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Literature summary for 2.7.7.7 extracted from

  • Kasiviswanathan, R.; Longley, M.J.; Young, M.J.; Copeland, W.C.
    Purification and functional characterization of human mitochondrial DNA polymerase gamma harboring disease mutations (2010), Methods, 51, 379-384.
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

Cloned (Comment) Organism
the catalytic subunit is encoded by gene POLG at chromosomal locus 15q2, the accessory subunit is encoded by gene POLG2 at chromosomal locus 17q24.1, expression of polymerase point mutations combined with the D198A/E200A exonuclease mutation, the mutant is also lacking the mitochondrial targeting sequence, expression of N-terminally His6-tagged wild-type enzyme and mutant R946C in Spodoptera frugiperda Sf9 cells, expression of His6-tagged full-length p55 subunit without its mitochondrial targeting sequence in Escherichia coli strain BL21(DE3) Homo sapiens

Protein Variants

Protein Variants Comment Organism
A467T naturally occuring mutation, the mutation is the most common POLG mutation and has been found to be associated with all of the disease symptoms analyzed. The A467T pol gamma possesses only 4% of the wild-type DNA polymerase activity and is compromised for its ability to interact with the p55 accessory subunit Homo sapiens
A957S naturally occuring mutation, involved in autosomal dominant progressive external ophthalmoplegia, the mutation is associated with motiif B in the active site Homo sapiens
D198A/E200A site-directed mutagenesis in the exonuclease domain resulting in loss of exonuclease activity Homo sapiens
E1143G naturally occuring mutation, that is a frequent cause of ataxia-neuropathy syndrome, and found in 4% of European populations Homo sapiens
G848S naturally occuring mutation, involved in Alpers syndrome, the mutant shows compromised DNA binding ability that affects its overall functional efficiency Homo sapiens
G923D naturally occuring mutation, involved in autosomal dominant progressive external ophthalmoplegia, the mutation is associated with motiif B in the active site Homo sapiens
R852C naturally occuring mutation, involved in Alpers syndrome, the mutant shows compromised DNA binding ability that affects its overall functional efficiency Homo sapiens
R853Q naturally occuring mutation, involved in Alpers syndrome, the mutant shows compromised DNA binding ability that affects its overall functional efficiency Homo sapiens
R943H naturally occuring mutation, involved in autosomal dominant progressive external ophthalmoplegia, the mutation is associated with motiif B in the active site, the mutant retains less than 1% of the wild-type polymerase activity and displays a severe decrease in processivity Homo sapiens
R964C naturally occuring mutation Homo sapiens
T851A naturally occuring mutation, involved in Alpers syndrome, the mutant shows compromised DNA binding ability that affects its overall functional efficiency Homo sapiens
W748S naturally occuring mutation that has intrinsic lower polymerase activity as well as a demonstrated lower affinity for DNA compared to the wild-type enzyme Homo sapiens
W748S/E1143G naturally occuring mutation, the E1143G single-nucleotide polymorphism can modulate the deleterious effect of the W748S mutation Homo sapiens
Y955C naturally occuring mutation, involved in autosomal dominant progressive external ophthalmoplegia, the mutation is associated with motiif B in the active site, the mutant retains less than 1% of the wild-type polymerase activity and displays a severe decrease in processivity, the mutation increases nucleotide misinsertion replication errors 10-100 fold in the absence of exonucleolytic proofreading Homo sapiens

Localization

Localization Comment Organism GeneOntology No. Textmining
mitochondrion
-
Homo sapiens 5739
-

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
140000
-
x * 140000, catalytic subunit, + 55000, accessory subunit, SDS-PAGE Homo sapiens

Organism

Organism UniProt Comment Textmining
Homo sapiens
-
gene POLG
-

Purification (Commentary)

Purification (Comment) Organism
recombinant C-terminally His6-tagged full-length p55 subunit from Escherichia coli strain BL21(DE3) to homogeneity, by nickel affinity chromatography, recombinant N-terminally His6-tagged wild-type enzyme and mutant R946C from Sf9 insect cells by nickel affinity chromatography, gel filtration, and anion exchange chromatography Homo sapiens

Subunits

Subunits Comment Organism
? x * 140000, catalytic subunit, + 55000, accessory subunit, SDS-PAGE Homo sapiens
More the holoenzyme of pol gamma consists of a catalytic subunit and a dimeric form of its accessory subunit. The catalytic subunit is a 140 kDa enzyme, i.e. p140, that contains an N-terminal exonuclease domain connected by a linker region to a C-terminal polymerase domain and has DNA polymerase, 3'->5' exonuclease and 5' dRP lyase activities. The accessory subunit is a 55 kDa protein, i.e. p55, required for tight DNA binding and processive DNA synthesis Homo sapiens

Synonyms

Synonyms Comment Organism
DNA polymerase gamma
-
Homo sapiens
Pol gamma
-
Homo sapiens

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
22
-
assay at room temperature Homo sapiens

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8
-
assay at Homo sapiens

General Information

General Information Comment Organism
malfunction more than 150 different point mutations in POLG, the gene encoding the human mitochondrial DNA polymerase gamma, cause a broad spectrum of childhood and adult onset diseases. Disorders associated with POLG mutations include: 1. myocerebrohepatopathy spectrum disorder 2. Alpers syndrome 3. ataxia neuropathy spectrum disorder 4. myoclonus epilepsy myopathy sensory ataxia 5. autosomal recessive progressive external ophthalmoplegia 6. autosomal dominant progressive external ophthalmoplegia. Also, alteration of the (CAG)10 repeat in the 2nd exon of POLG is implicated in male infertility Homo sapiens
metabolism the pol gamma holoenzyme functions in conjunction with the mitochondrial DNA helicase and the mitochondrial SSB to form the minimal replication apparatus Homo sapiens
additional information the holoenzyme of pol gamma consists of a catalytic subunit and a dimeric form of its accessory subunit, interaction of the accessory subunit with the pol gamma catalytic subunit enhances the processivity bx 50fold and the DNA binding properties of the catalytic subunit. The catalytic subunit is a 140 kDa enzyme, i.e. p140, that contains an N-terminal exonuclease domain connected by a linker region to a C-terminal polymerase domain and has DNA polymerase, 3'->5' exonuclease and 5' dRP lyase activities. The accessory subunit is a 55 kDa protein, i.e. p55, required for tight DNA binding and processive DNA synthesis Homo sapiens
physiological function pol gamma is absolutely essential for mitochondrial DNA replication and repair Homo sapiens