POLG is located on the q arm of chromosome 15 in position 26.1 and has 23 exons. The POLG gene produces a 140 kDa protein composed of 1239 amino acids.[3][4] POLG, the protein encoded by this gene, is a member of the DNA polymerase type-A family. It is a mitochondrion nucleiod with an Mg2+ cofactor and 15 turns, 52 beta strands, and 39 alpha helixes.[5][6] POLG contains a polyglutamine tract near its N-terminus that may be polymorphic. Two transcript variants encoding the same protein have been found for this gene. [2]
Function
POLG is a gene that codes for the catalytic subunit of the mitochondrial DNA polymerase, called DNA polymerase gamma.[2] The human POLG cDNA and gene were cloned and mapped to chromosome band 15q25.[7] In eukaryotic cells, the mitochondrial DNA is replicated by DNA polymerase gamma, a trimeric protein complex composed of a catalytic subunit, POLG, and a dimeric accessory subunit of 55 kDa encoded by the POLG2 gene.[8] The catalytic subunit contains three enzymatic activities, a DNA polymerase activity, a 3’-5’ exonuclease activity that proofreads misincorporated nucleotides, and a 5’-dRP lyase activity required for base excision repair.
↑Zullo SJ, Butler L, Zahorchak RJ, Macville M, Wilkes C, Merril CR (Mar 1998). "Localization by fluorescence in situ hybridization (FISH) of human mitochondrial polymerase gamma (POLG) to human chromosome band 15q24-->q26, and of mouse mitochondrial polymerase gamma (Polg) to mouse chromosome band 7E, with confirmation by direct sequence analysis of bacterial artificial chromosomes (BACs)". Cytogenetics and Cell Genetics. 78 (3–4): 281–4. doi:10.1159/000134672. PMID9465903.
↑Ropp PA, Copeland WC (September 1996). "Cloning and characterization of the human mitochondrial DNA polymerase, DNA polymerase gamma". Genomics. 36 (3): 449–58. doi:10.1006/geno.1996.0490. PMID8884268.
↑Graziewicz MA, Longley MJ, Copeland WC (February 2006). "DNA polymerase gamma in mitochondrial DNA replication and repair". Chemical Reviews. 106 (2): 383–405. doi:10.1021/cr040463d. PMID16464011.
Graziewicz MA, Longley MJ, Copeland WC (February 2006). "DNA polymerase gamma in mitochondrial DNA replication and repair". Chemical Reviews. 106 (2): 383–405. doi:10.1021/cr040463d. PMID16464011.
Hudson G, Chinnery PF (October 2006). "Mitochondrial DNA polymerase-gamma and human disease". Human Molecular Genetics. 15 Spec No 2: R244–52. doi:10.1093/hmg/ddl233. PMID16987890.
Lestienne P (August 1987). "Evidence for a direct role of the DNA polymerase gamma in the replication of the human mitochondrial DNA in vitro". Biochemical and Biophysical Research Communications. 146 (3): 1146–53. doi:10.1016/0006-291X(87)90767-4. PMID3619920.
Ropp PA, Copeland WC (September 1996). "Cloning and characterization of the human mitochondrial DNA polymerase, DNA polymerase gamma". Genomics. 36 (3): 449–58. doi:10.1006/geno.1996.0490. PMID8884268.
Lecrenier N, Van Der Bruggen P, Foury F (January 1997). "Mitochondrial DNA polymerases from yeast to man: a new family of polymerases". Gene. 185 (1): 147–52. doi:10.1016/S0378-1119(96)00663-4. PMID9034326.
Walker RL, Anziano P, Meltzer PS (March 1997). "A PAC containing the human mitochondrial DNA polymerase gamma gene (POLG) maps to chromosome 15q25". Genomics. 40 (2): 376–8. doi:10.1006/geno.1996.4580. PMID9119411.
Spelbrink JN, Toivonen JM, Hakkaart GA, Kurkela JM, Cooper HM, Lehtinen SK, Lecrenier N, Back JW, Speijer D, Foury F, Jacobs HT (August 2000). "In vivo functional analysis of the human mitochondrial DNA polymerase POLG expressed in cultured human cells". The Journal of Biological Chemistry. 275 (32): 24818–28. doi:10.1074/jbc.M000559200. PMID10827171.
Van Goethem G, Dermaut B, Löfgren A, Martin JJ, Van Broeckhoven C (July 2001). "Mutation of POLG is associated with progressive external ophthalmoplegia characterized by mtDNA deletions". Nature Genetics. 28 (3): 211–2. doi:10.1038/90034. PMID11431686.
Hirano M, DiMauro S (December 2001). "ANT1, Twinkle, POLG, and TP: new genes open our eyes to ophthalmoplegia". Neurology. 57 (12): 2163–5. doi:10.1212/wnl.57.12.2163. PMID11756592.
Ponamarev MV, Longley MJ, Nguyen D, Kunkel TA, Copeland WC (May 2002). "Active site mutation in DNA polymerase gamma associated with progressive external ophthalmoplegia causes error-prone DNA synthesis". The Journal of Biological Chemistry. 277 (18): 15225–8. doi:10.1074/jbc.C200100200. PMID11897778.
Nitanai Y, Satow Y, Adachi H, Tsujimoto M (August 2002). "Crystal structure of human renal dipeptidase involved in beta-lactam hydrolysis". Journal of Molecular Biology. 321 (2): 177–84. doi:10.1016/S0022-2836(02)00632-0. PMID12144777.
Lamantea E, Tiranti V, Bordoni A, Toscano A, Bono F, Servidei S, Papadimitriou A, Spelbrink H, Silvestri L, Casari G, Comi GP, Zeviani M (August 2002). "Mutations of mitochondrial DNA polymerase gammaA are a frequent cause of autosomal dominant or recessive progressive external ophthalmoplegia". Annals of Neurology. 52 (2): 211–9. doi:10.1002/ana.10278. PMID12210792.
Van Goethem G, Martin JJ, Dermaut B, Löfgren A, Wibail A, Ververken D, Tack P, Dehaene I, Van Zandijcke M, Moonen M, Ceuterick C, De Jonghe P, Van Broeckhoven C (February 2003). "Recessive POLG mutations presenting with sensory and ataxic neuropathy in compound heterozygote patients with progressive external ophthalmoplegia". Neuromuscular Disorders. 13 (2): 133–42. doi:10.1016/S0960-8966(02)00216-X. PMID12565911.
Jazayeri M, Andreyev A, Will Y, Ward M, Anderson CM, Clevenger W (March 2003). "Inducible expression of a dominant negative DNA polymerase-gamma depletes mitochondrial DNA and produces a rho0 phenotype". The Journal of Biological Chemistry. 278 (11): 9823–30. doi:10.1074/jbc.M211730200. PMID12645575.
Agostino A, Valletta L, Chinnery PF, Ferrari G, Carrara F, Taylor RW, Schaefer AM, Turnbull DM, Tiranti V, Zeviani M (April 2003). "Mutations of ANT1, Twinkle, and POLG1 in sporadic progressive external ophthalmoplegia (PEO)". Neurology. 60 (8): 1354–6. doi:10.1212/01.wnl.0000056088.09408.3c. PMID12707443.
Van Goethem G, Schwartz M, Löfgren A, Dermaut B, Van Broeckhoven C, Vissing J (July 2003). "Novel POLG mutations in progressive external ophthalmoplegia mimicking mitochondrial neurogastrointestinal encephalomyopathy". European Journal of Human Genetics. 11 (7): 547–9. doi:10.1038/sj.ejhg.5201002. PMID12825077.
Zullo SJ, Butler L, Zahorchak RJ, Macville M, Wilkes C, Merril CR (Mar 1998). "Localization by fluorescence in situ hybridization (FISH) of human mitochondrial polymerase gamma (POLG) to human chromosome band 15q24-->q26, and of mouse mitochondrial polymerase gamma (Polg) to mouse chromosome band 7E, with confirmation by direct sequence analysis of bacterial artificial chromosomes (BACs)". Cytogenetics and Cell Genetics. 78 (3–4): 281–4. doi:10.1159/000134672. PMID9465903.