| Structural highlights
Function
DPOLB_HUMAN Repair polymerase that plays a key role in base-excision repair. Has 5'-deoxyribose-5-phosphate lyase (dRP lyase) activity that removes the 5' sugar phosphate and also acts as a DNA polymerase that adds one nucleotide to the 3' end of the arising single-nucleotide gap. Conducts 'gap-filling' DNA synthesis in a stepwise distributive fashion rather than in a processive fashion as for other DNA polymerases.[1] [2] [3] [4]
Publication Abstract from PubMed
4,6-Diamino-5-formamidopyrimidine (Fapy*dG) is an abundant form of oxidative DNA damage that is mutagenic and contributes to the pathogenesis of human disease. When Fapy*dG is in its nucleotide triphosphate form, Fapy*dGTP, it is inefficiently cleansed from the nucleotide pool by the responsible enzyme in Escherichia coli MutT and its mammalian homolog MTH1. Therefore, under oxidative stress conditions, Fapy*dGTP could become a pro-mutagenic substrate for insertion into the genome by DNA polymerases. Here, we evaluated insertion kinetics and high-resolution ternary complex crystal structures of a configurationally stable Fapy*dGTP analog, beta-C-Fapy*dGTP, with DNA polymerase beta. The crystallographic snapshots and kinetic data indicate that binding of beta-C-Fapy*dGTP impedes enzyme closure, thus hindering insertion. The structures reveal that an active site residue, Asp276, positions beta-C-Fapy*dGTP so that it distorts the geometry of critical catalytic atoms. Removal of this guardian side chain permits enzyme closure and increases the efficiency of beta-C-Fapy*dG insertion opposite dC. These results highlight the stringent requirements necessary to achieve a closed DNA polymerase active site poised for efficient nucleotide incorporation and illustrate how DNA polymerase beta has evolved to hinder Fapy*dGTP insertion.
A guardian residue hinders insertion of a Fapy*dGTP analog by modulating the open-closed DNA polymerase transition.,Smith MR, Shock DD, Beard WA, Greenberg MM, Freudenthal BD, Wilson SH Nucleic Acids Res. 2019 Jan 16. pii: 5289696. doi: 10.1093/nar/gkz002. PMID:30649431[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Bennett RA, Wilson DM 3rd, Wong D, Demple B. Interaction of human apurinic endonuclease and DNA polymerase beta in the base excision repair pathway. Proc Natl Acad Sci U S A. 1997 Jul 8;94(14):7166-9. PMID:9207062
- ↑ Matsumoto Y, Kim K, Katz DS, Feng JA. Catalytic center of DNA polymerase beta for excision of deoxyribose phosphate groups. Biochemistry. 1998 May 5;37(18):6456-64. PMID:9572863 doi:10.1021/bi9727545
- ↑ DeMott MS, Beyret E, Wong D, Bales BC, Hwang JT, Greenberg MM, Demple B. Covalent trapping of human DNA polymerase beta by the oxidative DNA lesion 2-deoxyribonolactone. J Biol Chem. 2002 Mar 8;277(10):7637-40. Epub 2002 Jan 22. PMID:11805079 doi:10.1074/jbc.C100577200
- ↑ Parsons JL, Dianova II, Khoronenkova SV, Edelmann MJ, Kessler BM, Dianov GL. USP47 is a deubiquitylating enzyme that regulates base excision repair by controlling steady-state levels of DNA polymerase beta. Mol Cell. 2011 Mar 4;41(5):609-15. doi: 10.1016/j.molcel.2011.02.016. PMID:21362556 doi:10.1016/j.molcel.2011.02.016
- ↑ Smith MR, Shock DD, Beard WA, Greenberg MM, Freudenthal BD, Wilson SH. A guardian residue hinders insertion of a Fapy*dGTP analog by modulating the open-closed DNA polymerase transition. Nucleic Acids Res. 2019 Jan 16. pii: 5289696. doi: 10.1093/nar/gkz002. PMID:30649431 doi:http://dx.doi.org/10.1093/nar/gkz002
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