Cytochrome c oxidase biogenesis - from translation to early assembly of the core subunit COX1.

Mitochondria are the power houses of the cell as they produce the majority of ATP with their OXPHOS (oxidative phosphorylation) machinery. The OXPHOS system is composed of the F F ATP-synthase and four mitochondrial respiratory chain complexes, the terminal enzyme of which is the cytochrome c oxidase (complex IV) that transfers electrons to oxygen, generating water. Complex IV comprises of 14 structural subunits of dual genetic origin: while the three core subunits are mitochondrial-encoded, the remaining constituents are encoded by the nuclear genome. Hence, the assembly of complex IV requires the coordination of two spatially separated gene expression machineries. Recent efforts elucidated an increasing number of proteins involved in mitochondrial gene expression, which are linked to complex IV assembly. Additionally, several COX1 biogenesis factors have been intensively biochemically investigated and an increasing number of structural snapshots shed light on the organization of macromolecular complexes such as the mitoribosome or the cytochrome c oxidase. Here, we focus on COX1 translation regulation and highlight the advanced understanding of early steps during COX1 assembly and its link to mitochondrial translation regulation.