Arabidopsis homolog of Pha13, AtSAP5, is also involved in virus resistance. Pha13 and AtSAP5 are early induced by exogenous SA treatment, and participate in the expression of SA-mediated immune responsive genes, including the master regulator gene of plant immunity, NPR1, as well as NPR1-independent virus defense genes. SA also induced the proteasome degradation of Pha13. Functional domain analysis revealed that AN1 domain of Pha13 is involved in expression of orchid NPR1 through its AN1 domain, whereas dual A20/AN1 domains orchestrated the overall virus resistance. Subcellular localization analysis suggested that Pha13 can be found localized in the nucleus. Self-ubiquitination assay revealed that Pha13 confer E3 ligase activity, and the main E3 ligase activity was mapped to the A20 domain. Identification of Pha13 interacting proteins and substrate by yeast two-hybrid screening revealed mainly ubiquitin proteins. Further detailed biochemical analysis revealed that A20 domain of Pha13 binds to various polyubiquitin chains, suggesting that Pha13 may interact with multiple ubiquitinated proteins. Our findings revealed that Pha13 serves as an important regulatory hub in plant antiviral immunity, and uncover a delicate mode of immune regulation through the coordination of A20 and/or AN1 domains, as well as through the modulation of E3 ligase and ubiquitin chain binding activity of Pha13. © 2018 Chang et al. http://creativecommons.org/licenses/by/4.0/.
Other Subjects
Arabidopsis protein; glutaredoxin; heat shock protein; phytohemagglutinin; phytohormone; plant protein; protein A20; recombinant protein; salicylic acid; short hairpin RNA; ubiquitin protein ligase E3; unclassified drug; antivirus agent; Arabidopsis protein; plant protein; protein binding; ubiquitin; ubiquitin protein ligase; zinc finger protein; Arabidopsis; Article; binding affinity; cellular distribution; comparative study; confocal microscopy; controlled study; Cymbidium; enzyme activity; gene expression; gene knockdown; gene ontology; gene overexpression; gene silencing; genetic screening; genetic transcription; immune response; immunoblotting; immunoprecipitation; immunoregulation; microarray analysis; mutational analysis; nonhuman; Orchidaceae; Pha13 gene; Phalaenopsis; PhaNPR1 gene; PhaPR1 gene; phylogeny; plant gene; plant immunity; polyacrylamide gel electrophoresis; protein degradation; protein interaction; protein purification; regulator gene; reverse transcription polymerase chain reaction; sequence analysis; signal transduction; transgenic plant; ubiquitination; upregulation; virus infection; virus resistance; zinc finger motif; amino acid sequence; biological model; chemistry; genetics; host pathogen interaction; immunology; metabolism; pathogenicity; physiology; plant virus; protein domain; sequence homology; virology; Amino Acid Sequence; Antiviral Agents; Arabidopsis; Arabidopsis Proteins; Genes, Plant; Host-Pathogen Interactions; Models, Biological; Orchidaceae; Plant Immunity; Plant Proteins; Plant Viruses; Plants, Genetically Modified; Protein Binding; Protein Domains; Salicylic Acid; Sequence Homology, Amino Acid; Ubiquitin; Ubiquitin-Protein Ligases; Zinc Fingers
Description
Article number: e1007288
Type
journal article