Redox Control of Human Mitochondrial Outer Membrane Protein MitoNEET [2Fe-2S] Clusters by Biological Thiols and Hydrogen Peroxide [Metabolism]

January 8th, 2014 by Landry, A. P., Ding, H.

Human mitochondrial outer membrane protein mitoNEET is a novel target of type II diabetes drug pioglitazone. The C-terminal cytosolic domain of mitoNEET hosts a redox active [2Fe-2S] cluster via an unusual ligand arrangement of three cysteine and one histidine residues. Here we report that human mitoNEET [2Fe-2S] clusters are fully reduced when expressed in Escherichia coli cells. In vitro studies show that purified mitoNEET [2Fe-2S] clusters can be partially reduced by monothiols such as reduced glutathione, L-cysteine or N-acetyl-L-cysteine, and fully reduced by dithiothreitol or the E. coli thioredoxin/thioredoxin reductase system under anaerobic conditions. Importantly, the thiol-reduced mitoNEET [2Fe-2S] clusters can be reversibly oxidized by hydrogen peroxide without disruption of the clusters in vitro and in E. coli cells, indicating that mitoNEET may act as a sensor of oxidative signals to regulate mitochondrial functions via its [2Fe-2S] clusters. Furthermore, binding of type II diabetes drug pioglitazone in mitoNEET effectively inhibits the thiol-mediated reduction of the [2Fe-2S] clusters, suggesting that pioglitazone may modulate the function of mitoNEET by blocking the thiol-mediated reduction of the [2Fe-2S] clusters in the protein.
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