DNA polymerase eta (Pol η), is a protein that in humans is encoded by the POLHgene.[1][2][3]
DNA polymerase eta is a eukaryotic DNA polymerase involved in the DNA repair by translesion synthesis. The gene encoding DNA polymerase eta is POLH, also known as XPV, because loss of this gene results in the disease xeroderma pigmentosum. Polymerase eta is particularly important for allowing accurate translesion synthesis of DNA damage resulting from ultraviolet radiation or UV.
This gene encodes a member of the Y family of specialized DNA polymerases. It copies undamaged DNA with a lower fidelity than other DNA-directed polymerases. However, it accurately replicates UV-damaged DNA; when thymine dimers are present, this polymerase inserts the complementary nucleotides in the newly synthesized DNA, thereby bypassing the lesion and suppressing the mutagenic effect of UV-induced DNA damage. This polymerase is thought to be involved in hypermutation during immunoglobulin class switch recombination.[1]
Bypass of 8-oxoguanine
During DNA replication of the Saccharomyces cerevisiaechromosome, the oxidative DNA damage8-oxoguanine triggers a switch to translesion synthesis by DNA polymerase eta.[4] This polymerase replicates 8-oxoguanine with an accuracy (insertion of a cytosine opposite the 8-oxoguanine) of approximately 94%. Replication of 8-oxoguanine in the absence of DNA polymerase eta is less than 40%.
Clinical significance
Mutations in this gene result in XPV, a variant type of xeroderma pigmentosum, characterized by sun sensitivity, elevated incidence of skin cancer, and at the cellular level, by delayed replication and hypermutability after UV-irradiation[5][6]
↑Masutani C, Kusumoto R, Yamada A, Dohmae N, Yokoi M, Yuasa M, Araki M, Iwai S, Takio K, Hanaoka F (June 1999). "The XPV (xeroderma pigmentosum variant) gene encodes human DNA polymerase eta". Nature. 399 (6737): 700–4. doi:10.1038/21447. PMID10385124.
Plachta M, Halas, McIntyre J, Sledziewska-Gojska E (2015). "The steady-state level and stability of TLS polymerase eta are cellcycle dependent in the yeast S. cerevisiae". DNA Repair. 29: 147–153. doi:10.1016/j.dnarep.2015.02.015. PMID25766643.
Skoneczna A, McIn Atyre J, Skoneczny M, Policinska Z, Sledziewska-Gojska E (2007). "Polymerase eta is a short-lived, proteasomally degraded protein that is temporarily stabilized following UV irradiation in Saccharomyces cerevisiae". J. Mol. Biol. 366 (4): 1074–86. doi:10.1016/j.jmb.2006.11.093. PMID17198712.
Masutani C, Kusumoto R, Yamada A, Dohmae N, Yokoi M, Yuasa M, Araki M, Iwai S, Takio K, Hanaoka F (1999). "The XPV (xeroderma pigmentosum variant) gene encodes human DNA polymerase eta". Nature. 399 (6737): 700–4. doi:10.1038/21447. PMID10385124.
Johnson RE, Kondratick CM, Prakash S, Prakash L (1999). "hRAD30 mutations in the variant form of xeroderma pigmentosum". Science. 285 (5425): 263–5. doi:10.1126/science.285.5425.263. PMID10398605.
Yuasa M, Masutani C, Eki T, Hanaoka F (2000). "Genomic structure, chromosomal localization and identification of mutations in the xeroderma pigmentosum variant (XPV) gene". Oncogene. 19 (41): 4721–8. doi:10.1038/sj.onc.1203842. PMID11032022.
Itoh T, Linn S, Kamide R, Tokushige H, Katori N, Hosaka Y, Yamaizumi M (2000). "Xeroderma pigmentosum variant heterozygotes show reduced levels of recovery of replicative DNA synthesis in the presence of caffeine after ultraviolet irradiation". J. Invest. Dermatol. 115 (6): 981–5. doi:10.1046/j.1523-1747.2000.00154.x. PMID11121129.
Zeng X, Winter DB, Kasmer C, Kraemer KH, Lehmann AR, Gearhart PJ (2001). "DNA polymerase eta is an A-T mutator in somatic hypermutation of immunoglobulin variable genes". Nat. Immunol. 2 (6): 537–41. doi:10.1038/88740. PMID11376341.
Matsuda T, Bebenek K, Masutani C, Rogozin IB, Hanaoka F, Kunkel TA (2001). "Error rate and specificity of human and murine DNA polymerase eta". J. Mol. Biol. 312 (2): 335–46. doi:10.1006/jmbi.2001.4937. PMID11554790.
Chiapperino D, Kroth H, Kramarczuk IH, Sayer JM, Masutani C, Hanaoka F, Jerina DM, Cheh AM (2002). "Preferential misincorporation of purine nucleotides by human DNA polymerase eta opposite benzo[a]pyrene 7,8-diol 9,10-epoxide deoxyguanosine adducts". J. Biol. Chem. 277 (14): 11765–71. doi:10.1074/jbc.M112139200. PMID11821420.
Kusumoto R, Masutani C, Iwai S, Hanaoka F (2002). "Translesion synthesis by human DNA polymerase eta across thymine glycol lesions". Biochemistry. 41 (19): 6090–9. doi:10.1021/bi025549k. PMID11994004.
Yavuz S, Yavuz AS, Kraemer KH, Lipsky PE (2002). "The role of polymerase eta in somatic hypermutation determined by analysis of mutations in a patient with xeroderma pigmentosum variant". J. Immunol. 169 (7): 3825–30. doi:10.4049/jimmunol.169.7.3825. PMID12244178.
Yang IY, Miller H, Wang Z, Frank EG, Ohmori H, Hanaoka F, Moriya M (2003). "Mammalian translesion DNA synthesis across an acrolein-derived deoxyguanosine adduct. Participation of DNA polymerase eta in error-prone synthesis in human cells". J. Biol. Chem. 278 (16): 13989–94. doi:10.1074/jbc.M212535200. PMID12584190.
