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Crystal structure of human DNA polymerase eta in ternary complex with a cisplatin DNA adduct
Structural highlights
DiseasePOLH_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] FunctionPOLH_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] Publication Abstract from PubMedA major clinical problem in the use of cisplatin to treat cancers is tumor resistance. DNA polymerase eta (Pol-eta) is a crucial polymerase that allows cancer cells to cope with the cisplatin-DNA adducts that are formed during chemotherapy. We present here a structure of human Pol-eta inserting deoxycytidine triphosphate (dCTP) opposite a cisplatin intrastrand cross-link (PtGpG). We show that the specificity of human Pol-eta for PtGpG derives from an active site that is open to permit Watson-Crick geometry of the nascent PtGpG-dCTP base pair and to accommodate the lesion without steric hindrance. This specificity is augmented by the residues Gln38 and Ser62, which interact with PtGpG, and Arg61, which interacts with the incoming dCTP. Collectively, the structure provides a basis for understanding how Pol-eta in human cells can tolerate the DNA damage caused by cisplatin chemotherapy and offers a framework for the design of inhibitors in cancer therapy. Structural basis for cisplatin DNA damage tolerance by human polymerase eta during cancer chemotherapy.,Ummat A, Rechkoblit O, Jain R, Roy Choudhury J, Johnson RE, Silverstein TD, Buku A, Lone S, Prakash L, Prakash S, Aggarwal AK Nat Struct Mol Biol. 2012 May 6;19(6):628-32. doi: 10.1038/nsmb.2295. PMID:22562137[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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