1
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Goodall DJ, Warecka D, Hawkins M, Rudolph CJ. Interplay between chromosomal architecture and termination of DNA replication in bacteria. Front Microbiol 2023; 14:1180848. [PMID: 37434703 PMCID: PMC10331603 DOI: 10.3389/fmicb.2023.1180848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 06/05/2023] [Indexed: 07/13/2023] Open
Abstract
Faithful transmission of the genome from one generation to the next is key to life in all cellular organisms. In the majority of bacteria, the genome is comprised of a single circular chromosome that is normally replicated from a single origin, though additional genetic information may be encoded within much smaller extrachromosomal elements called plasmids. By contrast, the genome of a eukaryote is distributed across multiple linear chromosomes, each of which is replicated from multiple origins. The genomes of archaeal species are circular, but are predominantly replicated from multiple origins. In all three cases, replication is bidirectional and terminates when converging replication fork complexes merge and 'fuse' as replication of the chromosomal DNA is completed. While the mechanics of replication initiation are quite well understood, exactly what happens during termination is far from clear, although studies in bacterial and eukaryotic models over recent years have started to provide some insight. Bacterial models with a circular chromosome and a single bidirectional origin offer the distinct advantage that there is normally just one fusion event between two replication fork complexes as synthesis terminates. Moreover, whereas termination of replication appears to happen in many bacteria wherever forks happen to meet, termination in some bacterial species, including the well-studied bacteria Escherichia coli and Bacillus subtilis, is more restrictive and confined to a 'replication fork trap' region, making termination even more tractable. This region is defined by multiple genomic terminator (ter) sites, which, if bound by specific terminator proteins, form unidirectional fork barriers. In this review we discuss a range of experimental results highlighting how the fork fusion process can trigger significant pathologies that interfere with the successful conclusion of DNA replication, how these pathologies might be resolved in bacteria without a fork trap system and how the acquisition of a fork trap might have provided an alternative and cleaner solution, thus explaining why in bacterial species that have acquired a fork trap system, this system is remarkably well maintained. Finally, we consider how eukaryotic cells can cope with a much-increased number of termination events.
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Affiliation(s)
- Daniel J. Goodall
- Division of Biosciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | | | | | - Christian J. Rudolph
- Division of Biosciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, United Kingdom
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2
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Toft CJ, Moreau MJJ, Perutka J, Mandapati S, Enyeart P, Sorenson AE, Ellington AD, Schaeffer PM. Delineation of the Ancestral Tus-Dependent Replication Fork Trap. Int J Mol Sci 2021; 22:ijms222413533. [PMID: 34948327 PMCID: PMC8707476 DOI: 10.3390/ijms222413533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/10/2021] [Accepted: 12/15/2021] [Indexed: 12/28/2022] Open
Abstract
In Escherichia coli, DNA replication termination is orchestrated by two clusters of Ter sites forming a DNA replication fork trap when bound by Tus proteins. The formation of a ‘locked’ Tus–Ter complex is essential for halting incoming DNA replication forks. However, the absence of replication fork arrest at some Ter sites raised questions about their significance. In this study, we examined the genome-wide distribution of Tus and found that only the six innermost Ter sites (TerA–E and G) were significantly bound by Tus. We also found that a single ectopic insertion of TerB in its non-permissive orientation could not be achieved, advocating against a need for ‘back-up’ Ter sites. Finally, examination of the genomes of a variety of Enterobacterales revealed a new replication fork trap architecture mostly found outside the Enterobacteriaceae family. Taken together, our data enabled the delineation of a narrow ancestral Tus-dependent DNA replication fork trap consisting of only two Ter sites.
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Affiliation(s)
- Casey J. Toft
- Molecular and Cell Biology, College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, QLD 4811, Australia; (C.J.T.); (M.J.J.M.); (A.E.S.)
- Centre of Tropical Bioinformatics and Molecular Biology, James Cook University, Douglas, QLD 4811, Australia
| | - Morgane J. J. Moreau
- Molecular and Cell Biology, College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, QLD 4811, Australia; (C.J.T.); (M.J.J.M.); (A.E.S.)
| | - Jiri Perutka
- Institute for Cell and Molecular Biology, University of Texas, Austin, TX 78712, USA; (J.P.); (S.M.); (P.E.); (A.D.E.)
| | - Savitri Mandapati
- Institute for Cell and Molecular Biology, University of Texas, Austin, TX 78712, USA; (J.P.); (S.M.); (P.E.); (A.D.E.)
| | - Peter Enyeart
- Institute for Cell and Molecular Biology, University of Texas, Austin, TX 78712, USA; (J.P.); (S.M.); (P.E.); (A.D.E.)
| | - Alanna E. Sorenson
- Molecular and Cell Biology, College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, QLD 4811, Australia; (C.J.T.); (M.J.J.M.); (A.E.S.)
| | - Andrew D. Ellington
- Institute for Cell and Molecular Biology, University of Texas, Austin, TX 78712, USA; (J.P.); (S.M.); (P.E.); (A.D.E.)
| | - Patrick M. Schaeffer
- Molecular and Cell Biology, College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, QLD 4811, Australia; (C.J.T.); (M.J.J.M.); (A.E.S.)
- Centre of Tropical Bioinformatics and Molecular Biology, James Cook University, Douglas, QLD 4811, Australia
- Correspondence: ; Tel.: +61-(0)-7-4781-4448; Fax: +61-(0)-7-4781-6078
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3
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Jameson KH, Rudolph CJ, Hawkins M. Termination of DNA replication at Tus-ter barriers results in under-replication of template DNA. J Biol Chem 2021; 297:101409. [PMID: 34780717 DOI: 10.1016/j.jbc.2021.101409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 11/02/2021] [Accepted: 11/10/2021] [Indexed: 02/05/2023] Open
Abstract
The complete and accurate duplication of genomic information is vital to maintain genome stability in all domains of life. In Escherichia coli, replication termination, the final stage of the duplication process, is confined to the 'replication fork trap' region by multiple unidirectional fork barriers formed by the binding of Tus protein to genomic ter sites. Termination typically occurs away from Tus-ter complexes, but they become part of the fork fusion process when a delay to one replisome allows the second replisome to travel more than halfway around the chromosome. In this instance, replisome progression is blocked at the non-permissive interface of the Tus-ter complex, termination then occurs when a converging replisome meets the permissive interface. To investigate the consequences of replication fork fusion at Tus-ter complexes, we established a plasmid-based replication system where we could mimic the termination process at Tus-ter complexes in vitro. We developed a termination mapping assay to measure leading strand replication fork progression and demonstrate that the DNA template is under-replicated by 15-24 bases when replication forks fuse at Tus-ter complexes. This gap could not be closed by the addition of lagging strand processing enzymes or by the inclusion of several helicases that promote DNA replication. Our results indicate that accurate fork fusion at Tus-ter barriers requires further enzymatic processing, highlighting large gaps that still exist in our understanding of the final stages of chromosome duplication and the evolutionary advantage of having a replication fork trap.
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Affiliation(s)
- Katie H Jameson
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Christian J Rudolph
- Division of Biosciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK
| | - Michelle Hawkins
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
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4
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González-Acosta D, Blanco-Romero E, Ubieto-Capella P, Mutreja K, Míguez S, Llanos S, García F, Muñoz J, Blanco L, Lopes M, Méndez J. PrimPol-mediated repriming facilitates replication traverse of DNA interstrand crosslinks. EMBO J 2021; 40:e106355. [PMID: 34128550 PMCID: PMC8280817 DOI: 10.15252/embj.2020106355] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 05/04/2021] [Accepted: 05/04/2021] [Indexed: 12/22/2022] Open
Abstract
DNA interstrand crosslinks (ICLs) induced by endogenous aldehydes or chemotherapeutic agents interfere with essential processes such as replication and transcription. ICL recognition and repair by the Fanconi Anemia pathway require the formation of an X‐shaped DNA structure that may arise from convergence of two replication forks at the crosslink or traversing of the lesion by a single replication fork. Here, we report that ICL traverse strictly requires DNA repriming events downstream of the lesion, which are carried out by PrimPol, the second primase‐polymerase identified in mammalian cells after Polα/Primase. The recruitment of PrimPol to the vicinity of ICLs depends on its interaction with RPA, but not on FANCM translocase or the BLM/TOP3A/RMI1‐2 (BTR) complex that also participate in ICL traverse. Genetic ablation of PRIMPOL makes cells more dependent on the fork convergence mechanism to initiate ICL repair, and PRIMPOL KO cells and mice display hypersensitivity to ICL‐inducing drugs. These results open the possibility of targeting PrimPol activity to enhance the efficacy of chemotherapy based on DNA crosslinking agents.
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Affiliation(s)
- Daniel González-Acosta
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Elena Blanco-Romero
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Patricia Ubieto-Capella
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Karun Mutreja
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Samuel Míguez
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Susana Llanos
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Fernando García
- Proteomics Unit-ProteoRed-ISCIII, Biotechnology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Javier Muñoz
- Proteomics Unit-ProteoRed-ISCIII, Biotechnology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Luis Blanco
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Juan Méndez
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
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5
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Byrne SR, Rokita SE. Unraveling Reversible DNA Cross-Links with a Biological Machine. Chem Res Toxicol 2020; 33:2903-2913. [PMID: 33147957 DOI: 10.1021/acs.chemrestox.0c00413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reversible generation and capture of certain electrophilic quinone methide intermediates support dynamic reactions with DNA that allow for migration and transfer of alkylation and cross-linking. This reversibility also expands the possible consequences that can be envisioned when confronted by DNA repair processes and biological machines. To begin testing the response to such an encounter, quinone methide-based modification of DNA has now been challenged with a helicase (T7 bacteriophage gene protein four, T7gp4) that promotes 5' to 3' translocation and unwinding. This model protein was selected based on its widespread application, well characterized mechanism and detailed structural information. Little over one-half of the cross-linking generated by a bisfunctional quinone methide remained stable to T7gp4 and did not suppress its activity. The helicase likely avoids the topological block generated by this fraction of cross-linking by its ability to shift from single- to double-stranded translocation. The remaining fraction of cross-linking was destroyed during T7gp4 catalysis. Thus, this helicase is chemically competent to promote release of the quinone methide from DNA. The ability of T7gp4 to act as a Brownian ratchet for unwinding DNA may block recapture of the QM intermediate by DNA during its transient release from a donor strand. Most surprisingly, T7gp4 releases the quinone methide from both the translocating strand that passes through its central channel and the excluded strand that was typically unaffected by other lesions. The ability of T7gp4 to reverse the cross-link formed by the quinone methide does not extend to that formed irreversibly by the nitrogen mustard mechlorethamine.
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Affiliation(s)
- Shane R Byrne
- Chemistry Biology Interface Graduate Training Program and Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218, United States
| | - Steven E Rokita
- Chemistry Biology Interface Graduate Training Program and Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218, United States
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6
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Berghuis BA, Raducanu VS, Elshenawy MM, Jergic S, Depken M, Dixon NE, Hamdan SM, Dekker NH. What is all this fuss about Tus? Comparison of recent findings from biophysical and biochemical experiments. Crit Rev Biochem Mol Biol 2017; 53:49-63. [DOI: 10.1080/10409238.2017.1394264] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Bojk A. Berghuis
- Department of Bionanoscience, Kavli institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Vlad-Stefan Raducanu
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Mohamed M. Elshenawy
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Slobodan Jergic
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales, Australia
| | - Martin Depken
- Department of Bionanoscience, Kavli institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Nicholas E. Dixon
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales, Australia
| | - Samir M. Hamdan
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Nynke H. Dekker
- Department of Bionanoscience, Kavli institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
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7
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Felczak MM, Chodavarapu S, Kaguni JM. DnaC, the indispensable companion of DnaB helicase, controls the accessibility of DnaB helicase by primase. J Biol Chem 2017; 292:20871-20882. [PMID: 29070678 DOI: 10.1074/jbc.m117.807644] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/11/2017] [Indexed: 11/06/2022] Open
Abstract
Former studies relying on hydrogen/deuterium exchange analysis suggest that DnaC bound to DnaB alters the conformation of the N-terminal domain (NTD) of DnaB to impair the ability of this DNA helicase to interact with primase. Supporting this idea, the work described herein based on biosensor experiments and enzyme-linked immunosorbent assays shows that the DnaB-DnaC complex binds poorly to primase in comparison with DnaB alone. Using a structural model of DnaB complexed with the C-terminal domain of primase, we found that Ile-85 is located at the interface in the NTD of DnaB that contacts primase. An alanine substitution for Ile-85 specifically interfered with this interaction and impeded DnaB function in DNA replication, but not its activity as a DNA helicase or its ability to bind to ssDNA. By comparison, substitutions of Asn for Ile-136 (I136N) and Thr for Ile-142 (I142T) in a subdomain previously named the helical hairpin in the NTD of DnaB altered the conformation of the helical hairpin and/or compromised its pairwise arrangement with the companion subdomain in each brace of protomers of the DnaB hexamer. In contrast with the I85A mutant, the latter were defective in DNA replication due to impaired binding to both ssDNA and primase. In view of these findings, we propose that DnaC controls the ability of DnaB to interact with primase by modifying the conformation of the NTD of DnaB.
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Affiliation(s)
- Magdalena M Felczak
- From the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319
| | - Sundari Chodavarapu
- From the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319
| | - Jon M Kaguni
- From the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319
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8
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Trakselis MA, Seidman MM, Brosh RM. Mechanistic insights into how CMG helicase facilitates replication past DNA roadblocks. DNA Repair (Amst) 2017; 55:76-82. [PMID: 28554039 DOI: 10.1016/j.dnarep.2017.05.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 05/13/2017] [Indexed: 02/07/2023]
Abstract
Before leaving the house, it is a good idea to check for road closures that may affect the morning commute. Otherwise, one may encounter significant delays arriving at the destination. While this is commonly true, motorists may be able to consult a live interactive traffic map and pick an alternate route or detour to avoid being late. However, this is not the case if one needs to catch the train which follows a single track to the terminus; if something blocks the track, there is a delay. Such is the case for the DNA replisome responsible for copying the genetic information that provides the recipe of life. When the replication machinery encounters a DNA roadblock, the outcome can be devastating if the obstacle is not overcome in an efficient manner. Fortunately, the cell's DNA synthesis apparatus can bypass certain DNA obstructions, but the mechanism(s) are still poorly understood. Very recently, two papers from the O'Donnell lab, one structural (Georgescu et al., 2017 [1]) and the other biochemical (Langston and O'Donnell, 2017 [2]), have challenged the conventional thinking of how the replicative CMG helicase is arranged on DNA, unwinds double-stranded DNA, and handles barricades in its path. These new findings raise important questions in the search for mechanistic insights into how DNA is copied, particularly when the replication machinery encounters a roadblock.
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Affiliation(s)
- Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States.
| | - Michael M Seidman
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 251 Bayview Blvd, Baltimore, MD 21224, United States.
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 251 Bayview Blvd, Baltimore, MD 21224, United States.
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9
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Berghuis BA, Köber M, van Laar T, Dekker NH. High-throughput, high-force probing of DNA-protein interactions with magnetic tweezers. Methods 2016; 105:90-8. [DOI: 10.1016/j.ymeth.2016.03.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 03/23/2016] [Accepted: 03/29/2016] [Indexed: 12/19/2022] Open
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10
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Moolman MC, Tiruvadi Krishnan S, Kerssemakers JWJ, de Leeuw R, Lorent V, Sherratt DJ, Dekker NH. The progression of replication forks at natural replication barriers in live bacteria. Nucleic Acids Res 2016; 44:6262-73. [PMID: 27166373 PMCID: PMC5291258 DOI: 10.1093/nar/gkw397] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 04/27/2016] [Accepted: 04/28/2016] [Indexed: 01/07/2023] Open
Abstract
Protein-DNA complexes are one of the principal barriers the replisome encounters during replication. One such barrier is the Tus-ter complex, which is a direction dependent barrier for replication fork progression. The details concerning the dynamics of the replisome when encountering these Tus-ter barriers in the cell are poorly understood. By performing quantitative fluorescence microscopy with microfuidics, we investigate the effect on the replisome when encountering these barriers in live Escherichia coli cells. We make use of an E. coli variant that includes only an ectopic origin of replication that is positioned such that one of the two replisomes encounters a Tus-ter barrier before the other replisome. This enables us to single out the effect of encountering a Tus-ter roadblock on an individual replisome. We demonstrate that the replisome remains stably bound after encountering a Tus-ter complex from the non-permissive direction. Furthermore, the replisome is only transiently blocked, and continues replication beyond the barrier. Additionally, we demonstrate that these barriers affect sister chromosome segregation by visualizing specific chromosomal loci in the presence and absence of the Tus protein. These observations demonstrate the resilience of the replication fork to natural barriers and the sensitivity of chromosome alignment to fork progression.
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Affiliation(s)
- M Charl Moolman
- Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Sriram Tiruvadi Krishnan
- Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Jacob W J Kerssemakers
- Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Roy de Leeuw
- Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Vincent Lorent
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, CNRS, (UMR 7538), F-93430 Villetaneuse, France
| | - David J Sherratt
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Nynke H Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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11
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Wang Y, Lin Z, Fan H, Peng X. Photoinduced DNA Interstrand Cross-Link Formation by Naphthalene Boronates via a Carbocation. Chemistry 2016; 22:10382-6. [DOI: 10.1002/chem.201601504] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Indexed: 12/12/2022]
Affiliation(s)
- Yibin Wang
- Department of Chemistry and Biochemistry; University of Wisconsin Milwaukee; 3210 N. Cramer St. Milwaukee WI 53211 USA
| | - Zechao Lin
- Department of Chemistry and Biochemistry; University of Wisconsin Milwaukee; 3210 N. Cramer St. Milwaukee WI 53211 USA
| | - Heli Fan
- Department of Chemistry and Biochemistry; University of Wisconsin Milwaukee; 3210 N. Cramer St. Milwaukee WI 53211 USA
| | - Xiaohua Peng
- Department of Chemistry and Biochemistry; University of Wisconsin Milwaukee; 3210 N. Cramer St. Milwaukee WI 53211 USA
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12
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Elshenawy MM, Jergic S, Xu ZQ, Sobhy MA, Takahashi M, Oakley AJ, Dixon NE, Hamdan SM. Replisome speed determines the efficiency of the Tus−Ter replication termination barrier. Nature 2015; 525:394-8. [DOI: 10.1038/nature14866] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 06/26/2015] [Indexed: 11/09/2022]
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13
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Larsen NB, Hickson ID, Mankouri HW. Tus-Ter as a tool to study site-specific DNA replication perturbation in eukaryotes. Cell Cycle 2015; 13:2994-8. [PMID: 25486560 DOI: 10.4161/15384101.2014.958912] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The high-affinity binding of the Tus protein to specific 21-bp sequences, called Ter, causes site-specific, and polar, DNA replication fork arrest in E coli. The Tus-Ter complex serves to coordinate DNA replication with chromosome segregation in this organism. A number of recent and ongoing studies have demonstrated that Tus-Ter can be used as a heterologous tool to generate site-specific perturbation of DNA replication when reconstituted in eukaryotes. Here, we review these recent findings and explore the molecular mechanism by which Tus-Ter mediates replication fork (RF) arrest in the budding yeast, S. cerevisiae. We propose that Tus-Ter is a versatile, genetically tractable, and regulatable RF blocking system that can be utilized for disrupting DNA replication in a diverse range of host cells.
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Affiliation(s)
- Nicolai B Larsen
- a Center for Healthy Aging; Department of Cellular and Molecular Medicine ; University of Copenhagen ; Copenhagen , Denmark
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14
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Fan J, Strick TR. Unlocking the secrets of fork arrest. Nat Chem Biol 2015; 11:550-1. [DOI: 10.1038/nchembio.1860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Berghuis BA, Dulin D, Xu ZQ, van Laar T, Cross B, Janissen R, Jergic S, Dixon NE, Depken M, Dekker NH. Strand separation establishes a sustained lock at the Tus-Ter replication fork barrier. Nat Chem Biol 2015; 11:579-85. [PMID: 26147356 DOI: 10.1038/nchembio.1857] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Accepted: 05/20/2015] [Indexed: 01/30/2023]
Abstract
The bidirectional replication of a circular chromosome by many bacteria necessitates proper termination to avoid the head-on collision of the opposing replisomes. In Escherichia coli, replisome progression beyond the termination site is prevented by Tus proteins bound to asymmetric Ter sites. Structural evidence indicates that strand separation on the blocking (nonpermissive) side of Tus-Ter triggers roadblock formation, but biochemical evidence also suggests roles for protein-protein interactions. Here DNA unzipping experiments demonstrate that nonpermissively oriented Tus-Ter forms a tight lock in the absence of replicative proteins, whereas permissively oriented Tus-Ter allows nearly unhindered strand separation. Quantifying the lock strength reveals the existence of several intermediate lock states that are impacted by mutations in the lock domain but not by mutations in the DNA-binding domain. Lock formation is highly specific and exceeds reported in vivo efficiencies. We postulate that protein-protein interactions may actually hinder, rather than promote, proper lock formation.
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Affiliation(s)
- Bojk A Berghuis
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - David Dulin
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Zhi-Qiang Xu
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia
| | - Theo van Laar
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Bronwen Cross
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Richard Janissen
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Slobodan Jergic
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia
| | - Nicholas E Dixon
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia
| | - Martin Depken
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Nynke H Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
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16
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Beattie TR, Reyes-Lamothe R. A Replisome's journey through the bacterial chromosome. Front Microbiol 2015; 6:562. [PMID: 26097470 PMCID: PMC4456610 DOI: 10.3389/fmicb.2015.00562] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 05/21/2015] [Indexed: 01/03/2023] Open
Abstract
Genome duplication requires the coordinated activity of a multi-component machine, the replisome. In contrast to the background of metabolic diversity across the bacterial domain, the composition and architecture of the bacterial replisome seem to have suffered few changes during evolution. This immutability underlines the replisome’s efficiency in copying the genome. It also highlights the success of various strategies inherent to the replisome for responding to stress and avoiding problems during critical stages of DNA synthesis. Here we summarize current understanding of bacterial replisome architecture and highlight the known variations in different bacterial taxa. We then look at the mechanisms in place to ensure that the bacterial replisome is assembled appropriately on DNA, kept together during elongation, and disassembled upon termination. We put forward the idea that the architecture of the replisome may be more flexible that previously thought and speculate on elements of the replisome that maintain its stability to ensure a safe journey from origin to terminus.
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17
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Pandey M, Elshenawy MM, Jergic S, Takahashi M, Dixon NE, Hamdan SM, Patel SS. Two mechanisms coordinate replication termination by the Escherichia coli Tus-Ter complex. Nucleic Acids Res 2015; 43:5924-35. [PMID: 26007657 PMCID: PMC4499146 DOI: 10.1093/nar/gkv527] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/10/2015] [Indexed: 11/28/2022] Open
Abstract
The Escherichia coli replication terminator protein (Tus) binds to Ter sequences to block replication forks approaching from one direction. Here, we used single molecule and transient state kinetics to study responses of the heterologous phage T7 replisome to the Tus–Ter complex. The T7 replisome was arrested at the non-permissive end of Tus–Ter in a manner that is explained by a composite mousetrap and dynamic clamp model. An unpaired C(6) that forms a lock by binding into the cytosine binding pocket of Tus was most effective in arresting the replisome and mutation of C(6) removed the barrier. Isolated helicase was also blocked at the non-permissive end, but unexpectedly the isolated polymerase was not, unless C(6) was unpaired. Instead, the polymerase was blocked at the permissive end. This indicates that the Tus–Ter mechanism is sensitive to the translocation polarity of the DNA motor. The polymerase tracking along the template strand traps the C(6) to prevent lock formation; the helicase tracking along the other strand traps the complementary G(6) to aid lock formation. Our results are consistent with the model where strand separation by the helicase unpairs the GC(6) base pair and triggers lock formation immediately before the polymerase can sequester the C(6) base.
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Affiliation(s)
- Manjula Pandey
- Department of Biochemistry and Molecular Biology, Rutgers, the State University of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | - Mohamed M Elshenawy
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
| | - Slobodan Jergic
- Centre for Medical and Molecular Bioscience, University of Wollongong, New South Wales 2522, Australia
| | - Masateru Takahashi
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
| | - Nicholas E Dixon
- Centre for Medical and Molecular Bioscience, University of Wollongong, New South Wales 2522, Australia
| | - Samir M Hamdan
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Rutgers, the State University of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
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18
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Jaiswal R, Singh SK, Bastia D, Escalante CR. Crystallization and preliminary X-ray characterization of the eukaryotic replication terminator Reb1-Ter DNA complex. Acta Crystallogr F Struct Biol Commun 2015; 71:414-8. [PMID: 25849502 PMCID: PMC4388176 DOI: 10.1107/s2053230x15004112] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 02/26/2015] [Indexed: 11/10/2022] Open
Abstract
The Reb1 protein from Schizosaccharomyces pombe is a member of a family of proteins that control programmed replication termination and/or transcription termination in eukaryotic cells. These events occur at naturally occurring replication fork barriers (RFBs), where Reb1 binds to termination (Ter) DNA sites and coordinates the polar arrest of replication forks and transcription approaching in opposite directions. The Reb1 DNA-binding and replication-termination domain was expressed in Escherichia coli, purified and crystallized in complex with a 26-mer DNA Ter site. Batch crystallization under oil was required to produce crystals of good quality for data collection. Crystals grew in space group P2₁, with unit-cell parameters a = 68.9, b = 162.9, c = 71.1 Å, β = 94.7°. The crystals diffracted to a resolution of 3.0 Å. The crystals were mosaic and required two or three cycles of annealing. This study is the first to yield structural information about this important family of proteins and will provide insights into the mechanism of replication and transcription termination.
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Affiliation(s)
- Rahul Jaiswal
- Department of Physiology and Biophysics, Virginia Commonwealth University, 1220 East Broad Street, Richmond, VA 23298, USA
- Nanyang Technological University, SBS, 60 Nanyang Drive, Singapore-637551
| | - Samarendra K. Singh
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
- National Institutes of Health, Bethesda, MD 20892, USA
| | - Deepak Bastia
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Carlos R. Escalante
- Department of Physiology and Biophysics, Virginia Commonwealth University, 1220 East Broad Street, Richmond, VA 23298, USA
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19
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Bastia D, Singh SK. "Chromosome kissing" and modulation of replication termination. BIOARCHITECTURE 2014; 1:24-28. [PMID: 21866258 DOI: 10.4161/bioa.1.1.14664] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 12/22/2010] [Accepted: 12/24/2010] [Indexed: 12/29/2022]
Abstract
Previously, inter-chromosomal interactions called "chromosome kissing" have been reported to control tissue-specific transcription and cell fate determination. Using the fission yeast as a model system we have shown that physiologically programmed replication termination is also modulated by chromosome kissing. The published report reviewed here shows that a myb-like replication terminator protein Reb1 of S. pombe and its cognate binding sites (Ter) are involved in chromosome kissing that promotes a cooperative mechanism of replication termination. We also suggest that at least one other replication terminator protein namely Sap1, which is also an origin binding protein, is likely to be involved in a similar mechanism of control not only of fork arrest but also of replication initiation and in possible ori-Ter interaction. We discuss the roles of chromatin remodeling and other proteins in this novel mechanism of replication control.
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Affiliation(s)
- Deepak Bastia
- Department of Biochemistry and Molecular Biology; Medical University of South Carolina; Charleston, SC USA
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20
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Rybenkov VV. Maintenance of chromosome structure in Pseudomonas aeruginosa. FEMS Microbiol Lett 2014; 356:154-65. [PMID: 24863732 DOI: 10.1111/1574-6968.12478] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 04/11/2014] [Accepted: 05/19/2014] [Indexed: 11/30/2022] Open
Abstract
Replication and segregation of genetic information are the activities central to the well-being of all living cells. Concerted mechanisms have evolved that ensure that each cellular chromosome is replicated once and only once per cell cycle and then faithfully segregated into daughter cells. Despite remarkable taxonomic diversity, these mechanisms are largely conserved across eubacteria, although species-specific distinctions can often be noted. Here, we provide an overview of the current state of knowledge about maintenance of the chromosome structure in Pseudomonas aeruginosa. We focus on global chromosome organization and its dynamics during DNA replication and cell division. Special emphasis is made on contrasting these activities in P. aeruginosa and other bacteria. Among unique P. aeruginosa, features are the presence of two distinct autonomously replicating sequences and multiple condensins, which suggests existence of novel regulatory mechanisms.
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Affiliation(s)
- Valentin V Rybenkov
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA
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21
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Tsang E, Miyabe I, Iraqui I, Zheng J, Lambert SAE, Carr AM. The extent of error-prone replication restart by homologous recombination is controlled by Exo1 and checkpoint proteins. J Cell Sci 2014; 127:2983-94. [PMID: 24806966 PMCID: PMC4075360 DOI: 10.1242/jcs.152678] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Genetic instability, a hallmark of cancer, can occur when the replication machinery encounters a barrier. The intra-S-phase checkpoint maintains stalled replication forks in a replication-competent configuration by phosphorylating replisome components and DNA repair proteins to prevent forks from catastrophically collapsing. Here, we report a novel function of the core Schizosaccharomyces pombe checkpoint sensor kinase, Rad3 (an ATR orthologue), that is independent of Chk1 and Cds1 (a CHK2 orthologue); Rad3ATR regulates the association of recombination factors with collapsed forks, thus limiting their genetic instability. We further reveal antagonistic roles for Rad3ATR and the 9-1-1 clamp – Rad3ATR restrains MRN- and Exo1-dependent resection, whereas the 9-1-1 complex promotes Exo1 activity. Interestingly, the MRN complex, but not its nuclease activity, promotes resection and the subsequent association of recombination factors at collapsed forks. The biological significance of this regulation is revealed by the observation that Rad3ATR prevents Exo1-dependent genome instability upstream of a collapsed fork without affecting the efficiency of recombination-mediated replication restart. We propose that the interplay between Rad3ATR and the 9-1-1 clamp functions to fine-tune the balance between the need for the recovery of replication through recombination and the risk of increased genome instability.
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Affiliation(s)
- Ellen Tsang
- Genome Damage and Stability Centre, University of Sussex, Brighton, Sussex BN1 9RQ, UK
| | - Izumi Miyabe
- Genome Damage and Stability Centre, University of Sussex, Brighton, Sussex BN1 9RQ, UK
| | - Ismail Iraqui
- Institut Curie-Centre National de la Recherche Scientifique, UMR3348, Réponse Cellulaire aux Perturbations de la Réplication, Centre Universitaire, Bat 110, 91405 Orsay, France
| | - Jiping Zheng
- Department of Biotechnology, College of Agriculture, No.58 Renmin Avenue, Haikou, Hainan Province 570228, P.R. China
| | - Sarah A E Lambert
- Institut Curie-Centre National de la Recherche Scientifique, UMR3348, Réponse Cellulaire aux Perturbations de la Réplication, Centre Universitaire, Bat 110, 91405 Orsay, France
| | - Antony M Carr
- Genome Damage and Stability Centre, University of Sussex, Brighton, Sussex BN1 9RQ, UK
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22
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Bastia D, Zaman S. Mechanism and physiological significance of programmed replication termination. Semin Cell Dev Biol 2014; 30:165-73. [PMID: 24811316 DOI: 10.1016/j.semcdb.2014.04.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 04/25/2014] [Indexed: 11/26/2022]
Abstract
Replication forks in both prokaryotic and eukaryotic systems pause at random sites due to depletion of dNTP pools, DNA damage, tight binding nonhistone proteins or unusual DNA sequences and/or structures, in a mostly non-polar fashion. However, there is also physiologically programmed replication termination at sequence-specific authentic replication termini. Here, the structure and functions of programmed replication termini, their mechanism of action and their diverse physiological functions in prokaryotes and eukaryotes have been reviewed.
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Affiliation(s)
- Deepak Bastia
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, United States.
| | - Shamsu Zaman
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, United States
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23
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Larsen NB, Sass E, Suski C, Mankouri HW, Hickson ID. The Escherichia coli Tus-Ter replication fork barrier causes site-specific DNA replication perturbation in yeast. Nat Commun 2014; 5:3574. [PMID: 24705096 DOI: 10.1038/ncomms4574] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 03/06/2014] [Indexed: 01/01/2023] Open
Abstract
Replication fork (RF) pausing occurs at both 'programmed' sites and non-physiological barriers (for example, DNA adducts). Programmed RF pausing is required for site-specific DNA replication termination in Escherichia coli, and this process requires the binding of the polar terminator protein, Tus, to specific DNA sequences called Ter. Here, we demonstrate that Tus-Ter modules also induce polar RF pausing when engineered into the Saccharomyces cerevisiae genome. This heterologous RF barrier is distinct from a number of previously characterized, protein-mediated, RF pause sites in yeast, as it is neither Tof1-dependent nor counteracted by the Rrm3 helicase. Although the yeast replisome can overcome RF pausing at Tus-Ter modules, this event triggers site-specific homologous recombination that requires the RecQ helicase, Sgs1, for its timely resolution. We propose that Tus-Ter can be utilized as a versatile, site-specific, heterologous DNA replication-perturbing system, with a variety of potential applications.
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Affiliation(s)
- Nicolai B Larsen
- Nordea Center for Healthy Aging, Department of Cellular and Molecular Medicine, Panum Institute 18.1, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Ehud Sass
- 1] Nordea Center for Healthy Aging, Department of Cellular and Molecular Medicine, Panum Institute 18.1, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark [2] Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK [3]
| | - Catherine Suski
- 1] Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK [2]
| | - Hocine W Mankouri
- 1] Nordea Center for Healthy Aging, Department of Cellular and Molecular Medicine, Panum Institute 18.1, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark [2] Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Ian D Hickson
- 1] Nordea Center for Healthy Aging, Department of Cellular and Molecular Medicine, Panum Institute 18.1, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark [2] Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
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24
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Leman AR, Noguchi E. The replication fork: understanding the eukaryotic replication machinery and the challenges to genome duplication. Genes (Basel) 2014; 4:1-32. [PMID: 23599899 PMCID: PMC3627427 DOI: 10.3390/genes4010001] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Eukaryotic cells must accurately and efficiently duplicate their genomes during each round of the cell cycle. Multiple linear chromosomes, an abundance of regulatory elements, and chromosome packaging are all challenges that the eukaryotic DNA replication machinery must successfully overcome. The replication machinery, the “replisome” complex, is composed of many specialized proteins with functions in supporting replication by DNA polymerases. Efficient replisome progression relies on tight coordination between the various factors of the replisome. Further, replisome progression must occur on less than ideal templates at various genomic loci. Here, we describe the functions of the major replisome components, as well as some of the obstacles to efficient DNA replication that the replisome confronts. Together, this review summarizes current understanding of the vastly complicated task of replicating eukaryotic DNA.
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Affiliation(s)
- Adam R. Leman
- Authors to whom correspondence should be addressed; E-Mails: (A.R.L.); (E.N.); Tel.: +1-215-762-4825 (E.N.); Fax: +1-215-762-4452 (E.N.)
| | - Eishi Noguchi
- Authors to whom correspondence should be addressed; E-Mails: (A.R.L.); (E.N.); Tel.: +1-215-762-4825 (E.N.); Fax: +1-215-762-4452 (E.N.)
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25
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Huang J, Liu S, Bellani MA, Thazhathveetil AK, Ling C, de Winter JP, Wang Y, Wang W, Seidman MM. The DNA translocase FANCM/MHF promotes replication traverse of DNA interstrand crosslinks. Mol Cell 2013; 52:434-46. [PMID: 24207054 DOI: 10.1016/j.molcel.2013.09.021] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 09/09/2013] [Accepted: 09/19/2013] [Indexed: 10/26/2022]
Abstract
The replicative machinery encounters many impediments, some of which can be overcome by lesion bypass or replication restart pathways, leaving repair for a later time. However, interstrand crosslinks (ICLs), which preclude DNA unwinding, are considered absolute blocks to replication. Current models suggest that fork collisions, either from one or both sides of an ICL, initiate repair processes required for resumption of replication. To test these proposals, we developed a single-molecule technique for visualizing encounters of replication forks with ICLs as they occur in living cells. Surprisingly, the most frequent patterns were consistent with replication traverse of an ICL, without lesion repair. The traverse frequency was strongly reduced by inactivation of the translocase and DNA binding activities of the FANCM/MHF complex. The results indicate that translocase-based mechanisms enable DNA synthesis to continue past ICLs and that these lesions are not always absolute blocks to replication.
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Affiliation(s)
- Jing Huang
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
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26
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Moreau MJJ, Schaeffer PM. Differential Tus-Ter binding and lock formation: implications for DNA replication termination in Escherichia coli. MOLECULAR BIOSYSTEMS 2013; 8:2783-91. [PMID: 22859262 DOI: 10.1039/c2mb25281c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In E. coli, DNA replication termination occurs at Ter sites and is mediated by Tus. Two clusters of five Ter sites are located on each side of the terminus region and constrain replication forks in a polar manner. The polarity is due to the formation of the Tus-Ter-lock intermediate. Recently, it has been shown that DnaB helicase which unwinds DNA at the replication fork is preferentially stopped at the non-permissive face of a Tus-Ter complex without formation of the Tus-Ter-lock and that fork pausing efficiency is sequence dependent, raising two essential questions: Does the affinity of Tus for the different Ter sites correlate with fork pausing efficiency? Is formation of the Tus-Ter-lock the key factor in fork pausing? The combined use of surface plasmon resonance and GFP-Basta showed that Tus binds strongly to TerA-E and G, moderately to TerH-J and weakly to TerF. Out of these ten Ter sites only two, TerF and H, were not able to form significant Tus-Ter-locks. Finally, Tus's resistance to dissociation from Ter sites and the strength of the Tus-Ter-locks correlate with the differences in fork pausing efficiency observed for the different Ter sites by Duggin and Bell (2009).
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Affiliation(s)
- Morgane J J Moreau
- School of Pharmacy and Molecular Sciences, James Cook University, DB 21, James Cook Drive, Townsville, QLD 4811, Australia
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27
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Moreau MJJ, Schaeffer PM. Dissecting the salt dependence of the Tus–Ter protein–DNA complexes by high-throughput differential scanning fluorimetry of a GFP-tagged Tus. MOLECULAR BIOSYSTEMS 2013; 9:3146-54. [DOI: 10.1039/c3mb70426b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Byrnes J, Garcia-Diaz M. Mitochondrial transcription: how does it end? Transcription 2012; 2:32-6. [PMID: 21326908 DOI: 10.4161/trns.2.1.14006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 10/21/2010] [Accepted: 10/22/2010] [Indexed: 11/19/2022] Open
Abstract
The structure of the mitochondrial transcription termination factor (MTERF1) provides novel insight into the mechanism of binding, recognition of the termination sequence and the conformational changes involved in mediating termination. Besides its functional implications, this structure provides a framework to understand the consequences of numerous diseases associated with mitochondrial DNA mutations.
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Affiliation(s)
- James Byrnes
- Department of Pharmacology, Stony Brook University, NY, USA
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29
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Singh SK, Sabatinos S, Forsburg S, Bastia D. Regulation of replication termination by Reb1 protein-mediated action at a distance. Cell 2010; 142:868-78. [PMID: 20850009 DOI: 10.1016/j.cell.2010.08.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 06/08/2010] [Accepted: 07/26/2010] [Indexed: 11/30/2022]
Abstract
DNA transactions driven by long-range protein-mediated inter- and intrachromosomal interactions have been reported to influence gene expression. Here, we report that site-specific replication termination in Schizosaccharomyces pombe is modulated by protein-mediated interactions between pairs of Ter sites located either on the same or on different chromosomes. The dimeric Reb1 protein catalyzes termination and mediates interaction between Ter sites. The Reb1-dependent interactions between two antiparallel Ter sites in cis caused looping out of the intervening DNA in vitro and enhancement of fork arrest in vivo. A Ter site on chromosome 2 interacted pairwise with two Ter sites located on chromosome 1 by chromosome kissing. Mutational inactivation of the major interacting Ter site on chromosome 1 significantly reduced fork arrest at the Ter site on chromosome 2, thereby revealing a cooperative mechanism of control of replication termination.
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Affiliation(s)
- Samarendra K Singh
- Department of Molecular Biology and Biochemistry, Medical University of South Carolina, Charleston, SC 29425, USA
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30
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31
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An essential DnaB helicase of Bacillus anthracis: identification, characterization, and mechanism of action. J Bacteriol 2008; 191:249-60. [PMID: 18931108 DOI: 10.1128/jb.01259-08] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have described a novel essential replicative DNA helicase from Bacillus anthracis, the identification of its gene, and the elucidation of its enzymatic characteristics. Anthrax DnaB helicase (DnaB(BA)) is a 453-amino-acid, 50-kDa polypeptide with ATPase and DNA helicase activities. DnaB(BA) displayed distinct enzymatic and kinetic properties. DnaB(BA) has low single-stranded DNA (ssDNA)-dependent ATPase activity but possesses a strong 5'-->3' DNA helicase activity. The stimulation of ATPase activity appeared to be a function of the length of the ssDNA template rather than of ssDNA binding alone. The highest specific activity was observed with M13mp19 ssDNA. The results presented here indicated that the ATPase activity of DnaB(BA) was coupled to its migration on an ssDNA template rather than to DNA binding alone. It did not require nucleotide to bind ssDNA. DnaB(BA) demonstrated a strong DNA helicase activity that required ATP or dATP. Therefore, DnaB(BA) has an attenuated ATPase activity and a highly active DNA helicase activity. Based on the ratio of DNA helicase and ATPase activities, DnaB(BA) is highly efficient in DNA unwinding and its coupling to ATP consumption.
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32
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Duggin IG, Wake RG, Bell SD, Hill TM. The replication fork trap and termination of chromosome replication. Mol Microbiol 2008; 70:1323-33. [PMID: 19019156 DOI: 10.1111/j.1365-2958.2008.06500.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bacteria that have a circular chromosome with a bidirectional DNA replication origin are thought to utilize a 'replication fork trap' to control termination of replication. The fork trap is an arrangement of replication pause sites that ensures that the two replication forks fuse within the terminus region of the chromosome, approximately opposite the origin on the circular map. However, the biological significance of the replication fork trap has been mysterious, as its inactivation has no obvious consequence. Here we review the research that led to the replication fork trap theory, and we aim to integrate several recent findings that contribute towards an understanding of the physiological roles of the replication fork trap. Likely roles include the prevention of over-replication, and the optimization of post-replicative mechanisms of chromosome segregation, such as that involving FtsK in Escherichia coli.
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Affiliation(s)
- Iain G Duggin
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
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33
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Mechanistic insights into replication termination as revealed by investigations of the Reb1-Ter3 complex of Schizosaccharomyces pombe. Mol Cell Biol 2008; 28:6844-57. [PMID: 18794373 DOI: 10.1128/mcb.01235-08] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Relatively little is known about the interaction of eukaryotic replication terminator proteins with the cognate termini and the replication termination mechanism. Here, we report a biochemical analysis of the interaction of the Reb1 terminator protein of Schizosaccharomyces pombe, which binds to the Ter3 site present in the nontranscribed spacers of ribosomal DNA, located in chromosome III. We show that Reb1 is a dimeric protein and that the N-terminal dimerization domain of the protein is dispensable for replication termination. Unlike its mammalian counterpart Ttf1, Reb1 did not need an accessory protein to bind to Ter3. The two myb/SANT domains and an adjacent, N-terminal 154-amino-acid-long segment (called the myb-associated domain) were both necessary and sufficient for optimal DNA binding in vitro and fork arrest in vivo. The protein and its binding site Ter3 were unable to arrest forks initiated in vivo from ars of Saccharomyces cerevisiae in the cell milieu of the latter despite the facts that the protein retained the proper affinity of binding, was located in vivo at the Ter site, and apparently was not displaced by the "sweepase" Rrm3. These observations suggest that replication fork arrest is not an intrinsic property of the Reb1-Ter3 complex.
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