Related Experiment Video
Updated: Aug 24, 2026
Simultaneous Mapping and Quantitation of Ribonucleotides in Human Mitochondrial DNA
Published on: November 14, 2017
DNA polymerase gamma, the mitochondrial replicase
1Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, USA. lskaguni@msu.edu
Abstract:
DNA polymerase (pol) gamma is the sole DNA polymerase in animal mitochondria. Biochemical and genetic evidence document a key role for pol gamma in mitochondrial DNA replication, and whereas DNA repair and recombination were thought to be limited or absent in animal mitochondria, both have been demonstrated in recent years. Thus, the mitochondrial replicase is also apparently responsible for the relevant DNA synthetic reactions in these processes. Pol gamma comprises a catalytic core in a heterodimeric complex with an accessory subunit. The two-subunit holoenzyme is an efficient and processive polymerase, which exhibits high fidelity in nucleotide selection and incorporation while proofreading errors with its intrinsic 3' 5' exonuclease. Incorporation of nucleotide analogs followed by proofreading failure leads to mitochondrial toxicity in antiviral therapy, and misincorporation during DNA replication leads to mitochondrial mutagenesis and dysfunction. This review describes our current understanding of pol gamma biochemistry and biology, and it introduces other key proteins that function at the mitochondrial DNA replication fork.
Insights
Mitochondrial DNA polymerase gamma (pol gamma) replicates and repairs mitochondrial DNA. Its high fidelity prevents mutations and toxicity, crucial for mitochondrial health.
Area of Science:
- Mitochondrial Biology
- Molecular Genetics
- Biochemistry
Background:
- Animal mitochondria possess a single DNA polymerase, pol gamma, essential for DNA replication.
- Historically, DNA repair and recombination were considered absent in mitochondria, but recent evidence shows their presence.
Observation:
- Pol gamma functions as a heterodimeric holoenzyme with a catalytic core and accessory subunit.
- This holoenzyme demonstrates high fidelity in nucleotide selection and proofreading via its 3' to 5' exonuclease activity.
Findings:
- Pol gamma is responsible for DNA synthesis in mitochondrial replication, repair, and recombination.
- Proofreading failures of pol gamma during nucleotide analog incorporation cause mitochondrial toxicity, linked to antiviral therapies.
- Errors in pol gamma's replication process lead to mitochondrial mutagenesis and dysfunction.
Implications:
- Understanding pol gamma's function is critical for developing safe antiviral therapies.
- Pol gamma's role in maintaining mitochondrial DNA integrity is vital for preventing disease.
- Further research into pol gamma and associated replication fork proteins can illuminate mitochondrial dysfunction.
Related Concept Videos
03:01The Replisome
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
03:01The Replisome
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
02:10Translesion DNA Polymerases
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
01:29Replication in Eukaryotes
Many Proteins Orchestrate Replication at the Origin
Eukaryotic replication follows many of the same...
02:31Replication in Eukaryotes
01:29Replication in Eukaryotes
Many Proteins Orchestrate Replication at the Origin
Eukaryotic replication follows many of the same...