Modulation of Nitrosative Stress by S-Nitrosoglutathione Reductase Is Critical for Thermotolerance and Plant Growth in Arabidopsis

Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, Arizona 85721, USA.
The Plant Cell (Impact Factor: 9.34). 04/2008; 20(3):786-802. DOI: 10.1105/tpc.107.052647
Source: PubMed


Nitric oxide (NO) is a key signaling molecule in plants. This analysis of Arabidopsis thaliana HOT5 (sensitive to hot temperatures), which is required for thermotolerance, uncovers a role of NO in thermotolerance and plant development. HOT5 encodes S-nitrosoglutathione reductase (GSNOR), which metabolizes the NO adduct S-nitrosoglutathione. Two hot5 missense alleles and two T-DNA insertion, protein null alleles were characterized. The missense alleles cannot acclimate to heat as dark-grown seedlings but grow normally and can heat-acclimate in the light. The null alleles cannot heat-acclimate as light-grown plants and have other phenotypes, including failure to grow on nutrient plates, increased reproductive shoots, and reduced fertility. The fertility defect of hot5 is due to both reduced stamen elongation and male and female fertilization defects. The hot5 null alleles show increased nitrate and nitroso species levels, and the heat sensitivity of both missense and null alleles is associated with increased NO species. Heat sensitivity is enhanced in wild-type and mutant plants by NO donors, and the heat sensitivity of hot5 mutants can be rescued by an NO scavenger. An NO-overproducing mutant is also defective in thermotolerance. Together, our results expand the importance of GSNOR-regulated NO homeostasis to abiotic stress and plant development.

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    • "Arabidopsis thaliana overexpressing GSNOR displays lower levels of nitrosothiols (SNO), suggesting that regulation of GSNO levels modulates S-nitrosylation (Lee et al., 2008). GSNOR is responsive to pathogen attack, wounding, cadmium stress, and salicylic and jasmonic acids (Díaz et al., 2003; Feechan et al., 2005; Barroso et al., 2006; Rustérucci et al., 2007). "
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    ABSTRACT: Background and aims: Auxin is the main phytohormone controlling root development in plants. This study uses pharmacological and genetic approaches to examine the role of auxin and nitric oxide (NO) in the activation of NADPH-dependent thioredoxin reductase (NTR), and the effect that this activity has on root growth responses in Arabidopsis thaliana. Methods: Arabidopsis seedlings were treated with auxin with or without the NTR inhibitors auranofin (ANF) and 1-chloro-2, 4-dinitrobenzene (DNCB). NTR activity, lateral root (LR) formation and S-nitrosothiol content were measured in roots. Protein S-nitrosylation was analysed by the biotin switch method in wild-type arabidopsis and in the double mutant ntra ntrb. Key results: The auxin-mediated induction of NTR activity is inhibited by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO), suggesting that NO is downstream of auxin in this regulatory pathway. The NTR inhibitors ANF and DNCB prevent auxin-mediated activation of NTR and LR formation. Moreover, ANF and DNCB also inhibit auxin-induced DR5 : : GUS and BA3 : : GUS gene expression, suggesting that the auxin signalling pathway is compromised without full NTR activity. Treatment of roots with ANF and DNCB increases total nitrosothiols (SNO) content and protein S-nitrosylation, suggesting a role of the NTR-thioredoxin (Trx)-redox system in protein denitrosylation. In agreement with these results, the level of S-nitrosylated proteins is increased in the arabidopsis double mutant ntra ntrb as compared with the wild-type. Conclusions: The results support for the idea that NTR is involved in protein denitrosylation during auxin-mediated root development. The fact that a high NO concentration induces NTR activity suggests that a feedback mechanism to control massive and unregulated protein S-nitrosylation could be operating in plant cells.
    No preview · Article · Jul 2015 · Annals of Botany
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    • "Consistently, the chlorophyll level in the gsnor1-3 seedlings was significantly reduced compared with that in the wild type (Fig. 5C). A similar result was also obtained in a previous study on the hot5 mutant allele (Lee et al., 2008). Together, these results suggest that the increased level of NO is correlated to the reduced chlorophyll level, which is likely involved in the S-nitrosylation of enzymes in the chlorophyll metabolism and the related pathways. "
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    ABSTRACT: Nitric oxide (NO) regulates multiple developmental events and stress responses in plants. A major biologically active species of NO is S-nitrosoglutathione (GSNO) that is irreversibly degraded by GSNO reductase (GSNOR). The major physiological effect of NO is protein S-nitrosylation, a redox-based posttranslational modification mechanism by covalently linking a NO molecule to a cysteine thiol. However, little is known about the mechanisms of S-nitrosylation-regulated signaling, partly due to limited S-nitrosylated proteins being identified. In this study, we identified 1,195 endogenously S-nitrosylated peptides in 926 proteins from the Arabidopsis (Arabidopsis thaliana) by a site-specific nitrosoproteomic approach, which, up to date, is the largest dataset of S-nitrosylated proteins among all organisms. Consensus sequence analysis of these peptides identified several motifs that contain acidic, but not basic, amino acid residues flanking the S-nitrosylated cysteine residues. These S-nitrosylated proteins are involved in a wide range of biological processes and are significantly enriched in chlorophyll metabolism, photosynthesis, carbohydrate metabolism, and stress responses. Consistently, the gsnor1-3 mutant shows the decreased chlorophyll content and altered photosynthetic properties, suggesting that S-nitrosylation is an important regulatory mechanism in these processes. These results have provided valuable resources and new clues to the studies on S-nitrosylation-regulated signaling in plants. Copyright © 2015, Plant Physiology.
    Full-text · Article · Feb 2015 · Plant physiology
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    • "Recent reports demonstrate that GSNOR activity is required for competitive viability [40] [41] and that it regulates multiple developmental and metabolic programs, so these phenomena may account for the pleiotropic effects of the gsnor mutation [42]. The role of NO in cell death and gene regulation is supported by the analysis of mutants affecting these processes, which produced higher amounts of NO thus linking NO to the compromised phenotypes. "
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    ABSTRACT: Nitric oxide (NO) was identified as a key player in plant defence responses approximately 20 years ago and a large body of evidence has accumulated since then supporting its role as a signalling molecule. However, there are many discrepancies in current NO detection assays and the enzymatic pathways responsible for its synthesis have yet to be determined. This has provoked strong debates concerning the function of NO in plants, even questioning its existence in planta. Here we gather data obtained using the model pathosystem Arabidopsis/Pseudomonas, which confirms the production of NO during the hypersensitive response and supports is role as a trigger of hypersensitive cell death and a mediator of defence gene expression. Finally, we discuss potential sources of NO synthesis, focusing on the role of nitrite as major substrate for NO production during incompatible interactions.
    Full-text · Article · Jul 2014 · Nitric Oxide
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