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de Vasconcelos Junior AA, Tirado-Vélez JM, Martín-Galiano AJ, Megias D, Ferrándiz MJ, Hernández P, Amblar M, de la Campa AG. StaR Is a Positive Regulator of Topoisomerase I Activity Involved in Supercoiling Maintenance in Streptococcus pneumoniae. Int J Mol Sci 2023; 24:ijms24065973. [PMID: 36983048 PMCID: PMC10053502 DOI: 10.3390/ijms24065973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/16/2023] [Accepted: 03/18/2023] [Indexed: 03/30/2023] Open
Abstract
The DNA topoisomerases gyrase and topoisomerase I as well as the nucleoid-associated protein HU maintain supercoiling levels in Streptococcus pneumoniae, a main human pathogen. Here, we characterized, for the first time, a topoisomerase I regulator protein (StaR). In the presence of sub-inhibitory novobiocin concentrations, which inhibit gyrase activity, higher doubling times were observed in a strain lacking staR, and in two strains in which StaR was over-expressed either under the control of the ZnSO4-inducible PZn promoter (strain ΔstaRPZnstaR) or of the maltose-inducible PMal promoter (strain ΔstaRpLS1ROMstaR). These results suggest that StaR has a direct role in novobiocin susceptibility and that the StaR level needs to be maintained within a narrow range. Treatment of ΔstaRPZnstaR with inhibitory novobiocin concentrations resulted in a change of the negative DNA supercoiling density (σ) in vivo, which was higher in the absence of StaR (σ = -0.049) than when StaR was overproduced (σ = -0.045). We have located this protein in the nucleoid by using super-resolution confocal microscopy. Through in vitro activity assays, we demonstrated that StaR stimulates TopoI relaxation activity, while it has no effect on gyrase activity. Interaction between TopoI and StaR was detected both in vitro and in vivo by co-immunoprecipitation. No alteration of the transcriptome was associated with StaR amount variation. The results suggest that StaR is a new streptococcal nucleoid-associated protein that activates topoisomerase I activity by direct protein-protein interaction.
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Affiliation(s)
| | - Jose M Tirado-Vélez
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, 28220 Madrid, Spain
| | - Antonio J Martín-Galiano
- Unidades Centrales Científico-Técnicas, Instituto de Salud Carlos III, Majadahonda, 28220 Madrid, Spain
| | - Diego Megias
- Unidad de Microscopía Confocal, Instituto de Salud Carlos III, Majadahonda, 28220 Madrid, Spain
| | - María-José Ferrándiz
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, 28220 Madrid, Spain
| | - Pablo Hernández
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain
| | - Mónica Amblar
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, 28220 Madrid, Spain
| | - Adela G de la Campa
- Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, 28220 Madrid, Spain
- Presidencia, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain
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2
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García-López M, Megias D, Ferrándiz MJ, de la Campa AG. The balance between gyrase and topoisomerase I activities determines levels of supercoiling, nucleoid compaction, and viability in bacteria. Front Microbiol 2023; 13:1094692. [PMID: 36713152 PMCID: PMC9875019 DOI: 10.3389/fmicb.2022.1094692] [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: 11/10/2022] [Accepted: 12/23/2022] [Indexed: 01/13/2023] Open
Abstract
Two enzymes are responsible for maintaining supercoiling in the human pathogen Streptococcus pneumoniae, gyrase (GyrA2GyrB2) and topoisomerase I. To attain diverse levels of topoisomerase I (TopoI, encoded by topA), two isogenic strains derived from wild-type strain R6 were constructed: PZn topA, carrying an ectopic topA copy under the control of the ZnSO4-regulated PZn promoter and its derivative ΔtopAPZn topA, which carries a topA deletion at its native chromosomal location. We estimated the number of TopoI and GyrA molecules per cell by using Western-blot and CFUs counting, and correlated these values with supercoiling levels. Supercoiling was estimated in two ways. We used classical 2D-agarose gel electrophoresis of plasmid topoisomers to determine supercoiling density (σ) and we measured compaction of nucleoids using for the first time super-resolution confocal microscopy. Notably, we observed a good correlation between both supercoiling calculations. In R6, with σ = -0.057, the average number of GyrA molecules per cell (2,184) was higher than that of TopoI (1,432), being the GyrA:TopoI proportion of 1:0.65. In ΔtopAPZn topA, the number of TopoI molecules depended, as expected, on ZnSO4 concentration in the culture media, being the proportions of GyrA:TopoI molecules in 75, 150, and 300 μM ZnSO4 of 1:0.43, 1:0.47, and 1:0.63, respectively, which allowed normal supercoiling and growth. However, in the absence of ZnSO4, a higher GyrA:TopoI ratio (1:0.09) caused hyper-supercoiling (σ = -0.086) and lethality. Likewise, growth of ΔtopAPZn topA in the absence of ZnSO4 was restored when gyrase was inhibited with novobiocin, coincidentally with the resolution of hyper-supercoiling (σ change from -0.080 to -0.068). Given that TopoI is a monomer and two molecules of GyrA are present in the gyrase heterotetramer, the gyrase:TopoI enzymes proportion would be 1:1.30 (wild type R6) or of 1:1.26-0.86 (ΔtopAPZn topA under viable conditions). Higher proportions, such as 1:0.18 observed in ΔtopAPZn topA in the absence of ZnSO4 yielded to hyper-supercoiling and lethality. These results support a role of the equilibrium between gyrase and TopoI activities in supercoiling maintenance, nucleoid compaction, and viability. Our results shed new light on the mechanism of action of topoisomerase-targeting antibiotics, paving the way for the use of combination therapies.
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Affiliation(s)
- Míriam García-López
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Diego Megias
- Unidad de Microscopía Confocal, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - María-José Ferrándiz
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain,*Correspondence: María-José Ferrándiz, ✉
| | - Adela G. de la Campa
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain,Presidencia, Consejo Superior de Investigaciones Científicas, Madrid, Spain,Adela G. de la Campa, ✉
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3
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Chromatin Is Frequently Unknotted at the Megabase Scale. Biophys J 2019; 118:2268-2279. [PMID: 31818464 PMCID: PMC7202934 DOI: 10.1016/j.bpj.2019.11.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/03/2019] [Accepted: 11/05/2019] [Indexed: 11/20/2022] Open
Abstract
Knots in the human genome would greatly impact diverse cellular processes ranging from transcription to gene regulation. To date, it has not been possible to directly examine the genome in vivo for the presence of knots. Recently, methods for serial fluorescent in situ hybridization have made it possible to measure the three-dimensional position of dozens of consecutive genomic loci in vivo. However, the determination of whether genomic trajectories are knotted remains challenging because small errors in the localization of a single locus can transform an unknotted trajectory into a highly knotted trajectory and vice versa. Here, we use stochastic closure analysis to determine if a genomic trajectory is knotted in the setting of experimental noise. We analyze 4727 deposited genomic trajectories of a 2-Mb-long chromatin interval from human chromosome 21. For 243 of these trajectories, their knottedness could be reliably determined despite the possibility of localization errors. Strikingly, in each of these 243 cases, the trajectory was unknotted. We note a potential source of bias insofar as knotted contours may be more difficult to reliably resolve. Nevertheless, our data are consistent with a model in which, at the scales probed, the human genome is often free of knots.
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Mensà E, Latini S, Ramini D, Storci G, Bonafè M, Olivieri F. The telomere world and aging: Analytical challenges and future perspectives. Ageing Res Rev 2019; 50:27-42. [PMID: 30615937 DOI: 10.1016/j.arr.2019.01.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/15/2018] [Accepted: 01/03/2019] [Indexed: 12/12/2022]
Abstract
Telomeres, the terminal nucleoprotein structures of eukaryotic chromosomes, play pleiotropic functions in cellular and organismal aging. Telomere length (TL) varies throughout life due to the influence of genetic factors and to a complex balancing between "shortening" and "elongation" signals. Telomerase, the only enzyme that can elongate a telomeric DNA chain, and telomeric repeat-containing RNA (TERRA), a long non-coding RNA involved in looping maintenance, play key roles in TL during life. Despite recent advances in the knowledge of TL, TERRA and telomerase activity (TA) biology and their measurement techniques, the experimental and theoretical issues involved raise a number of problems that should carefully be considered by researchers approaching the "telomere world". The increasing use of such parameters - hailed as promising clinically relevant biomarkers - has failed to be paralleled by the development of automated and standardized measurement technology. Consequently, associating given TL values to specific pathological conditions involves on the one hand technological issues and on the other clinical-biological issues related to the planning of clinically relevant association studies. Addressing these issues would help avoid major biases in association studies involving TL and a number of outcomes, especially those focusing on psychological and bio-behavioral variables. The main challenge in telomere research is the development of accurate and reliable measurement methods to achieve simple and sensitive TL, TERRA, and TA detection. The discovery of the localization of telomeres and TERRA in cellular and extracellular compartments had added an additional layer of complexity to the measurement of these age-related biomarkers. Since combined analysis of TL, TERRA and TA may well provide more exhaustive clinical information than a single parameter, we feel it is important for researchers in the various fields to become familiar with their most common measurement techniques and to be aware of the respective merits and drawbacks of these approaches.
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Affiliation(s)
- Emanuela Mensà
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy
| | - Silvia Latini
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy
| | - Deborah Ramini
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy
| | - Gianluca Storci
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy; Interdepartmental Centre "L. Galvani" (CIG), University of Bologna, Bologna, Italy
| | - Massimiliano Bonafè
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy; Interdepartmental Centre "L. Galvani" (CIG), University of Bologna, Bologna, Italy; Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST), IRCCS, Biosciences Laboratory, Meldola, Italy
| | - Fabiola Olivieri
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy; Center of Clinical Pathology and Innovative Therapy, IRCCS INRCA, Ancona, Italy.
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Castán A, Fernández-Calleja V, Hernández P, Krimer DB, Schvartzman JB, Fernández-Nestosa MJ. Analysis of DNA topology of EBV minichromosomes in HEK 293 cells. PLoS One 2017; 12:e0188172. [PMID: 29186176 PMCID: PMC5706722 DOI: 10.1371/journal.pone.0188172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 10/30/2017] [Indexed: 11/21/2022] Open
Abstract
Simian Virus 40 (SV40) and Epstein-Barr Virus (EBV) are frequently used as model systems to study DNA replication. Their genomes are both circular duplex DNAs organized in a single replicon where replication initiates at a precise site upon binding of a specific protein: the large tumor (T) antigen for SV40 and the Epstein-Barr Nuclear Antigen 1 (EBNA-1) for EBV. Despite the abundant information available on the genetics and biochemistry of the replication process in these systems, little is known about the changes in DNA topology that take place as molecules are transfected into eukaryotic cells, assembled into chromatin and bind initiator proteins to start replication. Here we used high-resolution two-dimensional agarose gel electrophoresis to demonstrate that in Human Embryonic Kidney (HEK) 293 cells, minichromosomes of almost the same mass carrying either the SV40 or the EBV replication origin showed similar topological features. The patterns were very similar regardless of the initiator proteins. We also showed that in a hybrid minichromosome, pEco3’Δ, that initiates replication from the SV40 origin, the presence of EBNA-1 and its putative binding to the EBV “family of repeats” induces no significant topological change. These observations challenge the idea that binding of EBNA-1 to oriP could induce negative supercoiling and favor a model suggesting that it binds to oriP in a two-step process where only the second step causes structural changes in a transient cell cycle specific manner.
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Affiliation(s)
- Alicia Castán
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain
| | - Vanessa Fernández-Calleja
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain
| | - Pablo Hernández
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain
| | - Dora B. Krimer
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain
| | - Jorge B. Schvartzman
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain
- * E-mail: (JBS); (JFN)
| | - María-José Fernández-Nestosa
- Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción, SL, San Lorenzo, Paraguay
- * E-mail: (JBS); (JFN)
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6
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Krueger E, Shim J, Fathizadeh A, Chang AN, Subei B, Yocham KM, Davis PH, Graugnard E, Khalili-Araghi F, Bashir R, Estrada D, Fologea D. Modeling and Analysis of Intercalant Effects on Circular DNA Conformation. ACS NANO 2016; 10:8910-7. [PMID: 27559753 PMCID: PMC5111899 DOI: 10.1021/acsnano.6b04876] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The large-scale conformation of DNA molecules plays a critical role in many basic elements of cellular functionality and viability. By targeting the structural properties of DNA, many cancer drugs, such as anthracyclines, effectively inhibit tumor growth but can also produce dangerous side effects. To enhance the development of innovative medications, rapid screening of structural changes to DNA can provide important insight into their mechanism of interaction. In this study, we report changes to circular DNA conformation from intercalation with ethidium bromide using all-atom molecular dynamics simulations and characterized experimentally by translocation through a silicon nitride solid-state nanopore. Our measurements reveal three distinct current blockade levels and a 6-fold increase in translocation times for ethidium bromide-treated circular DNA as compared to untreated circular DNA. We attribute these increases to changes in the supercoiled configuration hypothesized to be branched or looped structures formed in the circular DNA molecule. Further evidence of the conformational changes is demonstrated by qualitative atomic force microscopy analysis. These results expand the current methodology for predicting and characterizing DNA tertiary structure and advance nanopore technology as a platform for deciphering structural changes of other important biomolecules.
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Affiliation(s)
- Eric Krueger
- Department of Physics, Boise State University, Boise, ID, United States
- Department of Materials Science and Engineering, Boise State University, Boise, ID, United States
| | - Jiwook Shim
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Arman Fathizadeh
- Department of Physics, University of Illinois at Chicago, Chicago, IL, United States
| | - A. Nicole Chang
- Department of Materials Science and Engineering, Boise State University, Boise, ID, United States
| | - Basheer Subei
- Department of Physics, University of Illinois at Chicago, Chicago, IL, United States
| | - Katie M. Yocham
- Department of Materials Science and Engineering, Boise State University, Boise, ID, United States
| | - Paul H. Davis
- Department of Materials Science and Engineering, Boise State University, Boise, ID, United States
| | - Elton Graugnard
- Department of Materials Science and Engineering, Boise State University, Boise, ID, United States
| | | | - Rashid Bashir
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - David Estrada
- Department of Materials Science and Engineering, Boise State University, Boise, ID, United States
| | - Daniel Fologea
- Department of Physics, Boise State University, Boise, ID, United States
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7
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Cebrián J, Castán A, Martínez V, Kadomatsu-Hermosa MJ, Parra C, Fernández-Nestosa MJ, Schaerer C, Hernández P, Krimer DB, Schvartzman JB. Direct Evidence for the Formation of Precatenanes during DNA Replication. J Biol Chem 2015; 290:13725-35. [PMID: 25829493 PMCID: PMC4447951 DOI: 10.1074/jbc.m115.642272] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/30/2015] [Indexed: 11/06/2022] Open
Abstract
The dynamics of DNA topology during replication are still poorly understood. Bacterial plasmids are negatively supercoiled. This underwinding facilitates strand separation of the DNA duplex during replication. Leading the replisome, a DNA helicase separates the parental strands that are to be used as templates. This strand separation causes overwinding of the duplex ahead. If this overwinding persists, it would eventually impede fork progression. In bacteria, DNA gyrase and topoisomerase IV act ahead of the fork to keep DNA underwound. However, the processivity of the DNA helicase might overcome DNA gyrase and topoisomerase IV. It was proposed that the overwinding that builds up ahead of the fork could force it to swivel and diffuse this positive supercoiling behind the fork where topoisomerase IV would also act to maintain replicating the DNA underwound. Putative intertwining of sister duplexes in the replicated region are called precatenanes. Fork swiveling and the formation of precatenanes, however, are still questioned. Here, we used classical genetics and high resolution two-dimensional agarose gel electrophoresis to examine the torsional tension of replication intermediates of three bacterial plasmids with the fork stalled at different sites before termination. The results obtained indicated that precatenanes do form as replication progresses before termination.
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Affiliation(s)
- Jorge Cebrián
- From the Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040, Madrid, Spain and
| | - Alicia Castán
- From the Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040, Madrid, Spain and
| | - Víctor Martínez
- the Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción. P.O. Box 2111 SL. San Lorenzo, Paraguay
| | - Maridian J Kadomatsu-Hermosa
- the Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción. P.O. Box 2111 SL. San Lorenzo, Paraguay
| | - Cristina Parra
- the Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción. P.O. Box 2111 SL. San Lorenzo, Paraguay
| | - María José Fernández-Nestosa
- the Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción. P.O. Box 2111 SL. San Lorenzo, Paraguay
| | - Christian Schaerer
- the Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción. P.O. Box 2111 SL. San Lorenzo, Paraguay
| | - Pablo Hernández
- From the Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040, Madrid, Spain and
| | - Dora B Krimer
- From the Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040, Madrid, Spain and
| | - Jorge B Schvartzman
- From the Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040, Madrid, Spain and
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8
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Cebrián J, Kadomatsu-Hermosa MJ, Castán A, Martínez V, Parra C, Fernández-Nestosa MJ, Schaerer C, Martínez-Robles ML, Hernández P, Krimer DB, Stasiak A, Schvartzman JB. Electrophoretic mobility of supercoiled, catenated and knotted DNA molecules. Nucleic Acids Res 2014; 43:e24. [PMID: 25414338 PMCID: PMC4344484 DOI: 10.1093/nar/gku1255] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We systematically varied conditions of two-dimensional (2D) agarose gel electrophoresis to optimize separation of DNA topoisomers that differ either by the extent of knotting, the extent of catenation or the extent of supercoiling. To this aim we compared electrophoretic behavior of three different families of DNA topoisomers: (i) supercoiled DNA molecules, where supercoiling covered the range extending from covalently closed relaxed up to naturally supercoiled DNA molecules; (ii) postreplicative catenanes with catenation number increasing from 1 to ∼15, where both catenated rings were nicked; (iii) knotted but nicked DNA molecules with a naturally arising spectrum of knots. For better comparison, we studied topoisomer families where each member had the same total molecular mass. For knotted and supercoiled molecules, we analyzed dimeric plasmids whereas catenanes were composed of monomeric forms of the same plasmid. We observed that catenated, knotted and supercoiled families of topoisomers showed different reactions to changes of agarose concentration and voltage during electrophoresis. These differences permitted us to optimize conditions for their separation and shed light on physical characteristics of these different types of DNA topoisomers during electrophoresis.
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Affiliation(s)
- Jorge Cebrián
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Maridian J Kadomatsu-Hermosa
- Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción, P.O. Box 2111, SL. San Lorenzo, Paraguay
| | - Alicia Castán
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Víctor Martínez
- Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción, P.O. Box 2111, SL. San Lorenzo, Paraguay
| | - Cristina Parra
- Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción, P.O. Box 2111, SL. San Lorenzo, Paraguay
| | - María José Fernández-Nestosa
- Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción, P.O. Box 2111, SL. San Lorenzo, Paraguay
| | - Christian Schaerer
- Scientific and Applied Computing Laboratory, Polytechnic School, National University of Asunción, P.O. Box 2111, SL. San Lorenzo, Paraguay
| | - María-Luisa Martínez-Robles
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Pablo Hernández
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Dora B Krimer
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Andrzej Stasiak
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Jorge B Schvartzman
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
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9
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Topoisomerase 2 is dispensable for the replication and segregation of small yeast artificial chromosomes (YACs). PLoS One 2014; 9:e104995. [PMID: 25115861 PMCID: PMC4130621 DOI: 10.1371/journal.pone.0104995] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 07/15/2014] [Indexed: 11/19/2022] Open
Abstract
DNA topoisomerases are thought to play a critical role in transcription, replication and recombination as well as in the condensation and segregation of sister duplexes during cell division. Here, we used high-resolution two-dimensional agarose gel electrophoresis to study the replication intermediates and final products of small circular and linear minichromosomes of Saccharomyces cerevisiae in the presence and absence of DNA topoisomerase 2. The results obtained confirmed that whereas for circular minichromosomes, catenated sister duplexes accumulated in the absence of topoisomerase 2, linear YACs were able to replicate and segregate regardless of this topoisomerase. The patterns of replication intermediates for circular and linear YACs displayed significant differences suggesting that DNA supercoiling might play a key role in the modulation of replication fork progression. Altogether, this data supports the notion that for linear chromosomes the torsional tension generated by transcription and replication dissipates freely throughout the telomeres.
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