Proteomics of Dictyostelium discoideum mitochondria

There is a paucity of data regarding what proteins localize to the mitochondria in the social amoeba Dictyostelium discoideum. Therefore, here, we utilized high-throughput tandem mass tag (TMT)-based protein quantitation to identify proteins in the whole-cell lysate, as well as in crude and purified mitochondrial samples. We then calculated the ratio of a protein’s abundance in the mitochondria isolates, both crude and highly purified, versus its abundance in the whole-cell lysate. The resulting value, indicating its enrichment in mitochondrial preparations, was further normalized to the average enrichment ratio of 47 reference mitochondrial proteins, to compute the relative enrichment ratio. Using this approach, we identified 908 putative mitochondrial proteins. We ultimately combined proteomic and in silico analyses to yield a comprehensive mitochondrial protein compendium. Our compendium lays the foundation for future studies to understand the functions of conserved mitochondrial proteins in health and diseases using D. discoideum as the model. It also provides an entry to study many fascinating mitochondrial processes that are unique in protists. Additionally, through comparative genomics, our compendium will complement mitochondrial protein discovery in other organisms and may shed light on the evolution of mitochondrial proteomes and processes.