Reconstitution of Mammalian Mitochondrial Translation System Capable of Long Polypeptide Synthesis.

Mammalian mitochondria have their own dedicated protein synthesis system, which produces 13 essential subunits of the oxidative phosphorylation complexes. Here, we describe the in vitro reconstitution of the mammalian mitochondrial translation system, utilizing purified recombinant mitochondrial translation factors, 55S ribosomes from pig liver mitochondria, and a heterologous yeast tRNA mixture. The system is capable of translating leaderless mRNAs encoding model proteins, such as nanoluciferase with a molecular weight of 19 kDa, and is readily applicable for in vitro evaluations of mRNAs and nascent peptide chain sequences, as well as factors and small molecules that affect mitochondrial translation.