Abstract
Mutations in mitochondrial DNA (mtDNA) are associated with aging, and they can cause tissue degeneration and neuromuscular pathologies known as mitochondrial diseases. Because DNA polymerase γ (pol γ) is the enzyme responsible for replication and repair of mitochondrial DNA, the burden of faithful duplication of mitochondrial DNA, both in preventing spontaneous errors and in DNA repair synthesis, falls on pol γ. Investigating the biological functions of pol γ and its inhibitors aids our understanding of the sources of mtDNA mutations. In animal cells, pol γ is composed of two subunits, a larger catalytic subunit of 125–140 kDa and second subunit of 35–55 kDa. The catalytic subunit contains DNA polymerase activity, 3’-5’ exonuclease activity, and a 5’-dRP lyase activity. The accessory subunit is required for highly processive DNA synthesis and increases the affinity of pol gamma to the DNA.
Highlights
DNA polymerase γ is the enzyme responsible for replication of mitochondrial DNA in eukaryotic cells
With the exception of the trypanosomatid parasite[1,2], pol γ is the sole DNA polymerase found in mitochondria, and as such, pol γ must participate in all DNA replication and repair processes
Disruption of the yeast pol γ gene (MIP1)[12] and inhibition of mitochondrial DNA (mtDNA) replication in mitochondrial extracts with antibodies raised against pol γ[13] provided further evidence for the role of pol γ
Summary
Mutations in mitochondrial DNA (mtDNA) are associated with aging, and they can cause tissue degeneration and neuromuscular pathologies known as mitochondrial diseases. Because DNA polymerase γ (pol γ) is the enzyme responsible for replication and repair of mitochondrial DNA, the burden of faithful duplication of mitochondrial DNA, both in preventing spontaneous errors and in DNA repair synthesis, falls on pol γ. Investigating the biological functions of pol γ and its inhibitors aids our understanding of the sources of mtDNA mutations. Pol γ is composed of two subunits, a larger catalytic subunit of 125– 140 kDa and second subunit of 35–55 kDa. The catalytic subunit contains DNA polymerase activity, 3’-5’ exonuclease activity, and a 5’-dRP lyase activity.
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