Complexome profiling of heart mitochondria from mouse expressing alternative oxidase

Ciona intestinalis alternative oxidase (AOX) is a mitochondrial respiratory enzyme that acts as an alternative electron sink for ubiquinol (reduced quinone) when the cytochrome bc1 complex (complex III) and/or cytochrome c oxidase (complex IV) are inhibited or impaired (El-Khoury et al., 2014). AOX thus enables electron flux through the mitochondrial electron transport chain (ETC) and thereby prevents reverse electron transport from succinate dehydrogenase (complex II) to NADH:ubiquinone oxidoreductase (complex I) and mitochondrial ROS production, restores redox balance and Krebs cycle activity. As a non-proton-motive enzyme, however, AOX does not directly support ATP production. Previously, a mouse model was generated that despite ubiquitous expression of AOX revealed no deviations from normal physiology and which now is used as model to test mitochondrial disease paradigms (Szibor et al., 2017).