6n2s

Ternary complex crystal structure of DNA polymerase Beta with 5-carboxy-dC (5-caC) at the templating positionTernary complex crystal structure of DNA polymerase Beta with 5-carboxy-dC (5-caC) at the templating position

Structural highlights

6n2s is a 4 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.457Å
Ligands:	, , ,
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

DNA methylation is an epigenetic mark that regulates gene expression in mammals. One method of methylation removal is through TET-catalyzed oxidation and the base excision repair pathway. The iterative oxidation of 5-methylcytosine (5mC) catalyzed by TET enzymes produces three oxidized forms of cytosine: 5-hydroxmethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxycytosine (5caC). The effect these modifications have on the efficiency and fidelity of the base excision repair pathway during the repair of opposing base damage, and in particular DNA polymerization, remains to be elucidated. Using kinetic assays, we show that the catalytic efficiency for the incorporation of dGTP catalyzed by human DNA Polymerase beta is not affected when 5mC, 5hmC, 5fC are in the DNA template. In contrast, the catalytic efficiency of dGTP insertion decreases ~20-fold when 5caC is in the templating position, as compared to unmodified cytosine. However, DNA polymerase fidelity is unaltered when these modifications are in the templating position. Structural analysis reveals that the methyl, hydroxymethyl, and formyl modifications are easily accommodated within the polymerase active site. However, to accommodate the carboxy modification, the phosphate backbone on the templating nucleotide shifts ~2.5 A to avoid a potential steric/repulsive clash. This altered conformation is stabilized by lysine 280 which makes a direct interaction with the carboxy modification and the phosphate backbone of the templating strand. This work provides the molecular basis for the accommodation of epigenetic base modifications in a polymerase active site and suggests that these modifications are not mutagenically copied during BER.

Molecular basis for the faithful replication of 5-methylcytosine and its oxidized forms by DNA Polymerase ss.,Howard MJ, Foley KG, Shock DD, Batra VK, Wilson SH J Biol Chem. 2019 Mar 18. pii: RA118.006809. doi: 10.1074/jbc.RA118.006809. PMID:30885943^[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
↑ Howard MJ, Foley KG, Shock DD, Batra VK, Wilson SH. Molecular basis for the faithful replication of 5-methylcytosine and its oxidized forms by DNA Polymerase ss. J Biol Chem. 2019 Mar 18. pii: RA118.006809. doi: 10.1074/jbc.RA118.006809. PMID:30885943 doi:http://dx.doi.org/10.1074/jbc.RA118.006809

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA

[1] 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

[2] 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

[3] 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

[4] 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

[5] Howard MJ, Foley KG, Shock DD, Batra VK, Wilson SH. Molecular basis for the faithful replication of 5-methylcytosine and its oxidized forms by DNA Polymerase ss. J Biol Chem. 2019 Mar 18. pii: RA118.006809. doi: 10.1074/jbc.RA118.006809. PMID:30885943 doi:http://dx.doi.org/10.1074/jbc.RA118.006809

[1]

[2]

[3]

[4]

[5]