Hibernation is super complex: dynamics of electron transport system supercomplexes
Abstract
The electron transport system complexes form supercomplexes (SCs) within mitochondrial membranes, perhaps increasing respiratory capacity or reducing reactive oxygen species production. My project aimed to determine the abundance, composition, and stability of SCs in a hibernator. Hibernators have dynamic metabolisms that change greatly during the winter. I isolated mitochondria from rats and thirteen-lined ground squirrels (TLGS) in different hibernation states and measured mitochondrial respiration. I extracted mitochondrial proteins using two detergents of different strengths, and quantified SC abundance using 2-dimensional gel electrophoresis and immunoblotting. Rats had fewer SCs than TLGS. SCs are dynamic in hibernation and the complex III composition of different SCs differed between hibernation states and seasons. There was no correlation between SC abundance and mitochondrial respiration. The stability of SCs differed: torpor SCs were most stable. This is the first report of SC changes during hibernation, and the first to demonstrate their dynamics on a short timescale.