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Structural highlights

Disease

POLH_HUMAN Defects in POLH are the cause of xeroderma pigmentosum variant type (XPV) [MIM:278750; also designated as XP-V. Xeroderma pigmentosum (XP) is an autosomal recessive disease due to deficient nucleotide excision repair. It is characterized by hypersensitivity of the skin to sunlight, followed by high incidence of skin cancer and frequent neurologic abnormalities. XPV shows normal nucleotide excision repair, but an exaggerated delay in recovery of replicative DNA synthesis. Most XPV patients do not develop clinical symptoms and skin neoplasias until a later age. Clinical manifestations are limited to photo-induced deterioration of the skin and eyes.^{[1] [2] [3] [4] [5]}

Function

POLH_HUMAN DNA polymerase specifically involved in DNA repair. Plays an important role in translesion synthesis, where the normal high fidelity DNA polymerases cannot proceed and DNA synthesis stalls. Plays an important role in the repair of UV-induced pyrimidine dimers. Depending on the context, it inserts the correct base, but causes frequent base transitions and transversions. May play a role in hypermutation at immunoglobulin genes. Forms a Schiff base with 5'-deoxyribose phosphate at abasic sites, but does not have lyase activity. Targets POLI to replication foci.^{[6] [7] [8] [9] [10]}

References

1. ↑ Masutani C, Kusumoto R, Yamada A, Dohmae N, Yokoi M, Yuasa M, Araki M, Iwai S, Takio K, Hanaoka F. The XPV (xeroderma pigmentosum variant) gene encodes human DNA polymerase eta. Nature. 1999 Jun 17;399(6737):700-4. PMID:10385124 doi:10.1038/21447
2. ↑ Johnson RE, Kondratick CM, Prakash S, Prakash L. hRAD30 mutations in the variant form of xeroderma pigmentosum. Science. 1999 Jul 9;285(5425):263-5. PMID:10398605
3. ↑ Yuasa M, Masutani C, Eki T, Hanaoka F. Genomic structure, chromosomal localization and identification of mutations in the xeroderma pigmentosum variant (XPV) gene. Oncogene. 2000 Sep 28;19(41):4721-8. PMID:11032022 doi:10.1038/sj.onc.1203842
4. ↑ Itoh T, Linn S, Kamide R, Tokushige H, Katori N, Hosaka Y, Yamaizumi M. Xeroderma pigmentosum variant heterozygotes show reduced levels of recovery of replicative DNA synthesis in the presence of caffeine after ultraviolet irradiation. J Invest Dermatol. 2000 Dec;115(6):981-5. PMID:11121129 doi:10.1046/j.1523-1747.2000.00154.x
5. ↑ Broughton BC, Cordonnier A, Kleijer WJ, Jaspers NG, Fawcett H, Raams A, Garritsen VH, Stary A, Avril MF, Boudsocq F, Masutani C, Hanaoka F, Fuchs RP, Sarasin A, Lehmann AR. Molecular analysis of mutations in DNA polymerase eta in xeroderma pigmentosum-variant patients. Proc Natl Acad Sci U S A. 2002 Jan 22;99(2):815-20. Epub 2002 Jan 2. PMID:11773631 doi:10.1073/pnas.022473899
6. ↑ Masutani C, Kusumoto R, Yamada A, Dohmae N, Yokoi M, Yuasa M, Araki M, Iwai S, Takio K, Hanaoka F. The XPV (xeroderma pigmentosum variant) gene encodes human DNA polymerase eta. Nature. 1999 Jun 17;399(6737):700-4. PMID:10385124 doi:10.1038/21447
7. ↑ Glick E, Vigna KL, Loeb LA. Mutations in human DNA polymerase eta motif II alter bypass of DNA lesions. EMBO J. 2001 Dec 17;20(24):7303-12. PMID:11743006 doi:10.1093/emboj/20.24.7303
8. ↑ Zeng X, Winter DB, Kasmer C, Kraemer KH, Lehmann AR, Gearhart PJ. DNA polymerase eta is an A-T mutator in somatic hypermutation of immunoglobulin variable genes. Nat Immunol. 2001 Jun;2(6):537-41. PMID:11376341 doi:10.1038/88740
9. ↑ Haracska L, Prakash L, Prakash S. A mechanism for the exclusion of low-fidelity human Y-family DNA polymerases from base excision repair. Genes Dev. 2003 Nov 15;17(22):2777-85. PMID:14630940 doi:10.1101/gad.1146103
10. ↑ Faili A, Aoufouchi S, Weller S, Vuillier F, Stary A, Sarasin A, Reynaud CA, Weill JC. DNA polymerase eta is involved in hypermutation occurring during immunoglobulin class switch recombination. J Exp Med. 2004 Jan 19;199(2):265-70. PMID:14734526 doi:10.1084/jem.20031831