@misc{10481/64325,
year = {2020},
month = {9},
url = {http://hdl.handle.net/10481/64325},
abstract = {The ascorbate–glutathione cycle is a metabolic pathway that detoxifies hydrogen peroxide and involves enzymatic
and non-enzymatic antioxidants. Proteomic studies have shown that some enzymes in this cycle such as ascorbate
peroxidase (APX), monodehydroascorbate reductase (MDAR), and glutathione reductase (GR) are potential targets
for post-translational modifications (PMTs) mediated by nitric oxide-derived molecules. Using purified recombinant
pea peroxisomal MDAR and cytosolic and chloroplastic GR enzymes produced in Escherichia coli, the effects of peroxynitrite
(ONOO–) and S-nitrosoglutathione (GSNO) which are known to mediate protein nitration and S-nitrosylation
processes, respectively, were analysed. Although ONOO– and GSNO inhibit peroxisomal MDAR activity, chloroplastic
and cytosolic GR were not affected by these molecules. Mass spectrometric analysis of the nitrated MDAR revealed
that Tyr213, Try292, and Tyr345 were exclusively nitrated to 3-nitrotyrosine by ONOO–. The location of these residues in
the structure of pea peroxisomal MDAR reveals that Tyr345 is found at 3.3 Å of His313 which is involved in the NADPbinding
site. Site-directed mutagenesis confirmed Tyr345 as the primary site of nitration responsible for the inhibition
of MDAR activity by ONOO–. These results provide new insights into the molecular regulation of MDAR which is deactivated
by nitration and S-nitrosylation. However, GR was not affected by ONOO– or GSNO, suggesting the existence
of a mechanism to conserve redox status by maintaining the level of reduced GSH. Under a nitro-oxidative stress
induced by salinity (150 mM NaCl), MDAR expression (mRNA, protein, and enzyme activity levels) was increased,
probably to compensate the inhibitory effects of S-nitrosylation and nitration on the enzyme. The present data show
the modulation of the antioxidative response of key enzymes in the ascorbate–glutathione cycle by nitric oxide (NO)-
PTMs, thus indicating the close involvement of NO and reactive oxygen species metabolism in antioxidant defence
against nitro-oxidative stress situations in plants.},
organization = {Spanish Government},
organization = {ERDF - Ministry of Economy and Competitiveness 	
BIO2012-33904},
organization = {Junta de Andalucía

BIO286
BIO192},
publisher = {Christine Foyer},
keywords = {Glutathione reductase},
keywords = {Monodehydroascorbate reductase},
keywords = {Nitration},
keywords = {Nitric oxide},
keywords = {Peroxynitrite},
keywords = {Reactive nitrogen species},
keywords = {Salinity},
keywords = {S-nitrosylation},
keywords = {S-Nitrosoglutathione},
title = {Differential molecular response of monodehydroascorbate reductase and glutathione reductase by nitration and S-nitrosylation},
doi = {10.1093/jxb/erv306},
author = {Begara Morales, Juan C. and López Jaramillo, Francisco Javier and Corpas Aguirre, Francisco Javier},
}