Dataset Information

Differential inhibition of Arabidopsis superoxide dismutases by peroxynitrite-mediated tyrosine nitration.

ABSTRACT: Despite the importance of superoxide dismutases (SODs) in the plant antioxidant defence system little is known about their regulation by post-translational modifications. Here, we investigated the in vitro effects of nitric oxide derivatives on the seven SOD isoforms of Arabidopsis thaliana. S-nitrosoglutathione, which causes S-nitrosylation of cysteine residues, did not influence SOD activities. By contrast, peroxynitrite inhibited the mitochondrial manganese SOD1 (MSD1), peroxisomal copper/zinc SOD3 (CSD3), and chloroplastic iron SOD3 (FSD3), but no other SODs. MSD1 was inhibited by up to 90% but CSD3 and FSD3 only by a maximum of 30%. Down-regulation of these SOD isoforms correlated with tyrosine (Tyr) nitration and both could be prevented by the peroxynitrite scavenger urate. Site-directed mutagenesis revealed that-amongst the 10 Tyr residues present in MSD1-Tyr63 was the main target responsible for nitration and inactivation of the enzyme. Tyr63 is located nearby the active centre at a distance of only 5.26 Å indicating that nitration could affect accessibility of the substrate binding pocket. The corresponding Tyr34 of human manganese SOD is also nitrated, suggesting that this might be an evolutionarily conserved mechanism for regulation of manganese SODs.

SUBMITTER: Holzmeister C

PROVIDER: S-EPMC4321555 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Differential inhibition of Arabidopsis superoxide dismutases by peroxynitrite-mediated tyrosine nitration.

Holzmeister Christian C Gaupels Frank F Geerlof Arie A Sarioglu Hakan H Sattler Michael M Durner Jörg J Lindermayr Christian C

Journal of experimental botany 20141126 3

Despite the importance of superoxide dismutases (SODs) in the plant antioxidant defence system little is known about their regulation by post-translational modifications. Here, we investigated the in vitro effects of nitric oxide derivatives on the seven SOD isoforms of Arabidopsis thaliana. S-nitrosoglutathione, which causes S-nitrosylation of cysteine residues, did not influence SOD activities. By contrast, peroxynitrite inhibited the mitochondrial manganese SOD1 (MSD1), peroxisomal copper/zin ...[more]

PMID: 25428993

Similar Datasets

Project description:Protein tyrosine nitration has been observed in a variety of human diseases associated with oxidative stress, such as inflammatory, neurodegenerative, and cardiovascular conditions. However, the pathways leading to nitration of tyrosine residues are still unclear. Recent studies have shown that peroxynitrite (PN), produced by the reaction of superoxide and nitric oxide, can lead to protein nitration and inactivation. Tyrosine nitration may also be mediated by nitrogen dioxide produced by the oxidation of nitrite by peroxidases. Manganese superoxide dismutase (MnSOD), which plays a critical role in cellular defense against oxidative stress by decomposing superoxide within mitochondria, is nitrated and inactivated under pathological conditions. In this study, MnSOD is shown to catalyze PN-mediated self-nitration. Direct, spectroscopic observation of the kinetics of PN decay and nitrotyrosine formation (k(cat) = 9.3 × 10(2) M(-1) s(-1)) indicates that the mechanism involves redox cycling between Mn(2+) and Mn(3+), similar to that observed with superoxide. Distinctive patterns of tyrosine nitration within MnSOD by various reagents were revealed and quantified by MS/MS analysis of MnSOD trypsin digest peptides. These analyses showed that three of the seven tyrosine residues of MnSOD (Tyr34, Tyr9, and Tyr11) were the most susceptible to nitration and that the relative amounts of nitration of these residues varied widely depending upon the nature of the nitrating agent. Notably, nitration mediated by PN, in both the presence and absence of CO2, resulted in nitration of the active site tyrosine, Tyr34, while nitration by freely diffusing nitrogen dioxide led to surface nitration at Tyr9 and Tyr11. Flux analysis of the nitration of Tyr34 by PN-CO2 showed that the nitration rate coincided with the kinetics of the reaction of PN with CO2. These kinetics and the 20-fold increase in the efficiency of tyrosine nitration in the presence of CO2 suggest a specific role for the carbonate radical anion (•CO3(-)) in MnSOD nitration by PN. We also observed that the nitration of Tyr34 caused inactivation of the enzyme, while nitration of Tyr9 and Tyr11 did not interfere with the superoxide dismutase activity. The loss of MnSOD activity upon Tyr34 nitration implies that the responsible reagent in vivo is peroxynitrite, acting either directly or through the action of •CO3(-).

Project description:T-helper 17 cells and regulatory T cells (Treg) are critical regulators in the pathogenesis of multiple sclerosis (MS) but the factors affecting Treg/Th17 balance remains largely unknown. Redox balance is crucial to maintaining immune homeostasis and reducing the severity of MS but the underlying mechanisms are unclear yet. Herein, we tested the hypothesis that peroxynitrite, a representative molecule of reactive nitrogen species (RNS), could inhibit peripheral Treg cells, disrupt Treg/Th17 balance and aggravate MS pathology by inducing nitration of interleukin-2 receptor (IL-2R) and down-regulating RAS/JNK-AP-1 signalling pathway. Experimental autoimmune encephalomyelitis (EAE) mouse model and serum samples of MS patients were used in the study. We found that the increases of 3-nitrotyrosine and IL-2R nitration in Treg cells were coincided with disease severity in the active EAE mice. Mechanistically, peroxynitrite-induced IL-2R nitration down-regulated RAS/JNK signalling pathway, subsequently impairing peripheral Treg expansion and function, increasing Teff infiltration into the central nerve system (CNS), aggravating demyelination and neurological deficits in the EAE mice. Those changes were abolished by peroxynitrite decomposition catalyst (PDC) treatment. Furthermore, transplantation of the PDC-treated-autologous Treg cells from donor EAE mice significantly decreased Th17 cells in both axillary lymph nodes and lumbar spinal cord, and ameliorated the neuropathology of the recipient EAE mice. Those results suggest that peroxynitrite could disrupt peripheral Treg/Th17 balance, and aggravate neuroinflammation and neurological deficit in active EAE/MS pathogenesis. The underlying mechanisms are related to induce the nitration of IL-2R and inhibit the RAS/JNK-AP-1 signalling pathway in Treg cells. The study highlights that targeting peroxynitrite-mediated peripheral IL-2R nitration in Treg cells could be a novel therapeutic strategy to restore Treg/Th17 balance and ameliorate MS/EAE pathogenesis. The study provides valuable insights into potential role of peripheral redox balance in maintaining CNS immune homeostasis.

Dataset Information

Differential inhibition of Arabidopsis superoxide dismutases by peroxynitrite-mediated tyrosine nitration.

Publications

Differential inhibition of Arabidopsis superoxide dismutases by peroxynitrite-mediated tyrosine nitration.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets