Ribonucleotides in mitochondrial DNA

The incorporation of ribonucleotides ( rNMP s) into DNA during genome replication has gained substantial attention in recent years and has been shown to be a significant source of genomic instability. Studies in yeast and mammals have shown that the two genomes, the nuclear DNA ( nDNA ) and the mitochondrial DNA (mt DNA ), differ with regard to their rNMP content. This is largely due to differences in rNMP repair – whereas rNMP s are efficiently removed from the nuclear genome, mitochondria lack robust mechanisms for removal of single rNMP s incorporated during DNA replication. In this minireview, we describe the processes that determine the frequency of rNMP s in the mitochondrial genome and summarise recent findings regarding the effect of incorporated rNMP s on mt DNA stability and function.