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Estep KN, Butler TJ, Ding J, Brosh RM. G4-Interacting DNA Helicases and Polymerases: Potential Therapeutic Targets. Curr Med Chem 2019; 26:2881-2897. [PMID: 29149833 DOI: 10.2174/0929867324666171116123345] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 10/16/2017] [Accepted: 10/16/2017] [Indexed: 02/07/2023]
Abstract
BACKGROUND Guanine-rich DNA can fold into highly stable four-stranded DNA structures called G-quadruplexes (G4). In recent years, the G-quadruplex field has blossomed as new evidence strongly suggests that such alternately folded DNA structures are likely to exist in vivo. G4 DNA presents obstacles for the replication machinery, and both eukaryotic DNA helicases and polymerases have evolved to resolve and copy G4 DNA in vivo. In addition, G4-forming sequences are prevalent in gene promoters, suggesting that G4-resolving helicases act to modulate transcription. METHODS We have searched the PubMed database to compile an up-to-date and comprehensive assessment of the field's current knowledge to provide an overview of the molecular interactions of Gquadruplexes with DNA helicases and polymerases implicated in their resolution. RESULTS Novel computational tools and alternative strategies have emerged to detect G4-forming sequences and assess their biological consequences. Specialized DNA helicases and polymerases catalytically act upon G4-forming sequences to maintain normal replication and genomic stability as well as appropriate gene regulation and cellular homeostasis. G4 helicases also resolve telomeric repeats to maintain chromosomal DNA ends. Bypass of many G4-forming sequences is achieved by the action of translesion DNS polymerases or the PrimPol DNA polymerase. While the collective work has supported a role of G4 in nuclear DNA metabolism, an emerging field centers on G4 abundance in the mitochondrial genome. CONCLUSION Discovery of small molecules that specifically bind and modulate DNA helicases and polymerases or interact with the G4 DNA structure itself may be useful for the development of anticancer regimes.
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Affiliation(s)
- Katrina N Estep
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd Baltimore, MD 21224, United States
| | - Thomas J Butler
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd Baltimore, MD 21224, United States
| | - Jun Ding
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd Baltimore, MD 21224, United States
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd Baltimore, MD 21224, United States
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2
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Rutledge MT, Russo M, Belton JM, Dekker J, Broach JR. The yeast genome undergoes significant topological reorganization in quiescence. Nucleic Acids Res 2015. [PMID: 26202961 PMCID: PMC4787801 DOI: 10.1093/nar/gkv723] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
We have examined the three-dimensional organization of the yeast genome during quiescence by a chromosome capture technique as a means of understanding how genome organization changes during development. For exponentially growing cells we observe high levels of inter-centromeric interaction but otherwise a predominance of intrachromosomal interactions over interchromosomal interactions, consistent with aggregation of centromeres at the spindle pole body and compartmentalization of individual chromosomes within the nucleoplasm. Three major changes occur in the organization of the quiescent cell genome. First, intrachromosomal associations increase at longer distances in quiescence as compared to growing cells. This suggests that chromosomes undergo condensation in quiescence, which we confirmed by microscopy by measurement of the intrachromosomal distances between two sites on one chromosome. This compaction in quiescence requires the condensin complex. Second, inter-centromeric interactions decrease, consistent with prior data indicating that centromeres disperse along an array of microtubules during quiescence. Third, inter-telomeric interactions significantly increase in quiescence, an observation also confirmed by direct measurement. Thus, survival during quiescence is associated with substantial topological reorganization of the genome.
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Affiliation(s)
- Mark T Rutledge
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Mariano Russo
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Jon-Matthew Belton
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Job Dekker
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - James R Broach
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
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3
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Skoneczna A, Kaniak A, Skoneczny M. Genetic instability in budding and fission yeast-sources and mechanisms. FEMS Microbiol Rev 2015; 39:917-67. [PMID: 26109598 PMCID: PMC4608483 DOI: 10.1093/femsre/fuv028] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2015] [Indexed: 12/17/2022] Open
Abstract
Cells are constantly confronted with endogenous and exogenous factors that affect their genomes. Eons of evolution have allowed the cellular mechanisms responsible for preserving the genome to adjust for achieving contradictory objectives: to maintain the genome unchanged and to acquire mutations that allow adaptation to environmental changes. One evolutionary mechanism that has been refined for survival is genetic variation. In this review, we describe the mechanisms responsible for two biological processes: genome maintenance and mutation tolerance involved in generations of genetic variations in mitotic cells of both Saccharomyces cerevisiae and Schizosaccharomyces pombe. These processes encompass mechanisms that ensure the fidelity of replication, DNA lesion sensing and DNA damage response pathways, as well as mechanisms that ensure precision in chromosome segregation during cell division. We discuss various factors that may influence genome stability, such as cellular ploidy, the phase of the cell cycle, transcriptional activity of a particular region of DNA, the proficiency of DNA quality control systems, the metabolic stage of the cell and its respiratory potential, and finally potential exposure to endogenous or environmental stress. The stability of budding and fission yeast genomes is influenced by two contradictory factors: (1) the need to be fully functional, which is ensured through the replication fidelity pathways of nuclear and mitochondrial genomes through sensing and repairing DNA damage, through precise chromosome segregation during cell division; and (2) the need to acquire changes for adaptation to environmental challenges.
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Affiliation(s)
- Adrianna Skoneczna
- Laboratory of Mutagenesis and DNA Repair, Institute of Biochemistry and Biophysics, Polish Academy of Science, 02-106 Warsaw, Poland
| | - Aneta Kaniak
- Laboratory of Mutagenesis and DNA Repair, Institute of Biochemistry and Biophysics, Polish Academy of Science, 02-106 Warsaw, Poland
| | - Marek Skoneczny
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Science, 02-106 Warsaw, Poland
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Garbacz M, Araki H, Flis K, Bebenek A, Zawada AE, Jonczyk P, Makiela-Dzbenska K, Fijalkowska IJ. Fidelity consequences of the impaired interaction between DNA polymerase epsilon and the GINS complex. DNA Repair (Amst) 2015; 29:23-35. [PMID: 25758782 DOI: 10.1016/j.dnarep.2015.02.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/03/2015] [Accepted: 02/04/2015] [Indexed: 01/08/2023]
Abstract
DNA polymerase epsilon interacts with the CMG (Cdc45-MCM-GINS) complex by Dpb2p, the non-catalytic subunit of DNA polymerase epsilon. It is postulated that CMG is responsible for targeting of Pol ɛ to the leading strand. We isolated a mutator dpb2-100 allele which encodes the mutant form of Dpb2p. We showed previously that Dpb2-100p has impaired interactions with Pol2p, the catalytic subunit of Pol ɛ. Here, we present that Dpb2-100p has strongly impaired interaction with the Psf1 and Psf3 subunits of the GINS complex. Our in vitro results suggest that while dpb2-100 does not alter Pol ɛ's biochemical properties including catalytic efficiency, processivity or proofreading activity - it moderately decreases the fidelity of DNA synthesis. As the in vitro results did not explain the strong in vivo mutator effect of the dpb2-100 allele we analyzed the mutation spectrum in vivo. The analysis of the mutation rates in the dpb2-100 mutant indicated an increased participation of the error-prone DNA polymerase zeta in replication. However, even in the absence of Pol ζ activity the presence of the dpb2-100 allele was mutagenic, indicating that a significant part of mutagenesis is Pol ζ-independent. A strong synergistic mutator effect observed for transversions in the triple mutant dpb2-100 pol2-4 rev3Δ as compared to pol2-4 rev3Δ and dpb2-100 rev3Δ suggests that in the presence of the dpb2-100 allele the number of replication errors is enhanced. We hypothesize that in the dpb2-100 strain, where the interaction between Pol ɛ and GINS is weakened, the access of Pol δ to the leading strand may be increased. The increased participation of Pol δ on the leading strand in the dpb2-100 mutant may explain the synergistic mutator effect observed in the dpb2-100 pol3-5DV double mutant.
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Affiliation(s)
- Marta Garbacz
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Laboratory of Mutagenesis and DNA Repair, Pawinskiego 5A, Warsaw 02-106, Poland
| | - Hiroyuki Araki
- National Institute of Genetics, Division of Microbial Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Krzysztof Flis
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Laboratory of Mutagenesis and DNA Repair, Pawinskiego 5A, Warsaw 02-106, Poland
| | - Anna Bebenek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Department of Molecular Biology, Pawinskiego 5A, Warsaw 02-106, Poland
| | - Anna E Zawada
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Laboratory of Mutagenesis and DNA Repair, Pawinskiego 5A, Warsaw 02-106, Poland
| | - Piotr Jonczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Laboratory of Mutagenesis and DNA Repair, Pawinskiego 5A, Warsaw 02-106, Poland
| | - Karolina Makiela-Dzbenska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Laboratory of Mutagenesis and DNA Repair, Pawinskiego 5A, Warsaw 02-106, Poland.
| | - Iwona J Fijalkowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Laboratory of Mutagenesis and DNA Repair, Pawinskiego 5A, Warsaw 02-106, Poland.
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6
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Supady A, Klipp E, Barberis M. A variable fork rate affects timing of origin firing and S phase dynamics in Saccharomyces cerevisiae. J Biotechnol 2013; 168:174-84. [PMID: 23850861 DOI: 10.1016/j.jbiotec.2013.06.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 05/23/2013] [Accepted: 06/27/2013] [Indexed: 10/26/2022]
Abstract
Activation (in the following referred to as firing) of replication origins is a continuous and irreversible process regulated by availability of DNA replication molecules and cyclin-dependent kinase activities, which are often altered in human cancers. The temporal, progressive origin firing throughout S phase appears as a characteristic replication profile, and computational models have been developed to describe this process. Although evidence from yeast to human indicates that a range of replication fork rates is observed experimentally in order to complete a timely S phase, those models incorporate velocities that are uniform across the genome. Taking advantage of the availability of replication profiles, chromosomal position and replication timing, here we investigated how fork rate may affect origin firing in budding yeast. Our analysis suggested that patterns of origin firing can be observed from a modulation of the fork rate that strongly correlates with origin density. Replication profiles of chromosomes with a low origin density were fitted with a variable fork rate, whereas for the ones with a high origin density a constant fork rate was appropriate. This indeed supports the previously reported correlation between inter-origin distance and fork rate changes. Intriguingly, the calculated correlation between fork rate and timing of origin firing allowed the estimation of firing efficiencies for the replication origins. This approach correctly retrieved origin efficiencies previously determined for chromosome VI and provided testable prediction for other chromosomal origins. Our results gain deeper insights into the temporal coordination of genome duplication, indicating that control of the replication fork rate is required for the timely origin firing during S phase.
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Affiliation(s)
- Adriana Supady
- Institute for Biology, Theoretical Biophysics, Humboldt University Berlin, Invalidenstraβe 42, 10115 Berlin, Germany
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7
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Abstract
Budding yeast, like other eukaryotes, carries its genetic information on chromosomes that are sequestered from other cellular constituents by a double membrane, which forms the nucleus. An elaborate molecular machinery forms large pores that span the double membrane and regulate the traffic of macromolecules into and out of the nucleus. In multicellular eukaryotes, an intermediate filament meshwork formed of lamin proteins bridges from pore to pore and helps the nucleus reform after mitosis. Yeast, however, lacks lamins, and the nuclear envelope is not disrupted during yeast mitosis. The mitotic spindle nucleates from the nucleoplasmic face of the spindle pole body, which is embedded in the nuclear envelope. Surprisingly, the kinetochores remain attached to short microtubules throughout interphase, influencing the position of centromeres in the interphase nucleus, and telomeres are found clustered in foci at the nuclear periphery. In addition to this chromosomal organization, the yeast nucleus is functionally compartmentalized to allow efficient gene expression, repression, RNA processing, genomic replication, and repair. The formation of functional subcompartments is achieved in the nucleus without intranuclear membranes and depends instead on sequence elements, protein-protein interactions, specific anchorage sites at the nuclear envelope or at pores, and long-range contacts between specific chromosomal loci, such as telomeres. Here we review the spatial organization of the budding yeast nucleus, the proteins involved in forming nuclear subcompartments, and evidence suggesting that the spatial organization of the nucleus is important for nuclear function.
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Waisertreiger ISR, Liston VG, Menezes MR, Kim HM, Lobachev KS, Stepchenkova EI, Tahirov TH, Rogozin IB, Pavlov YI. Modulation of mutagenesis in eukaryotes by DNA replication fork dynamics and quality of nucleotide pools. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2012; 53:699-724. [PMID: 23055184 PMCID: PMC3893020 DOI: 10.1002/em.21735] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/13/2012] [Accepted: 08/15/2012] [Indexed: 06/01/2023]
Abstract
The rate of mutations in eukaryotes depends on a plethora of factors and is not immediately derived from the fidelity of DNA polymerases (Pols). Replication of chromosomes containing the anti-parallel strands of duplex DNA occurs through the copying of leading and lagging strand templates by a trio of Pols α, δ and ϵ, with the assistance of Pol ζ and Y-family Pols at difficult DNA template structures or sites of DNA damage. The parameters of the synthesis at a given location are dictated by the quality and quantity of nucleotides in the pools, replication fork architecture, transcription status, regulation of Pol switches, and structure of chromatin. The result of these transactions is a subject of survey and editing by DNA repair.
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Affiliation(s)
- Irina S.-R. Waisertreiger
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Victoria G. Liston
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Miriam R. Menezes
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Hyun-Min Kim
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A
| | - Kirill S. Lobachev
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A
| | - Elena I. Stepchenkova
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
- Saint Petersburg Branch of Vavilov Institute of General Genetics, Universitetskaya emb. 7/9, St Petersburg, 199034, Russia
- Department of Genetics, Saint Petersburg University, Universitetskaya emb. 7/9, St Petersburg, 199034, Russia
| | - Tahir H. Tahirov
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
| | - Igor B. Rogozin
- National Center for Biotechnology Information NLM, National Institutes of Health, Bethesda, MD 20894, U.S.A
- Institute of Cytology and Genetics, 630090 Novosibirsk, Russia
| | - Youri. I. Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases, ESH 7009, 986805 Nebraska Medical Center, Omaha, NE 68198-6805, U.S.A
- Department of Genetics, Saint Petersburg University, Universitetskaya emb. 7/9, St Petersburg, 199034, Russia
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Vaisica JA, Baryshnikova A, Costanzo M, Boone C, Brown GW. Mms1 and Mms22 stabilize the replisome during replication stress. Mol Biol Cell 2011; 22:2396-408. [PMID: 21593207 PMCID: PMC3128540 DOI: 10.1091/mbc.e10-10-0848] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A mechanism is shown by which Mms1 and Mms22 promote DNA replication in the presence of replication stress: they stabilize the replisome at stalled replication forks. Mms1 and Mms22 form a Cul4Ddb1-like E3 ubiquitin ligase with the cullin Rtt101. In this complex, Rtt101 is bound to the substrate-specific adaptor Mms22 through a linker protein, Mms1. Although the Rtt101Mms1/Mms22 ubiquitin ligase is important in promoting replication through damaged templates, how it does so has yet to be determined. Here we show that mms1Δ and mms22Δ cells fail to properly regulate DNA replication fork progression when replication stress is present and are defective in recovery from replication fork stress. Consistent with a role in promoting DNA replication, we find that Mms1 is enriched at sites where replication forks have stalled and that this localization requires the known binding partners of Mms1—Rtt101 and Mms22. Mms1 and Mms22 stabilize the replisome during replication stress, as binding of the fork-pausing complex components Mrc1 and Csm3, and DNA polymerase ε, at stalled replication forks is decreased in mms1Δ and mms22Δ. Taken together, these data indicate that Mms1 and Mms22 are important for maintaining the integrity of the replisome when DNA replication forks are slowed by hydroxyurea and thereby promote efficient recovery from replication stress.
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Affiliation(s)
- Jessica A Vaisica
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
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10
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Abstract
Duplication of chromosomal DNA is a temporally and spatially regulated process. The timing of DNA replication initiation at various origins is highly coordinated; some origins fire early and others late during S phase. Moreover, inside the nuclei, the bulk of DNA replication is physically organized in replication factories, consisting of DNA polymerases and other replication proteins. In this review article, we discuss how DNA replication is organized and regulated spatially within the nucleus and how this spatial organization is linked to temporal regulation. We focus on DNA replication in budding yeast and fission yeast and, where applicable, compare yeast DNA replication with that in bacteria and metazoans.
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Affiliation(s)
- Toyoaki Natsume
- Wellcome Trust Centre for Gene Regulation and Expression, University of Dundee, Dundee, DD1 5EH, UK
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Spiesser TW, Diener C, Barberis M, Klipp E. What influences DNA replication rate in budding yeast? PLoS One 2010; 5:e10203. [PMID: 20436919 PMCID: PMC2860512 DOI: 10.1371/journal.pone.0010203] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Accepted: 03/12/2010] [Indexed: 11/18/2022] Open
Abstract
Background DNA replication begins at specific locations called replication origins, where helicase and polymerase act in concert to unwind and process the single DNA filaments. The sites of active DNA synthesis are called replication forks. The density of initiation events is low when replication forks travel fast, and is high when forks travel slowly. Despite the potential involvement of epigenetic factors, transcriptional regulation and nucleotide availability, the causes of differences in replication times during DNA synthesis have not been established satisfactorily, yet. Methodology/Principal Findings Here, we aimed at quantifying to which extent sequence properties contribute to the DNA replication time in budding yeast. We interpreted the movement of the replication machinery along the DNA template as a directed random walk, decomposing influences on DNA replication time into sequence-specific and sequence-independent components. We found that for a large part of the genome the elongation time can be well described by a global average replication rate, thus by a single parameter. However, we also showed that there are regions within the genomic landscape of budding yeast with highly specific replication rates, which cannot be explained by global properties of the replication machinery. Conclusion/Significance Computational models of DNA replication in budding yeast that can predict replication dynamics have rarely been developed yet. We show here that even beyond the level of initiation there are effects governing the replication time that can not be explained by the movement of the polymerase along the DNA template alone. This allows us to characterize genomic regions with significantly altered elongation characteristics, independent of initiation times or sequence composition.
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Affiliation(s)
- Thomas W. Spiesser
- Theoretical Biophysics, Institute for Biology, Humboldt University Berlin, Berlin, Germany
| | - Christian Diener
- Theoretical Biophysics, Institute for Biology, Humboldt University Berlin, Berlin, Germany
| | - Matteo Barberis
- Theoretical Biophysics, Institute for Biology, Humboldt University Berlin, Berlin, Germany
- Max Planck Institute for Molecular Genetics, Berlin, Germany
- * E-mail: (MB); (EK)
| | - Edda Klipp
- Theoretical Biophysics, Institute for Biology, Humboldt University Berlin, Berlin, Germany
- * E-mail: (MB); (EK)
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Sekedat MD, Fenyö D, Rogers RS, Tackett AJ, Aitchison JD, Chait BT. GINS motion reveals replication fork progression is remarkably uniform throughout the yeast genome. Mol Syst Biol 2010; 6:353. [PMID: 20212525 PMCID: PMC2858444 DOI: 10.1038/msb.2010.8] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Accepted: 01/18/2010] [Indexed: 11/22/2022] Open
Abstract
Time-resolved ChIP-chip can be utilized to monitor the genome-wide dynamics of the GINS complex, yielding quantitative information on replication fork movement. Replication forks progress at remarkably uniform rates across the genome, regardless of location. GINS progression appears to be arrested, albeit with very low frequency, at sites of highly transcribed genes. Comparison of simulation with data leads to novel biological insights regarding the dynamics of replication fork progression
In mitotic division, cells duplicate their DNA in S phase to ensure that the proper genetic material is passed on to their progeny. This process of DNA replication is initiated from several hundred specific sites, termed origins of replication, spaced across the genome. It is essential for replication to begin only after G1 and finish before the initiation of anaphase (Blow and Dutta, 2005; Machida et al, 2005). To ensure proper timing, the beginning stages of DNA replication are tightly coupled to the cell cycle through the activity of cyclin-dependent kinases (Nguyen et al, 2001; Masumoto et al, 2002; Sclafani and Holzen, 2007), which promote the accumulation of the pre-RC at the origins and initiate replication. Replication fork movement occurs subsequent to the firing of origins on recruitment of the replicative helicase and the other fork-associated proteins as the cell enters S phase (Diffley, 2004). The replication machinery itself (polymerases, PCNA, etc.) trails behind the helicase, copying the newly unwound DNA in the wake of the replication fork. One component of the pre-RC, the GINS complex, consists of a highly conserved set of paralogous proteins (Psf1, Psf2, Psf3 and Sld5 (Kanemaki et al, 2003; Kubota et al, 2003; Takayama et al, 2003)). Previous work suggests that the GINS complex is an integral component of the replication fork and that its interaction with the genome correlates directly to the movement of the fork (reviewed in Labib and Gambus, 2007). Here, we used the GINS complex as a surrogate to measure features of the dynamics of replication—that is, to determine which origins in the genome are active, the timing of their firing and the rates of replication fork progression. The timing of origin firing and the rates of fork progression have also been investigated by monitoring nascent DNA synthesis (Raghuraman et al, 2001; Yabuki et al, 2002). Origin firing was observed to occur as early as 14 min into the cell cycle and as late as 44 min (Raghuraman et al, 2001). A wide range of nucleotide incorporation rates (0.5–11 kb/min) were observed, with a mean of 2.9 kb/min (Raghuraman et al, 2001), whereas a second study reported a comparable mean rate of DNA duplication of 2.8±1.0 kb/min (Yabuki et al, 2002). In addition to these observations, replication has been inferred to progress asymmetrically from certain origins (Raghuraman et al, 2001). These data have been interpreted to mean that the dynamics of replication fork progression are strongly affected by local chromatin structure or architecture, and perhaps by interaction with the machineries controlling transcription, repair and epigenetic maintenance (Deshpande and Newlon, 1996; Rothstein et al, 2000; Raghuraman et al, 2001; Ivessa et al, 2003). In this study, we adopted a complementary ChIP-chip approach for assaying replication dynamics, in which we followed GINS complexes as they traverse the genome during the cell cycle (Figure 1). These data reveal that GINS binds to active replication origins and spreads bi-directionally and symmetrically as S phase progresses (Figure 3). The majority of origins appear to fire in the first ∼15 min of S phase. A small fraction (∼10%) of the origins to which GINS binds show no evidence of spreading (category 3 origins), although it remains possible that these peaks represent passively fired origins (Shirahige et al, 1998). Once an active origin fires, the GINS complex moves at an almost constant rate of 1.6±0.3 kb/min. Its movement through the inter-origin regions is consistent with that of a protein complex associated with a smoothly moving replication fork. This progression rate is considerably lower and more tightly distributed than those inferred from previous genome-wide measurements assayed through nascent DNA production (Raghuraman et al, 2001; Yabuki et al, 2002). Our study leads us to a different view of replication fork dynamics wherein fork progression is highly uniform in rate and little affected by genomic location. In this work, we also observe a large number of low-intensity persistent features at sites of high transcriptional activity (e.g. tRNA genes). We were able to accurately simulate these features by assuming they are the result of low probability arrest of replication forks at these sites, rather than fork pausing (Deshpande and Newlon, 1996). The extremely low frequency of these events in wild-type cells suggests they are due to low probability stochastic occurrences during the replication process. It is hoped that future studies will resolve whether these persistent features indeed represent rare instances of fork arrest, or are the result of some alternative process. These may include, for example, the deposition of GINS complexes (or perhaps more specifically Psf2) once a pause has been resolved. In this work, we have made extensive use of modeling to test a number of different hypotheses and assumptions. In particular, iterative modeling allowed us to infer that GINS progression is uniform and smooth throughout the genome. We have also demonstrated the potential of simulations for estimating firing efficiencies. In the future, extending such firing efficiency simulations to the whole genome should allow us to make correlations with chromosomal features such as nucleosome occupancy. Such correlations may help in determining factors that govern the probability of replication initiation throughout the genome. Previous studies have led to a picture wherein the replication of DNA progresses at variable rates over different parts of the budding yeast genome. These prior experiments, focused on production of nascent DNA, have been interpreted to imply that the dynamics of replication fork progression are strongly affected by local chromatin structure/architecture, and by interaction with machineries controlling transcription, repair and epigenetic maintenance. Here, we adopted a complementary approach for assaying replication dynamics using whole genome time-resolved chromatin immunoprecipitation combined with microarray analysis of the GINS complex, an integral member of the replication fork. Surprisingly, our data show that this complex progresses at highly uniform rates regardless of genomic location, revealing that replication fork dynamics in yeast is simpler and more uniform than previously envisaged. In addition, we show how the synergistic use of experiment and modeling leads to novel biological insights. In particular, a parsimonious model allowed us to accurately simulate fork movement throughout the genome and also revealed a subtle phenomenon, which we interpret as arising from low-frequency fork arrest.
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Affiliation(s)
- Matthew D Sekedat
- Laboratory for Gaseous Ion Chemistry, The Rockefeller University, New York, NY 10065, USA
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13
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Pavlov YI, Shcherbakova PV. DNA polymerases at the eukaryotic fork-20 years later. Mutat Res 2009; 685:45-53. [PMID: 19682465 DOI: 10.1016/j.mrfmmm.2009.08.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 08/05/2009] [Indexed: 10/20/2022]
Abstract
Function of the eukaryotic genome depends on efficient and accurate replication of anti-parallel DNA strands. Eukaryotic DNA polymerases have different properties adapted to perform a wide spectrum of DNA transactions. Here we focus on major players in the bulk replication, DNA polymerases of the B-family. We review the organization of the replication fork in eukaryotes in a historical perspective, analyze contemporary models and propose a new integrative model of the fork.
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Affiliation(s)
- Youri I Pavlov
- Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha, NE 68198-6805, USA.
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14
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Oo AKS, Kaneko G, Hirayama M, Kinoshita S, Watabe S. Identification of genes differentially expressed by calorie restriction in the rotifer (Brachionus plicatilis). J Comp Physiol B 2009; 180:105-16. [PMID: 19618192 DOI: 10.1007/s00360-009-0389-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 06/24/2009] [Accepted: 06/29/2009] [Indexed: 01/05/2023]
Abstract
A monogonont rotifer Brachionus plicatilis has been widely used as a model organism for physiological, ecological studies and for ecotoxicology. Because of the availability of parthenogenetic mode of reproduction as well as its versatility to be used as live food in aquaculture, the population dynamic studies using the rotifer have become more important and acquired the priority over those using other species. Although many studies have been conducted to identify environmental factors that influence rotifer populations, the molecular mechanisms involved still remain to be elucidated. In this study, gene(s) differentially expressed by calorie restriction in the rotifer was analyzed, where a calorie-restricted group was fed 3 h day(-1) and a well-fed group fed ad libitum. A subtracted cDNA library from the calorie-restricted rotifer was constructed using suppression subtractive hybridization (SSH). One hundred sixty-three expressed sequence tags (ESTs) were identified, which included 109 putative genes with a high identity to known genes in the publicly available database as well as 54 unknown ESTs. After assembling, a total of 38 different genes were obtained among 109 ESTs. Further validation of expression by semi-quantitative reverse transcription-PCR showed that 29 out of the 38 genes obtained by SSH were up regulated by calorie restriction.
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Affiliation(s)
- Aung Kyaw Swar Oo
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, 113-8657, Japan
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15
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Chilkova O, Stenlund P, Isoz I, Stith CM, Grabowski P, Lundström EB, Burgers PM, Johansson E. The eukaryotic leading and lagging strand DNA polymerases are loaded onto primer-ends via separate mechanisms but have comparable processivity in the presence of PCNA. Nucleic Acids Res 2007; 35:6588-97. [PMID: 17905813 PMCID: PMC2095795 DOI: 10.1093/nar/gkm741] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Saccharomyces cerevisiae DNA polymerase delta (Pol delta) and DNA polymerase epsilon (Pol epsilon) are replicative DNA polymerases at the replication fork. Both enzymes are stimulated by PCNA, although to different levels. To understand why and to explore the interaction with PCNA, we compared Pol delta and Pol epsilon in physical interactions with PCNA and nucleic acids (with or without RPA), and in functional assays measuring activity and processivity. Using surface plasmon resonance technique, we show that Pol epsilon has a high affinity for DNA, but a low affinity for PCNA. In contrast, Pol delta has a low affinity for DNA and a high affinity for PCNA. The true processivity of Pol delta and Pol epsilon was measured for the first time in the presence of RPA, PCNA and RFC on single-stranded DNA. Remarkably, in the presence of PCNA, the processivity of Pol delta and Pol epsilon on RPA-coated DNA is comparable. Finally, more PCNA molecules were found on the template after it was replicated by Pol epsilon when compared to Pol delta. We conclude that Pol epsilon and Pol delta exhibit comparable processivity, but are loaded on the primer-end via different mechanisms.
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Affiliation(s)
- Olga Chilkova
- Department of Medical Biochemistry and Biophysics, Department of Biochemistry, Umeå University, 901 87 Umeå, Sweden and Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Peter Stenlund
- Department of Medical Biochemistry and Biophysics, Department of Biochemistry, Umeå University, 901 87 Umeå, Sweden and Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Isabelle Isoz
- Department of Medical Biochemistry and Biophysics, Department of Biochemistry, Umeå University, 901 87 Umeå, Sweden and Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Carrie M. Stith
- Department of Medical Biochemistry and Biophysics, Department of Biochemistry, Umeå University, 901 87 Umeå, Sweden and Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Pawel Grabowski
- Department of Medical Biochemistry and Biophysics, Department of Biochemistry, Umeå University, 901 87 Umeå, Sweden and Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Else-Britt Lundström
- Department of Medical Biochemistry and Biophysics, Department of Biochemistry, Umeå University, 901 87 Umeå, Sweden and Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Peter M. Burgers
- Department of Medical Biochemistry and Biophysics, Department of Biochemistry, Umeå University, 901 87 Umeå, Sweden and Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Erik Johansson
- Department of Medical Biochemistry and Biophysics, Department of Biochemistry, Umeå University, 901 87 Umeå, Sweden and Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA
- *To whom correspondence should be addressed. +46 90 786 6638+46 90 786 9795
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16
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Sweasy JB, Lauper JM, Eckert KA. DNA polymerases and human diseases. Radiat Res 2006; 166:693-714. [PMID: 17067213 DOI: 10.1667/rr0706.1] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Accepted: 07/12/2006] [Indexed: 11/03/2022]
Abstract
DNA polymerases function in DNA replication, repair, recombination and translesion synthesis. Currently, 15 DNA polymerase genes have been identified in human cells, belonging to four distinct families. In this review, we briefly describe the biochemical activities and known cellular roles of each DNA polymerase. Our major focus is on the phenotypic consequences of mutation or ablation of individual DNA polymerase genes. We discuss phenotypes of current mouse models and altered polymerase functions and the relationship of DNA polymerase gene mutations to human cell phenotypes. Interestingly, over 120 single nucleotide polymorphisms (SNPs) have been identified in human populations that are predicted to result in nonsynonymous amino acid substitutions of DNA polymerases. We discuss the putative functional consequences of these SNPs in relation to human disease.
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Affiliation(s)
- Joann B Sweasy
- Department of Therapeutic Radiology, Yale University School of Medicine, 15 York Street, HRT 313D, P.O. Box 208040, New Haven, CT 06520-8040, USA.
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17
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Nedelcheva-Veleva MN, Krastev DB, Stoynov SS. Coordination of DNA synthesis and replicative unwinding by the S-phase checkpoint pathways. Nucleic Acids Res 2006; 34:4138-46. [PMID: 16935878 PMCID: PMC1616944 DOI: 10.1093/nar/gkl528] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The process of DNA replication includes duplex unwinding, followed immediately by DNA synthesis. In eukaryotes, DNA synthesis is disturbed in damaged DNA regions, in replication slow zones, or as a result of insufficient nucleotide level. This review aims to discuss the mechanisms that coordinate DNA unwinding and synthesis, allowing replication to be completed even in the presence of genomic insults. There is a growing body of evidence which suggests that S-phase checkpoint pathways regulate both replicative unwinding and DNA synthesis, to synchronize the two processes, thus ensuring genome stability.
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Affiliation(s)
| | | | - Stoyno S. Stoynov
- To whom correspondence should be addressed. Tel: +359 979 36 89; Fax: +359 2 72 25 077;
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18
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Shikata K, Sasa-Masuda T, Okuno Y, Waga S, Sugino A. The DNA polymerase activity of Pol epsilon holoenzyme is required for rapid and efficient chromosomal DNA replication in Xenopus egg extracts. BMC BIOCHEMISTRY 2006; 7:21. [PMID: 16925818 PMCID: PMC1560149 DOI: 10.1186/1471-2091-7-21] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Accepted: 08/22/2006] [Indexed: 12/31/2022]
Abstract
BACKGROUND DNA polymerase epsilon (Pol epsilon) is involved in DNA replication, repair, and cell-cycle checkpoint control in eukaryotic cells. Although the roles of replicative Pol alpha and Pol delta in chromosomal DNA replication are relatively well understood and well documented, the precise role of Pol epsilon in chromosomal DNA replication is not well understood. RESULTS This study uses a Xenopus egg extract DNA replication system to further elucidate the replicative role(s) played by Pol epsilon. Previous studies show that the initiation timing and elongation of chromosomal DNA replication are markedly impaired in Pol epsilon-depleted Xenopus egg extracts, with reduced accumulation of replicative intermediates and products. This study shows that normal replication is restored by addition of Pol epsilon holoenzyme to Pol epsilon-depleted extracts, but not by addition of polymerase-deficient forms of Pol epsilon, including polymerase point or deletion mutants or incomplete enzyme complexes. Evidence is also provided that Pol epsilon holoenzyme interacts directly with GINS, Cdc45p and Cut5p, each of which plays an important role in initiation of chromosomal DNA replication in eukaryotic cells. CONCLUSION These results indicate that the DNA polymerase activity of Pol epsilon holoenzyme plays an essential role in normal chromosomal DNA replication in Xenopus egg extracts. These are the first biochemical data to show the DNA polymerase activity of Pol epsilon holoenzyme is essential for chromosomal DNA replication in higher eukaryotes, unlike in yeasts.
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Affiliation(s)
- Koh Shikata
- Laboratories for Biomolecular Networks, Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamada-oka, Suita, Osaka 565-0871, Japan
- Research Institute, Thermostable Enzyme Laboratory Co., Ltd, 1-8-31 Midoriga-oka, Ikeda, Osaka 563-8577, Japan
| | - Taro Sasa-Masuda
- Laboratories for Biomolecular Networks, Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamada-oka, Suita, Osaka 565-0871, Japan
- Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
- Braun Laboratories 147-75, California Institute of Technology, Pasadena, California 91125, USA
| | - Yukiko Okuno
- Laboratories for Biomolecular Networks, Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamada-oka, Suita, Osaka 565-0871, Japan
- Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Shou Waga
- Laboratories for Biomolecular Networks, Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Akio Sugino
- Laboratories for Biomolecular Networks, Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamada-oka, Suita, Osaka 565-0871, Japan
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19
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Nasheuer HP, Pospiech H, Syväoja J. Progress Towards the Anatomy of the Eukaryotic DNA Replication Fork. Genome Integr 2006. [DOI: 10.1007/7050_016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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20
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Seki T, Akita M, Kamimura Y, Muramatsu S, Araki H, Sugino A. GINS Is a DNA Polymerase ϵ Accessory Factor during Chromosomal DNA Replication in Budding Yeast. J Biol Chem 2006; 281:21422-21432. [PMID: 16714283 DOI: 10.1074/jbc.m603482200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
GINS is a protein complex found in eukaryotic cells that is composed of Sld5p, Psf1p, Psf2p, and Psf3p. GINS polypeptides are highly conserved in eukaryotes, and the GINS complex is required for chromosomal DNA replication in yeasts and Xenopus egg. This study reports purification and biochemical characterization of GINS from Saccharomyces cerevisiae. The results presented here demonstrate that GINS forms a 1:1 complex with DNA polymerase epsilon (Pol epsilon) holoenzyme and greatly stimulates its catalytic activity in vitro. In the presence of GINS, Pol epsilon is more processive and dissociates more readily from replicated DNA, while under identical conditions, proliferating cell nuclear antigen slightly stimulates Pol epsilon in vitro. These results strongly suggest that GINS is a Pol epsilon accessory protein during chromosomal DNA replication in budding yeast. Based on these results, we propose a model for molecular dynamics at eukaryotic chromosomal replication fork.
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Affiliation(s)
- Takashi Seki
- Laboratories for Biomolecular Networks, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871; Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602
| | - Masaki Akita
- Laboratories for Biomolecular Networks, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871
| | - Yoichiro Kamimura
- Division of Microbial Genetics, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Sachiko Muramatsu
- Division of Microbial Genetics, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Hiroyuki Araki
- Division of Microbial Genetics, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Akio Sugino
- Laboratories for Biomolecular Networks, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871; Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602.
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21
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Kitamura E, Blow JJ, Tanaka TU. Live-cell imaging reveals replication of individual replicons in eukaryotic replication factories. Cell 2006; 125:1297-308. [PMID: 16814716 PMCID: PMC3019746 DOI: 10.1016/j.cell.2006.04.041] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 03/14/2006] [Accepted: 04/13/2006] [Indexed: 11/25/2022]
Abstract
Faithful DNA replication ensures genetic integrity in eukaryotic cells, but it is still obscure how replication is organized in space and time within the nucleus. Using timelapse microscopy, we have developed a new assay to analyze the dynamics of DNA replication both spatially and temporally in individual Saccharomyces cerevisiae cells. This allowed us to visualize replication factories, nuclear foci consisting of replication proteins where the bulk of DNA synthesis occurs. We show that the formation of replication factories is a consequence of DNA replication itself. Our analyses of replication at specific DNA sequences support a long-standing hypothesis that sister replication forks generated from the same origin stay associated with each other within a replication factory while the entire replicon is replicated. This assay system allows replication to be studied at extremely high temporal resolution in individual cells, thereby opening a window into how replication dynamics vary from cell to cell.
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Affiliation(s)
- Etsushi Kitamura
- School of Life Sciences, University of Dundee, Wellcome Trust Biocentre, Dow Street, Dundee, UK
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22
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Rytkönen AK, Vaara M, Nethanel T, Kaufmann G, Sormunen R, Läärä E, Nasheuer HP, Rahmeh A, Lee MYWT, Syväoja JE, Pospiech H. Distinctive activities of DNA polymerases during human DNA replication. FEBS J 2006; 273:2984-3001. [PMID: 16762037 DOI: 10.1111/j.1742-4658.2006.05310.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The contributions of human DNA polymerases (pols) alpha, delta and epsilon during S-phase progression were studied in order to elaborate how these enzymes co-ordinate their functions during nuclear DNA replication. Pol delta was three to four times more intensely UV cross-linked to nascent DNA in late compared with early S phase, whereas the cross-linking of pols alpha and epsilon remained nearly constant throughout the S phase. Consistently, the chromatin-bound fraction of pol delta, unlike pols alpha and epsilon, increased in the late S phase. Moreover, pol delta neutralizing antibodies inhibited replicative DNA synthesis most efficiently in late S-phase nuclei, whereas antibodies against pol epsilon were most potent in early S phase. Ultrastructural localization of the pols by immuno-electron microscopy revealed pol epsilon to localize predominantly to ring-shaped clusters at electron-dense regions of the nucleus, whereas pol delta was mainly dispersed on fibrous structures. Pol alpha and proliferating cell nuclear antigen displayed partial colocalization with pol delta and epsilon, despite the very limited colocalization of the latter two pols. These data are consistent with models where pols delta and epsilon pursue their functions at least partly independently during DNA replication.
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Affiliation(s)
- Anna K Rytkönen
- Biocenter Oulu and Department of Biochemistry, University of Oulu, Finland
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23
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Taricani L, Wang TS. Rad4TopBP1, a scaffold protein, plays separate roles in DNA damage and replication checkpoints and DNA replication. Mol Biol Cell 2006; 17:3456-68. [PMID: 16723501 PMCID: PMC1525248 DOI: 10.1091/mbc.e06-01-0056] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Rad4TopBP1, a BRCT domain protein, is required for both DNA replication and checkpoint responses. Little is known about how the multiple roles of Rad4TopBP1 are coordinated in maintaining genome integrity. We show here that Rad4TopBP1 of fission yeast physically interacts with the checkpoint sensor proteins, the replicative DNA polymerases, and a WD-repeat protein, Crb3. We identified four novel mutants to investigate how Rad4TopBP1 could have multiple roles in maintaining genomic integrity. A novel mutation in the third BRCT domain of rad4+TopBP1 abolishes DNA damage checkpoint response, but not DNA replication, replication checkpoint, and cell cycle progression. This mutant protein is able to associate with all three replicative polymerases and checkpoint proteins Rad3ATR-Rad26ATRIP, Hus1, Rad9, and Rad17 but has a compromised association with Crb3. Furthermore, the damaged-induced Rad9 phosphorylation is significantly reduced in this rad4TopBP1 mutant. Genetic and biochemical analyses suggest that Crb3 has a role in the maintenance of DNA damage checkpoint and influences the Rad4TopBP1 damage checkpoint function. Taken together, our data suggest that Rad4TopBP1 provides a scaffold to a large complex containing checkpoint and replication proteins thereby separately enforcing checkpoint responses to DNA damage and replication perturbations during the cell cycle.
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Affiliation(s)
- Lorena Taricani
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305-5324
| | - Teresa S.F. Wang
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305-5324
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24
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Pavlov YI, Shcherbakova PV, Rogozin IB. Roles of DNA Polymerases in Replication, Repair, and Recombination in Eukaryotes. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 255:41-132. [PMID: 17178465 DOI: 10.1016/s0074-7696(06)55002-8] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The functioning of the eukaryotic genome depends on efficient and accurate DNA replication and repair. The process of replication is complicated by the ongoing decomposition of DNA and damage of the genome by endogenous and exogenous factors. DNA damage can alter base coding potential resulting in mutations, or block DNA replication, which can lead to double-strand breaks (DSB) and to subsequent chromosome loss. Replication is coordinated with DNA repair systems that operate in cells to remove or tolerate DNA lesions. DNA polymerases can serve as sensors in the cell cycle checkpoint pathways that delay cell division until damaged DNA is repaired and replication is completed. Eukaryotic DNA template-dependent DNA polymerases have different properties adapted to perform an amazingly wide spectrum of DNA transactions. In this review, we discuss the structure, the mechanism, and the evolutionary relationships of DNA polymerases and their possible functions in the replication of intact and damaged chromosomes, DNA damage repair, and recombination.
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Affiliation(s)
- Youri I Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases, Departments of Biochemistry and Molecular Biology, and Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA
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25
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Current awareness on yeast. Yeast 2005; 22:919-26. [PMID: 16201058 DOI: 10.1002/yea.1167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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