Abstract Tu123: Redox Biology of the Mitochondrial Protein mitoNEET and Ascorbate

Abstract

Background: It has been proposed that mitoNEET is an Fe-S transfer/repair enzyme, playing a role under conditions of oxidative stress. mitoNEET protects mitochondria against oxidative stress in cardiomyocytes. Loss of mitoNEET is linked with age-related heart failure. Oxidized mitoNEET, [2Fe-2S] 2+ , exports Fe-S cluster from mitochondria to cytosol. Redox control of mitochondrion is essential for the proper functioning of the organelle/mitochondria. However, the molecular mechanisms involved in the redox biology of mitoNEET is not fully studied. Hypothesis: Ascorbate regulates redox reactions and Fe-S cluster transport function of mitoNEET in the mitochondria. Aims: The objective of this work is to evaluate the redox reactions between mitoNEET and ascorbate. Methods: Room temperature and low temperature (77 K) electron paramagnetic resonance (EPR) spectroscopy techniques were used to measure the oxidation of ascorbate and reduced mitoNEET, respectively. Results: EPR spectroscopic study shows that mitoNEET oxidizes ascorbate to ascorbate radical. The formation of ascorbate radical increases with increasing concentration of ascorbate. The formation of ascorbate radical is decreased in the presence of menadione. Low temperature EPR study shows that one electron reduction of mitoNEET by ascorbate. Conclusion: This study suggest that ascorbate is a substrate/cofactor for mitoNEET. Ascorbate regulates the Fe-S cluster transport function of mitoNEET. Ascorbate plays an important role in the redox biology of mitoNEET under physiological and pathophysiological conditions.