title: 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.
authors.affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 München/Neuherberg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Holzmeister
authors.affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 München/Neuherberg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Gaupels
authors.affiliation: Institute of Structural Biology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 München/Neuherberg, Germany.
authors.forename: Arie
authors.initials: A
authors.lastname: Geerlof
authors.affiliation: Department of Protein Science, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 München/Neuherberg, Germany.
authors.forename: Hakan
authors.initials: H
authors.lastname: Sarioglu
authors.affiliation: Institute of Structural Biology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 München/Neuherberg, Germany Munich Center for Integrated Protein Science at Chair of Biomolecular NMR, Department Chemie, Technische Universität München, 85747 Garching, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Sattler
authors.affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 München/Neuherberg, Germany Chair of Biochemical Plant Pathology, Technische Universität München, 85354 Freising, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Durner
authors.affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 München/Neuherberg, Germany Lindermayr@helmholtz-muenchen.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Lindermayr
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D016415:Sequence Alignment; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D030421:Peroxynitrous Acid; D014443:Tyrosine; D013482:Superoxide Dismutase
keywords: Antioxidant system; nitric oxide; nitrosative stress; post-translational modification; superoxide dismutase; tyrosine nitration.