Biochemical control of the mitochondrial protein MitoNEET by biological thiols and lipid-derived electrophiles

Abstract

MitoNEET is a mitochondrial [2Fe-2S]-containing protein known for its involvement in cellular metabolism, iron regulation, and oxidative stress. The protein has been associated with diseases ranging from diabetes to Parkinson's disease, prompting the development of compounds designed to target mitoNEET selectively. Unfortunately, drug development is limited due to a lack of mechanistic understanding of how mitoNEET integrates into pathophysiological processes, and biological compounds that govern mitoNEET function are still ill-defined. We demonstrate an oxygen-dependent reaction with biological thiols catalyzed by mitoNEET. Specifically, we observed that mitoNEET converts L-cysteine to cystine. Finally, we showed that reduced glutathione (L-GSH) regulates the reactivity of two lipid-derived biomarkers of oxidative stress, 4-HNE and 4-ONE, towards mitoNEET. We found that exposure to L-GSH before treatment with either of the electrophilic aldehydes prevents the formation of a covalently linked mitoNEET dimer. Meanwhile, adding L-GSH after electrophile treatment recovers mitoNEET from the 4-HNE induced modification but not from the modification induced by 4-ONE. These results indicate a possible role for mitoNEET in thiol-mediated oxidative stress and may facilitate the development of drugs designed to modulate mitoNEET activity to improve pathophysiological states.