Mitochondrial super complexes in the colorless chlorophycean alga Polytomella parva

Chlorophycean algae of the genera Chlamydomonas and Polytomella share a common photosynthetic ancestor. However, members of the Polytomella lineage have adopted a heterotrophic lifestyle, having lost the photosynthetic apparatus and relying instead on acetate or ethanol as carbon sources, with energy production centered on oxidative phosphorylation (OXPHOS). In this study, we investigated the composition of the mitochondrial supercomplexes of the colorless alga Polytomella parva . OXPHOS complexes were solubilized using mild detergents such as glycol-diosgenin and digitonin, followed by separation of protein assemblies via Blue Native electrophoresis and Fast Protein Liquid Chromatography (FPLC). Additionally, complexome profiling of solubilized mitochondria resolved by Blue Native Gel Electrophoresis was carried out. The resulting data indicate that the OXPHOS supercomplexes of Polytomella closely resemble those observed in situ in the mitochondria of its green relative Chlamydomonas reinhardtii , as revealed by electron cryo-tomography and subtomogram averaging.