Evolution and diversification of mitochondrial protein import systems

More than 95% of mitochondrial proteins are encoded in the nucleus, synthesised in the cytosol and imported into the organelle. The evolution of mitochondrial protein import systems was therefore a prerequisite for the conversion of the alpha-proteobacterial mitochondrial ancestor into an organelle. Here, I review that the origin of the mitochondrial outer membrane import receptors can best be understood by convergent evolution. Subsequently, I discuss an evolutionary scenario that was proposed to explain the diversification of the inner membrane carrier protein translocases between yeast and mammals. Finally, I illustrate a scenario that can explain how the two specialised inner membrane protein translocase complexes found in most eukaryotes were reduced to a single multifunctional one in trypanosomes.

Automated summary

This article reviews the origin and evolution of mitochondrial protein import systems and proposes evolutionary scenarios to explain the diversification of inner membrane carrier protein translocases. Additionally, the article illustrates a scenario that explains how two specialized inner membrane protein translocase complexes found in most eukaryotes were reduced to a single complex in trypanosomes.