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Oxidative stress induced S-glutathionylation and proteolytic degradation of mitochondrial thymidine kinase 2.

ABSTRACT: Protein glutathionylation in response to oxidative stress can affect both the stability and activity of target proteins. Mitochondrial thymidine kinase 2 (TK2) is a key enzyme in mitochondrial DNA precursor synthesis. Using an antibody specific for glutathione (GSH), S-glutathionylated TK2 was detected after the addition of glutathione disulfide (GSSG) but not GSH. This was reversed by the addition of dithiothreitol, suggesting that S-glutathionylation of TK2 is reversible. Site-directed mutagenesis of the cysteine residues and subsequent analysis of mutant enzymes demonstrated that Cys-189 and Cys-264 were specifically glutathionylated by GSSG. These cysteine residues do not appear to be part of the active site, as demonstrated by kinetic studies of the mutant enzymes. Treatment of isolated rat mitochondria with hydrogen peroxide resulted in S-glutathionylation of added recombinant TK2. Treatment of intact cells with hydrogen peroxide led to reduction of mitochondrial TK2 activity and protein levels, as well as S-glutathionylation of TK2. Furthermore, the addition of S-glutathionylated recombinant TK2 to mitochondria isolated from hydrogen peroxide-treated cells led to degradation of the S-glutathionylated TK2, which was not observed with unmodified TK2. S-Glutathionylation on Cys-189 was responsible for the observed selective degradation of TK2 in mitochondria. These results strongly suggest that oxidative damage-induced S-glutathionylation and degradation of TK2 have significant impact on mitochondrial DNA precursor synthesis.

SUBMITTER: Sun R

PROVIDER: S-EPMC3397856 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature

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Oxidative stress induced S-glutathionylation and proteolytic degradation of mitochondrial thymidine kinase 2.

Sun Ren R Eriksson Staffan S Wang Liya L

The Journal of biological chemistry 20120601 29

Protein glutathionylation in response to oxidative stress can affect both the stability and activity of target proteins. Mitochondrial thymidine kinase 2 (TK2) is a key enzyme in mitochondrial DNA precursor synthesis. Using an antibody specific for glutathione (GSH), S-glutathionylated TK2 was detected after the addition of glutathione disulfide (GSSG) but not GSH. This was reversed by the addition of dithiothreitol, suggesting that S-glutathionylation of TK2 is reversible. Site-directed mutagen ...[more]

PMID: 22661713

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Project description:Lipopolysaccharide (LPS) is a known inducer of inflammatory signaling which triggers generation of reactive oxygen species (ROS) and cell death in responsive cells like THP-1 promonocytes and freshly isolated human monocytes. A key LPS-responsive metabolic pivot point is the 9.5 megadalton mitochondrial pyruvate dehydrogenase complex (PDC), which provides pyruvate dehydrogenase (E1), lipoamide-linked transacetylase (E2) and lipoamide dehydrogenase (E3) activities to produce acetyl-CoA from pyruvate. While phosphorylation-dependent decreases in PDC activity following LPS treatment or sepsis have been deeply investigated, redox-linked processes have received less attention. Data presented here demonstrate that LPS-induced reversible oxidation within PDC occurs in PDCE2 in both THP-1 cells and primary monocytes. Knockout of PDCE2 by CRISPR and expression of FLAG-tagged PDCE2 in THP-1 cells demonstrated that LPS-induced glutathionylation is associated with wild type PDCE2 but not mutant protein lacking the lipoamide-linking lysine residues. Moreover, the mitochondrially-targeted electrophile MitoCDNB elevates ROS similar to LPS but does not cause PDCE2 glutathionylation. However, both LPS and MitoCDNB together are synergistic for PDCE2 glutathionylation, ROS production, and cell death. These results suggest that glutathionylation on PDCE2 lipoamide sulfurs is a specific modification associated with LPS and cell death which is not recapitulated by a general rise in mitochondrial ROS, but is enhanced after LPS treatment by rising oxidative stress exerted by MitoCDNB that impairs reductase systems.HighlightsPDCE2 is oxidized and glutathionylated (-SSG) during acute inflammation in monocytesPDCE2 knockout cells exhibit decreased ROS production during acute inflammationLipopolysaccharide-induced PDCE2-SSG occurs in THP1 cells and fresh monocytesLipoamide-deficient PDCE2 exhibits lower LPS-induced PDCE2-SSG and ROS productionMitoCDNB leads to ROS production but not PDCE2-SSG, but is synergistic with LPS.

Dataset Information

Oxidative stress induced S-glutathionylation and proteolytic degradation of mitochondrial thymidine kinase 2.

Publications

Oxidative stress induced S-glutathionylation and proteolytic degradation of mitochondrial thymidine kinase 2.

Similar Datasets

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