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
8-Halogenated guanine (haloG), a major DNA adduct formed by reactive halogen species during inflammation, is a promutagenic lesion that promotes misincorporation of G opposite the lesion by various DNA polymerases. Currently, the structural basis for such misincorporation is unknown. To gain insights into the mechanism of misincorporation across haloG by polymerase, we determined seven X-ray structures of human DNA polymerase beta (polbeta) bound to DNA bearing 8-bromoguanine (BrG). We determined two pre-catalytic ternary-complex structures of polbeta with an incoming nonhydrolyzable dGTP or dCTP analog paired with templating BrG. We also determined five binary-complex structures of polbeta in complex with DNA containing BrG:C/T at post-insertion and post-extension sites. In the BrG:dGTP ternary structure, BrG adopts syn conformation and forms Hoogsteen base pairing with the incoming dGTP analog. In the BrG:dCTP ternary structure, BrG adopts anti conformation and forms Watson-Crick base pairing with the incoming dCTP analog. In addition, our polbeta binary post-extension structures show Hoogsteen BrG:G base pair and Watson-Crick BrG:C base pair. Taken together, the first structures of haloG-containing DNA bound to a protein indicate that both BrG:G and BrG:C base pairs are accommodated in the active site of polbeta. Our structures suggest that Hoogsteen-type base pairing between G and C8-modified G could be accommodated in the active site of a DNA polymerase, promoting G to C mutation.
Structural basis for promutagenicity of 8-halogenated guanine.,Koag MC, Min K, Lee S J Biol Chem. 2014 Jan 14. PMID:24425881[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
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
- ↑ Koag MC, Min K, Lee S. Structural basis for promutagenicity of 8-halogenated guanine. J Biol Chem. 2014 Jan 14. PMID:24425881 doi:http://dx.doi.org/10.1074/jbc.M113.537803
