Plant Immunity Requires Conformational Charges of NPR1 via S-Nitrosylation and Thioredoxins

By Y. Tada, Steven H. Spoel, Karolina Pajerowska-Mukhtar, Z. Mou, Junqi Song, Chun Wang, Jianru Zuo, Xinnian Dong. Science, 2008

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Changes in redox status have been observed during immune responses in different organisms, but the associated signaling mechanisms are poorly understood. In plants, these redox changes regulate the conformation of NPR1, a master regulator of salicylic acid (SA)–mediated defense genes. NPR1 is sequestered in the cytoplasm as an oligomer through intermolecular disulfide bonds. We report that S-nitrosylation of NPR1 by S-nitrosoglutathione (GSNO) at cysteine-156 facilitates its oligomerization, which maintains protein homeostasis upon SA induction. Conversely, the SA-induced NPR1 oligomer-to-monomer reaction is catalyzed by thioredoxins (TRXs). Mutations in both NPR1 cysteine-156 and TRX compromised NPR1-mediated disease resistance. Thus, the regulation of NPR1 is through the opposing action of GSNO and TRX. These findings suggest a link between pathogen-triggered redox changes and gene regulation in plant immunity.

Subfields: Molecular Biology, Plant Science

View Paper: https://www.semanticscholar.org/paper/e650a27b2b5303d2365d189b3e697aabdf4e289d

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Citations in the corpus

Interactions between hormone and redox signalling pathways in the control of growth and cross tolerance to stress (2013, background): “, 2003) and Trxh (Tada et al., 2008) are inked in the activation of this pathway.”
The Arabidopsis NPR1 protein is a receptor for the plant defense hormone salicylic acid. (2012, background): “The redox status of NPR1 is maintained by the interplay of different reducing and oxidizing agents such as GSH/GSSG, S-nitrosoglutathione and thioredoxin (Mou et al., 2003; Tada et al., 2008).”
Photosynthesis and antioxidative defense mechanisms in deciphering drought stress tolerance of crop plants (2016, background): “The intracellular redox status is sensed also by transcription factors such as NPR1, whose monomerization permits the translocation of protein into the nucleus, thereby enhancing the defense response (Tada et al. 2008).”
Hormonal modulation of plant immunity. (2012, background): “In resting cells, the majority of NPR1 is sequestered in the cytoplasm as an oligomer through intermolecular disulfide bonds that are facilitated by Snitrosylation of NPR1 via S-nitrosoglutathione (Tada et al. 2008), a process in which NO is covalently attached to a reactive cysteine thiol to form a”
Systemic acquired resistance: turning local infection into global defense. (2013, neutral): “This fluctuation can be sensed by NPR1, as it switches between oligomer and monomer reversibly both in vitro and in vivo (95, 127).”
A review of soil NO transformation: associated processes and possible physiological significance on organisms (2015, background): “S-1451 nitrosylation is involved in gene regulation, modulates phytohormon 1452 signalling and can control programmed cell death (PCD) in opposing ways 1453 (promote or inactivate) (Hara et al., 2005; Melotto et al., 2006; Belenghi, 1454 2007; Forman et al., 2008; Tada et al., 2008).”
Growth-defense tradeoffs in plants: a balancing act to optimize fitness. (2014, positive): “SA accumulation in response to pathogen detection triggers the release of NPR1 monomers, which then translocate to the nucleus and activate defense gene expression (Kinkema et al., 2000; Mou et al., 2003; Tada et al., 2008).”
Salicylic Acid, a multifaceted hormone to combat disease. (2009, background): “Moreover, a mutant form of NPR1 that is constitutively monomeric and present in the nucleus was recently shown to enhance resistance (192).”
Ascorbate and Glutathione: The Heart of the Redox Hub1 (2011, background): “GSNO may be an important physiological nitric oxide donor in the regulation of NPR1 activity (Tada et al., 2008).”