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Complex I within oxidatively stressed bovine heart mitochondria is glutathionylated on Cys-531 and Cys-704 of the 75-kDa subunit: potential role of CYS residues in decreasing oxidative damage.

ABSTRACT: Complex I has reactive thiols on its surface that interact with the mitochondrial glutathione pool and are implicated in oxidative damage in many pathologies. However, the Cys residues and the thiol modifications involved are not known. Here we investigate complex I thiol modification within oxidatively stressed mammalian mitochondria, containing physiological levels of glutathione and glutaredoxin 2. In mitochondria incubated with the thiol oxidant diamide, complex I is only glutathionylated on the 75-kDa subunit. Of the 17 Cys residues on the 75-kDa subunit, 6 are not involved in iron-sulfur centers, making them plausible candidates for glutathionylation. Mass spectrometry of complex I from oxidatively stressed bovine heart mitochondria showed that only Cys-531 and Cys-704 were glutathionylated. The other four non-iron-sulfur center Cys residues remained as free thiols. Complex I glutathionylation also occurred in response to relatively mild oxidative stress caused by increased superoxide production from the respiratory chain. Although complex I glutathionylation within oxidatively stressed mitochondria correlated with loss of activity, it did not increase superoxide formation, and reversal of glutathionylation did not restore complex I activity. Comparison with the known structure of the 75-kDa ortholog Nqo3 from Thermus thermophilus complex I suggested that Cys-531 and Cys-704 are on the surface of mammalian complex I, exposed to the mitochondrial glutathione pool. These findings suggest that Cys-531 and Cys-704 may be important in preventing oxidative damage to complex I by reacting with free radicals and other damaging species, with subsequent glutathionylation recycling the thiyl radicals and sulfenic acids formed on the Cys residues back to free thiols.

SUBMITTER: Hurd TR

PROVIDER: S-EPMC2529008 | biostudies-literature | 2008 Sep

REPOSITORIES: biostudies-literature

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Complex I within oxidatively stressed bovine heart mitochondria is glutathionylated on Cys-531 and Cys-704 of the 75-kDa subunit: potential role of CYS residues in decreasing oxidative damage.

Hurd Thomas R TR Requejo Raquel R Filipovska Aleksandra A Brown Stephanie S Prime Tracy A TA Robinson Alan J AJ Fearnley Ian M IM Murphy Michael P MP

The Journal of biological chemistry 20080708 36

Complex I has reactive thiols on its surface that interact with the mitochondrial glutathione pool and are implicated in oxidative damage in many pathologies. However, the Cys residues and the thiol modifications involved are not known. Here we investigate complex I thiol modification within oxidatively stressed mammalian mitochondria, containing physiological levels of glutathione and glutaredoxin 2. In mitochondria incubated with the thiol oxidant diamide, complex I is only glutathionylated on ...[more]

PMID: 18611857

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Project description:Complement component 3 fragment C3a is an anaphylatoxin involved in promoting cellular responses important in immune response and host defense. Its receptor (C3a receptor, C3aR) is distributed on the plasma membrane; however, lysosomal localization in immune cells has been reported. Oxidative stress increases intracellular reactive oxygen species (ROS), and ROS activate complement signaling in immune cells and metabolic reprogramming. Here we tested oxidative stress and intracellular complement in mitochondrial dysfunction in RPE cells using high resolution live-cell imaging, and metabolism analysis in isolated mitochondria using Seahorse technology. While C3aR levels were unaffected by oxidative stress, its cell membrane levels decreased and mitochondrial (mt) localization increased. Trafficking was dependent on endocytosis, utilizing endosomal-to-mitochondrial cargo transfer. H2O2-treatment also increased C3a-mtC3aR co-localization dose-dependently. In isolated mitochondria from H2O2-treated cells C3a increased mitochondrial Ca2+ uptake, that could be inhibited by C3aR antagonism (SB290157), mitochondrial Ca2+ uniporter blocker (Ru360), and Gαi-protein inhibition (pertussis toxin, PTX); and inhibited mitochondrial repiration in an SB290157- and PTX-dependent manner. Specifically, mtC3aR activation inhibited state III ADP-driven respiration and maximal respiratory capacity. Mitochondria from control cells did not respond to C3a. Furthermore, transmitochondrial cybrid ARPE-19 cells harboring J haplogroup mitochondria that confer risk for age-related macular degeneration, showed high levels of mtC3aR and reduced ATP production upon C3a stimulation. Our findings suggest that oxidative stress increases mtC3aR, leading to altered mitochondrial calcium uptake and ATP production. These studies will have important implication in our understanding on the balance of extra- and intracellular complement signaling in controlling cellular health and dysfunction.

Dataset Information

Complex I within oxidatively stressed bovine heart mitochondria is glutathionylated on Cys-531 and Cys-704 of the 75-kDa subunit: potential role of CYS residues in decreasing oxidative damage.

Publications

Complex I within oxidatively stressed bovine heart mitochondria is glutathionylated on Cys-531 and Cys-704 of the 75-kDa subunit: potential role of CYS residues in decreasing oxidative damage.

Similar Datasets

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