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Kaszubowski JD, Trakselis MA. Beyond the Lesion: Back to High Fidelity DNA Synthesis. Front Mol Biosci 2022; 8:811540. [PMID: 35071328 PMCID: PMC8766770 DOI: 10.3389/fmolb.2021.811540] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 12/16/2021] [Indexed: 12/16/2022] Open
Abstract
High fidelity (HiFi) DNA polymerases (Pols) perform the bulk of DNA synthesis required to duplicate genomes in all forms of life. Their structural features, enzymatic mechanisms, and inherent properties are well-described over several decades of research. HiFi Pols are so accurate that they become stalled at sites of DNA damage or lesions that are not one of the four canonical DNA bases. Once stalled, the replisome becomes compromised and vulnerable to further DNA damage. One mechanism to relieve stalling is to recruit a translesion synthesis (TLS) Pol to rapidly synthesize over and past the damage. These TLS Pols have good specificities for the lesion but are less accurate when synthesizing opposite undamaged DNA, and so, mechanisms are needed to limit TLS Pol synthesis and recruit back a HiFi Pol to reestablish the replisome. The overall TLS process can be complicated with several cellular Pols, multifaceted protein contacts, and variable nucleotide incorporation kinetics all contributing to several discrete substitution (or template hand-off) steps. In this review, we highlight the mechanistic differences between distributive equilibrium exchange events and concerted contact-dependent switching by DNA Pols for insertion, extension, and resumption of high-fidelity synthesis beyond the lesion.
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Liu Y, Wang L, Xu X, Yuan Y, Zhang B, Li Z, Xie Y, Yan R, Zheng Z, Ji J, Murray JM, Carr AM, Kong D. The intra-S phase checkpoint directly regulates replication elongation to preserve the integrity of stalled replisomes. Proc Natl Acad Sci U S A 2021; 118:e2019183118. [PMID: 34108240 PMCID: PMC8214678 DOI: 10.1073/pnas.2019183118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
DNA replication is dramatically slowed down under replication stress. The regulation of replication speed is a conserved response in eukaryotes and, in fission yeast, requires the checkpoint kinases Rad3ATR and Cds1Chk2 However, the underlying mechanism of this checkpoint regulation remains unresolved. Here, we report that the Rad3ATR-Cds1Chk2 checkpoint directly targets the Cdc45-MCM-GINS (CMG) replicative helicase under replication stress. When replication forks stall, the Cds1Chk2 kinase directly phosphorylates Cdc45 on the S275, S322, and S397 residues, which significantly reduces CMG helicase activity. Furthermore, in cds1Chk2 -mutated cells, the CMG helicase and DNA polymerases are physically separated, potentially disrupting replisomes and collapsing replication forks. This study demonstrates that the intra-S phase checkpoint directly regulates replication elongation, reduces CMG helicase processivity, prevents CMG helicase delinking from DNA polymerases, and therefore helps preserve the integrity of stalled replisomes and replication forks.
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Affiliation(s)
- Yang Liu
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Lu Wang
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Xin Xu
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Yue Yuan
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Bo Zhang
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Zeyang Li
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Yuchen Xie
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Rui Yan
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Zeqi Zheng
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Jianguo Ji
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Johanne M Murray
- Genome Damage and Stability Center, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, United Kingdom
| | - Antony M Carr
- Genome Damage and Stability Center, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, United Kingdom
| | - Daochun Kong
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China;
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
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Cranford MT, Kaszubowski JD, Trakselis MA. A hand-off of DNA between archaeal polymerases allows high-fidelity replication to resume at a discrete intermediate three bases past 8-oxoguanine. Nucleic Acids Res 2020; 48:10986-10997. [PMID: 32997110 PMCID: PMC7641752 DOI: 10.1093/nar/gkaa803] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/22/2020] [Accepted: 09/16/2020] [Indexed: 01/12/2023] Open
Abstract
During DNA replication, the presence of 8-oxoguanine (8-oxoG) lesions in the template strand cause the high-fidelity (HiFi) DNA polymerase (Pol) to stall. An early response to 8-oxoG lesions involves ‘on-the-fly’ translesion synthesis (TLS), in which a specialized TLS Pol is recruited and replaces the stalled HiFi Pol for lesion bypass. The length of TLS must be long enough for effective bypass, but it must also be regulated to minimize replication errors by the TLS Pol. The exact position where the TLS Pol ends and the HiFi Pol resumes (i.e. the length of the TLS patch) has not been described. We use steady-state and pre-steady-state kinetic assays to characterize lesion bypass intermediates formed by different archaeal polymerase holoenzyme complexes that include PCNA123 and RFC. After bypass of 8-oxoG by TLS PolY, products accumulate at the template position three base pairs beyond the lesion. PolY is catalytically poor for subsequent extension from this +3 position beyond 8-oxoG, but this inefficiency is overcome by rapid extension of HiFi PolB1. The reciprocation of Pol activities at this intermediate indicates a defined position where TLS Pol extension is limited and where the DNA substrate is handed back to the HiFi Pol after bypass of 8-oxoG.
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Affiliation(s)
- Matthew T Cranford
- Baylor University, Department of Chemistry and Biochemistry, One Bear Place, #97348, Waco, TX 76798, USA
| | - Joseph D Kaszubowski
- Baylor University, Department of Chemistry and Biochemistry, One Bear Place, #97348, Waco, TX 76798, USA
| | - Michael A Trakselis
- Baylor University, Department of Chemistry and Biochemistry, One Bear Place, #97348, Waco, TX 76798, USA
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Jain R, Dhiman S, Grogan DW. Genetic Control of Oxidative Mutagenesis in Sulfolobus acidocaldarius. J Bacteriol 2020; 202:JB.00756-19. [PMID: 32482723 PMCID: PMC8404708 DOI: 10.1128/jb.00756-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 05/26/2020] [Indexed: 02/01/2023] Open
Abstract
To identify DNA-oxidation defenses of hyperthermophilic archaea, we deleted genes encoding the putative 7,8-dihydro-8-oxoguanine (oxoG)-targeted N-glycosylase of S. acidocaldarius (ogg; Saci_01367), the Y-family DNA polymerase (dbh; Saci_0554), or both, and measured the effects on cellular survival, replication accuracy, and oxoG bypass in vivo Spontaneous G:C to T:A transversions were elevated in all Δogg and Δdbh constructs, and the Δogg Δdbh double mutant lost viability at a faster rate than isogenic WT and ogg strains. The distribution of G:C to T:A transversions within mutation-detector genes suggested that reactivity of G toward oxidation and the effect on translation contribute heavily to the pattern of mutations that are recovered. An impact of the Ogg protein on overall efficiency of bypassing oxoG in transforming DNA was evident only in the absence of Dbh, and Ogg status did not affect the accuracy of bypass. Dbh function, in contrast, dramatically influenced both the efficiency and accuracy of oxoG bypass. Thus, Ogg and Dbh were found to work independently to avoid mutagenesis by oxoG, and inactivating this simple but effective defense system by deleting both genes imposed a severe mutational burden on S. acidocaldarius cells.IMPORTANCE Hyperthermophilic archaea are expected to have effective (and perhaps atypical) mechanisms to limit the genetic consequences of DNA damage, but few gene products have been demonstrated to have genome-preserving functions in vivo This study confirmed by genetic criteria that the S. acidocaldarius Ogg protein avoids the characteristic mutagenesis of G oxidation. This enzyme and the bypass polymerase Dbh have similar impacts on genome stability but work independently, and may comprise most of the DNA-oxidation defense of S. acidocaldarius The critical dependence of accurate oxoG bypass on the accessory DNA polymerase Dbh further argues that some form of polymerase exchange is important for accurate genome replication in Sulfolobus, and perhaps in related hyperthermophilic archaea.
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Affiliation(s)
- Rupal Jain
- Department of Biological Sciences, 614 Rieveschl Hall, ML0006, University of Cincinnati 513-556-9748
| | - Samuel Dhiman
- Department of Biological Sciences, 614 Rieveschl Hall, ML0006, University of Cincinnati 513-556-9748
| | - Dennis W Grogan
- Department of Biological Sciences, 614 Rieveschl Hall, ML0006, University of Cincinnati 513-556-9748
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Bailey LJ, Bianchi J, Doherty AJ. PrimPol is required for the maintenance of efficient nuclear and mitochondrial DNA replication in human cells. Nucleic Acids Res 2019; 47:4026-4038. [PMID: 30715459 PMCID: PMC6486543 DOI: 10.1093/nar/gkz056] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 01/14/2019] [Accepted: 01/28/2019] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic Primase-Polymerase (PrimPol) is an enzyme that maintains efficient DNA duplication by repriming replication restart downstream of replicase stalling lesions and structures. To elucidate the cellular requirements for PrimPol in human cells, we generated PrimPol-deleted cell lines and show that it plays key roles in maintaining active replication in both the nucleus and mitochondrion, even in the absence of exogenous damage. Human cells lacking PrimPol exhibit delayed recovery after UV-C damage and increased mutation frequency, micronuclei and sister chromatin exchanges but are not sensitive to genotoxins. PrimPol is also required during mitochondrial replication, with PrimPol-deficient cells having increased mtDNA copy number but displaying a significant decrease in replication. Deletion of PrimPol in XPV cells, lacking functional polymerase Eta, causes an increase in DNA damage sensitivity and pronounced fork stalling after UV-C treatment. We show that, unlike canonical TLS polymerases, PrimPol is important for allowing active replication to proceed, even in the absence of exogenous damage, thus preventing the accumulation of excessive fork stalling and genetic mutations. Together, these findings highlight the importance of PrimPol for maintaining efficient DNA replication in unperturbed cells and its complementary roles, with Pol Eta, in damage tolerance in human cells.
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Affiliation(s)
- Laura J Bailey
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Julie Bianchi
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Aidan J Doherty
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
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Mueller SH, Spenkelink LM, van Oijen AM. When proteins play tag: the dynamic nature of the replisome. Biophys Rev 2019; 11:641-651. [PMID: 31273608 PMCID: PMC6682189 DOI: 10.1007/s12551-019-00569-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 06/24/2019] [Indexed: 02/06/2023] Open
Abstract
DNA replication, or the copying of DNA, is a fundamental process to all life. The system of proteins that carries out replication, the replisome, encounters many roadblocks on its way. An inability of the replisome to properly overcome these roadblocks will negatively affect genomic integrity which in turn can lead to disease. Over the past decades, efforts by many researchers using a broad array of approaches have revealed roles for many different proteins during the initial response of the replisome upon encountering roadblocks. Here, we revisit what is known about DNA replication and the effect of roadblocks during DNA replication across different organisms. We also address how advances in single-molecule techniques have changed our view of the replisome from a highly stable machine with behavior dictated by deterministic principles to a dynamic system that is controlled by stochastic processes. We propose that these dynamics will play crucial roles in roadblock bypass. Further single-molecule studies of this bypass will, therefore, be essential to facilitate the in-depth investigation of multi-protein complexes that is necessary to understand complicated collisions on the DNA.
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Affiliation(s)
- Stefan H Mueller
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales, 2522, Australia
- Illawarra Health & Medical Research Institute, Wollongong, New South Wales, 2522, Australia
| | - Lisanne M Spenkelink
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales, 2522, Australia
- Illawarra Health & Medical Research Institute, Wollongong, New South Wales, 2522, Australia
| | - Antoine M van Oijen
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales, 2522, Australia.
- Illawarra Health & Medical Research Institute, Wollongong, New South Wales, 2522, Australia.
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