DNA polymerase subunit gamma-2, mitochondrial is a
protein that in humans is encoded by the POLG2gene. The POLG2 gene encodes a 55 kDa accessory subunit protein that imparts high processivity and salt tolerance to the catalytic subunit of
DNA polymerase gamma, encoded by the POLG gene.[5][6] Mutations in this gene result in
autosomal dominant progressive external
ophthalmoplegia with
mitochondrial DNA deletions.[7]
POLG2 encodes the processivity subunit of the mitochondrial
DNA polymerase gamma. The encoded protein forms a heterotrimer containing one catalytic subunit and two processivity subunits. This protein enhances
DNA binding, stimulates
polymerase and
exonuclease activity, and promotes processive
DNA synthesis.[7][8][9]
Mutations in POLG2 have been associated with
progressive external ophthalmoplegia with mitochondrial DNA deletions. This disease results in progressive weakness of
ocular muscles and levator muscle of the upper eyelid and patients with it may also manifest skeletal
myopathy, ragged-red fibers and atrophy shown on muscle biopsy,
cataracts,
hearing loss, sensory axonal neuropathy,
ataxia, depression,
hypogonadism, and
parkinsonism. This mutlisystemic disease has been linked to a G451E mutation that disrupts the DNA polymerase gamma subunits.[8][9][10]
In patients with chronic
hepatitis C, those carrying the
DDX5 minor allele or DDX5-POLG2 haplotypes are thought to be at an increased risk of advanced
fibrosis. It is important to note, however, that those carrying the
CPT1A minor allele are believed to be at a decreased risk.[11]
Interactions
POLG2 has been shown to have 39 binary
protein-protein interactions including 19 co-complex interactions. POLG2 appears to interact with
POLG.[12]
Johnson AA, Tsai Y, Graves SW, Johnson KA (February 2000). "Human mitochondrial DNA polymerase holoenzyme: reconstitution and characterization". Biochemistry. 39 (7): 1702–8.
doi:
10.1021/bi992104w.
PMID10677218.
Overview of all the structural information available in the
PDB for
UniProt: Q9UHN1 (Human DNA polymerase subunit gamma-2, mitochondrial) at the
PDBe-KB.
Overview of all the structural information available in the
PDB for
UniProt: Q9QZM2 (Mouse DNA polymerase subunit gamma-2, mitochondrial) at the
PDBe-KB.