Editing Mitochondrial DNA (section)

=== mtDNA mutational spectrum is sensitive to species-specific life-history traits ===
De novo mutations arise either due to mistakes during DNA replication or due to unrepaired damage caused in turn by endogenous and exogenous mutagens. It has been long believed that mtDNA can be particularly sensitive to damage caused by reactive oxygen species (ROS), however, G>T substitutions, the hallmark of the oxidative damage in the nuclear genome, are very rare in mtDNA and do not increase with age. Comparing the mtDNA mutational spectra of hundreds of mammalian species, it has been recently demonstrated that species with extended lifespans have an increased rate of A>G substitutions on single-stranded heavy chains.<ref>{{Cite journal |display-authors=6 |vauthors=Mikhailova AG, Mikhailova AA, Ushakova K, Tretiakov EO, Iliushchenko D, Shamansky V, Lobanova V, Kozenkov I, Efimenko B, Yurchenko AA, Kozenkova E, Zdobnov EM, Makeev V, Yurov V, Tanaka M, Gostimskaya I, Fleischmann Z, Annis S, Franco M, Wasko K, Denisov S, Kunz WS, Knorre D, Mazunin I, Nikolaev S, Fellay J, Reymond A, Khrapko K, Gunbin K, Popadin K |date=October 2022 |title=A mitochondria-specific mutational signature of aging: increased rate of A &gt; G substitutions on the heavy strand |journal=Nucleic Acids Research |volume=50 |issue=18 |pages=10264–10277 |doi=10.1093/nar/gkac779 |pmc=9561281 |pmid=36130228}}</ref> This discovery led to the hypothesis that A>G is a mitochondria-specific marker of age-associated oxidative damage. This finding provides a mutational (contrary to the selective one) explanation for the observation that long-lived species have GC-rich mtDNA: long-lived species become GC-rich simply because of their biased process of mutagenesis. An association between mtDNA mutational spectrum and species-specific life-history traits in mammals opens a possibility to link these factors together discovering new life-history-specific mutagens in different groups of organisms.{{cn|date=November 2024}}