Nitric oxide evolution and perception. J Exp Bot

Centre for Research in Plant Science, Faculty of Applied Sciences, University of the West of England, Bristol, Bristol BS16 1Q, UK.
Journal of Experimental Botany (Impact Factor: 5.53). 02/2008; 59(1):25-35. DOI: 10.1093/jxb/erm218
Source: PubMed

ABSTRACT Various experimental data indicate signalling roles for nitric oxide (NO) in processes such as xylogenesis, programmed cell death, pathogen defence, flowering, stomatal closure, and gravitropism. However, it still remains unclear how NO is synthesized. Nitric oxide synthase-like activity has been measured in various plant extracts, NO can be generated from nitrite via nitrate reductase and other mechanisms of NO generation are also likely to exist. NO removal mechanisms, for example, by reaction with haemoglobins, have also been identified. NO is a gas emitted by plants, with the rate of evolution increasing under conditions such as pathogen challenge or hypoxia. However, exactly how NO evolution relates to its bioactivity in planta remains to be established. NO has both aqueous and lipid solubility, but is relatively reactive and easily oxidized to other nitrogen oxides. It reacts with superoxide to form peroxynitrite, with other cellular components such as transition metals and haem-containing proteins and with thiol groups to form S-nitrosothiols. Thus, diffusion of NO within the plant may be relatively restricted and there might exist 'NO hot-spots' depending on the sites of NO generation and the local biochemical micro-environment. Alternatively, it is possible that NO is transported as chemical precursors such as nitrite or as nitrosothiols that might function as NO reservoirs. Cellular perception of NO may occur through its reaction with biologically active molecules that could function as 'NO-sensors'. These might include either haem-containing proteins such as guanylyl cyclase which generates the second messenger cGMP or other proteins containing exposed reactive thiol groups. Protein S-nitrosylation alters protein conformation, is reversible and thus, is likely to be of biological significance.

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Available from: John T Hancock, Mar 16, 2015
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    • "Nitric oxide (NO) is a key player in redox signaling pathways in plant cell revealing concentration-dependent effects—from the mild regulation of morphogenesis to the triggering of the programmed cell death (PCD) events (Neill et al., 2008; Baudouin, 2011). Dinitrogen trioxide (N 2 O 3 ), nitrogen dioxide (NO 2 ), and highly reactive molecule of nitrogen monoxide (NO) that exist in cell in three interchangeable forms [nitrosonium cation (NO + ), nitroxyl anion (NO − ) and free radical (NO • )] along with peroxynitrite (ONOO − ) and S-nitrosothiols (GSNOs) are named reactive nitrogen species (RNS) (Neill et al., 2008). RNS are able to modify numerous proteins affecting their structure, protein–protein interaction and/or function ( " loss " / " gain " and the enhanced protein turnover) (Lindermayr et al., 2005; Abello et al., 2009). "
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    ABSTRACT: During last years, selective tyrosine nitration of plant proteins gains importance as well-recognized pathway of direct nitric oxide (NO) signal transduction. Plant microtubules are one of the intracellular signaling targets for NO, however, the molecular mechanisms of NO signal transduction with the involvement of cytoskeletal proteins remain to be elucidated. Since biochemical evidence of plant α-tubulin tyrosine nitration has been obtained recently, potential role of this posttranslational modification in regulation of microtubules organization in plant cell is estimated in current paper. It was shown that 3-nitrotyrosine (3-NO2-Tyr) induced partially reversible Arabidopsis primary root growth inhibition, alterations of root hairs morphology and organization of microtubules in root cells. It was also revealed that 3-NO2-Tyr intensively decorates such highly dynamic microtubular arrays as preprophase bands, mitotic spindles and phragmoplasts of Nicotiana tabacum Bright Yellow-2 (BY-2) cells under physiological conditions. Moreover, 3D models of the mitotic kinesin-8 complexes with the tail of detyrosinated, tyrosinated and tyrosine nitrated α-tubulin (on C-terminal Tyr 450 residue) from Arabidopsis were reconstructed in silico to investigate the potential influence of tubulin nitrotyrosination on the molecular dynamics of α-tubulin and kinesin-8 interaction. Generally, presented data suggest that plant α-tubulin tyrosine nitration can be considered as its common posttranslational modification, the direct mechanism of NO signal transduction with the participation of microtubules under physiological conditions and one of the hallmarks of the increased microtubule dynamics.
    Frontiers in Plant Science 12/2013; 4:530. DOI:10.3389/fpls.2013.00530 · 3.95 Impact Factor
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    • "ROS-exposed cellular components (proteins, lipids, polysaccharides, and DNA) can be damaged, especially under environmental conditions leading to oxidative stress. Recent works also point to NO as an emerging oxidative compound (Lamotte et al., 2005; Grun et al., 2006; Neill et al., 2008a,b; Wilson et al., 2008) The NO-derived species are called reactive nitrogen species (RNS) and S-nitrosylation is the post-translational change they promote. ROS and RNS levels are controlled by thiol peroxidase-like plastid peroxiredoxins (PRX). "
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    ABSTRACT: The sessile nature of plants forces them to face an ever-changing environment instead of escape from hostile conditions as animals do. In order to overcome this survival challenge, a fine monitoring and controlling of the status of the photosynthetic electron transport chain and the general metabolism is vital for these organisms. Frequently, evolutionary plant adaptation has consisted in the appearance of multigenic families, comprising an array of enzymes, structural components, or sensing, and signaling elements, in numerous occasions with highly conserved primary sequences that sometimes make it difficult to discern between redundancy and specificity among the members of a same family. However, all this gene diversity is aimed to sort environment-derived plant signals to efficiently channel the external incoming information inducing a right physiological answer. Oxygenic photosynthesis is a powerful source of reactive oxygen species (ROS), molecules with a dual oxidative/signaling nature. In response to ROS, one of the most frequent post-translational modifications occurring in redox signaling proteins is the formation of disulfide bridges (from Cys oxidation). This review is focused on the role of plastid thioredoxins (pTRXs), proteins containing two Cys in their active site and largely known as part of the plant redox-signaling network. Several pTRXs types have been described so far, namely, TRX f, m, x, y, and z. In recent years, improvements in proteomic techniques and the study of loss-of-function mutants have enabled us to grasp the importance of TRXs for the plastid physiology. We will analyze the specific signaling function of each TRX type and discuss about the emerging role in non-photosynthetic plastids of these redox switchers.
    Frontiers in Plant Science 11/2013; 4:463. DOI:10.3389/fpls.2013.00463 · 3.95 Impact Factor
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    • "Therefore, the identification of the regulatory signaling network underlying the symbiotic interaction is of utmost importance and has been the subject of intense research (for recent reviews, see Oldroyd et al., 2011; Udvardi and Poole, 2013). In recent years, nitric oxide (NO), widely recognized as an endogenous signaling molecule, emerged as an important player in the legume–rhizobium interaction, but its mechanisms of action are still far from being understood (Besson-Bard et al., 2008; Neill et al., 2008; Meilhoc et al., 2011; Puppo et al., 2013). To unravel the signal transduction cascade and ultimately NO function, it is necessary to identify its molecular targets. "
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    ABSTRACT: Nitric oxide (NO) is emerging as an important regulatory player in the Rhizobium-legume symbiosis. The occurrence of NO during several steps of the symbiotic interaction suggests an important, but yet unknown, signaling role of this molecule for root nodule formation and functioning. The identification of the molecular targets of NO is key for the assembly of the signal transduction cascade that will ultimately help to unravel NO function. We have recently shown that the key nitrogen assimilatory enzyme glutamine synthetase (GS) is a molecular target of NO in root nodules of Medicago truncatula, being post-translationally regulated by tyrosine nitration in relation to nitrogen fixation. In functional nodules of M. truncatula NO formation has been located in the bacteroid containing cells of the fixation zone, where the ammonium generated by bacterial nitrogenase is released to the plant cytosol and assimilated into the organic pools by plant GS. We propose that the NO-mediated GS post-translational inactivation is connected to nitrogenase inhibition induced by NO and is related to metabolite channeling to boost the nodule antioxidant defenses. Glutamate, a substrate for GS activity is also the precursor for the synthesis of glutathione (GSH), which is highly abundant in root nodules of several plant species and known to play a major role in the antioxidant defense participating in the ascorbate/GSH cycle. Existing evidence suggests that upon NO-mediated GS inhibition, glutamate could be channeled for the synthesis of GSH. According to this hypothesis, GS would be involved in the NO-signaling responses in root nodules and the NO-signaling events would meet the nodule metabolic pathways to provide an adaptive response to the inhibition of symbiotic nitrogen fixation by reactive nitrogen species.
    Frontiers in Plant Science 09/2013; 4:372. DOI:10.3389/fpls.2013.00372 · 3.95 Impact Factor
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