title: Proteasome-mediated turnover of the transcription coactivator NPR1 plays dual roles in regulating plant immunity.
abstract: Systemic acquired resistance (SAR) is a broad-spectrum plant immune response involving profound transcriptional changes that are regulated by the coactivator NPR1. Nuclear translocation of NPR1 is a critical regulatory step, but how the protein is regulated in the nucleus is unknown. Here, we show that turnover of nuclear NPR1 protein plays an important role in modulating transcription of its target genes. In the absence of pathogen challenge, NPR1 is continuously cleared from the nucleus by the proteasome, which restricts its coactivator activity to prevent untimely activation of SAR. Surprisingly, inducers of SAR promote NPR1 phosphorylation at residues Ser11/Ser15, and then facilitate its recruitment to a Cullin3-based ubiquitin ligase. Turnover of phosphorylated NPR1 is required for full induction of target genes and establishment of SAR. These in vivo data demonstrate dual roles for coactivator turnover in both preventing and stimulating gene transcription to regulate plant immunity.
authors.affiliation: Department of Biology, Duke University, Durham, NC 27708, USA.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Spoel
authors.forename: Zhonglin
authors.initials: Z
authors.lastname: Mou
authors.forename: Yasuomi
authors.initials: Y
authors.lastname: Tada
authors.forename: Natalie W
authors.initials: NW
authors.lastname: Spivey
authors.forename: Pascal
authors.initials: P
authors.lastname: Genschik
authors.forename: Xinnian
authors.initials: X
authors.lastname: Dong
mesh_terms: D017360:Arabidopsis / Q000276:immunology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000276:immunology*; D002352:Carrier Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D044842:Cullin Proteins; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C500789:AT1G26830 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D044842:Cullin Proteins; C105496:NPR1 protein, Arabidopsis; D046988:Proteasome Endopeptidase Complex