151
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Resolving individual steps of Okazaki-fragment maturation at a millisecond timescale. Nat Struct Mol Biol 2016; 23:402-8. [PMID: 27065195 PMCID: PMC4857878 DOI: 10.1038/nsmb.3207] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/18/2016] [Indexed: 11/08/2022]
Abstract
DNA polymerase delta (Pol δ) is responsible for elongation and maturation of Okazaki fragments. Pol δ and the flap endonuclease FEN1, coordinated by the PCNA clamp, remove RNA primers and produce ligatable nicks. We studied this process in the Saccharomyces cerevisiae machinery at millisecond resolution. During elongation, PCNA increased the Pol δ catalytic rate by >30-fold. When Pol δ invaded double-stranded RNA-DNA representing unmatured Okazaki fragments, the incorporation rate of each nucleotide decreased successively to 10-20% that of the preceding nucleotide. Thus, the nascent flap acts as a progressive molecular brake on the polymerase, and consequently FEN1 cuts predominantly single-nucleotide flaps. Kinetic and enzyme-trapping experiments support a model in which a stable PCNA-DNA-Pol δ-FEN1 complex moves processively through iterative steps of nick translation, ultimately completely removing primer RNA. Finally, whereas elongation rates are under dynamic dNTP control, maturation rates are buffered against changes in dNTP concentrations.
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152
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Gouda N, Shiwa Y, Akashi M, Yoshikawa H, Kasahara K, Furusawa M. Distribution of human single-nucleotide polymorphisms is approximated by the power law and represents a fractal structure. Genes Cells 2016; 21:396-407. [PMID: 27030000 DOI: 10.1111/gtc.12344] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 12/12/2015] [Indexed: 01/31/2023]
Abstract
Single-nucleotide polymorphisms (SNPs) are one of the main causes of evolution. The distribution of human SNPs, which were examined in detail genomewide, was analyzed. Three discrete databases of human SNPs were used for this analysis, and similar results were obtained from these databases. It was found that the distribution of the distance between SNPs was approximated by the power law, and the shape of the regions including SNPs had the so-called fractal structure. Although the reason why the distribution of SNPs obeys such a certain law of physics is unclear, a speculation was attempted in connection with the three-dimensional structure of human chromatin which has a fractal structure.
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Affiliation(s)
- Norio Gouda
- Department of Systems Medicine, Sakaguchi Laboratory, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
| | - Yuh Shiwa
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Motohiro Akashi
- Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Hirofumi Yoshikawa
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan.,Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Ken Kasahara
- Chitose Laboratory Corp., Biotechnology Research Center, 907 Nogawa, Miyamae-ku, Kawasaki, 216-0001, Japan
| | - Mitsuru Furusawa
- Chitose Laboratory Corp., Biotechnology Research Center, 907 Nogawa, Miyamae-ku, Kawasaki, 216-0001, Japan
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153
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Koc KN, Singh SP, Stodola JL, Burgers PM, Galletto R. Pif1 removes a Rap1-dependent barrier to the strand displacement activity of DNA polymerase δ. Nucleic Acids Res 2016; 44:3811-9. [PMID: 27001517 PMCID: PMC4856994 DOI: 10.1093/nar/gkw181] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 03/08/2016] [Indexed: 11/13/2022] Open
Abstract
Using an in vitro reconstituted system in this work we provide direct evidence that the yeast repressor/activator protein 1 (Rap1), tightly bound to its consensus site, forms a strong non-polar barrier for the strand displacement activity of DNA polymerase δ. We propose that relief of inhibition may be mediated by the activity of an accessory helicase. To this end, we show that Pif1, a 5'-3' helicase, not only stimulates the strand displacement activity of Pol δ but it also allows efficient replication through the block, by removing bound Rap1 in front of the polymerase. This stimulatory activity of Pif1 is not limited to the displacement of a single Rap1 molecule; Pif1 also allows Pol δ to carry out DNA synthesis across an array of bound Rap1 molecules that mimics a telomeric DNA-protein assembly. This activity of Pif1 represents a novel function of this helicase during DNA replication.
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Affiliation(s)
- Katrina N Koc
- 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
| | - Joseph L Stodola
- 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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154
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Cerritelli SM, Crouch RJ. The Balancing Act of Ribonucleotides in DNA. Trends Biochem Sci 2016; 41:434-445. [PMID: 26996833 DOI: 10.1016/j.tibs.2016.02.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/01/2016] [Accepted: 02/09/2016] [Indexed: 11/28/2022]
Abstract
The abundance of ribonucleotides in DNA remained undetected until recently because they are efficiently removed by the ribonucleotide excision repair (RER) pathway, a process similar to Okazaki fragment (OF) processing after incision by Ribonuclease H2 (RNase H2). All DNA polymerases incorporate ribonucleotides during DNA synthesis. How many, when, and why they are incorporated has been the focus of intense work during recent years by many labs. In this review, we discuss recent advances in ribonucleotide incorporation by eukaryotic DNA polymerases that suggest an evolutionarily conserved role for ribonucleotides in DNA. We also review the data that indicate that removal of ribonucleotides has an important role in maintaining genome stability.
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Affiliation(s)
- Susana M Cerritelli
- Section on Formation of RNA, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Robert J Crouch
- Section on Formation of RNA, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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155
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Baranovskiy AG, Babayeva ND, Zhang Y, Gu J, Suwa Y, Pavlov YI, Tahirov TH. Mechanism of Concerted RNA-DNA Primer Synthesis by the Human Primosome. J Biol Chem 2016; 291:10006-20. [PMID: 26975377 DOI: 10.1074/jbc.m116.717405] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Indexed: 12/31/2022] Open
Abstract
The human primosome, a 340-kilodalton complex of primase and DNA polymerase α (Polα), synthesizes chimeric RNA-DNA primers to be extended by replicative DNA polymerases δ and ϵ. The intricate mechanism of concerted primer synthesis by two catalytic centers was an enigma for over three decades. Here we report the crystal structures of two key complexes, the human primosome and the C-terminal domain of the primase large subunit (p58C) with bound DNA/RNA duplex. These structures, along with analysis of primase/polymerase activities, provide a plausible mechanism for all transactions of the primosome including initiation, elongation, accurate counting of RNA primer length, primer transfer to Polα, and concerted autoregulation of alternate activation/inhibition of the catalytic centers. Our findings reveal a central role of p58C in the coordinated actions of two catalytic domains in the primosome and ultimately could impact the design of anticancer drugs.
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Affiliation(s)
- Andrey G Baranovskiy
- From the Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center and
| | - Nigar D Babayeva
- From the Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center and
| | - Yinbo Zhang
- From the Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center and the Departments of Biochemistry and Molecular Biology and
| | - Jianyou Gu
- From the Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center and
| | - Yoshiaki Suwa
- From the Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center and
| | - Youri I Pavlov
- From the Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center and the Departments of Biochemistry and Molecular Biology and Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198
| | - Tahir H Tahirov
- From the Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center and
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156
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Watt DL, Buckland RJ, Lujan SA, Kunkel TA, Chabes A. Genome-wide analysis of the specificity and mechanisms of replication infidelity driven by imbalanced dNTP pools. Nucleic Acids Res 2016; 44:1669-80. [PMID: 26609135 PMCID: PMC4770217 DOI: 10.1093/nar/gkv1298] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 11/05/2015] [Accepted: 11/06/2015] [Indexed: 01/07/2023] Open
Abstract
The absolute and relative concentrations of the four dNTPs are key determinants of DNA replication fidelity, yet the consequences of altered dNTP pools on replication fidelity have not previously been investigated on a genome-wide scale. Here, we use deep sequencing to determine the types, rates and locations of uncorrected replication errors that accumulate in the nuclear genome of a mismatch repair-deficient diploid yeast strain with elevated dCTP and dTTP concentrations. These imbalanced dNTP pools promote replication errors in specific DNA sequence motifs suggesting increased misinsertion and increased mismatch extension at the expense of proofreading. Interestingly, substitution rates are similar for leading and lagging strand replication, but are higher in regions replicated late in S phase. Remarkably, the rate of single base deletions is preferentially increased in coding sequences and in short rather than long mononucleotides runs. Based on DNA sequence motifs, we propose two distinct mechanisms for generating single base deletions in vivo. Collectively, the results indicate that elevated dCTP and dTTP pools increase mismatch formation and decrease error correction across the nuclear genome, and most strongly increases mutation rates in coding and late replicating sequences.
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Affiliation(s)
- Danielle L Watt
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87, Umeå, Sweden Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA
| | - Robert J Buckland
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87, Umeå, Sweden Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, SE-901 87, Umeå, Sweden
| | - Scott A Lujan
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87, Umeå, Sweden Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, SE-901 87, Umeå, Sweden
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157
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Gao Z, Wyman MJ, Sella G, Przeworski M. Interpreting the Dependence of Mutation Rates on Age and Time. PLoS Biol 2016; 14:e1002355. [PMID: 26761240 PMCID: PMC4711947 DOI: 10.1371/journal.pbio.1002355] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 12/11/2015] [Indexed: 01/06/2023] Open
Abstract
Mutations can originate from the chance misincorporation of nucleotides during DNA replication or from DNA lesions that arise between replication cycles and are not repaired correctly. We introduce a model that relates the source of mutations to their accumulation with cell divisions, providing a framework for understanding how mutation rates depend on sex, age, and cell division rate. We show that the accrual of mutations should track cell divisions not only when mutations are replicative in origin but also when they are non-replicative and repaired efficiently. One implication is that observations from diverse fields that to date have been interpreted as pointing to a replicative origin of most mutations could instead reflect the accumulation of mutations arising from endogenous reactions or exogenous mutagens. We further find that only mutations that arise from inefficiently repaired lesions will accrue according to absolute time; thus, unless life history traits co-vary, the phylogenetic “molecular clock” should not be expected to run steadily across species. Modeling how the source of mutations relates to their rate of accumulation with age, sex, and number of cell divisions helps to explain perplexing observations about germline and somatic mutations. We relate how mutations arise to how they accumulate in different sexes, with age and with cell division. This model provides a single framework within which to interpret emerging results from evolutionary biology, human genetics, and cancer genetics. We show that the accrual of mutations should track cell divisions not only when mutations originate during DNA replication but also when they arise through non-replicative mechanisms and are repaired efficiently. This realization means that previous observations of correlations between mutation and cell division rates actually provide little support to the commonly held belief that most germline and somatic mutations arise from replication errors. We further find that only mutations that arise from inefficiently repaired lesions will accrue according to absolute time; thus, without covariation in life history traits, the phylogenetic “molecular clock” should not be expected to run at constant rates across species.
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Affiliation(s)
- Ziyue Gao
- Committee on Genetics, Genomics and Systems Biology, University of Chicago, Chicago, Illinois, United States of America
- * E-mail: (ZG); (MP)
| | - Minyoung J. Wyman
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - Guy Sella
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - Molly Przeworski
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
- Department of Systems Biology, Columbia University, New York, New York, United States of America
- * E-mail: (ZG); (MP)
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158
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Seplyarskiy VB, Soldatov RA, Popadin KY, Antonarakis SE, Bazykin GA, Nikolaev SI. APOBEC-induced mutations in human cancers are strongly enriched on the lagging DNA strand during replication. Genome Res 2016; 26:174-82. [PMID: 26755635 PMCID: PMC4728370 DOI: 10.1101/gr.197046.115] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 12/10/2015] [Indexed: 12/31/2022]
Abstract
APOBEC3A and APOBEC3B, cytidine deaminases of the APOBEC family, are among the main factors causing mutations in human cancers. APOBEC deaminates cytosines in single-stranded DNA (ssDNA). A fraction of the APOBEC-induced mutations occur as clusters ("kataegis") in single-stranded DNA produced during repair of double-stranded breaks (DSBs). However, the properties of the remaining 87% of nonclustered APOBEC-induced mutations, the source and the genomic distribution of the ssDNA where they occur, are largely unknown. By analyzing genomic and exomic cancer databases, we show that >33% of dispersed APOBEC-induced mutations occur on the lagging strand during DNA replication, thus unraveling the major source of ssDNA targeted by APOBEC in cancer. Although methylated cytosine is generally more mutation-prone than nonmethylated cytosine, we report that methylation reduces the rate of APOBEC-induced mutations by a factor of roughly two. Finally, we show that in cancers with extensive APOBEC-induced mutagenesis, there is almost no increase in mutation rates in late replicating regions (contrary to other cancers). Because late-replicating regions are depleted in exons, this results in a 1.3-fold higher fraction of mutations residing within exons in such cancers. This study provides novel insight into the APOBEC-induced mutagenesis and describes the peculiarity of the mutational processes in cancers with the signature of APOBEC-induced mutations.
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Affiliation(s)
- Vladimir B Seplyarskiy
- Institute of Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia, 127051; Lomonosov Moscow State University, Moscow, Russia, 119991; Pirogov Russian National Research Medical University, Moscow, Russia, 117997
| | - Ruslan A Soldatov
- Institute of Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia, 127051; Lomonosov Moscow State University, Moscow, Russia, 119991
| | - Konstantin Y Popadin
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva, Switzerland; Institute of Genetics and Genomics in Geneva, 1211 Geneva, Switzerland
| | - Stylianos E Antonarakis
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva, Switzerland; Institute of Genetics and Genomics in Geneva, 1211 Geneva, Switzerland
| | - Georgii A Bazykin
- Institute of Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia, 127051; Lomonosov Moscow State University, Moscow, Russia, 119991; Pirogov Russian National Research Medical University, Moscow, Russia, 117997
| | - Sergey I Nikolaev
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva, Switzerland; Institute of Genetics and Genomics in Geneva, 1211 Geneva, Switzerland; Service of Genetic Medicine, University Hospitals of Geneva, 1211 Geneva, Switzerland
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159
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Araya CL, Cenik C, Reuter JA, Kiss G, Pande VS, Snyder MP, Greenleaf WJ. Identification of significantly mutated regions across cancer types highlights a rich landscape of functional molecular alterations. Nat Genet 2015; 48:117-25. [PMID: 26691984 PMCID: PMC4731297 DOI: 10.1038/ng.3471] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 11/20/2015] [Indexed: 02/07/2023]
Abstract
Cancer sequencing studies have primarily identified cancer-driver genes by the accumulation of protein-altering mutations. An improved method would be annotation-independent, sensitive to unknown distributions of functions within proteins, and inclusive of non-coding drivers. We employed density-based clustering methods in 21 tumor types to detect variably-sized significantly mutated regions (SMRs). SMRs reveal recurrent alterations across a spectrum of coding and non-coding elements, including transcription factor binding sites and untranslated regions mutated in up to ∼15% of specific tumor types. SMRs reveal spatial clustering of mutations at molecular domains and interfaces, often with associated changes in signaling. Mutation frequencies in SMRs demonstrate that distinct protein regions are differentially mutated among tumor types, as exemplified by a linker region of PIK3CA in which biophysical simulations suggest mutations affect regulatory interactions. The functional diversity of SMRs underscores both the varied mechanisms of oncogenic misregulation and the advantage of functionally-agnostic driver identification.
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Affiliation(s)
- Carlos L Araya
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Can Cenik
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Jason A Reuter
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Gert Kiss
- Department of Chemistry, Stanford University, Stanford, California, USA
| | - Vijay S Pande
- Department of Chemistry, Stanford University, Stanford, California, USA
| | - Michael P Snyder
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - William J Greenleaf
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA.,Department of Applied Physics, Stanford University, Stanford, California, USA
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160
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Lujan SA, Williams JS, Kunkel TA. Eukaryotic genome instability in light of asymmetric DNA replication. Crit Rev Biochem Mol Biol 2015; 51:43-52. [PMID: 26822554 DOI: 10.3109/10409238.2015.1117055] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The eukaryotic nuclear genome is replicated asymmetrically, with the leading strand replicated continuously and the lagging strand replicated as discontinuous Okazaki fragments that are subsequently joined. Both strands are replicated with high fidelity, but the processes used to achieve high fidelity are likely to differ. Here we review recent studies of similarities and differences in the fidelity with which the three major eukaryotic replicases, DNA polymerases α, δ, and ɛ, replicate the leading and lagging strands with high nucleotide selectivity and efficient proofreading. We then relate the asymmetric fidelity at the replication fork to the efficiency of DNA mismatch repair, ribonucleotide excision repair and topoisomerase 1 activity.
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Affiliation(s)
- Scott A Lujan
- a Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences , Research Triangle Park , NC , USA
| | - Jessica S Williams
- a Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences , Research Triangle Park , NC , USA
| | - Thomas A Kunkel
- a Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences , Research Triangle Park , NC , USA
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161
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Marion de Procé S. Des fragments d’ADN synthétisés par l’ADN polymérase α modifient notre génome. Med Sci (Paris) 2015; 31:821-3. [DOI: 10.1051/medsci/20153110002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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162
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Keszthelyi A, Daigaku Y, Ptasińska K, Miyabe I, Carr AM. Mapping ribonucleotides in genomic DNA and exploring replication dynamics by polymerase usage sequencing (Pu-seq). Nat Protoc 2015; 10:1786-801. [PMID: 26492137 DOI: 10.1038/nprot.2015.116] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ribonucleotides are frequently misincorporated into DNA during replication, and they are rapidly repaired by ribonucleotide excision repair (RER). Although ribonucleotides in template DNA perturb replicative polymerases and can be considered as DNA damage, they also serve positive biological functions, including directing the orientation of mismatch repair. Here we describe a method for ribonucleotide identification by high-throughput sequencing that allows mapping of the location of ribonucleotides across the genome. When combined with specific mutations in the replicative polymerases that incorporate ribonucleotides at elevated frequencies, our ribonucleotide identification method was adapted to map polymerase usage across the genome. Polymerase usage sequencing (Pu-seq) has been used to define, in unprecedented detail, replication dynamics in yeasts. Although other methods that examine replication dynamics provide direct measures of replication timing and indirect estimates of origin efficiency, Pu-seq directly ascertains origin efficiency. The Pu-seq protocol can be completed in 12-14 d.
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Affiliation(s)
- Andrea Keszthelyi
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Yasukazu Daigaku
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK.,Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, Japan
| | - Katie Ptasińska
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Izumi Miyabe
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Antony M Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
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163
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Polymerase δ replicates both strands after homologous recombination-dependent fork restart. Nat Struct Mol Biol 2015; 22:932-8. [PMID: 26436826 PMCID: PMC4655445 DOI: 10.1038/nsmb.3100] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 08/28/2015] [Indexed: 12/16/2022]
Abstract
To maintain genetic stability DNA must be replicated only once and replication completed even when individual replication forks are inactivated. Because fork inactivation is common, the passive convergence of an adjacent fork is insufficient to rescue all inactive forks. Thus, eukaryotic cells have evolved homologous recombination-dependent mechanisms to restart persistent inactive forks. Completing DNA synthesis via Homologous Recombination Restarted Replication (HoRReR) ensures cell survival, but at a cost. One such cost is increased mutagenesis caused by HoRReR being more error prone than canonical replication. This increased error rate implies that the HoRReR mechanism is distinct from that of a canonical fork. Here we exploit the fission yeast Schizosaccharomyces pombe to demonstrate that a DNA sequence duplicated by HoRReR during S phase is replicated semi-conservatively, but that both the leading and lagging strands are synthesised by DNA polymerase delta.
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164
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Elevated Genome-Wide Instability in Yeast Mutants Lacking RNase H Activity. Genetics 2015; 201:963-75. [PMID: 26400613 DOI: 10.1534/genetics.115.182725] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 09/16/2015] [Indexed: 11/18/2022] Open
Abstract
Two types of RNA:DNA associations can lead to genome instability: the formation of R-loops during transcription and the incorporation of ribonucleotide monophosphates (rNMPs) into DNA during replication. Both ribonuclease (RNase) H1 and RNase H2 degrade the RNA component of R-loops, whereas only RNase H2 can remove one or a few rNMPs from DNA. We performed high-resolution mapping of mitotic recombination events throughout the yeast genome in diploid strains of Saccharomyces cerevisiae lacking RNase H1 (rnh1Δ), RNase H2 (rnh201Δ), or both RNase H1 and RNase H2 (rnh1Δ rnh201Δ). We found little effect on recombination in the rnh1Δ strain, but elevated recombination in both the rnh201Δ and the double-mutant strains; levels of recombination in the double mutant were ∼50% higher than in the rnh201 single-mutant strain. An rnh201Δ mutant that additionally contained a mutation that reduces rNMP incorporation by DNA polymerase ε (pol2-M644L) had a level of instability similar to that observed in the presence of wild-type Pol ε. This result suggests that the elevated recombination observed in the absence of only RNase H2 is primarily a consequence of R-loops rather than misincorporated rNMPs.
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165
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Abstract
DNA damage is a constant threat to cells, causing cytotoxicity as well as inducing genetic alterations. The steady-state abundance of DNA lesions in a cell is minimized by a variety of DNA repair mechanisms, including DNA strand break repair, mismatch repair, nucleotide excision repair, base excision repair, and ribonucleotide excision repair. The efficiencies and mechanisms by which these pathways remove damage from chromosomes have been primarily characterized by investigating the processing of lesions at defined genomic loci, among bulk genomic DNA, on episomal DNA constructs, or using in vitro substrates. However, the structure of a chromosome is heterogeneous, consisting of heavily protein-bound heterochromatic regions, open regulatory regions, actively transcribed genes, and even areas of transient single stranded DNA. Consequently, DNA repair pathways function in a much more diverse set of chromosomal contexts than can be readily assessed using previous methods. Recent efforts to develop whole genome maps of DNA damage, repair processes, and even mutations promise to greatly expand our understanding of DNA repair and mutagenesis. Here we review the current efforts to utilize whole genome maps of DNA damage and mutation to understand how different chromosomal contexts affect DNA excision repair pathways.
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Affiliation(s)
- John J Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA; Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA.
| | - Steven A Roberts
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA.
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166
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Ding J, Taylor MS, Jackson AP, Reijns MAM. Genome-wide mapping of embedded ribonucleotides and other noncanonical nucleotides using emRiboSeq and EndoSeq. Nat Protoc 2015; 10:1433-44. [PMID: 26313479 DOI: 10.1038/nprot.2015.099] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ribonucleotides are the most common noncanonical nucleotides incorporated into the genome of replicating cells. They are efficiently removed by ribonucleotide excision repair initiated by RNase H2 cleavage. In the absence of RNase H2, such embedded ribonucleotides can be used to track DNA polymerase activity in vivo. To determine their precise location in Saccharomyces cerevisiae, we developed embedded ribonucleotide sequencing (emRiboSeq), which uses recombinant RNase H2 to selectively create ligatable 3'-hydroxyl groups, in contrast to alternative methods that use alkaline hydrolysis. EmRiboSeq allows reproducible, strand-specific and potentially quantitative detection of embedded ribonucleotides at single-nucleotide resolution. For the genome-wide mapping of other noncanonical bases, RNase H2 can be replaced with specific nicking endonucleases in this protocol; we term this method endonuclease sequencing (EndoSeq). With the protocol taking <5 d to complete, these methods allow the in vivo study of DNA replication and repair, including the identification of replication origins and termination regions.
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Affiliation(s)
- James Ding
- Medical Research Council (MRC) Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK
| | - Martin S Taylor
- Medical Research Council (MRC) Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK
| | - Andrew P Jackson
- Medical Research Council (MRC) Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK
| | - Martin A M Reijns
- Medical Research Council (MRC) Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK
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167
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Genetic Networks Required to Coordinate Chromosome Replication by DNA Polymerases α, δ, and ε in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2015; 5:2187-97. [PMID: 26297725 PMCID: PMC4593000 DOI: 10.1534/g3.115.021493] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Three major DNA polymerases replicate the linear eukaryotic chromosomes. DNA polymerase α-primase (Pol α) and DNA polymerase δ (Pol δ) replicate the lagging-strand and Pol α and DNA polymerase ε (Pol ε) the leading-strand. To identify factors affecting coordination of DNA replication, we have performed genome-wide quantitative fitness analyses of budding yeast cells containing defective polymerases. We combined temperature-sensitive mutations affecting the three replicative polymerases, Pol α, Pol δ, and Pol ε with genome-wide collections of null and reduced function mutations. We identify large numbers of genetic interactions that inform about the roles that specific genes play to help Pol α, Pol δ, and Pol ε function. Surprisingly, the overlap between the genetic networks affecting the three DNA polymerases does not represent the majority of the genetic interactions identified. Instead our data support a model for division of labor between the different DNA polymerases during DNA replication. For example, our genetic interaction data are consistent with biochemical data showing that Pol ε is more important to the Pre-Loading complex than either Pol α or Pol δ. We also observed distinct patterns of genetic interactions between leading- and lagging-strand DNA polymerases, with particular genes being important for coupling proliferating cell nuclear antigen loading/unloading (Ctf18, Elg1) with nucleosome assembly (chromatin assembly factor 1, histone regulatory HIR complex). Overall our data reveal specialized genetic networks that affect different aspects of leading- and lagging-strand DNA replication. To help others to engage with these data we have generated two novel, interactive visualization tools, DIXY and Profilyzer.
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168
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Vázquez E, Antequera F. Replication dynamics in fission and budding yeasts through DNA polymerase tracking. Bioessays 2015; 37:1067-73. [PMID: 26293347 PMCID: PMC5054902 DOI: 10.1002/bies.201500072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The dynamics of eukaryotic DNA polymerases has been difficult to establish because of the difficulty of tracking them along the chromosomes during DNA replication. Recent work has addressed this problem in the yeasts Schizosaccharomyces pombe and Saccharomyces cerevisiae through the engineering of replicative polymerases to render them prone to incorporating ribonucleotides at high rates. Their use as tracers of the passage of each polymerase has provided a picture of unprecedented resolution of the organization of replicons and replication origins in the two yeasts and has uncovered important differences between them. Additional studies have found an overlapping distribution of DNA polymorphisms and the junctions of Okazaki fragments along mononucleosomal DNA. This sequence instability is caused by the premature release of polymerase δ and the retention of non proof‐read DNA tracts replicated by polymerase α. The possible implementation of these new experimental approaches in multicellular organisms opens the door to the analysis of replication dynamics under a broad range of genetic backgrounds and physiological or pathological conditions.
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Affiliation(s)
- Enrique Vázquez
- Instituto de Biología, Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
| | - Francisco Antequera
- Instituto de Biología, Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca, Spain
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169
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Abstract
Eukaryotic replication disrupts each nucleosome as the fork passes, followed by re-assembly of disrupted nucleosomes and incorporation of newly synthesized histones into nucleosomes in the daughter genomes. In this review, we examine this process of replication-coupled nucleosome assembly to understand how characteristic steady state nucleosome landscapes are attained. Recent studies have begun to elucidate mechanisms involved in histone transfer during replication and maturation of the nucleosome landscape after disruption by replication. A fuller understanding of replication-coupled nucleosome assembly will be needed to explain how epigenetic information is replicated at every cell division.
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Affiliation(s)
- Srinivas Ramachandran
- Howard Hughes Medical Institute, Seattle, WA 98109, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute, Seattle, WA 98109, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
- Corresponding author. E-mail:
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170
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Young RS, Hayashizaki Y, Andersson R, Sandelin A, Kawaji H, Itoh M, Lassmann T, Carninci P, Bickmore WA, Forrest AR, Taylor MS. The frequent evolutionary birth and death of functional promoters in mouse and human. Genome Res 2015; 25:1546-57. [PMID: 26228054 PMCID: PMC4579340 DOI: 10.1101/gr.190546.115] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 07/28/2015] [Indexed: 12/04/2022]
Abstract
Promoters are central to the regulation of gene expression. Changes in gene regulation are thought to underlie much of the adaptive diversification between species and phenotypic variation within populations. In contrast to earlier work emphasizing the importance of enhancer evolution and subtle sequence changes at promoters, we show that dramatic changes such as the complete gain and loss (collectively, turnover) of functional promoters are common. Using quantitative measures of transcription initiation in both humans and mice across 52 matched tissues, we discriminate promoter sequence gains from losses and resolve the lineage of changes. We also identify expression divergence and functional turnover between orthologous promoters, finding only the latter is associated with local sequence changes. Promoter turnover has occurred at the majority (>56%) of protein-coding genes since humans and mice diverged. Tissue-restricted promoters are the most evolutionarily volatile where retrotransposition is an important, but not the sole, source of innovation. There is considerable heterogeneity of turnover rates between promoters in different tissues, but the consistency of these in both lineages suggests that the same biological systems are similarly inclined to transcriptional rewiring. The genes affected by promoter turnover show evidence of adaptive evolution. In mice, promoters are primarily lost through deletion of the promoter containing sequence, whereas in humans, many promoters appear to be gradually decaying with weak transcriptional output and relaxed selective constraint. Our results suggest that promoter gain and loss is an important process in the evolutionary rewiring of gene regulation and may be a significant source of phenotypic diversification.
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Affiliation(s)
- Robert S Young
- MRC Human Genetics Unit, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, United Kingdom
| | - Yoshihide Hayashizaki
- RIKEN Preventive Medicine and Diagnosis Innovation Program, Wako, Saitama, 351-0198, Japan
| | - Robin Andersson
- Department of Biology and Biotech Research and Innovation Centre, Copenhagen University, 2200 Copenhagen N, Denmark
| | - Albin Sandelin
- Department of Biology and Biotech Research and Innovation Centre, Copenhagen University, 2200 Copenhagen N, Denmark
| | - Hideya Kawaji
- RIKEN Preventive Medicine and Diagnosis Innovation Program, Wako, Saitama, 351-0198, Japan; RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Tsurumi-ku, Yokohama, 230-0045, Japan
| | - Masayoshi Itoh
- RIKEN Preventive Medicine and Diagnosis Innovation Program, Wako, Saitama, 351-0198, Japan; RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Tsurumi-ku, Yokohama, 230-0045, Japan
| | - Timo Lassmann
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Tsurumi-ku, Yokohama, 230-0045, Japan
| | - Piero Carninci
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Tsurumi-ku, Yokohama, 230-0045, Japan
| | | | - Wendy A Bickmore
- MRC Human Genetics Unit, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, United Kingdom
| | - Alistair R Forrest
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Tsurumi-ku, Yokohama, 230-0045, Japan; Systems Biology and Genomics, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Martin S Taylor
- MRC Human Genetics Unit, MRC Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, United Kingdom
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171
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Johnson RE, Klassen R, Prakash L, Prakash S. A Major Role of DNA Polymerase δ in Replication of Both the Leading and Lagging DNA Strands. Mol Cell 2015; 59:163-175. [PMID: 26145172 DOI: 10.1016/j.molcel.2015.05.038] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 03/20/2015] [Accepted: 05/28/2015] [Indexed: 01/08/2023]
Abstract
Genetic studies with S. cerevisiae Polδ (pol3-L612M) and Polε (pol2-M644G) mutant alleles, each of which display a higher rate for the generation of a specific mismatch, have led to the conclusion that Polε is the primary leading strand replicase and that Polδ is restricted to replicating the lagging strand template. Contrary to this widely accepted view, here we show that Polδ plays a major role in the replication of both DNA strands, and that the paucity of pol3-L612M-generated errors on the leading strand results from their more proficient removal. Thus, the apparent lack of Polδ contribution to leading strand replication is due to differential mismatch removal rather than differential mismatch generation. Altogether, our genetic studies with Pol3 and Pol2 mutator alleles support the conclusion that Polδ, and not Polε, is the major DNA polymerase for carrying out both leading and lagging DNA synthesis.
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Affiliation(s)
- Robert E Johnson
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-1061, USA
| | - Roland Klassen
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-1061, USA
| | - Louise Prakash
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-1061, USA
| | - Satya Prakash
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-1061, USA
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172
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Jinks-Robertson S, Klein HL. Ribonucleotides in DNA: hidden in plain sight. Nat Struct Mol Biol 2015; 22:176-8. [PMID: 25736085 DOI: 10.1038/nsmb.2981] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Hannah L Klein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, USA
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173
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Abstract
Species survival depends on the faithful replication of genetic information, which is continually monitored and maintained by DNA repair pathways that correct replication errors and the thousands of lesions that arise daily from the inherent chemical lability of DNA and the effects of genotoxic agents. Nonetheless, neutrally evolving DNA (not under purifying selection) accumulates base substitutions with time (the neutral mutation rate). Thus, repair processes are not 100% efficient. The neutral mutation rate varies both between and within chromosomes. For example it is 10-50 fold higher at CpGs than at non-CpG positions. Interestingly, the neutral mutation rate at non-CpG sites is positively correlated with CpG content. Although the basis of this correlation was not immediately apparent, some bioinformatic results were consistent with the induction of non-CpG mutations by DNA repair at flanking CpG sites. Recent studies with a model system showed that in vivo repair of preformed lesions (mismatches, abasic sites, single stranded nicks) can in fact induce mutations in flanking DNA. Mismatch repair (MMR) is an essential component for repair-induced mutations, which can occur as distant as 5 kb from the introduced lesions. Most, but not all, mutations involved the C of TpCpN (G of NpGpA) which is the target sequence of the C-preferring single-stranded DNA specific APOBEC deaminases. APOBEC-mediated mutations are not limited to our model system: Recent studies by others showed that some tumors harbor mutations with the same signature, as can intermediates in RNA-guided endonuclease-mediated genome editing. APOBEC deaminases participate in normal physiological functions such as generating mutations that inactivate viruses or endogenous retrotransposons, or that enhance immunoglobulin diversity in B cells. The recruitment of normally physiological error-prone processes during DNA repair would have important implications for disease, aging and evolution. This perspective briefly reviews both the bioinformatic and biochemical literature relevant to repair-induced mutagenesis and discusses future directions required to understand the mechanistic basis of this process.
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Affiliation(s)
- Jia Chen
- School of Life Science and Technology, ShanghaiTech University, Building 8, 319 Yueyang Road, Shanghai 200031, China
| | - Anthony V Furano
- Section on Genomic Structure and Function, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 8, Room 203, 8 Center Drive, MSC 0830, Bethesda, MD 20892-0830, USA.
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174
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Dissecting genetic and environmental mutation signatures with model organisms. Trends Genet 2015; 31:465-74. [PMID: 25940384 DOI: 10.1016/j.tig.2015.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 12/31/2022]
Abstract
Deep sequencing has impacted on cancer research by enabling routine sequencing of genomes and exomes to identify genetic changes associated with carcinogenesis. Researchers can now use the frequency, type, and context of all mutations in tumor genomes to extract mutation signatures that reflect the driving mutational processes. Identifying mutation signatures, however, may not immediately suggest a mechanism. Consequently, several recent studies have employed deep sequencing of model organisms exposed to discrete genetic or environmental perturbations. These studies exploit the simpler genomes and availability of powerful genetic tools in model organisms to analyze mutation signatures under controlled conditions, forging mechanistic links between mutational processes and signatures. We discuss the power of this approach and suggest that many such studies may be on the horizon.
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175
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Liu S, Lu G, Ali S, Liu W, Zheng L, Dai H, Li H, Xu H, Hua Y, Zhou Y, Ortega J, Li GM, Kunkel TA, Shen B. Okazaki fragment maturation involves α-segment error editing by the mammalian FEN1/MutSα functional complex. EMBO J 2015; 34:1829-43. [PMID: 25921062 DOI: 10.15252/embj.201489865] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 04/14/2015] [Indexed: 11/09/2022] Open
Abstract
During nuclear DNA replication, proofreading-deficient DNA polymerase α (Pol α) initiates Okazaki fragment synthesis with lower fidelity than bulk replication by proofreading-proficient Pol δ or Pol ε. Here, we provide evidence that the exonuclease activity of mammalian flap endonuclease (FEN1) excises Pol α replication errors in a MutSα-dependent, MutLα-independent mismatch repair process we call Pol α-segment error editing (AEE). We show that MSH2 interacts with FEN1 and facilitates its nuclease activity to remove mismatches near the 5' ends of DNA substrates. Mouse cells and mice encoding FEN1 mutations display AEE deficiency, a strong mutator phenotype, enhanced cellular transformation, and increased cancer susceptibility. The results identify a novel role for FEN1 in a specialized mismatch repair pathway and a new cancer etiological mechanism.
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Affiliation(s)
- Songbai Liu
- Colleges of Life Sciences and Agriculture and Biotechnology, Zhejiang University, Hangzhou Zhejiang, China Departments of Radiation Biology and Molecular Medicine, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA, USA
| | - Guojun Lu
- Departments of Radiation Biology and Molecular Medicine, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA, USA
| | - Shafat Ali
- Departments of Radiation Biology and Molecular Medicine, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA, USA
| | - Wenpeng Liu
- Colleges of Life Sciences and Agriculture and Biotechnology, Zhejiang University, Hangzhou Zhejiang, China Departments of Radiation Biology and Molecular Medicine, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA, USA
| | - Li Zheng
- Departments of Radiation Biology and Molecular Medicine, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA, USA
| | - Huifang Dai
- Departments of Radiation Biology and Molecular Medicine, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA, USA
| | - Hongzhi Li
- Departments of Radiation Biology and Molecular Medicine, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA, USA
| | - Hong Xu
- Colleges of Life Sciences and Agriculture and Biotechnology, Zhejiang University, Hangzhou Zhejiang, China
| | - Yuejin Hua
- Colleges of Life Sciences and Agriculture and Biotechnology, Zhejiang University, Hangzhou Zhejiang, China
| | - Yajing Zhou
- Institute of Life Sciences, Jiangsu University, Zhen Jiang Jiangsu, China
| | - Janice Ortega
- Graduate Center for Toxicology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Guo-Min Li
- Graduate Center for Toxicology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC, USA
| | - Binghui Shen
- Departments of Radiation Biology and Molecular Medicine, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA, USA
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176
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St Charles JA, Liberti SE, Williams JS, Lujan SA, Kunkel TA. Quantifying the contributions of base selectivity, proofreading and mismatch repair to nuclear DNA replication in Saccharomyces cerevisiae. DNA Repair (Amst) 2015; 31:41-51. [PMID: 25996407 DOI: 10.1016/j.dnarep.2015.04.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/13/2015] [Accepted: 04/22/2015] [Indexed: 12/19/2022]
Abstract
Mismatches generated during eukaryotic nuclear DNA replication are removed by two evolutionarily conserved error correction mechanisms acting in series, proofreading and mismatch repair (MMR). Defects in both processes are associated with increased susceptibility to cancer. To better understand these processes, we have quantified base selectivity, proofreading and MMR during nuclear DNA replication in Saccharomyces cerevisiae. In the absence of proofreading and MMR, the primary leading and lagging strand replicases, polymerase ɛ and polymerase δ respectively, synthesize DNA in vivo with somewhat different error rates and specificity, and with apparent base selectivity that is more than 100 times higher than measured in vitro. Moreover, leading and lagging strand replication fidelity rely on a different balance between proofreading and MMR. On average, proofreading contributes more to replication fidelity than does MMR, but their relative contributions vary from nearly all proofreading of some mismatches to mostly MMR of other mismatches. Thus accurate replication of the two DNA strands results from a non-uniform and variable balance between error prevention, proofreading and MMR.
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Affiliation(s)
- Jordan A St Charles
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA
| | - Sascha E Liberti
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA
| | - Jessica S Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA
| | - Scott A Lujan
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.
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177
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Suwa Y, Gu J, Baranovskiy AG, Babayeva ND, Pavlov YI, Tahirov TH. Crystal Structure of the Human Pol α B Subunit in Complex with the C-terminal Domain of the Catalytic Subunit. J Biol Chem 2015; 290:14328-37. [PMID: 25847248 DOI: 10.1074/jbc.m115.649954] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Indexed: 11/06/2022] Open
Abstract
In eukaryotic DNA replication, short RNA-DNA hybrid primers synthesized by primase-DNA polymerase α (Prim-Pol α) are needed to start DNA replication by the replicative DNA polymerases, Pol δ and Pol ϵ. The C terminus of the Pol α catalytic subunit (p180C) in complex with the B subunit (p70) regulates the RNA priming and DNA polymerizing activities of Prim-Pol α. It tethers Pol α and primase, facilitating RNA primer handover from primase to Pol α. To understand these regulatory mechanisms and to reveal the details of human Pol α organization, we determined the crystal structure of p70 in complex with p180C. The structured portion of p70 includes a phosphodiesterase (PDE) domain and an oligonucleotide/oligosaccharide binding (OB) domain. The N-terminal domain and the linker connecting it to the PDE domain are disordered in the reported crystal structure. The p180C adopts an elongated asymmetric saddle shape, with a three-helix bundle in the middle and zinc-binding modules (Zn1 and Zn2) on each side. The extensive p180C-p70 interactions involve 20 hydrogen bonds and a number of hydrophobic interactions resulting in an extended buried surface of 4080 Å(2). Importantly, in the structure of the p180C-p70 complex with full-length p70, the residues from the N-terminal to the OB domain contribute to interactions with p180C. The comparative structural analysis revealed both the conserved features and the differences between the human and yeast Pol α complexes.
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Affiliation(s)
- Yoshiaki Suwa
- From the Eppley Institute for Research in Cancer and Allied Diseases and
| | - Jianyou Gu
- From the Eppley Institute for Research in Cancer and Allied Diseases and
| | | | - Nigar D Babayeva
- From the Eppley Institute for Research in Cancer and Allied Diseases and
| | - Youri I Pavlov
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Departments of Biochemistry and Molecular Biology and Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198
| | - Tahir H Tahirov
- From the Eppley Institute for Research in Cancer and Allied Diseases and
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178
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Sparks JL, Burgers PM. Error-free and mutagenic processing of topoisomerase 1-provoked damage at genomic ribonucleotides. EMBO J 2015; 34:1259-69. [PMID: 25777529 DOI: 10.15252/embj.201490868] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/25/2015] [Indexed: 11/09/2022] Open
Abstract
Genomic ribonucleotides incorporated during DNA replication are commonly repaired by RNase H2-dependent ribonucleotide excision repair (RER). When RNase H2 is compromised, such as in Aicardi-Goutières patients, genomic ribonucleotides either persist or are processed by DNA topoisomerase 1 (Top1) by either error-free or mutagenic repair. Here, we present a biochemical analysis of these pathways. Top1 cleavage at genomic ribonucleotides can produce ribonucleoside-2',3'-cyclic phosphate-terminated nicks. Remarkably, this nick is rapidly reverted by Top1, thereby providing another opportunity for repair by RER. However, the 2',3'-cyclic phosphate-terminated nick is also processed by Top1 incision, generally 2 nucleotides upstream of the nick, which produces a covalent Top1-DNA complex with a 2-nucleotide gap. We show that these covalent complexes can be processed by proteolysis, followed by removal of the phospho-peptide by Tdp1 and the 3'-phosphate by Tpp1 to mediate error-free repair. However, when the 2-nucleotide gap is associated with a dinucleotide repeat sequence, sequence slippage re-alignment followed by Top1-mediated religation can occur which results in 2-nucleotide deletion. The efficiency of deletion formation shows strong sequence-context dependence.
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Affiliation(s)
- Justin L Sparks
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
| | - Peter M Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
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179
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Clausen AR, Lujan SA, Burkholder AB, Orebaugh CD, Williams JS, Clausen MF, Malc EP, Mieczkowski PA, Fargo DC, Smith DJ, Kunkel TA. Tracking replication enzymology in vivo by genome-wide mapping of ribonucleotide incorporation. Nat Struct Mol Biol 2015; 22:185-91. [PMID: 25622295 PMCID: PMC4351163 DOI: 10.1038/nsmb.2957] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 12/18/2014] [Indexed: 12/12/2022]
Abstract
Ribonucleotides are frequently incorporated into DNA during replication in eukaryotes. Here we map genome-wide distribution of these ribonucleotides as markers of replication enzymology in budding yeast, using a new 5' DNA end-mapping method, hydrolytic end sequencing (HydEn-seq). HydEn-seq of DNA from ribonucleotide excision repair-deficient strains reveals replicase- and strand-specific patterns of ribonucleotides in the nuclear genome. These patterns support the roles of DNA polymerases α and δ in lagging-strand replication and of DNA polymerase ɛ in leading-strand replication. They identify replication origins, termination zones and variations in ribonucleotide incorporation frequency across the genome that exceed three orders of magnitude. HydEn-seq also reveals strand-specific 5' DNA ends at mitochondrial replication origins, thus suggesting unidirectional replication of a circular genome. Given the conservation of enzymes that incorporate and process ribonucleotides in DNA, HydEn-seq can be used to track replication enzymology in other organisms.
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Affiliation(s)
- Anders R Clausen
- Genome Integrity &Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health (NIH), Research Triangle Park, North Carolina, USA
| | - Scott A Lujan
- Genome Integrity &Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health (NIH), Research Triangle Park, North Carolina, USA
| | - Adam B Burkholder
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina, USA
| | - Clinton D Orebaugh
- Genome Integrity &Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health (NIH), Research Triangle Park, North Carolina, USA
| | - Jessica S Williams
- Genome Integrity &Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health (NIH), Research Triangle Park, North Carolina, USA
| | - Maryam F Clausen
- Department of Genetics, High Throughput Sequencing Facility, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Ewa P Malc
- Department of Genetics, High Throughput Sequencing Facility, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Piotr A Mieczkowski
- Department of Genetics, High Throughput Sequencing Facility, University of North Carolina, Chapel Hill, North Carolina, USA
| | - David C Fargo
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina, USA
| | - Duncan J Smith
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, USA
| | - Thomas A Kunkel
- Genome Integrity &Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health (NIH), Research Triangle Park, North Carolina, USA
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180
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A global profile of replicative polymerase usage. Nat Struct Mol Biol 2015; 22:192-198. [PMID: 25664722 PMCID: PMC4789492 DOI: 10.1038/nsmb.2962] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 12/23/2014] [Indexed: 12/19/2022]
Abstract
Three eukaryotic DNA polymerases are essential for genome replication. Polymerase (Pol) α-primase initiates each synthesis event and is rapidly replaced by processive DNA polymerases: Polɛ replicates the leading strand, whereas Polδ performs lagging-strand synthesis. However, it is not known whether this division of labor is maintained across the whole genome or how uniform it is within single replicons. Using Schizosaccharomyces pombe, we have developed a polymerase usage sequencing (Pu-seq) strategy to map polymerase usage genome wide. Pu-seq provides direct replication-origin location and efficiency data and indirect estimates of replication timing. We confirm that the division of labor is broadly maintained across an entire genome. However, our data suggest a subtle variability in the usage of the two polymerases within individual replicons. We propose that this results from occasional leading-strand initiation by Polδ followed by exchange for Polɛ.
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181
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Koh KD, Balachander S, Hesselberth JR, Storici F. Ribose-seq: global mapping of ribonucleotides embedded in genomic DNA. Nat Methods 2015; 12:251-7, 3 p following 257. [PMID: 25622106 DOI: 10.1038/nmeth.3259] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 12/22/2014] [Indexed: 02/06/2023]
Abstract
Abundant ribonucleotide incorporation in DNA during replication and repair has profound consequences for genome stability, but the global distribution of ribonucleotide incorporation is unknown. We developed ribose-seq, a method for capturing unique products generated by alkaline cleavage of DNA at embedded ribonucleotides. High-throughput sequencing of these fragments in DNA from the yeast Saccharomyces cerevisiae revealed widespread ribonucleotide distribution, with a strong preference for cytidine and guanosine, and identified hotspots of ribonucleotide incorporation in nuclear and mitochondrial DNA. Ribonucleotides were primarily incorporated on the newly synthesized leading strand of nuclear DNA and were present upstream of (G+C)-rich tracts in the mitochondrial genome. Ribose-seq is a powerful tool for the systematic profiling of ribonucleotide incorporation in genomic DNA.
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Affiliation(s)
- Kyung Duk Koh
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Sathya Balachander
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Jay R Hesselberth
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, Colorado, USA
| | - Francesca Storici
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA
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182
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Abstract
Three processes act in series to accurately replicate the eukaryotic nuclear genome. The major replicative DNA polymerases strongly prevent mismatch formation, occasional mismatches that do form are proofread during replication, and rare mismatches that escape proofreading are corrected by mismatch repair (MMR). This review focuses on MMR in light of increasing knowledge about nuclear DNA replication enzymology and the rate and specificity with which mismatches are generated during leading- and lagging-strand replication. We consider differences in MMR efficiency in relation to mismatch recognition, signaling to direct MMR to the nascent strand, mismatch removal, and the timing of MMR. These studies are refining our understanding of relationships between generating and repairing replication errors to achieve accurate replication of both DNA strands of the nuclear genome.
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Affiliation(s)
- Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina 27709;
| | - Dorothy A Erie
- Department of Chemistry and Curriculum in Applied Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599-3290;
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183
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Ali S, Zheng L, Shen B. FEN1-mediated α-segment error editing during Okazaki fragment maturation. Cell Cycle 2015; 14:1767. [PMID: 26039417 PMCID: PMC4614633 DOI: 10.1080/15384101.2015.1046306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 04/27/2015] [Indexed: 10/23/2022] Open
Affiliation(s)
- Shafat Ali
- Department of Radiation Biology; Beckman Research Institute of City of Hope; Duarte, CA, USA
| | - Li Zheng
- Department of Radiation Biology; Beckman Research Institute of City of Hope; Duarte, CA, USA
| | - Binghui Shen
- Department of Radiation Biology; Beckman Research Institute of City of Hope; Duarte, CA, USA
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