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DNA Polymerase θ

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You may include any references to papers as in: the use of JSmol in Proteopedia ^[1] or to the article describing Jmol ^[2] to the rescue.

1 General Description
2 Structural Highlights
- 2.1 ddATP Opposite THF
- 2.2 dCMP Opposite ddGTP
3 Structural Insights into Function
4 Related Proteins

General Description

Human polymerase θ (pol θ) is large, 290kD enzyme consisting of three distinct domains ^[3]^[4]. An N-terminal helicase-like domain, whose exact cellular functions are a topic of on-going debate and research^[5]^[6], is linked to a C-terminal, family A DNA polymerase domain by a large and disordered central region^[4]. Notably, pol θ is the only known human polymerase to contain a polymerase and helicase domain in one molecule^[7]. Crystal structures have been solved for the apo form of the helicase-like domain and the ternary complex of the polymerase domain. The focus of this wiki is the polymerase domain.

Pol θ is thought to promote overall genomic stability by performing several distinct cellular functions. The primary role of the enzyme is to repair of double-stranded DNA breaks as the key enzyme in an error-prone non-homologous end-joining pathway called alternative end-joining^[8] or theta-mediated end-joining. Other functions include translesion synthesis, the ability of the polymerase to bypass and extend past a site of oxidative DNA damage^[9], base excision repair ^[10], and possibly DNA replication timing ^[11]. Pol θ has the specialized ability to extend DNA from minimally-paired primers (termed microhomologous)Template:Cn. Repair by this enzyme is considered to error-prone due to its tendency to add or delete short indels ^[8].

Several types of cancer, such as breast, ovarian, and oral carcinomas, have shown significantly higher expression levels of pol θ and correlate to poorer patient outcomes^[12]^[13]^[14]. Genomic studies have shown that more than half of epithelial ovarian cancers have defects in the error-free repair pathway of homologous recombination^[15] and, as a result, have an increased dependence on theta-mediated end-joining ^[12]. Double-stranded break repair by pol θ may be thought of as a "backup" pathway which cells depend on more when the machinery involved in homologous recombination is compromised or otherwise unavailable. This enzyme has been identified as a potential therapeutic target due to overexpression in cancers in combination with studies that have shown inhibition of pol θ to sensitize human and mouse cells to radiation and chemical agents which induce double-stranded breaks^[12]^[16]^[17].

Structural Highlights

Two crystal structures of the polymerase domain have been solved bound, inserting ddATP opposite tetrahydrofuran (THF, representing an abasic site) and inserting ddGTP opposite dCMP^[7]. An overall assessment of the structures display the canonical . The DNA is thought to "sit" on the palm and is enclosed by the thumb and fingers. The closed conformation of the polymerase domain becomes obvious when compared to the open conformation of a homologous structure, such as Thermus aquaticus DNA polymerase I.

ddATP Opposite THF

An inspection of the active site reveals the , in this instance calcium. This structure required the use of calcium, as opposed to the physiological magnesium, as the primer strand retains the 3' hydroxyl which would otherwise be subjected to nucleophilic attack. The similarly conserved .

dCMP Opposite ddGTP

from the same study was solved with magnesium as the coordinated metal, a 27 amino acid N-terminal truncation, and a blunted DNA oligomer to remove the 3' template overhang. The overall structure is virtually identical to the aforementioned structure complexed with calcium, with the exception of a slight shift in position of the O-helix to be closer to the cognate C:G basepair.

Structural Insights into Function

Related Proteins

This is a sample scene created with SAT to by Group, and another to make of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.

References

1. Yousefzadeh MJ, Wood RD. DNA polymerase POLQ and cellular defense against DNA damage. DNA Repair (Amst). 2013; 12:1–9. [PubMed: 23219161] 2. Seki M, Marini F, Wood RD. POLQ (Pol theta), a DNA polymerase and DNA-dependent ATPase in human cells. Nucleic Acids Res. 2003; 31:6117–6126. [PubMed: 14576298] 3. Sfeir RPA 4. Pomerantz Helicase PMID:29444826 5. Zahn 6. Newman 6. Yousefzadeh MJ, et al. Mechanism of Suppression of Chromosomal Instability by DNA Polymerase POLQ. PLoS Genet. 2014; 10:e1004654. [PubMed: 25275444] 7. Yoon JH, Roy Choudhury J, Park J, Prakash S, Prakash L. A role for DNA polymerase theta in promoting replication through oxidative DNA lesion, thymine glycol, in human cells. J Biol Chem. 2014; 289:13177–13185. [PubMed: 24648516] 8. Asagoshi K, et al. Single-nucleotide base excision repair DNA polymerase activity in C. elegans in the absence of DNA polymerase beta. Nucleic Acids Res. 2012; 40:670–681. [PubMed: 21917855] 9. Fernandez-Vidal A, et al. A role for DNA polymerase theta in the timing of DNA replication. Nat Commun. 2014; 5:4285. [PubMed: 24989122] 10. Ceccaldi 11. Lemee F, et al. DNA polymerase theta up-regulation is associated with poor survival in breast cancer, perturbs DNA replication, and promotes genetic instability. Proc Natl Acad Sci U S A. 2010; 107:13390–13395. [PubMed: 20624954] 12. Lessa RC, et al. Identification of upregulated genes in oral squamous cell carcinomas. Head Neck. 2013; 35:1475–1481. [PubMed: 22987617] 13. Cancer Genome Atlas Research, N. Integrated genomic analyses of ovarian carcinoma. Nature. 2011; 474:609–615.10.1038/nature10166 14. Goff JP, et al. Lack of DNA polymerase theta (POLQ) radiosensitizes bone marrow stromal cells in vitro and increases reticulocyte micronuclei after total-body irradiation. Radiat Res. 2009; 172:165–174. [PubMed: 19630521] 15. Higgins GS, et al. A small interfering RNA screen of genes involved in DNA repair identifies tumor-specific radiosensitization by POLQ knockdown. Cancer Res. 2010; 70:2984–2993. [PubMed: 20233878]

↑ Hanson, R. M., Prilusky, J., Renjian, Z., Nakane, T. and Sussman, J. L. (2013), JSmol and the Next-Generation Web-Based Representation of 3D Molecular Structure as Applied to Proteopedia. Isr. J. Chem., 53:207-216. doi:http://dx.doi.org/10.1002/ijch.201300024
↑ Herraez A. Biomolecules in the computer: Jmol to the rescue. Biochem Mol Biol Educ. 2006 Jul;34(4):255-61. doi: 10.1002/bmb.2006.494034042644. PMID:21638687 doi:10.1002/bmb.2006.494034042644
↑ Yousefzadeh MJ, Wood RD. DNA polymerase POLQ and cellular defense against DNA damage. DNA Repair (Amst). 2013 Jan 1;12(1):1-9. doi: 10.1016/j.dnarep.2012.10.004. Epub , 2012 Dec 4. PMID:23219161 doi:http://dx.doi.org/10.1016/j.dnarep.2012.10.004
↑ ^4.0 ^4.1 Seki M, Marini F, Wood RD. POLQ (Pol theta), a DNA polymerase and DNA-dependent ATPase in human cells. Nucleic Acids Res. 2003 Nov 1;31(21):6117-26. PMID:14576298
↑ Mateos-Gomez PA, Kent T, Deng SK, McDevitt S, Kashkina E, Hoang TM, Pomerantz RT, Sfeir A. The helicase domain of Poltheta counteracts RPA to promote alt-NHEJ. Nat Struct Mol Biol. 2017 Dec;24(12):1116-1123. doi: 10.1038/nsmb.3494. Epub 2017, Oct 23. PMID:29058711 doi:http://dx.doi.org/10.1038/nsmb.3494
↑ Ozdemir AY, Rusanov T, Kent T, Siddique LA, Pomerantz RT. Polymerase theta-helicase efficiently unwinds DNA and RNA-DNA hybrids. J Biol Chem. 2018 Apr 6;293(14):5259-5269. doi: 10.1074/jbc.RA117.000565. Epub, 2018 Feb 14. PMID:29444826 doi:http://dx.doi.org/10.1074/jbc.RA117.000565
↑ ^7.0 ^7.1 Nussbaum J, Zane EA, Thys DM. Esmolol for the treatment of hypercyanotic spells in infants with tetralogy of Fallot. J Cardiothorac Anesth. 1989 Apr;3(2):200-2. PMID:2577526
↑ ^8.0 ^8.1 PubMed:25275444
↑ PubMed:24648516
↑ PubMed:21917855
↑ PubMed:24989122
↑ ^12.0 ^12.1 ^12.2 Ceccaldi R, Liu JC, Amunugama R, Hajdu I, Primack B, Petalcorin MI, O'Connor KW, Konstantinopoulos PA, Elledge SJ, Boulton SJ, Yusufzai T, D'Andrea AD. Homologous-recombination-deficient tumours are dependent on Poltheta-mediated repair. Nature. 2015 Feb 12;518(7538):258-62. doi: 10.1038/nature14184. Epub 2015 Feb 2. PMID:25642963 doi:http://dx.doi.org/10.1038/nature14184
↑ PubMed:20624954
↑ PubMed:22987617
↑ . Integrated genomic analyses of ovarian carcinoma. Nature. 2011 Jun 29;474(7353):609-15. doi: 10.1038/nature10166. PMID:21720365 doi:http://dx.doi.org/10.1038/nature10166
↑ PubMed:19630521
↑ PubMed:20233878

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 == Structural Highlights ==
-Two crystal structures of the polymerase domain have been solved bound, inserting ddATP opposite tetrahydrofuran (THF, representing an abasic site) and inserting ddGTP opposite dCMP<ref name="Zahn" />. An overall assessment of the structures display the canonical <scene name='78/786633/Subdomains/1'>exonuclease, thumb, palm, and fingers subdomains</scene>. The DNA is thought to "sit" on the palm and is enclosed by the thumb and fingers.
+Two crystal structures of the polymerase domain have been solved bound, inserting ddATP opposite tetrahydrofuran (THF, representing an abasic site) and inserting ddGTP opposite dCMP<ref name="Zahn" />. An overall assessment of the structures display the canonical <scene name='78/786633/Subdomains/1'>exonuclease, thumb, palm, and fingers subdomains</scene>. The DNA is thought to "sit" on the palm and is enclosed by the thumb and fingers. The closed conformation of the polymerase domain becomes obvious when compared to the open conformation of a homologous structure, such as [http://www.rcsb.org/structure/1KTQ Thermus aquaticus DNA polymerase I].
 ===ddATP Opposite THF===

User:Scott H. Vanson/Sandbox 1

From Proteopedia

Revision as of 20:03, 29 April 2018

DNA Polymerase θ

Contents

General Description

Structural Highlights

ddATP Opposite THF

dCMP Opposite ddGTP

Structural Insights into Function

Related Proteins

References

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