Rescuing mitochondria in peril by targeting of a critical antioxidant protein

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This project aims to advance our understanding of how mitochondria are able to retain their function under severe stress. Mitochondria are fundamental components of animal cells that are essential for proper cell metabolism and physiology. Mitochondrial dysfunction is linked to ageing, and to numerous human pathologies and so the maintenance of their normal function is very important. The project will analyse how a critical antioxidant protein that normally resides in the cytoplasm is redirected into redox stressed mitochondria and how it is then able to ameliorate this stress. Protein import into mitochondria is essential for their construction. Most mitochondrial proteins (~10-15% of the human proteome) are synthesized in the cytosol and so must be imported following their synthesis. Under healthy conditions most of the import of most of these proteins is powered by the mitochondrial transmembrane energy gradient. Remarkably this antioxidant protein is imported by a system that does not require this energy gradient, which is just as well since that gradient is compromised under these severe redox stress conditions.Our findings offer the first opportunity to explore the mechanism of this entirely new import pathway that is critical to defend cells against deleterious oxidative stress. Our interdisciplinary approach outlined in this project will further our understanding of mitochondrial protein import and cell stress mechanisms and it is likely to provide a novel paradigm for understanding the coordination of oxidative stress signalling in eukaryotic cells.