6uol

From Proteopedia

Y271G DNA polymerase beta substrate complex with a templating cytosine and incoming rGTP

Structural highlights

6uol is a 4 chain structure with sequence from Homo sapiens and Synthetic construct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 1.936Å
Ligands:	CL, DOC, EDO, GTP, MN, NA
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

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

During oxidative stress, inflammation, or environmental exposure, ribo- and deoxyribonucleotides are oxidatively modified. 8-Oxo-7,8-dihydro-2'-guanosine (8-oxo-G) is a common oxidized nucleobase whose deoxyribonucleotide form, 8-oxo-dGTP, has been widely studied and demonstrated to be a mutagenic substrate for DNA polymerases. Guanine ribonucleotides are analogously oxidized to r8-oxo-GTP, which can constitute up to 5% of the rGTP pool. Because ribonucleotides are commonly misinserted into DNA, and 8-oxo-G causes replication errors, we were motivated to investigate how the oxidized ribonucleotide is utilized by DNA polymerases. To do this, here we employed human DNA polymerase beta (pol beta) and characterized r8-oxo-GTP insertion with DNA substrates containing either a templating cytosine (nonmutagenic) or adenine (mutagenic). Our results show that pol beta has a diminished catalytic efficiency for r8-oxo-GTP compared with canonical deoxyribonucleotides but that r8-oxo-GTP is inserted mutagenically at a rate similar to those of other common DNA replication errors (i.e. ribonucleotide and mismatch insertions). Using FRET assays to monitor conformational changes of pol beta with r8-oxo-GTP, we demonstrate impaired pol beta closure that correlates with a reduced insertion efficiency. X-ray crystallographic analyses revealed that, similar to 8-oxo-dGTP, r8-oxo-GTP adopts an anti conformation opposite a templating cytosine and a syn conformation opposite adenine. However, unlike 8-oxo-dGTP, r8-oxo-GTP did not form a planar base pair with either templating base. These results suggest that r8-oxo-GTP is a potential mutagenic substrate for DNA polymerases and provide structural insights into how r8-oxo-GTP is processed by DNA polymerases.

Molecular and structural characterization of oxidized ribonucleotide insertion into DNA by human DNA polymerase beta.,Smith MR, Alnajjar KS, Hoitsma NM, Sweasy JB, Freudenthal BD J Biol Chem. 2020 Feb 7;295(6):1613-1622. doi: 10.1074/jbc.RA119.011569. Epub, 2019 Dec 31. PMID:31892517^[5]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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Citations

reviews cite this structure

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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, Alnajjar KS, Hoitsma NM, Sweasy JB, Freudenthal BD. Molecular and structural characterization of oxidized ribonucleotide insertion into DNA by human DNA polymerase beta. J Biol Chem. 2020 Feb 7;295(6):1613-1622. doi: 10.1074/jbc.RA119.011569. Epub, 2019 Dec 31. PMID:31892517 doi:http://dx.doi.org/10.1074/jbc.RA119.011569