Complexome profiling of BRAWNIN KO mouse heart mitochondria

BRAWNIN (BR) is a mitochondrial microprotein important for assembly of complex III. Here we used complexome to study the composition of supercomplexes in BR KO mouse heart mitochondria. BR deficiency induces the formation of a higher order electron transport chain complex which we renamed as extra-large supercomplex (SC-XL). The stoichiometry of SC-XL is I2+III2. SC-XL formation in the BR KO system alleviates the CIII defects and promotes compensatory OXPHOS increase. It is of higher electron transport efficiency and of lower ROS generation.