Human mitochondrial transcription and translation

The maintenance and expression of the mammalian mitochondrial genome (mtDNA) is a fundamental aspect of mitochondrial biogenesis. The mtDNA is transcribed as precursor polycistronic transcripts containing 11 mRNAs, 2 rRNAs, punctuated by 22 tRNAs. They require to be processed to engage in the assembly of unique mitochondrial ribosomes (the rRNAs), or mRNA translation into 13 proteins, all components of the OXPHOS enzymes, essential for aerobic cellular energy production. Through evolution, most genes of the ancestral bacterial endosymbiont have been transferred to the nucleus. Therefore the regulation of all fundamental aspects of mitochondrial gene expression relies on proteins that are encoded by the nuclear genome, translated by cytosolic ribosomes, and imported into the mitochondria. In this chapter, we describe the mechanisms underlying mammalian mitochondrial transcription, and translation and the characteristics and function of the factors involved.