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

Holzmeister C, Gaupels F, Geerlof A, Sarioglu H, Sattler M, Durner J, Lindermayr C - J. Exp. Bot. (2014)

Bottom Line: 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.The corresponding Tyr34 of human manganese SOD is also nitrated, suggesting that this might be an evolutionarily conserved mechanism for regulation of manganese SODs.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 München/Neuherberg, Germany.

No MeSH data available.


Structural illustration of nitration of conserved Tyr63 of MSD1. (A) Alignment of amino acid sequences of Arabidopsis FSD isoforms, MSD1, and human MnSOD (Genbank accession number: CAA32502). Dashes: Introduced gaps to maximize sequence similarity. Tyr63 of MSD1 and the corresponding Tyr in FSD1 (Tyr43), FSD2 (Tyr85), FSD3 (Tyr82), and human MnSOD (Tyr34) are highlighted in red. (B) Part of the structural model of AtMSD1 showing the substrate binding pocket. The structural model of Arabidopsis MSD1 was generated using SWISS-MODEL with the crystal structure of Caenorhabditis elegans MnSOD as template (PDB code: 3DC6). Left: the substrate binding pocket is modelled with unmodified Tyr63 (left). The position where peroxynitrite attacks the aromatic ring system of Tyr63 is indicated with a red arrow. Right: the modelled substrate binding site is shown with nitrated Tyr63. Histidine and aspartate side chains are shown in yellow; the side chain of Tyr63 is marked in green. The distance of each side chain to the manganese ion within the active site is given.
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Figure 8: Structural illustration of nitration of conserved Tyr63 of MSD1. (A) Alignment of amino acid sequences of Arabidopsis FSD isoforms, MSD1, and human MnSOD (Genbank accession number: CAA32502). Dashes: Introduced gaps to maximize sequence similarity. Tyr63 of MSD1 and the corresponding Tyr in FSD1 (Tyr43), FSD2 (Tyr85), FSD3 (Tyr82), and human MnSOD (Tyr34) are highlighted in red. (B) Part of the structural model of AtMSD1 showing the substrate binding pocket. The structural model of Arabidopsis MSD1 was generated using SWISS-MODEL with the crystal structure of Caenorhabditis elegans MnSOD as template (PDB code: 3DC6). Left: the substrate binding pocket is modelled with unmodified Tyr63 (left). The position where peroxynitrite attacks the aromatic ring system of Tyr63 is indicated with a red arrow. Right: the modelled substrate binding site is shown with nitrated Tyr63. Histidine and aspartate side chains are shown in yellow; the side chain of Tyr63 is marked in green. The distance of each side chain to the manganese ion within the active site is given.

Mentions: Primarily nitration of Tyr63 was responsible for the ONOO– sensitivity of MSD1, as inferred by the finding that the ONOO–-dependent inhibition was strongly reduced in a MSD1 mutant with Tyr63 replaced by phenylalanine, which cannot be nitrated. Tyr63 is located very close to the active centre of the enzyme (5.26 Å distance) in an amino acid sequence, which is also conserved in human MnSOD (Fig. 8A). Accordingly, the corresponding Tyr34 of human MnSOD is nitrated by ONOO– resulting in down-regulation of the enzymatic activity (MacMillan-Crow et al., 1998; Yamakura et al., 1998). It was proposed that a -NO2 group at ortho-position of the aromatic ring further reduces the distance to the manganese-ion in the active centre (Fig. 8B), thereby affecting access and ligation of O2– to the substrate binding pocket. Moreover, crystal structure analyses of human MnSOD revealed a network of hydrogen bonds in the direct environment of the active centre (Perry et al., 2010). Tyr34 is part of this network that probably promotes the proton transfer onto a bond O2– anion. Nitration of the Tyr residue followed by a decrease of its pKa-value would probably deprotonate the phenol ring system causing a decrease or disruption of the hydrogen bond network. Other possible consequences of Tyr34 nitration include electrostatic interference between the nitro group and the negatively charged substrate O2– and a shift in the redox potential of the enzyme (Edwards et al., 2001). The observed inactivation of Arabidopsis MSD1 by ONOO–-mediated nitration of Tyr63 is probably based on a similar mechanism as described above for Tyr34 nitration of human MnSOD. However, it has to be mentioned that the activity of the MSD1 mutant (MSD1/Y63F) is still slightly inhibited by ONOO– (Fig. 7B), suggesting that probably also nitration of other tyrosine residues affect MSD1 activity, although to a much smaller extent than nitration of Tyr63.


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

Holzmeister C, Gaupels F, Geerlof A, Sarioglu H, Sattler M, Durner J, Lindermayr C - J. Exp. Bot. (2014)

Structural illustration of nitration of conserved Tyr63 of MSD1. (A) Alignment of amino acid sequences of Arabidopsis FSD isoforms, MSD1, and human MnSOD (Genbank accession number: CAA32502). Dashes: Introduced gaps to maximize sequence similarity. Tyr63 of MSD1 and the corresponding Tyr in FSD1 (Tyr43), FSD2 (Tyr85), FSD3 (Tyr82), and human MnSOD (Tyr34) are highlighted in red. (B) Part of the structural model of AtMSD1 showing the substrate binding pocket. The structural model of Arabidopsis MSD1 was generated using SWISS-MODEL with the crystal structure of Caenorhabditis elegans MnSOD as template (PDB code: 3DC6). Left: the substrate binding pocket is modelled with unmodified Tyr63 (left). The position where peroxynitrite attacks the aromatic ring system of Tyr63 is indicated with a red arrow. Right: the modelled substrate binding site is shown with nitrated Tyr63. Histidine and aspartate side chains are shown in yellow; the side chain of Tyr63 is marked in green. The distance of each side chain to the manganese ion within the active site is given.
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Related In: Results  -  Collection

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Figure 8: Structural illustration of nitration of conserved Tyr63 of MSD1. (A) Alignment of amino acid sequences of Arabidopsis FSD isoforms, MSD1, and human MnSOD (Genbank accession number: CAA32502). Dashes: Introduced gaps to maximize sequence similarity. Tyr63 of MSD1 and the corresponding Tyr in FSD1 (Tyr43), FSD2 (Tyr85), FSD3 (Tyr82), and human MnSOD (Tyr34) are highlighted in red. (B) Part of the structural model of AtMSD1 showing the substrate binding pocket. The structural model of Arabidopsis MSD1 was generated using SWISS-MODEL with the crystal structure of Caenorhabditis elegans MnSOD as template (PDB code: 3DC6). Left: the substrate binding pocket is modelled with unmodified Tyr63 (left). The position where peroxynitrite attacks the aromatic ring system of Tyr63 is indicated with a red arrow. Right: the modelled substrate binding site is shown with nitrated Tyr63. Histidine and aspartate side chains are shown in yellow; the side chain of Tyr63 is marked in green. The distance of each side chain to the manganese ion within the active site is given.
Mentions: Primarily nitration of Tyr63 was responsible for the ONOO– sensitivity of MSD1, as inferred by the finding that the ONOO–-dependent inhibition was strongly reduced in a MSD1 mutant with Tyr63 replaced by phenylalanine, which cannot be nitrated. Tyr63 is located very close to the active centre of the enzyme (5.26 Å distance) in an amino acid sequence, which is also conserved in human MnSOD (Fig. 8A). Accordingly, the corresponding Tyr34 of human MnSOD is nitrated by ONOO– resulting in down-regulation of the enzymatic activity (MacMillan-Crow et al., 1998; Yamakura et al., 1998). It was proposed that a -NO2 group at ortho-position of the aromatic ring further reduces the distance to the manganese-ion in the active centre (Fig. 8B), thereby affecting access and ligation of O2– to the substrate binding pocket. Moreover, crystal structure analyses of human MnSOD revealed a network of hydrogen bonds in the direct environment of the active centre (Perry et al., 2010). Tyr34 is part of this network that probably promotes the proton transfer onto a bond O2– anion. Nitration of the Tyr residue followed by a decrease of its pKa-value would probably deprotonate the phenol ring system causing a decrease or disruption of the hydrogen bond network. Other possible consequences of Tyr34 nitration include electrostatic interference between the nitro group and the negatively charged substrate O2– and a shift in the redox potential of the enzyme (Edwards et al., 2001). The observed inactivation of Arabidopsis MSD1 by ONOO–-mediated nitration of Tyr63 is probably based on a similar mechanism as described above for Tyr34 nitration of human MnSOD. However, it has to be mentioned that the activity of the MSD1 mutant (MSD1/Y63F) is still slightly inhibited by ONOO– (Fig. 7B), suggesting that probably also nitration of other tyrosine residues affect MSD1 activity, although to a much smaller extent than nitration of Tyr63.

Bottom Line: 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.The corresponding Tyr34 of human manganese SOD is also nitrated, suggesting that this might be an evolutionarily conserved mechanism for regulation of manganese SODs.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 München/Neuherberg, Germany.

No MeSH data available.