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Thomas C, Avalos-Irving L, Victorino J, Green S, Andrews M, Rodrigues N, Ebirim S, Mudd A, Towle-Weicksel JB. Melanoma-Derived DNA Polymerase Theta Variants Exhibit Altered DNA Polymerase Activity. Biochemistry 2024; 63:1107-1117. [PMID: 38671548 PMCID: PMC11080051 DOI: 10.1021/acs.biochem.3c00670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 04/19/2024] [Accepted: 04/22/2024] [Indexed: 04/28/2024]
Abstract
DNA polymerase θ (Pol θ or POLQ) is primarily involved in repairing double-stranded breaks in DNA through an alternative pathway known as microhomology-mediated end joining (MMEJ) or theta-mediated end joining (TMEJ). Unlike other DNA repair polymerases, Pol θ is thought to be highly error-prone yet critical for cell survival. We have identified several POLQ gene variants from human melanoma tumors that experience altered DNA polymerase activity, including a propensity for incorrect nucleotide selection and reduced polymerization rates compared to WT Pol θ. Variants are 30-fold less efficient at incorporating a nucleotide during repair and up to 70-fold less accurate at selecting the correct nucleotide opposite a templating base. This suggests that aberrant Pol θ has reduced DNA repair capabilities and may also contribute to increased mutagenesis. Moreover, the variants were identified in established tumors, suggesting that cancer cells may use mutated polymerases to promote metastasis and drug resistance.
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Affiliation(s)
- Corey Thomas
- Department of Physical Sciences, Rhode Island College, 600 Mount Pleasant Avenue, Providence, Rhode Island 02908, United States
| | - Lisbeth Avalos-Irving
- Department of Physical Sciences, Rhode Island College, 600 Mount Pleasant Avenue, Providence, Rhode Island 02908, United States
| | - Jorge Victorino
- Department of Physical Sciences, Rhode Island College, 600 Mount Pleasant Avenue, Providence, Rhode Island 02908, United States
| | - Sydney Green
- Department of Physical Sciences, Rhode Island College, 600 Mount Pleasant Avenue, Providence, Rhode Island 02908, United States
| | - Morgan Andrews
- Department of Physical Sciences, Rhode Island College, 600 Mount Pleasant Avenue, Providence, Rhode Island 02908, United States
| | - Naisha Rodrigues
- Department of Physical Sciences, Rhode Island College, 600 Mount Pleasant Avenue, Providence, Rhode Island 02908, United States
| | - Sarah Ebirim
- Department of Physical Sciences, Rhode Island College, 600 Mount Pleasant Avenue, Providence, Rhode Island 02908, United States
| | - Ayden Mudd
- Department of Physical Sciences, Rhode Island College, 600 Mount Pleasant Avenue, Providence, Rhode Island 02908, United States
| | - Jamie B. Towle-Weicksel
- Department of Physical Sciences, Rhode Island College, 600 Mount Pleasant Avenue, Providence, Rhode Island 02908, United States
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2
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Thomas C, Avalos-Irving L, Victorino J, Green S, Andrews M, Rodrigues N, Ebirim S, Mudd A, Towle-Weicksel JB. Melanoma-derived DNA polymerase theta variants exhibit altered DNA polymerase activity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.14.566933. [PMID: 38014040 PMCID: PMC10680777 DOI: 10.1101/2023.11.14.566933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
DNA Polymerase θ (Pol θ or POLQ) is primarily involved in repairing double-stranded breaks in DNA through the alternative pathway known as microhomology-mediated end joining (MMEJ) or theta-mediated end joining (TMEJ). Unlike other DNA repair polymerases, Pol θ is thought to be highly error prone, yet critical for cell survival. We have identified several mutations in the POLQ gene from human melanoma tumors. Through biochemical analysis, we have demonstrated that all three cancer-associated variants experienced altered DNA polymerase activity including a propensity for incorrect nucleotide selection and reduced polymerization rates compared to WT Pol θ. Moreover, the variants are 30 fold less efficient at incorporating a nucleotide during repair and up to 70 fold less accurate at selecting the correct nucleotide opposite a templating base. Taken together, this suggests that aberrant Pol θ has reduced DNA repair capabilities and may also contribute to increased mutagenesis. While this may be beneficial to normal cell survival, the variants were identified in established tumors suggesting that cancer cells may use this promiscuous polymerase to its advantage to promote metastasis and drug resistance.
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3
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Multifaceted Nature of DNA Polymerase θ. Int J Mol Sci 2023; 24:ijms24043619. [PMID: 36835031 PMCID: PMC9962433 DOI: 10.3390/ijms24043619] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/26/2023] [Accepted: 02/02/2023] [Indexed: 02/15/2023] Open
Abstract
DNA polymerase θ belongs to the A family of DNA polymerases and plays a key role in DNA repair and damage tolerance, including double-strand break repair and DNA translesion synthesis. Pol θ is often overexpressed in cancer cells and promotes their resistance to chemotherapeutic agents. In this review, we discuss unique biochemical properties and structural features of Pol θ, its multiple roles in protection of genome stability and the potential of Pol θ as a target for cancer treatment.
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Abstract
DNA polymerase θ (Pol θ) is a DNA repair enzyme widely conserved in animals and plants. Pol θ uses short DNA sequence homologies to initiate repair of double-strand breaks by theta-mediated end joining. The DNA polymerase domain of Pol θ is at the C terminus and is connected to an N-terminal DNA helicase-like domain by a central linker. Pol θ is crucial for maintenance of damaged genomes during development, protects DNA against extensive deletions, and limits loss of heterozygosity. The cost of using Pol θ for genome protection is that a few nucleotides are usually deleted or added at the repair site. Inactivation of Pol θ often enhances the sensitivity of cells to DNA strand-breaking chemicals and radiation. Since some homologous recombination-defective cancers depend on Pol θ for growth, inhibitors of Pol θ may be useful in treating such tumors.
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Affiliation(s)
- Richard D Wood
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, Texas, USA;
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA;
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Carvajal-Maldonado D, Drogalis Beckham L, Wood RD, Doublié S. When DNA Polymerases Multitask: Functions Beyond Nucleotidyl Transfer. Front Mol Biosci 2022; 8:815845. [PMID: 35071329 PMCID: PMC8782244 DOI: 10.3389/fmolb.2021.815845] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
DNA polymerases catalyze nucleotidyl transfer, the central reaction in synthesis of DNA polynucleotide chains. They function not only in DNA replication, but also in diverse aspects of DNA repair and recombination. Some DNA polymerases can perform translesion DNA synthesis, facilitating damage tolerance and leading to mutagenesis. In addition to these functions, many DNA polymerases conduct biochemically distinct reactions. This review presents examples of DNA polymerases that carry out nuclease (3'-5' exonuclease, 5' nuclease, or end-trimming nuclease) or lyase (5' dRP lyase) extracurricular activities. The discussion underscores how DNA polymerases have a remarkable ability to manipulate DNA strands, sometimes involving relatively large intramolecular movement.
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Affiliation(s)
- Denisse Carvajal-Maldonado
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, TX, United States
| | - Lea Drogalis Beckham
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, United States
| | - Richard D Wood
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, TX, United States
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, United States
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6
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Yuhas SC, Majumdar A, Greenberg MM. Protein Domain Specific Covalent Inhibition of Human DNA Polymerase β. Chembiochem 2021; 22:2619-2623. [PMID: 34213836 PMCID: PMC8373715 DOI: 10.1002/cbic.202100247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 07/01/2021] [Indexed: 11/10/2022]
Abstract
DNA polymerase β (Pol β) is a frequently overexpressed and/or mutated bifunctional repair enzyme. Pol β possesses polymerase and lyase active sites, that are employed in two steps of base excision repair. Pol β is an attractive therapeutic target for which there is a need for inhibitors. Two mechanistically inspired covalent inhibitors (1, IC50 =21.0 μM; 9, IC50 =18.7 μM) that modify lysine residues in different Pol β active sites are characterized. Despite modifying lysine residues in different active sites, 1 and 9 inactivate the polymerase and lyase activities of Pol β. Fluorescence anisotropy experiments indicate that they do so by preventing DNA binding. Inhibitors 1 and 9 provide the basis for a general approach to preparing domain selective inhibitors of bifunctional polymerases. Such molecules could prove to be useful tools for studying the role of wild type and mutant forms of Pol β and other polymerases in DNA repair.
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Affiliation(s)
- Shelby C. Yuhas
- Department of ChemistryJohns Hopkins University3400N. Charles St.BaltimoreMD 21218USA
| | - Ananya Majumdar
- Biomolecular NMR CenterJohns Hopkins UniversityBaltimoreMD 21218USA
| | - Marc M. Greenberg
- Department of ChemistryJohns Hopkins University3400N. Charles St.BaltimoreMD 21218USA
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Yuhas SC, Laverty DJ, Lee H, Majumdar A, Greenberg MM. Selective Inhibition of DNA Polymerase β by a Covalent Inhibitor. J Am Chem Soc 2021; 143:8099-8107. [PMID: 34014094 DOI: 10.1021/jacs.1c02453] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
DNA polymerase β (Pol β) plays a vital role in DNA repair and has been closely linked to cancer. Selective inhibitors of this enzyme are lacking. Inspired by DNA lesions produced by antitumor agents that inactivate Pol β, we have undertaken the development of covalent small-molecule inhibitors of this enzyme. Using a two-stage process involving chemically synthesized libraries, we identified a potent irreversible inhibitor (14) of Pol β (KI = 1.8 ± 0.45 μM, kinact = (7.0 ± 1.0) × 10-3 s-1). Inhibitor 14 selectively inactivates Pol β over other DNA polymerases. LC-MS/MS analysis of trypsin digests of Pol β treated with 14 identified two lysines within the polymerase binding site that are covalently modified, one of which was previously determined to play a role in DNA binding. Fluorescence anisotropy experiments show that pretreatment of Pol β with 14 prevents DNA binding. Experiments using a pro-inhibitor (pro-14) in wild type mouse embryonic fibroblasts (MEFs) indicate that the inhibitor (5 μM) is itself not cytotoxic but works synergistically with the DNA alkylating agent, methylmethanesulfonate (MMS), to kill cells. Moreover, experiments in Pol β null MEFs indicate that pro-14 is selective for the target enzyme. Finally, pro-14 also works synergistically with MMS and bleomycin to kill HeLa cells. The results suggest that pro-14 is a potentially useful tool in studies of the role of Pol β in disease.
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Affiliation(s)
- Shelby C Yuhas
- Johns Hopkins University, Department of Chemistry, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Daniel J Laverty
- Johns Hopkins University, Department of Chemistry, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Huijin Lee
- Johns Hopkins University, Department of Chemistry, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Ananya Majumdar
- Johns Hopkins University, Biomolecular NMR Center, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Marc M Greenberg
- Johns Hopkins University, Department of Chemistry, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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Zahn KE, Jensen RB, Wood RD, Doublié S. RETRACTED: Human DNA polymerase θ harbors DNA end-trimming activity critical for DNA repair. Mol Cell 2021; 81:1534-1547.e4. [PMID: 33577776 PMCID: PMC8231307 DOI: 10.1016/j.molcel.2021.01.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 11/24/2020] [Accepted: 01/15/2021] [Indexed: 12/12/2022]
Abstract
Cancers with hereditary defects in homologous recombination rely on DNA polymerase θ (pol θ) for repair of DNA double-strand breaks. During end joining, pol θ aligns microhomology tracts internal to 5'-resected broken ends. An unidentified nuclease trims the 3' ends before synthesis can occur. Here we report that a nuclease activity, which differs from the proofreading activity often associated with DNA polymerases, is intrinsic to the polymerase domain of pol θ. Like the DNA synthesis activity, the nuclease activity requires conserved metal-binding residues, metal ions, and dNTPs and is inhibited by ddNTPs or chain-terminated DNA. Our data indicate that pol θ repurposes metal ions in the polymerase active site for endonucleolytic cleavage and that the polymerase-active and end-trimming conformations of the enzyme are distinct. We reveal a nimble strategy of substrate processing that allows pol θ to trim or extend DNA depending on the DNA repair context.
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Affiliation(s)
- Karl E Zahn
- Department of Microbiology and Molecular Genetics, University of Vermont, 89 Beaumont Ave., Burlington, VT 05405, USA; Department of Therapeutic Radiology, Yale University, New Haven, CT 06510, USA
| | - Ryan B Jensen
- Department of Therapeutic Radiology, Yale University, New Haven, CT 06510, USA
| | - Richard D Wood
- Department of Epigenetics & Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX 78957, USA.
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, 89 Beaumont Ave., Burlington, VT 05405, USA.
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Schrempf A, Slyskova J, Loizou JI. Targeting the DNA Repair Enzyme Polymerase θ in Cancer Therapy. Trends Cancer 2021; 7:98-111. [PMID: 33109489 DOI: 10.1016/j.trecan.2020.09.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/21/2020] [Accepted: 09/28/2020] [Indexed: 12/21/2022]
Abstract
Targeted cancer therapies represent a milestone towards personalized treatment as they function via inhibition of cancer-specific alterations. Polymerase θ (POLQ), an error-prone translesion polymerase, also involved in DNA double-strand break (DSB) repair, is often upregulated in cancer. POLQ is synthetic lethal with various DNA repair genes, including known cancer drivers such as BRCA1/2, making it essential in homologous recombination-deficient cancers. Thus, POLQ represents a promising target in cancer therapy and efforts for the development of POLQ inhibitors are actively underway with first clinical trials due to start in 2021. This review summarizes the journey of POLQ from a backup DNA repair enzyme to a promising therapeutic target for cancer treatment.
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Affiliation(s)
- Anna Schrempf
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT 25.3, 1090 Vienna, Austria; Institute of Cancer Research, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, 1090 Vienna, Austria
| | - Jana Slyskova
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT 25.3, 1090 Vienna, Austria; Institute of Cancer Research, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, 1090 Vienna, Austria.
| | - Joanna I Loizou
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT 25.3, 1090 Vienna, Austria; Institute of Cancer Research, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, 1090 Vienna, Austria.
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10
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Fang Q, Andrews J, Sharma N, Wilk A, Clark J, Slyskova J, Koczor CA, Lans H, Prakash A, Sobol RW. Stability and sub-cellular localization of DNA polymerase β is regulated by interactions with NQO1 and XRCC1 in response to oxidative stress. Nucleic Acids Res 2020; 47:6269-6286. [PMID: 31287140 PMCID: PMC6614843 DOI: 10.1093/nar/gkz293] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 03/24/2019] [Accepted: 04/11/2019] [Indexed: 12/14/2022] Open
Abstract
Protein–protein interactions regulate many essential enzymatic processes in the cell. Somatic mutations outside of an enzyme active site can therefore impact cellular function by disruption of critical protein–protein interactions. In our investigation of the cellular impact of the T304I cancer mutation of DNA Polymerase β (Polβ), we find that mutation of this surface threonine residue impacts critical Polβ protein–protein interactions. We show that proteasome-mediated degradation of Polβ is regulated by both ubiquitin-dependent and ubiquitin-independent processes via unique protein–protein interactions. The ubiquitin-independent proteasome pathway regulates the stability of Polβ in the cytosol via interaction between Polβ and NAD(P)H quinone dehydrogenase 1 (NQO1) in an NADH-dependent manner. Conversely, the interaction of Polβ with the scaffold protein X-ray repair cross complementing 1 (XRCC1) plays a role in the localization of Polβ to the nuclear compartment and regulates the stability of Polβ via a ubiquitin-dependent pathway. Further, we find that oxidative stress promotes the dissociation of the Polβ/NQO1 complex, enhancing the interaction of Polβ with XRCC1. Our results reveal that somatic mutations such as T304I in Polβ impact critical protein–protein interactions, altering the stability and sub-cellular localization of Polβ and providing mechanistic insight into how key protein–protein interactions regulate cellular responses to stress.
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Affiliation(s)
- Qingming Fang
- University of South Alabama Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Joel Andrews
- University of South Alabama Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Nidhi Sharma
- University of South Alabama Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Anna Wilk
- University of South Alabama Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Jennifer Clark
- University of South Alabama Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Jana Slyskova
- Department of Molecular Genetics, Erasmus MC, Erasmus University Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands
| | - Christopher A Koczor
- University of South Alabama Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Hannes Lans
- Department of Molecular Genetics, Erasmus MC, Erasmus University Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands.,Oncode Institute, Erasmus MC, Erasmus University Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands
| | - Aishwarya Prakash
- University of South Alabama Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Robert W Sobol
- University of South Alabama Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
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Razskazovskiy Y, Tegomoh M, Roginskaya M. Association with Polyamines and Polypeptides Increases the Relative Yield of 2-Deoxyribonolactone Lesions in Radiation-Damaged DNA. Radiat Res 2019; 192:324-330. [DOI: 10.1667/rr15396.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
| | - Modeste Tegomoh
- Departments of Chemistry, East Tennessee State University, Johnson City, Tennessee 37614
| | - Marina Roginskaya
- Departments of Chemistry, East Tennessee State University, Johnson City, Tennessee 37614
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12
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Laverty DJ, Greenberg MM. Expanded Substrate Scope of DNA Polymerase θ and DNA Polymerase β: Lyase Activity on 5'-Overhangs and Clustered Lesions. Biochemistry 2018; 57:6119-6127. [PMID: 30299084 PMCID: PMC6200648 DOI: 10.1021/acs.biochem.8b00911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
DNA polymerase θ (Pol θ) is a multifunctional enzyme with double-strand break (DSB) repair, translesion synthesis, and lyase activities. Pol θ lyase activity on ternary substrates containing a 5'-dRP that are produced during base excision repair of abasic sites (AP) is weak compared to that of DNA polymerase β (Pol β), a polymerase integrally involved in base excision repair. This led us to explore whether Pol θ utilizes its lyase activity to remove 5'-dRP and incise abasic sites from alternative substrates that might be produced during DNA damage and repair. We found that Pol θ exhibited lyase activity on abasic lesions near DSB termini and on clustered lesions. To calibrate the Pol θ activity, Pol β reactivity was examined with the same substrates. Pol β excised 5'-dRP from within a 5'-overhang 80 times faster than did Pol θ. Pol θ and Pol β also incised AP within clustered lesions but showed opposite preferences with respect to the polarity of the lesions. AP lesions in 5'-overhangs were typically excised by Pol β 35-50 times faster than those in a duplex substrate but 15-20-fold more slowly than 5'-dRP in a ternary complex. This is the first report of Pol θ exhibiting lyase activity within an unincised strand. These results suggest that bifunctional polymerases may exhibit lyase activity on a greater variety of substrates than previously recognized. A role in DSB repair could potentially be beneficial, while the aberrant activity exhibited on clustered lesions may be deleterious because of their conversion to DSBs.
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Affiliation(s)
- Daniel J. Laverty
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218
| | - Marc M. Greenberg
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218
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