What is mitochondrial DNA polymerase?
Mitochondrial DNA is replicated and repaired by DNA polymerase γ (Pol γ). Pol γ, encoded by the POLG gene, is the only polymerase found in animal cell mitochondrial and is involved in replication, mutagenesis, and repair of mtDNA as well is a target of antiviral nucleoside analogs that cause mitochondrial toxicity.
What does gamma DNA polymerase do?
Pol γ is a DNA polymerase, which is a type of enzyme that “reads” sequences of DNA and uses them as templates to produce new DNA. These enzymes are important for copying (replicating) cells’ genetic material. DNA polymerases also play critical roles in DNA repair.
What is the function of mtDNA?
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP).
Where does haplogroup H originate?
Haplogroup H is a human mitochondrial DNA (mtDNA) haplogroup. The clade is believed to have originated in Southwest Asia, near present day Syria, around 20,000 to 25,000 years ago. Mitochondrial haplogroup H is today predominantly found in Europe, and is believed to have evolved before the Last Glacial Maximum (LGM).
Which DNA polymerase is required for mitochondrial DNA replication?
DNA polymerase γ
mtDNA replication factors DNA polymerase γ (POLγ) is the replicative polymerase in mitochondria. In human cells, POLγ is a heterotrimer with one catalytic subunit (POLγA) and two accessory subunits (POLγB) [3–5].
Where does mitochondrial DNA replication occur?
Human mtDNA encodes 13 proteins that are essential for oxidative phosphorylation, and the ribosomal and transfer RNAs necessary for their translation. RITOLS replication initiates in the major noncoding region, at OH and Ori-b, and OL is a major initiation site of lagging strand DNA synthesis in mammals.
Does mitochondrial DNA have proofreading?
Mitochondrial DNA (mtDNA) has a 10 times greater rate of mutation than nuclear DNA. As DNA polymerase gamma is the only known DNA polymerase within the mitochondrion, it is essential for faithful replication, proofreading and repair of mtDNA. Mitochondrial diseases can be caused by genetic and environmental factors.
Is POLG mutation fatal?
Alpers syndrome appears to be the most common autosomal recessive disease caused by mutations in the POLG gene. This early-onset fatal disease is characterized by intractable seizures, hepatic failure, and global neurological deterioration (Naviaux and Nguyen, 2004).