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Wysong BC, Schuck PL, Sridharan M, Carrison S, Murakami Y, Balakrishnan L, Stewart JA. Human CST Stimulates Base Excision Repair to Prevent the Accumulation of Oxidative DNA Damage. J Mol Biol 2024; 436:168672. [PMID: 38908783 DOI: 10.1016/j.jmb.2024.168672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 06/14/2024] [Accepted: 06/17/2024] [Indexed: 06/24/2024]
Abstract
CTC1-STN1-TEN1 (CST) is a single-stranded DNA binding protein vital for telomere length maintenance with additional genome-wide roles in DNA replication and repair. While CST was previously shown to function in double-strand break repair and promote replication restart, it is currently unclear whether it has specialized roles in other DNA repair pathways. Proper and efficient repair of DNA is critical to protecting genome integrity. Telomeres and other G-rich regions are strongly predisposed to oxidative DNA damage in the form of 8-oxoguanines, which are typically repaired by the base-excision repair (BER) pathway. Moreover, recent studies suggest that CST functions in the repair of oxidative DNA lesions. Therefore, we tested whether CST interacts with and regulates BER protein activity. Here, we show that CST robustly stimulates proteins involved in BER, including OGG1, Pol β, APE1, and LIGI, on both telomeric and non-telomeric DNA substrates. Biochemical reconstitution of the pathway indicates that CST stimulates BER. Finally, knockout of STN1 or CTC1 leads to increased levels of 8-oxoguanine, suggesting defective BER in the absence of CST. Combined, our results define an undiscovered function of CST in BER, where it acts as a stimulatory factor to promote efficient genome-wide oxidative repair.
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Affiliation(s)
- Brandon C Wysong
- Department of Biology, School of Science, Indiana University, Indianapolis, IN, USA
| | - P Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, USA
| | - Madhumita Sridharan
- Department of Biology, School of Science, Indiana University, Indianapolis, IN, USA
| | - Sophie Carrison
- Department of Biology, School of Science, Indiana University, Indianapolis, IN, USA
| | - Yuichihiro Murakami
- Department of Biology, School of Science, Indiana University, Indianapolis, IN, USA
| | - Lata Balakrishnan
- Department of Biology, School of Science, Indiana University, Indianapolis, IN, USA.
| | - Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, USA; Department of Biology, Western Kentucky University, Bowling Green, KY, USA.
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2
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Orren DK, Machwe A. Response to Replication Stress and Maintenance of Genome Stability by WRN, the Werner Syndrome Protein. Int J Mol Sci 2024; 25:8300. [PMID: 39125869 PMCID: PMC11311767 DOI: 10.3390/ijms25158300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 07/16/2024] [Accepted: 07/25/2024] [Indexed: 08/12/2024] Open
Abstract
Werner syndrome (WS) is an autosomal recessive disease caused by loss of function of WRN. WS is a segmental progeroid disease and shows early onset or increased frequency of many characteristics of normal aging. WRN possesses helicase, annealing, strand exchange, and exonuclease activities and acts on a variety of DNA substrates, even complex replication and recombination intermediates. Here, we review the genetics, biochemistry, and probably physiological functions of the WRN protein. Although its precise role is unclear, evidence suggests WRN plays a role in pathways that respond to replication stress and maintain genome stability particularly in telomeric regions.
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Affiliation(s)
- David K. Orren
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY 40536, USA;
- Markey Cancer Center, University of Kentucky, Lexington, KY 40506, USA
| | - Amrita Machwe
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY 40536, USA;
- Markey Cancer Center, University of Kentucky, Lexington, KY 40506, USA
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3
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Gadgil RY, Rider SD, Shrestha R, Alhawach V, Hitch D, Leffak M. Microsatellite break-induced replication generates highly mutagenized extrachromosomal circular DNAs. NAR Cancer 2024; 6:zcae027. [PMID: 38854437 PMCID: PMC11161834 DOI: 10.1093/narcan/zcae027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 05/17/2024] [Accepted: 05/24/2024] [Indexed: 06/11/2024] Open
Abstract
Extrachromosomal circular DNAs (eccDNAs) are produced from all regions of the eucaryotic genome. We used inverse PCR of non-B microsatellites capable of forming hairpin, triplex, quadruplex and AT-rich structures integrated at a common ectopic chromosomal site to show that these non-B DNAs generate highly mutagenized eccDNAs by replication-dependent mechanisms. Mutagenesis occurs within the non-B DNAs and extends several kilobases bidirectionally into flanking and nonallelic DNA. Each non-B DNA exhibits a different pattern of mutagenesis, while sister clones containing the same non-B DNA also display distinct patterns of recombination, microhomology-mediated template switching and base substitutions. Mutations include mismatches, short duplications, long nontemplated insertions, large deletions and template switches to sister chromatids and nonallelic chromosomes. Drug-induced replication stress or the depletion of DNA repair factors Rad51, the COPS2 signalosome subunit or POLη change the pattern of template switching and alter the eccDNA mutagenic profiles. We propose an asynchronous capture model based on break-induced replication from microsatellite-induced DNA double strand breaks to account for the generation and circularization of mutagenized eccDNAs and the appearance of genomic homologous recombination deficiency (HRD) scars. These results may help to explain the appearance of tumor eccDNAS and their roles in neoantigen production, oncogenesis and resistance to chemotherapy.
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Affiliation(s)
- Rujuta Yashodhan Gadgil
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - S Dean Rider
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - Resha Shrestha
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - Venicia Alhawach
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - David C Hitch
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - Michael Leffak
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
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4
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Guo L, Bao Y, Zhao Y, Ren Z, Bi L, Zhang X, Liu C, Hou X, Wang MD, Sun B. Joint Efforts of Replicative Helicase and SSB Ensure Inherent Replicative Tolerance of G-Quadruplex. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307696. [PMID: 38126671 PMCID: PMC10916570 DOI: 10.1002/advs.202307696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/28/2023] [Indexed: 12/23/2023]
Abstract
G-quadruplex (G4) is a four-stranded noncanonical DNA structure that has long been recognized as a potential hindrance to DNA replication. However, how replisomes effectively deal with G4s to avoid replication failure is still obscure. Here, using single-molecule and ensemble approaches, the consequence of the collision between bacteriophage T7 replisome and an intramolecular G4 located on either the leading or lagging strand is examined. It is found that the adjacent fork junctions induced by G4 formation incur the binding of T7 DNA polymerase (DNAP). In addition to G4, these inactive DNAPs present insuperable obstacles, impeding the progression of DNA synthesis. Nevertheless, T7 helicase can dismantle them and resolve lagging-strand G4s, paving the way for the advancement of the replication fork. Moreover, with the assistance of the single-stranded DNA binding protein (SSB) gp2.5, T7 helicase is also capable of maintaining a leading-strand G4 structure in an unfolded state, allowing for a fraction of T7 DNAPs to synthesize through without collapse. These findings broaden the functional repertoire of a replicative helicase and underscore the inherent G4 tolerance of a replisome.
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Affiliation(s)
- Lijuan Guo
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Yanling Bao
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Yilin Zhao
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Zhiyun Ren
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell BiologyChinese Academy of SciencesShanghai200031China
- University of Chinese Academy of SciencesBeijing100049China
| | - Lulu Bi
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Xia Zhang
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Cong Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai201210China
| | - Xi‐Miao Hou
- College of Life SciencesNorthwest A&F UniversityYanglingShaanxi712100China
| | - Michelle D. Wang
- Department of Physics, Laboratory of Atomic and Solid State PhysicsCornell UniversityIthacaNY14853USA
- Howard Hughes Medical InstituteCornell UniversityIthacaNY14853USA
| | - Bo Sun
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
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5
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Gadgil RY, Rider SD, Shrestha R, Alhawach V, Hitch DC, Leffak M. Microsatellite break-induced replication generates highly mutagenized extrachromosomal circular DNAs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.12.575055. [PMID: 38260482 PMCID: PMC10802558 DOI: 10.1101/2024.01.12.575055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Extrachromosomal circular DNAs (eccDNAs) are produced from all regions of the eucaryotic genome. In tumors, highly transcribed eccDNAs have been implicated in oncogenesis, neoantigen production and resistance to chemotherapy. Here we show that unstable microsatellites capable of forming hairpin, triplex, quadruplex and AT-rich structures generate eccDNAs when integrated at a common ectopic site in human cells. These non-B DNA prone microsatellites form eccDNAs by replication-dependent mechanisms. The microsatellite-based eccDNAs are highly mutagenized and display template switches to sister chromatids and to nonallelic chromosomal sites. High frequency mutagenesis occurs within the eccDNA microsatellites and extends bidirectionally for several kilobases into flanking DNA and nonallelic DNA. Mutations include mismatches, short duplications, longer nontemplated insertions and large deletions. Template switching leads to recurrent deletions and recombination domains within the eccDNAs. Template switching events are microhomology-mediated, but do not occur at all potential sites of complementarity. Each microsatellite exhibits a distinct pattern of recombination, microhomology choice and base substitution signature. Depletion of Rad51, the COPS2 signalosome subunit or POLη alter the eccDNA mutagenic profiles. We propose an asynchronous capture model based on break-induced replication from microsatellite-induced DNA breaks for the generation and circularization of mutagenized eccDNAs and genomic homologous recombination deficiency (HRD) scars.
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6
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Williams SL, Casas‐Delucchi CS, Raguseo F, Guneri D, Li Y, Minamino M, Fletcher EE, Yeeles JTP, Keyser UF, Waller ZAE, Di Antonio M, Coster G. Replication-induced DNA secondary structures drive fork uncoupling and breakage. EMBO J 2023; 42:e114334. [PMID: 37781931 PMCID: PMC10646557 DOI: 10.15252/embj.2023114334] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 09/20/2023] [Accepted: 09/21/2023] [Indexed: 10/03/2023] Open
Abstract
Sequences that form DNA secondary structures, such as G-quadruplexes (G4s) and intercalated-Motifs (iMs), are abundant in the human genome and play various physiological roles. However, they can also interfere with replication and threaten genome stability. Multiple lines of evidence suggest G4s inhibit replication, but the underlying mechanism remains unclear. Moreover, evidence of how iMs affect the replisome is lacking. Here, we reconstitute replication of physiologically derived structure-forming sequences to find that a single G4 or iM arrest DNA replication. Direct single-molecule structure detection within solid-state nanopores reveals structures form as a consequence of replication. Combined genetic and biophysical characterisation establishes that structure stability and probability of structure formation are key determinants of replisome arrest. Mechanistically, replication arrest is caused by impaired synthesis, resulting in helicase-polymerase uncoupling. Significantly, iMs also induce breakage of nascent DNA. Finally, stalled forks are only rescued by a specialised helicase, Pif1, but not Rrm3, Sgs1, Chl1 or Hrq1. Altogether, we provide a mechanism for quadruplex structure formation and resolution during replication and highlight G4s and iMs as endogenous sources of replication stress.
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Affiliation(s)
- Sophie L Williams
- Genome Replication Lab, Division of Cancer Biology, Institute of Cancer ResearchChester Beatty LaboratoriesLondonUK
| | - Corella S Casas‐Delucchi
- Genome Replication Lab, Division of Cancer Biology, Institute of Cancer ResearchChester Beatty LaboratoriesLondonUK
| | - Federica Raguseo
- Chemistry DepartmentImperial College London, MSRHLondonUK
- Institute of Chemical Biology, MSRHLondonUK
| | | | - Yunxuan Li
- Cavendish LaboratoryUniversity of CambridgeCambridgeUK
| | | | | | | | | | | | - Marco Di Antonio
- Chemistry DepartmentImperial College London, MSRHLondonUK
- Institute of Chemical Biology, MSRHLondonUK
- Francis Crick InstituteLondonUK
| | - Gideon Coster
- Genome Replication Lab, Division of Cancer Biology, Institute of Cancer ResearchChester Beatty LaboratoriesLondonUK
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7
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Njeri C, Pepenella S, Battapadi T, Bambara RA, Balakrishnan L. DNA Polymerase Delta Exhibits Altered Catalytic Properties on Lysine Acetylation. Genes (Basel) 2023; 14:genes14040774. [PMID: 37107532 PMCID: PMC10137900 DOI: 10.3390/genes14040774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/20/2023] [Accepted: 03/21/2023] [Indexed: 04/29/2023] Open
Abstract
DNA polymerase delta is the primary polymerase that is involved in undamaged nuclear lagging strand DNA replication. Our mass-spectroscopic analysis has revealed that the human DNA polymerase δ is acetylated on subunits p125, p68, and p12. Using substrates that simulate Okazaki fragment intermediates, we studied alterations in the catalytic properties of acetylated polymerase and compared it to the unmodified form. The current data show that the acetylated form of human pol δ displays a higher polymerization activity compared to the unmodified form of the enzyme. Additionally, acetylation enhances the ability of the polymerase to resolve complex structures such as G-quadruplexes and other secondary structures that might be present on the template strand. More importantly, the ability of pol δ to displace a downstream DNA fragment is enhanced upon acetylation. Our current results suggest that acetylation has a profound effect on the activity of pol δ and supports the hypothesis that acetylation may promote higher-fidelity DNA replication.
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Affiliation(s)
- Catherine Njeri
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Sharon Pepenella
- Department of Microbiology and Immunology, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Tripthi Battapadi
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Robert A Bambara
- Department of Microbiology and Immunology, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Lata Balakrishnan
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA
- Indiana University Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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8
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Brush GS. Anomalies in dye-terminator DNA sequencing caused by a natural G-quadruplex. PLoS One 2022; 17:e0279423. [PMID: 36574393 PMCID: PMC9794070 DOI: 10.1371/journal.pone.0279423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 11/24/2022] [Indexed: 12/29/2022] Open
Abstract
A G-rich DNA sequence from yeast that can form a non-canonical G-quadruplex structure was cloned into a plasmid vector and subjected to Sanger sequencing using dye-labeled dideoxynucleotides. Two different effects were observed. In one, presence of the G4 sequence on the template strand led to incorrect incorporation of an A residue at an internal position in the G4 sequence. In the other, the nascent strand caused attenuation of the readout coincident with synthesis of the G-rich DNA. The two effects are novel examples of disruption in DNA synthesis caused by a G4 sequence. These results provide a new example of a DNA structure that could influence genomic stability in human cells.
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Affiliation(s)
- George S. Brush
- Department of Oncology, Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine,Detroit, MI, United States of America
- * E-mail:
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9
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Williams SL, Coster G. Cloning and expansion of repetitive DNA sequences. Methods Cell Biol 2022; 182:167-185. [PMID: 38359975 DOI: 10.1016/bs.mcb.2022.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Repeat and structure-prone DNA sequences comprise a large proportion of the human genome. The instability of these sequences has been implicated in a range of diseases, including cancers and neurodegenerative disorders. However, the mechanism of pathogenicity is poorly understood. As such, further studies on repetitive DNA are required. Cloning and maintaining repeat-containing substrates is challenging due to their inherent ability to form non-B DNA secondary structures which are refractory to DNA polymerases and prone to undergo rearrangements. Here, we describe an approach to clone and expand tandem-repeat DNA without interruptions, thereby allowing for its manipulation and subsequent investigation.
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Affiliation(s)
- Sophie L Williams
- Genome Replication lab, Division of Cancer Biology, Institute of Cancer Research, Chester Beatty Laboratories, London, United Kingdom
| | - Gideon Coster
- Genome Replication lab, Division of Cancer Biology, Institute of Cancer Research, Chester Beatty Laboratories, London, United Kingdom.
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10
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Stein M, Hile SE, Weissensteiner MH, Lee M, Zhang S, Kejnovský E, Kejnovská I, Makova KD, Eckert KA. Variation in G-quadruplex sequence and topology differentially impacts human DNA polymerase fidelity. DNA Repair (Amst) 2022; 119:103402. [PMID: 36116264 PMCID: PMC9798401 DOI: 10.1016/j.dnarep.2022.103402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 08/12/2022] [Accepted: 09/02/2022] [Indexed: 12/31/2022]
Abstract
G-quadruplexes (G4s), a type of non-B DNA, play important roles in a wide range of molecular processes, including replication, transcription, and translation. Genome integrity relies on efficient and accurate DNA synthesis, and is compromised by various stressors, to which non-B DNA structures such as G4s can be particularly vulnerable. However, the impact of G4 structures on DNA polymerase fidelity is largely unknown. Using an in vitro forward mutation assay, we investigated the fidelity of human DNA polymerases delta (δ4, four-subunit), eta (η), and kappa (κ) during synthesis of G4 motifs representing those in the human genome. The motifs differ in sequence, topology, and stability, features that may affect DNA polymerase errors. Polymerase error rate hierarchy (δ4 < κ < η) is largely maintained during G4 synthesis. Importantly, we observed unique polymerase error signatures during synthesis of VEGF G4 motifs, stable G4s which form parallel topologies. These statistically significant errors occurred within, immediately flanking, and encompassing the G4 motif. For pol δ4, the errors were deletions, insertions and complex errors within the G4 or encompassing the G4 motif and surrounding sequence. For pol η, the errors occurred in 3' sequences flanking the G4 motif. For pol κ, the errors were frameshift mutations within G-tracts of the G4. Because these error signatures were not observed during synthesis of an antiparallel G4 and, to a lesser extent, a hybrid G4, we suggest that G4 topology and/or stability could influence polymerase fidelity. Using in silico analyses, we show that most polymerase errors are predicted to have minimal effects on predicted G4 stability. Our results provide a unique view of G4s not previously elucidated, showing that G4 motif heterogeneity differentially influences polymerase fidelity within the motif and flanking sequences. Thus, our study advances the understanding of how DNA polymerase errors contribute to G4 mutagenesis.
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Affiliation(s)
- MaryElizabeth Stein
- Department of Pathology, The Jake Gittlen Laboratories for Cancer Research, Penn State University College of Medicine, Hershey, PA, USA
| | - Suzanne E Hile
- Department of Pathology, The Jake Gittlen Laboratories for Cancer Research, Penn State University College of Medicine, Hershey, PA, USA
| | | | - Marietta Lee
- Department of Biochemistry & Molecular Biology, New York Medical College, Valhalla, NY, USA
| | - Sufang Zhang
- Department of Biochemistry & Molecular Biology, New York Medical College, Valhalla, NY, USA
| | - Eduard Kejnovský
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Iva Kejnovská
- Department of Biophysics of Nucleic Acids, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Kateryna D Makova
- Department of Biology, Penn State University Eberly College of Science, University Park, PA, USA
| | - Kristin A Eckert
- Department of Pathology, The Jake Gittlen Laboratories for Cancer Research, Penn State University College of Medicine, Hershey, PA, USA.
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11
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Liu X, Cui S, Qi Q, Lei H, Zhang Y, Shen W, Fu F, Tian T, Zhou X. G-quadruplex-guided RNA engineering to modulate CRISPR-based genomic regulation. Nucleic Acids Res 2022; 50:11387-11400. [PMID: 36263801 PMCID: PMC9638906 DOI: 10.1093/nar/gkac870] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/23/2022] [Accepted: 09/27/2022] [Indexed: 11/14/2022] Open
Abstract
It is important to develop small moelcule-based methods to modulate gene editing and expression in human cells. The roles of the G-quadruplex (G4) in biological systems have been widely studied. Here, G4-guided RNA engineering is performed to generate guide RNA with G4-forming units (G4-gRNA). We further demonstrate that chemical targeting of G4-gRNAs holds promise as a general approach for modulating gene editing and expression in human cells. The rich structural diversity of RNAs offers a reservoir of targets for small molecules to bind, thus creating the potential to modulate RNA biology.
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Affiliation(s)
- Xingyu Liu
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan 430072, Hubei, China
| | - Shuangyu Cui
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan 430072, Hubei, China
| | - Qianqian Qi
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan 430072, Hubei, China
| | - Huajun Lei
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan 430072, Hubei, China
| | - Yutong Zhang
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan 430072, Hubei, China
| | - Wei Shen
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan 430072, Hubei, China
| | - Fang Fu
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan 430072, Hubei, China
| | - Tian Tian
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan 430072, Hubei, China
| | - Xiang Zhou
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan 430072, Hubei, China
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12
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Research on Werner Syndrome: Trends from Past to Present and Future Prospects. Genes (Basel) 2022; 13:genes13101802. [PMID: 36292687 PMCID: PMC9601476 DOI: 10.3390/genes13101802] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/02/2022] [Accepted: 10/04/2022] [Indexed: 11/17/2022] Open
Abstract
A rare and autosomal recessive premature aging disorder, Werner syndrome (WS) is characterized by the early onset of aging-associated diseases, including shortening stature, alopecia, bilateral cataracts, skin ulcers, diabetes, osteoporosis, arteriosclerosis, and chromosomal instability, as well as cancer predisposition. WRN, the gene responsible for WS, encodes DNA helicase with a 3′ to 5′ exonuclease activity, and numerous studies have revealed that WRN helicase is involved in the maintenance of chromosome stability through actions in DNA, e.g., DNA replication, repair, recombination, and epigenetic regulation via interaction with DNA repair factors, telomere-binding proteins, histone modification enzymes, and other DNA metabolic factors. However, although these efforts have elucidated the cellular functions of the helicase in cell lines, they have not been linked to the treatment of the disease. Life expectancy has improved for WS patients over the past three decades, and it is hoped that a fundamental treatment for the disease will be developed. Disease-specific induced pluripotent stem (iPS) cells have been established, and these are expected to be used in drug discovery and regenerative medicine for WS patients. In this article, we review trends in research to date and present some perspectives on WS research with regard to the application of pluripotent stem cells. Furthermore, the elucidation of disease mechanisms and drug discovery utilizing the vast amount of scientific data accumulated to date will be discussed.
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13
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Dai Y, Guo H, Liu N, Chen W, Ai X, Li H, Sun B, Hou X, Rety S, Xi X. Structural mechanism underpinning Thermus oshimai Pif1-mediated G-quadruplex unfolding. EMBO Rep 2022; 23:e53874. [PMID: 35736675 PMCID: PMC9253758 DOI: 10.15252/embr.202153874] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 05/04/2022] [Accepted: 05/16/2022] [Indexed: 08/05/2023] Open
Abstract
G-quadruplexes (G4s) are unusual stable DNA structures that cause genomic instability. To overcome the potential barriers formed by G4s, cells have evolved different families of proteins that unfold G4s. Pif1 is a DNA helicase from superfamily 1 (SF1) conserved from bacteria to humans with high G4-unwinding activity. Here, we present the first X-ray crystal structure of the Thermus oshimai Pif1 (ToPif1) complexed with a G4. Our structure reveals that ToPif1 recognizes the entire native G4 via a cluster of amino acids at domains 1B/2B which constitute a G4-Recognizing Surface (GRS). The overall structure of the G4 maintains its three-layered propeller-type G4 topology, without significant reorganization of G-tetrads upon protein binding. The three G-tetrads in G4 are recognized by GRS residues mainly through electrostatic, ionic interactions, and hydrogen bonds formed between the GRS residues and the ribose-phosphate backbone. Compared with previously solved structures of SF2 helicases in complex with G4, our structure reveals how helicases from distinct superfamilies adopt different strategies for recognizing and unfolding G4s.
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Affiliation(s)
- Yang‐Xue Dai
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Hai‐Lei Guo
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Na‐Nv Liu
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Wei‐Fei Chen
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Xia Ai
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Hai‐Hong Li
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Bo Sun
- School of Life Science and TechnologyShanghaiTech UniversityShanghaiChina
| | - Xi‐Miao Hou
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Stephane Rety
- LBMCENS de LyonCNRS UMR 5239INSERM U1293Universite Claude Bernard Lyon 1LyonFrance
| | - Xu‐Guang Xi
- College of Life SciencesNorthwest A&F UniversityYanglingChina
- Laboratoire de Biologie et Pharmacologie Appliquée (LBPA)UMR8113 CNRSENS Paris‐SaclayUniversité Paris‐SaclayGif‐sur‐YvetteFrance
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14
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Biochemical analysis of DNA synthesis blockage by G-quadruplex structure and bypass facilitated by a G4-resolving helicase. Methods 2021; 204:207-214. [PMID: 34929333 PMCID: PMC9203602 DOI: 10.1016/j.ymeth.2021.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 12/07/2021] [Accepted: 12/14/2021] [Indexed: 12/21/2022] Open
Abstract
G-quadruplex (G4) DNA poses a unique obstacle to DNA synthesis during replication or DNA repair due to its unusual structure which deviates significantly from the conventional DNA double helix. A mechanism to overcome the G4 roadblock is provided by the action of a G4-resolving helicase that collaborates with the DNA polymerase to smoothly catalyze polynucleotide synthesis past the unwound G4. In this technique-focused paper, we describe the experimental approaches of the primer extension assay using a G4 DNA template to measure the extent and fidelity of DNA synthesis by a DNA polymerase acting in concert with a G4-resolving DNA helicase. Important parameters pertaining to reaction conditions and controls are discussed to aid in the design of experiments and interpretation of the data obtained. This methodology can be applied in multiple capacities that may depend on the DNA substrate, DNA polymerase, or DNA helicase under investigation.
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15
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Linke R, Limmer M, Juranek SA, Heine A, Paeschke K. The Relevance of G-Quadruplexes for DNA Repair. Int J Mol Sci 2021; 22:12599. [PMID: 34830478 PMCID: PMC8620898 DOI: 10.3390/ijms222212599] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/16/2021] [Accepted: 11/17/2021] [Indexed: 01/28/2023] Open
Abstract
DNA molecules can adopt a variety of alternative structures. Among these structures are G-quadruplex DNA structures (G4s), which support cellular function by affecting transcription, translation, and telomere maintenance. These structures can also induce genome instability by stalling replication, increasing DNA damage, and recombination events. G-quadruplex-driven genome instability is connected to tumorigenesis and other genetic disorders. In recent years, the connection between genome stability, DNA repair and G4 formation was further underlined by the identification of multiple DNA repair proteins and ligands which bind and stabilize said G4 structures to block specific DNA repair pathways. The relevance of G4s for different DNA repair pathways is complex and depends on the repair pathway itself. G4 structures can induce DNA damage and block efficient DNA repair, but they can also support the activity and function of certain repair pathways. In this review, we highlight the roles and consequences of G4 DNA structures for DNA repair initiation, processing, and the efficiency of various DNA repair pathways.
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Affiliation(s)
- Rebecca Linke
- Department of Oncology, Hematology, Rheumatology and Immune-Oncology, University Hospital Bonn, 53127 Bonn, Germany; (R.L.); (M.L.); (S.A.J.); (A.H.)
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010, Australia
| | - Michaela Limmer
- Department of Oncology, Hematology, Rheumatology and Immune-Oncology, University Hospital Bonn, 53127 Bonn, Germany; (R.L.); (M.L.); (S.A.J.); (A.H.)
| | - Stefan A. Juranek
- Department of Oncology, Hematology, Rheumatology and Immune-Oncology, University Hospital Bonn, 53127 Bonn, Germany; (R.L.); (M.L.); (S.A.J.); (A.H.)
| | - Annkristin Heine
- Department of Oncology, Hematology, Rheumatology and Immune-Oncology, University Hospital Bonn, 53127 Bonn, Germany; (R.L.); (M.L.); (S.A.J.); (A.H.)
| | - Katrin Paeschke
- Department of Oncology, Hematology, Rheumatology and Immune-Oncology, University Hospital Bonn, 53127 Bonn, Germany; (R.L.); (M.L.); (S.A.J.); (A.H.)
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16
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Impact of G-Quadruplexes and Chronic Inflammation on Genome Instability: Additive Effects during Carcinogenesis. Genes (Basel) 2021; 12:genes12111779. [PMID: 34828385 PMCID: PMC8619830 DOI: 10.3390/genes12111779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 02/07/2023] Open
Abstract
Genome instability is an enabling characteristic of cancer, essential for cancer cell evolution. Hotspots of genome instability, from small-scale point mutations to large-scale structural variants, are associated with sequences that potentially form non-B DNA structures. G-quadruplex (G4) forming motifs are enriched at structural variant endpoints in cancer genomes. Chronic inflammation is a physiological state underlying cancer development, and oxidative DNA damage is commonly invoked to explain how inflammation promotes genome instability. We summarize where G4s and oxidative stress overlap, with a focus on DNA replication. Guanine has low ionization potential, making G4s vulnerable to oxidative damage. Impacts to G4 structure are dependent upon lesion type, location, and G4 conformation. Occasionally, G4s pose a challenge to replicative DNA polymerases, requiring specialized DNA polymerases to maintain genome stability. Therefore, chronic inflammation creates a dual challenge for DNA polymerases to maintain genome stability: faithful G4 synthesis and bypassing unrepaired oxidative lesions. Inflammation is also accompanied by global transcriptome changes that may impact mutagenesis. Several studies suggest a regulatory role for G4s within cancer- and inflammatory-related gene promoters. We discuss the extent to which inflammation could influence gene regulation by G4s, thereby impacting genome instability, and highlight key areas for new investigation.
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17
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Kumar C, Batra S, Griffith JD, Remus D. The interplay of RNA:DNA hybrid structure and G-quadruplexes determines the outcome of R-loop-replisome collisions. eLife 2021; 10:72286. [PMID: 34494544 PMCID: PMC8479836 DOI: 10.7554/elife.72286] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Accepted: 09/07/2021] [Indexed: 12/11/2022] Open
Abstract
R-loops are a major source of genome instability associated with transcription-induced replication stress. However, how R-loops inherently impact replication fork progression is not understood. Here, we characterize R-loop-replisome collisions using a fully reconstituted eukaryotic DNA replication system. We find that RNA:DNA hybrids and G-quadruplexes at both co-directional and head-on R-loops can impact fork progression by inducing fork stalling, uncoupling of leading strand synthesis from replisome progression, and nascent strand gaps. RNase H1 and Pif1 suppress replication defects by resolving RNA:DNA hybrids and G-quadruplexes, respectively. We also identify an intrinsic capacity of replisomes to maintain fork progression at certain R-loops by unwinding RNA:DNA hybrids, repriming leading strand synthesis downstream of G-quadruplexes, or utilizing R-loop transcripts to prime leading strand restart during co-directional R-loop-replisome collisions. Collectively, the data demonstrates that the outcome of R-loop-replisome collisions is modulated by R-loop structure, providing a mechanistic basis for the distinction of deleterious from non-deleterious R-loops.
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Affiliation(s)
- Charanya Kumar
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Sahil Batra
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Jack D Griffith
- Lineberger Comprehensive Cancer Center and Departments of Microbiology and Immunology, and Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Dirk Remus
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
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18
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Pérez-Arnaiz P, Dattani A, Smith V, Allers T. Haloferax volcanii-a model archaeon for studying DNA replication and repair. Open Biol 2020; 10:200293. [PMID: 33259746 PMCID: PMC7776575 DOI: 10.1098/rsob.200293] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/09/2020] [Indexed: 12/16/2022] Open
Abstract
The tree of life shows the relationship between all organisms based on their common ancestry. Until 1977, it comprised two major branches: prokaryotes and eukaryotes. Work by Carl Woese and other microbiologists led to the recategorization of prokaryotes and the proposal of three primary domains: Eukarya, Bacteria and Archaea. Microbiological, genetic and biochemical techniques were then needed to study the third domain of life. Haloferax volcanii, a halophilic species belonging to the phylum Euryarchaeota, has provided many useful tools to study Archaea, including easy culturing methods, genetic manipulation and phenotypic screening. This review will focus on DNA replication and DNA repair pathways in H. volcanii, how this work has advanced our knowledge of archaeal cellular biology, and how it may deepen our understanding of bacterial and eukaryotic processes.
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Affiliation(s)
| | | | | | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK
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19
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Whalen JM, Freudenreich CH. Location, Location, Location: The Role of Nuclear Positioning in the Repair of Collapsed Forks and Protection of Genome Stability. Genes (Basel) 2020; 11:E635. [PMID: 32526925 PMCID: PMC7348918 DOI: 10.3390/genes11060635] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 05/29/2020] [Accepted: 06/04/2020] [Indexed: 12/14/2022] Open
Abstract
Components of the nuclear pore complex (NPC) have been shown to play a crucial role in protecting against replication stress, and recovery from some types of stalled or collapsed replication forks requires movement of the DNA to the NPC in order to maintain genome stability. The role that nuclear positioning has on DNA repair has been investigated in several systems that inhibit normal replication. These include structure forming sequences (expanded CAG repeats), protein mediated stalls (replication fork barriers (RFBs)), stalls within the telomere sequence, and the use of drugs known to stall or collapse replication forks (HU + MMS or aphidicolin). Recently, the mechanism of relocation for collapsed replication forks to the NPC has been elucidated. Here, we will review the types of replication stress that relocate to the NPC, the current models for the mechanism of relocation, and the currently known protective effects of this movement.
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Affiliation(s)
- Jenna M. Whalen
- Department of Biology, Tufts University, Medford, MA 02155, USA;
| | - Catherine H. Freudenreich
- Department of Biology, Tufts University, Medford, MA 02155, USA;
- Program in Genetics, Tufts University, Boston, MA 02111, USA
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20
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Berroyer A, Alvarado G, Larson ED. Response of Sulfolobus solfataricus Dpo4 polymerase in vitro to a DNA G-quadruplex. Mutagenesis 2020; 34:289-297. [PMID: 31169295 DOI: 10.1093/mutage/gez010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 05/06/2019] [Indexed: 12/12/2022] Open
Abstract
Repetitive DNA sequences support the formation of structures that can interrupt replication and repair, leading to breaks and mutagenesis. One particularly stable structure is G-quadruplex (G4) DNA, which is four-stranded and formed from tandemly repetitive guanine bases. When folded within a template, G4 interferes with DNA synthesis. Similar to non-duplex structures, DNA base lesions can also halt an advancing replication fork, but the Y-family polymerases solve this problem by bypassing the damage. In order to better understand how guanine-rich DNA is replicated, we have investigated the activity of the model Y-family polymerase, Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4), on guanine-rich templates in vitro. We find that Dpo4 progression on templates containing either a single GC-rich hairpin or a G4 DNA structure is greatly reduced and synthesis stalls at the structure. Human polymerase eta (hPol eta) showed the same pattern of stalling at G4; however, and in contrast to Klenow, hPol eta and Dpo4 partially synthesise into the guanine repeat. Substitution of the nucleotide selectivity residue in Dpo4 with alanine permitted ribonucleotide incorporation on unstructured templates, but this further reduced the ability of Dpo4 to synthesise across from the guanine repeats. The advancement of Dpo4 on G4 templates was highest when the reaction was supplied with only deoxycytidine triphosphate, suggesting that high-fidelity synthesis is favoured over misincorporation. Our results are consistent with a model where the Y-family polymerases pause upon encountering G4 structures but have an ability to negotiate some synthesis through tetrad-associated guanines. This suggests that the Y-family polymerases reduce mutagenesis by catalysing the accurate replication of repetitive DNA sequences, but most likely in concert with additional replication and structure resolution activities.
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Affiliation(s)
- Alexandra Berroyer
- School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - Gloria Alvarado
- School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - Erik D Larson
- School of Biological Sciences, Illinois State University, Normal, IL, USA
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21
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Sparks MA, Singh SP, Burgers PM, Galletto R. Complementary roles of Pif1 helicase and single stranded DNA binding proteins in stimulating DNA replication through G-quadruplexes. Nucleic Acids Res 2019; 47:8595-8605. [PMID: 31340040 PMCID: PMC7145523 DOI: 10.1093/nar/gkz608] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/28/2019] [Accepted: 07/18/2019] [Indexed: 01/16/2023] Open
Abstract
G-quadruplexes (G4s) are stable secondary structures that can lead to the stalling of replication forks and cause genomic instability. Pif1 is a 5′ to 3′ helicase, localized to both the mitochondria and nucleus that can unwind G4s in vitro and prevent fork stalling at G4 forming sequences in vivo. Using in vitro primer extension assays, we show that both G4s and stable hairpins form barriers to nuclear and mitochondrial DNA polymerases δ and γ, respectively. However, while single-stranded DNA binding proteins (SSBs) readily promote replication through hairpins, SSBs are only effective in promoting replication through weak G4s. Using a series of G4s with increasing stabilities, we reveal a threshold above which G4 through-replication is inhibited even with SSBs present, and Pif1 helicase is required. Because Pif1 moves along the template strand with a 5′-3′-directionality, head-on collisions between Pif1 and polymerase δ or γ result in the stimulation of their 3′-exonuclease activity. Both nuclear RPA and mitochondrial SSB play a protective role during DNA replication by preventing excessive DNA degradation caused by the helicase-polymerase conflict.
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Affiliation(s)
- Melanie A Sparks
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Saurabh P Singh
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Peter M Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Roberto Galletto
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, USA
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22
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Bryan TM. Mechanisms of DNA Replication and Repair: Insights from the Study of G-Quadruplexes. Molecules 2019; 24:E3439. [PMID: 31546714 PMCID: PMC6804030 DOI: 10.3390/molecules24193439] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 09/18/2019] [Accepted: 09/18/2019] [Indexed: 12/13/2022] Open
Abstract
G-quadruplexes are four-stranded guanine-rich structures that have been demonstrated to occur across the genome in humans and other organisms. They provide regulatory functions during transcription, translation and immunoglobulin gene rearrangement, but there is also a large amount of evidence that they can present a potent barrier to the DNA replication machinery. This mini-review will summarize recent advances in understanding the many strategies nature has evolved to overcome G-quadruplex-mediated replication blockage, including removal of the structure by helicases or nucleases, or circumventing the deleterious effects on the genome through homologous recombination, alternative end-joining or synthesis re-priming. Paradoxically, G-quadruplexes have also recently been demonstrated to provide a positive role in stimulating the initiation of DNA replication. These recent studies have not only illuminated the many roles and consequences of G-quadruplexes, but have also provided fundamental insights into the general mechanisms of DNA replication and its links with genetic and epigenetic stability.
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Affiliation(s)
- Tracy M Bryan
- Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia.
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23
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Schwindt E, Paeschke K. Mms1 is an assistant for regulating G-quadruplex DNA structures. Curr Genet 2018; 64:535-540. [PMID: 29098365 PMCID: PMC5948289 DOI: 10.1007/s00294-017-0773-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/24/2017] [Accepted: 10/26/2017] [Indexed: 12/25/2022]
Abstract
The preservation of genome stability is fundamental for every cell. Genomic integrity is constantly challenged. Among those challenges are also non-canonical nucleic acid structures. In recent years, scientists became aware of the impact of G-quadruplex (G4) structures on genome stability. It has been shown that folded G4-DNA structures cause changes in the cell, such as transcriptional up/down-regulation, replication stalling, or enhanced genome instability. Multiple helicases have been identified to regulate G4 structures and by this preserve genome stability. Interestingly, although these helicases are mostly ubiquitous expressed, they show specificity for G4 regulation in certain cellular processes (e.g., DNA replication). To this date, it is not clear how this process and target specificity of helicases are achieved. Recently, Mms1, an ubiquitin ligase complex protein, was identified as a novel G4-DNA-binding protein that supports genome stability by aiding Pif1 helicase binding to these regions. In this perspective review, we discuss the question if G4-DNA interacting proteins are fundamental for helicase function and specificity at G4-DNA structures.
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Affiliation(s)
- Eike Schwindt
- European Research Institute for the Biology of Ageing (ERIBA), University Medical Center Groningen, University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Katrin Paeschke
- European Research Institute for the Biology of Ageing (ERIBA), University Medical Center Groningen, University of Groningen, 9713 AV, Groningen, The Netherlands.
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24
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DNA Replication Origins and Fork Progression at Mammalian Telomeres. Genes (Basel) 2017; 8:genes8040112. [PMID: 28350373 PMCID: PMC5406859 DOI: 10.3390/genes8040112] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 12/20/2022] Open
Abstract
Telomeres are essential chromosomal regions that prevent critical shortening of linear chromosomes and genomic instability in eukaryotic cells. The bulk of telomeric DNA is replicated by semi-conservative DNA replication in the same way as the rest of the genome. However, recent findings revealed that replication of telomeric repeats is a potential cause of chromosomal instability, because DNA replication through telomeres is challenged by the repetitive telomeric sequences and specific structures that hamper the replication fork. In this review, we summarize current understanding of the mechanisms by which telomeres are faithfully and safely replicated in mammalian cells. Various telomere-associated proteins ensure efficient telomere replication at different steps, such as licensing of replication origins, passage of replication forks, proper fork restart after replication stress, and dissolution of post-replicative structures. In particular, shelterin proteins have central roles in the control of telomere replication. Through physical interactions, accessory proteins are recruited to maintain telomere integrity during DNA replication. Dormant replication origins and/or homology-directed repair may rescue inappropriate fork stalling or collapse that can cause defects in telomere structure and functions.
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25
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Gadaleta MC, Noguchi E. Regulation of DNA Replication through Natural Impediments in the Eukaryotic Genome. Genes (Basel) 2017; 8:genes8030098. [PMID: 28272375 PMCID: PMC5368702 DOI: 10.3390/genes8030098] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Accepted: 03/03/2017] [Indexed: 02/07/2023] Open
Abstract
All living organisms need to duplicate their genetic information while protecting it from unwanted mutations, which can lead to genetic disorders and cancer development. Inaccuracies during DNA replication are the major cause of genomic instability, as replication forks are prone to stalling and collapse, resulting in DNA damage. The presence of exogenous DNA damaging agents as well as endogenous difficult-to-replicate DNA regions containing DNA–protein complexes, repetitive DNA, secondary DNA structures, or transcribing RNA polymerases, increases the risk of genomic instability and thus threatens cell survival. Therefore, understanding the cellular mechanisms required to preserve the genetic information during S phase is of paramount importance. In this review, we will discuss our current understanding of how cells cope with these natural impediments in order to prevent DNA damage and genomic instability during DNA replication.
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Affiliation(s)
- Mariana C Gadaleta
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
| | - Eishi Noguchi
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
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26
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Wang X, Zhang S, Zheng R, Yue F, Lin SHS, Rahmeh AA, Lee EYC, Zhang Z, Lee MYWT. PDIP46 (DNA polymerase δ interacting protein 46) is an activating factor for human DNA polymerase δ. Oncotarget 2017; 7:6294-313. [PMID: 26819372 PMCID: PMC4868757 DOI: 10.18632/oncotarget.7034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 01/25/2016] [Indexed: 02/07/2023] Open
Abstract
PDIP46 (SKAR, POLDIP3) was discovered through its interaction with the p50 subunit of human DNA polymerase δ (Pol δ). Its functions in DNA replication are unknown. PDIP46 associates with Pol δ in cell extracts both by immunochemical and protein separation methods, as well as by ChIP analyses. PDIP46 also interacts with PCNA via multiple copies of a novel PCNA binding motif, the APIMs (AlkB homologue-2 PCNA-Interacting Motif). Sites for both p50 and PCNA binding were mapped to the N-terminal region containing the APIMs. Functional assays for the effects of PDIP46 on Pol δ activity on singly primed ssM13 DNA templates revealed that it is a novel and potent activator of Pol δ. The effects of PDIP46 on Pol δ in primer extension, strand displacement and synthesis through simple hairpin structures reveal a mechanism where PDIP46 facilitates Pol δ4 synthesis through regions of secondary structure on complex templates. In addition, evidence was obtained that PDIP46 is also capable of exerting its effects by a direct interaction with Pol δ, independent of PCNA. Mutation of the Pol δ and PCNA binding region resulted in a loss of PDIP46 functions. These studies support the view that PDIP46 is a novel accessory protein for Pol δ that is involved in cellular DNA replication. This raises the possibility that altered expression of PDIP46 or its mutation may affect Pol δ functions in vivo, and thereby be a nexus for altered genomic stability.
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Affiliation(s)
- Xiaoxiao Wang
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA
| | - Sufang Zhang
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA
| | - Rong Zheng
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA
| | - Fu Yue
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA
| | - Szu Hua Sharon Lin
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA
| | - Amal A Rahmeh
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA
| | - Ernest Y C Lee
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA
| | - Zhongtao Zhang
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA
| | - Marietta Y W T Lee
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA
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27
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The Werner Syndrome Helicase Coordinates Sequential Strand Displacement and FEN1-Mediated Flap Cleavage during Polymerase δ Elongation. Mol Cell Biol 2017; 37:MCB.00560-16. [PMID: 27849570 DOI: 10.1128/mcb.00560-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 11/08/2016] [Indexed: 02/01/2023] Open
Abstract
The Werner syndrome protein (WRN) suppresses the loss of telomeres replicated by lagging-strand synthesis by a yet to be defined mechanism. Here, we show that whereas either WRN or the Bloom syndrome helicase (BLM) stimulates DNA polymerase δ progression across telomeric G-rich repeats, only WRN promotes sequential strand displacement synthesis and FEN1 cleavage, a critical step in Okazaki fragment maturation, at these sequences. Helicase activity, as well as the conserved winged-helix (WH) motif and the helicase and RNase D C-terminal (HRDC) domain play important but distinct roles in this process. Remarkably, WRN also influences the formation of FEN1 cleavage products during strand displacement on a nontelomeric substrate, suggesting that WRN recruitment and cooperative interaction with FEN1 during lagging-strand synthesis may serve to regulate sequential strand displacement and flap cleavage at other genomic sites. These findings define a biochemical context for the physiological role of WRN in maintaining genetic stability.
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28
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Bag SS, Pradhan MK, Talukdar S. Tetrazolylpyrene unnatural nucleoside as a human telomeric multimeric G-quadruplex selective switch-on fluorescent sensor. Org Biomol Chem 2017; 15:10145-10150. [DOI: 10.1039/c7ob02433a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Specific sensing of dimeric H45 G-quadruplex DNA using a fluorescence light-up probe, tetrazolylpyrene nucleoside (TzPyBDo), is reported.
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Affiliation(s)
- Subhendu Sekhar Bag
- Bioorganic Chemistry Laboratory
- Department of Chemistry
- Indian Institute of Technology Guwahati
- North Guwhati-781039
- India
| | - Manoj Kumar Pradhan
- Bioorganic Chemistry Laboratory
- Department of Chemistry
- Indian Institute of Technology Guwahati
- North Guwhati-781039
- India
| | - Sangita Talukdar
- Bioorganic Chemistry Laboratory
- Department of Chemistry
- Indian Institute of Technology Guwahati
- North Guwhati-781039
- India
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Nicolas E, Golemis EA, Arora S. POLD1: Central mediator of DNA replication and repair, and implication in cancer and other pathologies. Gene 2016; 590:128-41. [PMID: 27320729 PMCID: PMC4969162 DOI: 10.1016/j.gene.2016.06.031] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 06/10/2016] [Accepted: 06/14/2016] [Indexed: 02/06/2023]
Abstract
The evolutionarily conserved human polymerase delta (POLD1) gene encodes the large p125 subunit which provides the essential catalytic activities of polymerase δ (Polδ), mediated by 5′–3′ DNA polymerase and 3′–5′ exonuclease moieties. POLD1 associates with three smaller subunits (POLD2, POLD3, POLD4), which together with Replication Factor C and Proliferating Nuclear Cell Antigen constitute the polymerase holoenzyme. Polδ function is essential for replication, with a primary role as the replicase for the lagging strand. Polδ also has an important proofreading ability conferred by the exonuclease activity, which is critical for ensuring replicative fidelity, but also serves to repair DNA lesions arising as a result of exposure to mutagens. Polδ has been shown to be important for multiple forms of DNA repair, including nucleotide excision repair, double strand break repair, base excision repair, and mismatch repair. A growing number of studies in the past decade have linked germline and sporadic mutations in POLD1 and the other subunits of Polδ with human pathologies. Mutations in Polδ in mice and humans lead to genomic instability, mutator phenotype and tumorigenesis. The advent of genome sequencing techniques has identified damaging mutations in the proofreading domain of POLD1 as the underlying cause of some inherited cancers, and suggested that mutations in POLD1 may influence therapeutic management. In addition, mutations in POLD1 have been identified in the developmental disorders of mandibular hypoplasia, deafness, progeroid features and lipodystrophy and atypical Werner syndrome, while changes in expression or activity of POLD1 have been linked to senescence and aging. Intriguingly, some recent evidence suggests that POLD1 function may also be altered in diabetes. We provide an overview of critical Polδ activities in the context of these pathologic conditions.
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Affiliation(s)
- Emmanuelle Nicolas
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Erica A Golemis
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Sanjeevani Arora
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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Wang SR, Min YQ, Wang JQ, Liu CX, Fu BS, Wu F, Wu LY, Qiao ZX, Song YY, Xu GH, Wu ZG, Huang G, Peng NF, Huang R, Mao WX, Peng S, Chen YQ, Zhu Y, Tian T, Zhang XL, Zhou X. A highly conserved G-rich consensus sequence in hepatitis C virus core gene represents a new anti-hepatitis C target. SCIENCE ADVANCES 2016; 2:e1501535. [PMID: 27051880 PMCID: PMC4820367 DOI: 10.1126/sciadv.1501535] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/18/2016] [Indexed: 05/24/2023]
Abstract
G-quadruplex (G4) is one of the most important secondary structures in nucleic acids. Until recently, G4 RNAs have not been reported in any ribovirus, such as the hepatitis C virus. Our bioinformatics analysis reveals highly conserved guanine-rich consensus sequences within the core gene of hepatitis C despite the high genetic variability of this ribovirus; we further show using various methods that such consensus sequences can fold into unimolecular G4 RNA structures, both in vitro and under physiological conditions. Furthermore, we provide direct evidences that small molecules specifically targeting G4 can stabilize this structure to reduce RNA replication and inhibit protein translation of intracellular hepatitis C. Ultimately, the stabilization of G4 RNA in the genome of hepatitis C represents a promising new strategy for anti-hepatitis C drug development.
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Affiliation(s)
- Shao-Ru Wang
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Yuan-Qin Min
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology and Department of Immunology, School of Medicine, Wuhan University, Wuhan 430071, Hubei, China
| | - Jia-Qi Wang
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Chao-Xing Liu
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Bo-Shi Fu
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Fan Wu
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Ling-Yu Wu
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Zhi-Xian Qiao
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China
| | - Yan-Yan Song
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Guo-Hua Xu
- Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, Hubei, China
| | - Zhi-Guo Wu
- College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
| | - Gai Huang
- College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
| | - Nan-Fang Peng
- College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
| | - Rong Huang
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Wu-Xiang Mao
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Shuang Peng
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Yu-Qi Chen
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Ying Zhu
- College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China
| | - Tian Tian
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
| | - Xiao-Lian Zhang
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology and Department of Immunology, School of Medicine, Wuhan University, Wuhan 430071, Hubei, China
| | - Xiang Zhou
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, Hubei, China
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31
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The DNA structure and sequence preferences of WRN underlie its function in telomeric recombination events. Nat Commun 2015; 6:8331. [PMID: 26420422 PMCID: PMC4589872 DOI: 10.1038/ncomms9331] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 08/11/2015] [Indexed: 12/27/2022] Open
Abstract
Telomeric abnormalities caused by loss of function of the RecQ helicase WRN are linked to the multiple premature ageing phenotypes that characterize Werner syndrome. Here we examine WRN's role in telomeric maintenance, by comparing its action on a variety of DNA structures without or with telomeric sequences. Our results show that WRN clearly prefers to act on strand invasion intermediates in a manner that favours strand invasion and exchange. Moreover, WRN unwinding of these recombination structures is further enhanced when the invading strand contains at least three G-rich single-stranded telomeric repeats. These selectivities are most pronounced at NaCl concentrations within the reported intranuclear monovalent cation concentration range, and are partly conferred by WRN's C-terminal region. Importantly, WRN's specificity for the G-rich telomeric sequence within this precise structural context is particularly relevant to telomere metabolism and strongly suggests a physiological role in telomeric recombination processes, including T-loop dynamics.
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Martínez P, Blasco MA. Replicating through telomeres: a means to an end. Trends Biochem Sci 2015; 40:504-15. [PMID: 26188776 DOI: 10.1016/j.tibs.2015.06.003] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 06/08/2015] [Accepted: 06/12/2015] [Indexed: 02/07/2023]
Abstract
Proper replication of the telomeric DNA at chromosome ends is critical for preserving genome integrity. Yet, telomeres present challenges for the replication machinery, such as their repetitive and heterochromatic nature and their potential to form non-Watson-Crick structures as well as the fact that they are transcribed. Numerous telomere-bound proteins are required to facilitate progression of the replication fork throughout telomeric DNA. In particular, shelterin plays crucial functions in telomere length regulation, protection of telomeres from nuclease degradation, control of DNA damage response at telomeres, and the recruitment of associated factors required for telomere DNA processing and replication. In this review we discuss the recently uncovered functions of mammalian telomere-specific and telomere-associated proteins that facilitate proper telomere replication.
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Affiliation(s)
- Paula Martínez
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Research Centre (CNIO), Madrid E-28029, Spain
| | - Maria A Blasco
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Research Centre (CNIO), Madrid E-28029, Spain.
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