Posttranslational Modifications of the Master Transcriptional Regulator NPR1 Enable Dynamic but Tight Control of Plant Immune Responses.
NPR1, a master regulator of basal and systemic acquired resistance in plants, confers immunity through a transcriptional cascade, which includes transcription activators (e.g., TGA3) and repressors (e.g., WRKY70), leading to the massive induction of antimicrobial genes. How this single protein orchestrates genome-wide transcriptional reprogramming in response to immune stimulus remains a major question. Paradoxically, while NPR1 is essential for defense gene induction, its turnover appears to be required for this function, suggesting that NPR1 activity and degradation are dynamically regulated. Here we show that sumoylation of NPR1 by SUMO3 activates defense gene expression by switching NPR1's association with the WRKY transcription repressors to TGA transcription activators. Sumoylation also triggers NPR1 degradation, rendering the immune induction transient. SUMO modification of NPR1 is inhibited by phosphorylation at Ser55/Ser59, which keeps NPR1 stable and quiescent. Thus, posttranslational modifications enable dynamic but tight and precise control of plant immune responses.
Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, NC 27708, USA.
Abdelaty
A
Saleh
Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, NC 27708, USA.
John
J
Withers
Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, NC 27708, USA.
Rajinikanth
R
Mohan
Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, NC 27708, USA.
Jorge
J
Marqués
Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, NC 27708, USA.
Yangnan
Y
Gu
Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, NC 27708, USA.
Shunping
S
Yan
Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, NC 27708, USA.
Raul
R
Zavaliev
Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
Mika
M
Nomoto
Center for Gene Research, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
Yasuomi
Y
Tada
Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, NC 27708, USA. Electronic address: xdong@duke.edu.
Xinnian
X
Dong
D017360:Arabidopsis / Q000276:immunology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D057865:Plant Immunity; D011485:Protein Binding; D059748:Proteolysis; D058207:Sumoylation; D014452:Ubiquitins / Q000378:metabolism
D029681:Arabidopsis Proteins; C105496:NPR1 protein, Arabidopsis; D014452:Ubiquitins