1
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Joyeux M. Tethered Particle Motion Technique in Crowded Media: Compaction of DNA by Globular Macromolecules. J Phys Chem B 2024; 128:7227-7236. [PMID: 38986040 DOI: 10.1021/acs.jpcb.4c03033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
Tethered Particle Motion (TPM) is a single molecule technique, which consists in tracking the motion of a nanoparticle (NP) immersed in a fluid and tethered to a glass surface by a DNA molecule. The present work addresses the question of the applicability of TPM to fluids which contain crowders at volume fractions ranging from that of the nucleoid of living bacteria (around 30%) up to the jamming threshold (around 66%). In particular, we were interested in determining whether TPM can be used to characterize the compaction of DNA by globular crowders. To this end, extensive Brownian Dynamics simulations were performed with a specifically built coarse-grained model. Analysis of the simulations reveals several effects not observed in dilute media, which impose constraints on the TPM setup. In particular, the Tethered Fluorophore Motion (TFM) technique, which consists in replacing the NP by a much smaller fluorophore, is probably better suited than standard TPM. Moreover, a sample preparation technique which does not involve hydrophilic patches may be required. Finally, the use of a DNA brush may be needed to achieve DNA concentrations close to in vivo ones.
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Affiliation(s)
- Marc Joyeux
- Laboratoire Interdisciplinaire de Physique, CNRS and Université Grenoble Alpes, 38400 St Martin d'Hères, France
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2
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Evans GW, Craggs T, Kapanidis AN. The Rate-limiting Step of DNA Synthesis by DNA Polymerase Occurs in the Fingers-closed Conformation. J Mol Biol 2022; 434:167410. [PMID: 34929202 PMCID: PMC8783057 DOI: 10.1016/j.jmb.2021.167410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/22/2021] [Accepted: 12/12/2021] [Indexed: 12/03/2022]
Abstract
DNA polymerases maintain genomic integrity by copying DNA with high fidelity, part of which relies on the polymerase fingers opening-closing transition, a series of conformational changes during the DNA synthesis reaction cycle. Fingers opening and closing has been challenging to study, mainly due to the need to synchronise molecular ensembles. We previously studied fingers opening-closing on single polymerase-DNA complexes using single-molecule FRET; however, our work was limited to pre-chemistry reaction steps. Here, we advance our analysis to extensible substrates, and observe DNA polymerase (Pol) conformational changes across the entire DNA polymerisation reaction in real-time, gaining direct access to an elusive post-chemistry step rate-limiting for DNA synthesis. Our results showed that Pol adopts the fingers-closed conformation during polymerisation, and that the post-chemistry rate-limiting step occurs in the fingers-closed conformation. We found that fingers-opening in the Pol-DNA binary complex in the absence of polymerisation is slow (∼5.3 s-1), and comparable to the rate of fingers-opening after polymerisation (3.4 s-1); this indicates that the fingers-opening step itself could be largely responsible for the slow post-chemistry step, with the residual rate potentially accounted for by pyrophosphase release. We also observed that DNA chain-termination of the 3' end of the primer increases substantially the rate of fingers-opening in the Pol-DNA binary complex (5.3 → 29 s-1), demonstrating that the 3'-OH residue is important for the kinetics of fingers conformational changes. Our observations offer mechanistic insight and tools to offer mechanistic insight for all nucleic acid polymerases.
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Affiliation(s)
- Geraint W Evans
- Department of Physics and Biological Physics Research Group, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom. https://twitter.com/geraintwe
| | - Timothy Craggs
- Department of Physics and Biological Physics Research Group, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom; Sheffield Institute for Nucleic Acids, Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, United Kingdom. https://twitter.com/Craggs_Lab
| | - Achillefs N Kapanidis
- Department of Physics and Biological Physics Research Group, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
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3
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van Dongen JE, Spoelstra LR, Berendsen JTW, Loessberg-Zahl JT, Eijkel JCT, Segerink LI. A Multiplexable Plasmonic Hairpin-DNA Sensor Based On Target-specific Tether Dynamics. ACS Sens 2021; 6:4297-4303. [PMID: 34851614 PMCID: PMC8715532 DOI: 10.1021/acssensors.1c02097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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The need for measurements
of multiple biomarkers simultaneously
at subnanomolar concentrations asks for the development of new sensors
with high sensitivity, specificity, precision, and accuracy. Currently,
multiplexed sensing in single molecule sensors increases the complexity
of the system in terms of reagents and sample read-out. In this letter,
we propose a novel approach to multiplex hairpin-based single-DNA
molecule sensors, which overcomes the limitations of the present approaches
for multiplexing. By target-dependent ssDNA hairpin design, we can
create DNA tethers that have distinct tether dynamics upon target
binding. Our numerical model shows that by changing the stem length
of the ssDNA hairpin, significantly different dynamic tether behavior
will be observed. By exploiting the distance-dependent coupling of
AuNPs to gold films, we can probe this dynamic behavior along the z-axis using a simple laser equipped microscope.
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Affiliation(s)
- Jeanne Elisabeth van Dongen
- BIOS Lab on a Chip Group, MESA+ & TechMed Institutes, Max Planck Center for Complex Fluid Dynamics, University of Twente, P.O. Box 217 7500 AE Enschede, The Netherlands
| | - Laurens Rudi Spoelstra
- BIOS Lab on a Chip Group, MESA+ & TechMed Institutes, Max Planck Center for Complex Fluid Dynamics, University of Twente, P.O. Box 217 7500 AE Enschede, The Netherlands
| | - Johanna Theodora Wilhelmina Berendsen
- BIOS Lab on a Chip Group, MESA+ & TechMed Institutes, Max Planck Center for Complex Fluid Dynamics, University of Twente, P.O. Box 217 7500 AE Enschede, The Netherlands
| | - Joshua Taylor Loessberg-Zahl
- BIOS Lab on a Chip Group, MESA+ & TechMed Institutes, Max Planck Center for Complex Fluid Dynamics, University of Twente, P.O. Box 217 7500 AE Enschede, The Netherlands
| | - Jan Cornelis Titus Eijkel
- BIOS Lab on a Chip Group, MESA+ & TechMed Institutes, Max Planck Center for Complex Fluid Dynamics, University of Twente, P.O. Box 217 7500 AE Enschede, The Netherlands
| | - Loes Irene Segerink
- BIOS Lab on a Chip Group, MESA+ & TechMed Institutes, Max Planck Center for Complex Fluid Dynamics, University of Twente, P.O. Box 217 7500 AE Enschede, The Netherlands
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4
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Lerner E, Barth A, Hendrix J, Ambrose B, Birkedal V, Blanchard SC, Börner R, Sung Chung H, Cordes T, Craggs TD, Deniz AA, Diao J, Fei J, Gonzalez RL, Gopich IV, Ha T, Hanke CA, Haran G, Hatzakis NS, Hohng S, Hong SC, Hugel T, Ingargiola A, Joo C, Kapanidis AN, Kim HD, Laurence T, Lee NK, Lee TH, Lemke EA, Margeat E, Michaelis J, Michalet X, Myong S, Nettels D, Peulen TO, Ploetz E, Razvag Y, Robb NC, Schuler B, Soleimaninejad H, Tang C, Vafabakhsh R, Lamb DC, Seidel CAM, Weiss S. FRET-based dynamic structural biology: Challenges, perspectives and an appeal for open-science practices. eLife 2021; 10:e60416. [PMID: 33779550 PMCID: PMC8007216 DOI: 10.7554/elife.60416] [Citation(s) in RCA: 135] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 02/09/2021] [Indexed: 12/18/2022] Open
Abstract
Single-molecule FRET (smFRET) has become a mainstream technique for studying biomolecular structural dynamics. The rapid and wide adoption of smFRET experiments by an ever-increasing number of groups has generated significant progress in sample preparation, measurement procedures, data analysis, algorithms and documentation. Several labs that employ smFRET approaches have joined forces to inform the smFRET community about streamlining how to perform experiments and analyze results for obtaining quantitative information on biomolecular structure and dynamics. The recent efforts include blind tests to assess the accuracy and the precision of smFRET experiments among different labs using various procedures. These multi-lab studies have led to the development of smFRET procedures and documentation, which are important when submitting entries into the archiving system for integrative structure models, PDB-Dev. This position paper describes the current 'state of the art' from different perspectives, points to unresolved methodological issues for quantitative structural studies, provides a set of 'soft recommendations' about which an emerging consensus exists, and lists openly available resources for newcomers and seasoned practitioners. To make further progress, we strongly encourage 'open science' practices.
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Affiliation(s)
- Eitan Lerner
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, and The Center for Nanoscience and Nanotechnology, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of JerusalemJerusalemIsrael
| | - Anders Barth
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-UniversitätDüsseldorfGermany
| | - Jelle Hendrix
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and Biomedical Research Institute (BIOMED), Hasselt UniversityDiepenbeekBelgium
| | - Benjamin Ambrose
- Department of Chemistry, University of SheffieldSheffieldUnited Kingdom
| | - Victoria Birkedal
- Department of Chemistry and iNANO center, Aarhus UniversityAarhusDenmark
| | - Scott C Blanchard
- Department of Structural Biology, St. Jude Children's Research HospitalMemphisUnited States
| | - Richard Börner
- Laserinstitut HS Mittweida, University of Applied Science MittweidaMittweidaGermany
| | - Hoi Sung Chung
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität MünchenPlanegg-MartinsriedGermany
| | - Timothy D Craggs
- Department of Chemistry, University of SheffieldSheffieldUnited Kingdom
| | - Ashok A Deniz
- Department of Integrative Structural and Computational Biology, The Scripps Research InstituteLa JollaUnited States
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati School of MedicineCincinnatiUnited States
| | - Jingyi Fei
- Department of Biochemistry and Molecular Biology and The Institute for Biophysical Dynamics, University of ChicagoChicagoUnited States
| | - Ruben L Gonzalez
- Department of Chemistry, Columbia UniversityNew YorkUnited States
| | - Irina V Gopich
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Howard Hughes Medical InstituteBaltimoreUnited States
| | - Christian A Hanke
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-UniversitätDüsseldorfGermany
| | - Gilad Haran
- Department of Chemical and Biological Physics, Weizmann Institute of ScienceRehovotIsrael
| | - Nikos S Hatzakis
- Department of Chemistry & Nanoscience Centre, University of CopenhagenCopenhagenDenmark
- Denmark Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of CopenhagenCopenhagenDenmark
| | - Sungchul Hohng
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National UniversitySeoulRepublic of Korea
| | - Seok-Cheol Hong
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science and Department of Physics, Korea UniversitySeoulRepublic of Korea
| | - Thorsten Hugel
- Institute of Physical Chemistry and Signalling Research Centres BIOSS and CIBSS, University of FreiburgFreiburgGermany
| | - Antonino Ingargiola
- Department of Chemistry and Biochemistry, and Department of Physiology, University of California, Los AngelesLos AngelesUnited States
| | - Chirlmin Joo
- Department of BioNanoScience, Kavli Institute of Nanoscience, Delft University of TechnologyDelftNetherlands
| | - Achillefs N Kapanidis
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of OxfordOxfordUnited Kingdom
| | - Harold D Kim
- School of Physics, Georgia Institute of TechnologyAtlantaUnited States
| | - Ted Laurence
- Physical and Life Sciences Directorate, Lawrence Livermore National LaboratoryLivermoreUnited States
| | - Nam Ki Lee
- School of Chemistry, Seoul National UniversitySeoulRepublic of Korea
| | - Tae-Hee Lee
- Department of Chemistry, Pennsylvania State UniversityUniversity ParkUnited States
| | - Edward A Lemke
- Departments of Biology and Chemistry, Johannes Gutenberg UniversityMainzGermany
- Institute of Molecular Biology (IMB)MainzGermany
| | - Emmanuel Margeat
- Centre de Biologie Structurale (CBS), CNRS, INSERM, Universitié de MontpellierMontpellierFrance
| | | | - Xavier Michalet
- Department of Chemistry and Biochemistry, and Department of Physiology, University of California, Los AngelesLos AngelesUnited States
| | - Sua Myong
- Department of Biophysics, Johns Hopkins UniversityBaltimoreUnited States
| | - Daniel Nettels
- Department of Biochemistry and Department of Physics, University of ZurichZurichSwitzerland
| | - Thomas-Otavio Peulen
- Department of Bioengineering and Therapeutic Sciences, University of California, San FranciscoSan FranciscoUnited States
| | - Evelyn Ploetz
- Physical Chemistry, Department of Chemistry, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-UniversitätMünchenGermany
| | - Yair Razvag
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, and The Center for Nanoscience and Nanotechnology, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of JerusalemJerusalemIsrael
| | - Nicole C Robb
- Warwick Medical School, University of WarwickCoventryUnited Kingdom
| | - Benjamin Schuler
- Department of Biochemistry and Department of Physics, University of ZurichZurichSwitzerland
| | - Hamid Soleimaninejad
- Biological Optical Microscopy Platform (BOMP), University of MelbourneParkvilleAustralia
| | - Chun Tang
- College of Chemistry and Molecular Engineering, PKU-Tsinghua Center for Life Sciences, Beijing National Laboratory for Molecular Sciences, Peking UniversityBeijingChina
| | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Don C Lamb
- Physical Chemistry, Department of Chemistry, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-UniversitätMünchenGermany
| | - Claus AM Seidel
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-UniversitätDüsseldorfGermany
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, and Department of Physiology, University of California, Los AngelesLos AngelesUnited States
- Department of Physiology, CaliforniaNanoSystems Institute, University of California, Los AngelesLos AngelesUnited States
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5
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Armstrong RE, Horáček M, Zijlstra P. Plasmonic Assemblies for Real-Time Single-Molecule Biosensing. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2003934. [PMID: 33258287 DOI: 10.1002/smll.202003934] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 10/09/2020] [Indexed: 05/11/2023]
Abstract
Their tunable optical properties and versatile surface functionalization have sparked applications of plasmonic assemblies in the fields of biosensing, nonlinear optics, and photonics. Particularly, in the field of biosensing, rapid advances have occurred in the use of plasmonic assemblies for real-time single-molecule sensing. Compared to individual particles, the use of assemblies as sensors provides stronger signals, more control over the optical properties, and access to a broader range of timescales. In the past years, they have been used to directly reveal single-molecule interactions, mechanical properties, and conformational dynamics. This review summarizes the development of real-time single-molecule sensors built around plasmonic assemblies. First, a brief overview of their optical properties is given, and then recent applications are described. The current challenges in the field and suggestions to overcome those challenges are discussed in detail. Their stability, specificity, and sensitivity as sensors provide a complementary approach to other single-molecule techniques like force spectroscopy and single-molecule fluorescence. In future applications, the impact in real-time sensing on ultralong timescales (hours) and ultrashort timescales (sub-millisecond), time windows that are difficult to access using other techniques, is particularly foreseen.
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Affiliation(s)
- Rachel E Armstrong
- Department of Applied Physics & Institute for Complex Molecular Systems, Eindhoven University of Technology, Postbus 513, Eindhoven, MB, 5600, the Netherlands
| | - Matěj Horáček
- Department of Applied Physics & Institute for Complex Molecular Systems, Eindhoven University of Technology, Postbus 513, Eindhoven, MB, 5600, the Netherlands
| | - Peter Zijlstra
- Department of Applied Physics & Institute for Complex Molecular Systems, Eindhoven University of Technology, Postbus 513, Eindhoven, MB, 5600, the Netherlands
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6
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Harden TT, Herlambang KS, Chamberlain M, Lalanne JB, Wells CD, Li GW, Landick R, Hochschild A, Kondev J, Gelles J. Alternative transcription cycle for bacterial RNA polymerase. Nat Commun 2020; 11:448. [PMID: 31974358 PMCID: PMC6978322 DOI: 10.1038/s41467-019-14208-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 12/10/2019] [Indexed: 11/18/2022] Open
Abstract
RNA polymerases (RNAPs) transcribe genes through a cycle of recruitment to promoter DNA, initiation, elongation, and termination. After termination, RNAP is thought to initiate the next round of transcription by detaching from DNA and rebinding a new promoter. Here we use single-molecule fluorescence microscopy to observe individual RNAP molecules after transcript release at a terminator. Following termination, RNAP almost always remains bound to DNA and sometimes exhibits one-dimensional sliding over thousands of basepairs. Unexpectedly, the DNA-bound RNAP often restarts transcription, usually in reverse direction, thus producing an antisense transcript. Furthermore, we report evidence of this secondary initiation in live cells, using genome-wide RNA sequencing. These findings reveal an alternative transcription cycle that allows RNAP to reinitiate without dissociating from DNA, which is likely to have important implications for gene regulation.
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Affiliation(s)
- Timothy T Harden
- Department of Physics, Brandeis University, Waltham, MA, 02454, USA
| | | | | | - Jean-Benoît Lalanne
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Christopher D Wells
- Department of Microbiology, Blavatnick Institute, Harvard Medical School, Boston, MA, 02115, USA
| | - Gene-Wei Li
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Robert Landick
- Department of Biochemistry and Department of Bacteriology, University of Wisconsin, Madison, WI, 53706, USA
| | - Ann Hochschild
- Department of Microbiology, Blavatnick Institute, Harvard Medical School, Boston, MA, 02115, USA
| | - Jane Kondev
- Department of Physics, Brandeis University, Waltham, MA, 02454, USA.
| | - Jeff Gelles
- Department of Biochemistry, Brandeis University, Waltham, MA, 02454, USA.
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7
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Mohapatra S, Lin CT, Feng XA, Basu A, Ha T. Single-Molecule Analysis and Engineering of DNA Motors. Chem Rev 2019; 120:36-78. [DOI: 10.1021/acs.chemrev.9b00361] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
| | | | | | | | - Taekjip Ha
- Howard Hughes Medical Institute, Baltimore, Maryland 21205, United States
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8
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Statistical physics and mesoscopic modeling to interpret tethered particle motion experiments. Methods 2019; 169:57-68. [PMID: 31302177 DOI: 10.1016/j.ymeth.2019.07.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/11/2019] [Accepted: 07/07/2019] [Indexed: 11/22/2022] Open
Abstract
Tethered particle motion experiments are versatile single-molecule techniques enabling one to address in vitro the molecular properties of DNA and its interactions with various partners involved in genetic regulations. These techniques provide raw data such as the tracked particle amplitude of movement, from which relevant information about DNA conformations or states must be recovered. Solving this inverse problem appeals to specific theoretical tools that have been designed in the two last decades, together with the data pre-processing procedures that ought to be implemented to avoid biases inherent to these experimental techniques. These statistical tools and models are reviewed in this paper.
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9
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Weber PM, Moessel F, Paredes GF, Viehboeck T, Vischer NO, Bulgheresi S. A Bidimensional Segregation Mode Maintains Symbiont Chromosome Orientation toward Its Host. Curr Biol 2019; 29:3018-3028.e4. [DOI: 10.1016/j.cub.2019.07.064] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 06/24/2019] [Accepted: 07/22/2019] [Indexed: 11/24/2022]
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10
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Bogdan MJ, Savin T. Errors in Energy Landscapes Measured with Particle Tracking. Biophys J 2019; 115:139-149. [PMID: 29972805 DOI: 10.1016/j.bpj.2018.05.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 04/28/2018] [Accepted: 05/01/2018] [Indexed: 01/29/2023] Open
Abstract
Tracking Brownian particles is often employed to map the energy landscape they explore. Such measurements have been exploited to study many biological processes and interactions in soft materials. Yet video tracking is irremediably contaminated by localization errors originating from two imaging artifacts: the "static" errors come from signal noise, and the "dynamic" errors arise from the motion blur due to finite frame-acquisition time. We show that these errors result in systematic and nontrivial biases in the measured energy landscapes. We derive a relationship between the true and the measured potential that elucidates, among other aberrations, the presence of false double-well minima in the apparent potentials reported in recent studies. We further assess several canonical trapping and pair-interaction potentials by using our analytically derived results and Brownian dynamics simulations. In particular, we show that the apparent spring stiffness of harmonic potentials (such as optical traps) is increased by dynamic errors but decreased by static errors. Our formula allows for the development of efficient corrections schemes, and we also present in this work a provisional method for reconstructing true potentials from the measured ones.
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Affiliation(s)
- Michał J Bogdan
- Department of Engineering, University of Cambridge, Cambridge, United Kingdom
| | - Thierry Savin
- Department of Engineering, University of Cambridge, Cambridge, United Kingdom.
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11
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Probing Mitotic CENP-E Kinesin with the Tethered Cargo Motion Assay and Laser Tweezers. Biophys J 2019; 114:2640-2652. [PMID: 29874614 DOI: 10.1016/j.bpj.2018.04.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 03/22/2018] [Accepted: 04/10/2018] [Indexed: 12/18/2022] Open
Abstract
Coiled-coil stalks of various kinesins differ significantly in predicted length and structure; this is an adaption that helps these motors carry out their specialized functions. However, little is known about the dynamic stalk configuration in moving motors. To gain insight into the conformational properties of the transporting motors, we developed a theoretical model to predict Brownian motion of a microbead tethered to the tail of a single, freely walking molecule. This approach, which we call the tethered cargo motion (TCM) assay, provides an accurate measure of the mechanical properties of motor-cargo tethering, verified using kinesin-1 conjugated to a microbead via DNA links in vitro. Applying the TCM assay to the mitotic kinesin CENP-E unexpectedly revealed that when walking along a microtubule track, this highly elongated molecule with a contour length of 230 nm formed a 20-nm-long tether. The stalk of a walking CENP-E could not be extended fully by application of sideways force with optical tweezers (up to 4 pN), implying that CENP-E carries its cargo in a compact configuration. Assisting force applied along the microtubule track accelerates CENP-E walking, but this increase does not depend on the presence of the CENP-E stalk. Our results suggest that the unusually large stalk of CENP-E has little role in regulating its function as a transporter. The adjustable stalk configuration may represent a regulatory mechanism for controlling the physical reach between kinetochore-bound CENP-E and spindle microtubules, or it may assist localizing various kinetochore regulators in the immediate vicinity of the kinetochore-embedded microtubule ends. The TCM assay and underlying theoretical framework will provide a general guide for determining the dynamic configurations of various molecular motors moving along their tracks, freely or under force.
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12
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Duss O, Stepanyuk GA, Grot A, O'Leary SE, Puglisi JD, Williamson JR. Real-time assembly of ribonucleoprotein complexes on nascent RNA transcripts. Nat Commun 2018; 9:5087. [PMID: 30504830 PMCID: PMC6269517 DOI: 10.1038/s41467-018-07423-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/26/2018] [Indexed: 12/22/2022] Open
Abstract
Cellular protein-RNA complexes assemble on nascent transcripts, but methods to observe transcription and protein binding in real time and at physiological concentrations are not available. Here, we report a single-molecule approach based on zero-mode waveguides that simultaneously tracks transcription progress and the binding of ribosomal protein S15 to nascent RNA transcripts during early ribosome biogenesis. We observe stable binding of S15 to single RNAs immediately after transcription for the majority of the transcripts at 35 °C but for less than half at 20 °C. The remaining transcripts exhibit either rapid and transient binding or are unable to bind S15, likely due to RNA misfolding. Our work establishes the foundation for studying transcription and its coupled co-transcriptional processes, including RNA folding, ligand binding, and enzymatic activity such as in coupling of transcription to splicing, ribosome assembly or translation. The early steps of ribosome assembly occur co-transcriptionally on the nascent ribosomal RNA. Here the authors demonstrate an approach that allows simultaneous monitoring of transcription and ribosomal protein assembly at the single-molecule level in real time.
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Affiliation(s)
- Olivier Duss
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA.,Department of Structural Biology, Stanford University School of Medicine, CA, 94305, California, USA
| | - Galina A Stepanyuk
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Annette Grot
- Department of Research and Development, Pacific Biosciences Inc, Menlo Park, CA, 94025, USA
| | - Seán E O'Leary
- Department of Structural Biology, Stanford University School of Medicine, CA, 94305, California, USA.,Department of Biochemistry, University of California, Riverside, CA, 92521, USA
| | - Joseph D Puglisi
- Department of Structural Biology, Stanford University School of Medicine, CA, 94305, California, USA.
| | - James R Williamson
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA.
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13
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Tethered multifluorophore motion reveals equilibrium transition kinetics of single DNA double helices. Proc Natl Acad Sci U S A 2018; 115:E7512-E7521. [PMID: 30037988 PMCID: PMC6094131 DOI: 10.1073/pnas.1800585115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Understanding cellular functions and dysfunctions often begins with quantifying the interactions between the binding partners involved in the processes. Learning about the kinetics of the interactions is of particular importance to understand the dynamics of cellular processes. We created a tethered multifluorophore motion assay using DNA origami that enables over 1-hour-long recordings of the statistical binding and unbinding of single pairs of biomolecules directly in equilibrium. The experimental concept is simple and the data interpretation is very direct, which makes the system easy to use for a wide variety of researchers. Due to the modularity and addressability of the DNA origami-based assay, our system may be readily adapted to study various other molecular interactions. We describe a tethered multifluorophore motion assay based on DNA origami for revealing bimolecular reaction kinetics on the single-molecule level. Molecular binding partners may be placed at user-defined positions and in user-defined stoichiometry; and binding states are read out by tracking the motion of quickly diffusing fluorescent reporter units. Multiple dyes per reporter unit enable singe-particle observation for more than 1 hour. We applied the system to study in equilibrium reversible hybridization and dissociation of complementary DNA single strands as a function of tether length, cation concentration, and sequence. We observed up to hundreds of hybridization and dissociation events per single reactant pair and could produce cumulative statistics with tens of thousands of binding and unbinding events. Because the binding partners per particle do not exchange, we could also detect subtle heterogeneity from molecule to molecule, which enabled separating data reflecting the actual target strand pair binding kinetics from falsifying influences stemming from chemically truncated oligonucleotides. Our data reflected that mainly DNA strand hybridization, but not strand dissociation, is affected by cation concentration, in agreement with previous results from different assays. We studied 8-bp-long DNA duplexes with virtually identical thermodynamic stability, but different sequences, and observed strongly differing hybridization kinetics. Complementary full-atom molecular-dynamics simulations indicated two opposing sequence-dependent phenomena: helical templating in purine-rich single strands and secondary structures. These two effects can increase or decrease, respectively, the fraction of strand collisions leading to successful nucleation events for duplex formation.
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Fan HF, Ma CH, Jayaram M. Single-Molecule Tethered Particle Motion: Stepwise Analyses of Site-Specific DNA Recombination. MICROMACHINES 2018; 9:E216. [PMID: 30424148 PMCID: PMC6187709 DOI: 10.3390/mi9050216] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 04/25/2018] [Accepted: 04/28/2018] [Indexed: 12/17/2022]
Abstract
Tethered particle motion/microscopy (TPM) is a biophysical tool used to analyze changes in the effective length of a polymer, tethered at one end, under changing conditions. The tether length is measured indirectly by recording the Brownian motion amplitude of a bead attached to the other end. In the biological realm, DNA, whose interactions with proteins are often accompanied by apparent or real changes in length, has almost exclusively been the subject of TPM studies. TPM has been employed to study DNA bending, looping and wrapping, DNA compaction, high-order DNA⁻protein assembly, and protein translocation along DNA. Our TPM analyses have focused on tyrosine and serine site-specific recombinases. Their pre-chemical interactions with DNA cause reversible changes in DNA length, detectable by TPM. The chemical steps of recombination, depending on the substrate and the type of recombinase, may result in a permanent length change. Single molecule TPM time traces provide thermodynamic and kinetic information on each step of the recombination pathway. They reveal how mechanistically related recombinases may differ in their early commitment to recombination, reversibility of individual steps, and in the rate-limiting step of the reaction. They shed light on the pre-chemical roles of catalytic residues, and on the mechanisms by which accessory proteins regulate recombination directionality.
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Affiliation(s)
- Hsiu-Fang Fan
- Biophotonics and Molecular Imaging Center, Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei 112, Taiwan.
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan.
| | - Chien-Hui Ma
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
| | - Makkuni Jayaram
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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Tardin C. The mechanics of DNA loops bridged by proteins unveiled by single-molecule experiments. Biochimie 2017; 142:80-92. [PMID: 28804000 DOI: 10.1016/j.biochi.2017.08.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 08/06/2017] [Indexed: 12/28/2022]
Abstract
Protein-induced DNA bridging and looping is a common mechanism for various and essential processes in bacterial chromosomes. This mechanism is preserved despite the very different bacterial conditions and their expected influence on the thermodynamic and kinetic characteristics of the bridge formation and stability. Over the last two decades, single-molecule techniques carried out on in vitro DNA systems have yielded valuable results which, in combination with theoretical works, have clarified the effects of different parameters of nucleoprotein complexes on the protein-induced DNA bridging and looping process. In this review, I will outline the features that can be measured for such processes with various single-molecule techniques in use in the field. I will then describe both the experimental results and the theoretical models that illuminate the contribution of the DNA molecule itself as well as that of the bridging proteins in the DNA looping mechanism at play in the nucleoid of E. coli.
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Affiliation(s)
- Catherine Tardin
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, France.
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Tutkus M, Marciulionis T, Sasnauskas G, Rutkauskas D. DNA-Endonuclease Complex Dynamics by Simultaneous FRET and Fluorophore Intensity in Evanescent Field. Biophys J 2017; 112:850-858. [PMID: 28297644 DOI: 10.1016/j.bpj.2017.01.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 01/06/2017] [Accepted: 01/24/2017] [Indexed: 11/25/2022] Open
Abstract
The single-molecule Förster resonance energy transfer (FRET) is a powerful tool to study interactions and conformational changes of biological molecules in the distance range from a few to 10 nm. In this study, we demonstrate a method to augment this range with longer distances. The method is based on the intensity changes of a tethered fluorophore, diffusing in the exponentially decaying evanescent excitation field. In combination with FRET it allowed us to reveal and characterize the dynamics of what had been inaccessible conformations of the DNA-protein complex. Our model system, restriction enzyme Ecl18kI, interacts with a FRET pair-labeled DNA fragment to form two different DNA loop conformations. The DNA-protein interaction geometry is such that the efficient FRET is expected for one of these conformations-"antiparallel" loop. In the alternative "parallel" loop, the expected distance between the dyes is outside the range accessible by FRET. Therefore, "antiparallel" looping is observed in a single-molecule time trajectory as discrete transitions to a state of high FRET efficiency. At the same time, transitions to a high-intensity state of the directly excited acceptor fluorophore on a DNA tether are due to a change of its average position in the evanescent field of excitation and can be associated with a loop of either "parallel" or "antiparallel" configuration. Simultaneous analysis of FRET and acceptor intensity trajectories then allows us to discriminate different DNA loop conformations and access the average lifetimes of different states.
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Affiliation(s)
- Marijonas Tutkus
- Institute of Physics, Center for Physical Sciences and Technology, Vilnius, Lithuania
| | - Tomas Marciulionis
- Institute of Physics, Center for Physical Sciences and Technology, Vilnius, Lithuania
| | | | - Danielis Rutkauskas
- Institute of Physics, Center for Physical Sciences and Technology, Vilnius, Lithuania.
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17
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Bacterial RNA polymerase can retain σ70 throughout transcription. Proc Natl Acad Sci U S A 2016; 113:602-7. [PMID: 26733675 DOI: 10.1073/pnas.1513899113] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Production of a messenger RNA proceeds through sequential stages of transcription initiation and transcript elongation and termination. During each of these stages, RNA polymerase (RNAP) function is regulated by RNAP-associated protein factors. In bacteria, RNAP-associated σ factors are strictly required for promoter recognition and have historically been regarded as dedicated initiation factors. However, the primary σ factor in Escherichia coli, σ(70), can remain associated with RNAP during the transition from initiation to elongation, influencing events that occur after initiation. Quantitative studies on the extent of σ(70) retention have been limited to complexes halted during early elongation. Here, we used multiwavelength single-molecule fluorescence-colocalization microscopy to observe the σ(70)-RNAP complex during initiation from the λ PR' promoter and throughout the elongation of a long (>2,000-nt) transcript. Our results provide direct measurements of the fraction of actively transcribing complexes with bound σ(70) and the kinetics of σ(70) release from actively transcribing complexes. σ(70) release from mature elongation complexes was slow (0.0038 s(-1)); a substantial subpopulation of elongation complexes retained σ(70) throughout transcript elongation, and this fraction depended on the sequence of the initially transcribed region. We also show that elongation complexes containing σ(70) manifest enhanced recognition of a promoter-like pause element positioned hundreds of nucleotides downstream of the promoter. Together, the results provide a quantitative framework for understanding the postinitiation roles of σ(70) during transcription.
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Assembly, translocation, and activation of XerCD-dif recombination by FtsK translocase analyzed in real-time by FRET and two-color tethered fluorophore motion. Proc Natl Acad Sci U S A 2015; 112:E5133-41. [PMID: 26324908 DOI: 10.1073/pnas.1510814112] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The FtsK dsDNA translocase functions in bacterial chromosome unlinking by activating XerCD-dif recombination in the replication terminus region. To analyze FtsK assembly and translocation, and the subsequent activation of XerCD-dif recombination, we extended the tethered fluorophore motion technique, using two spectrally distinct fluorophores to monitor two effective lengths along the same tethered DNA molecule. We observed that FtsK assembled stepwise on DNA into a single hexamer, and began translocation rapidly (∼ 0.25 s). Without extruding DNA loops, single FtsK hexamers approached XerCD-dif and resided there for ∼ 0.5 s irrespective of whether XerCD-dif was synapsed or unsynapsed. FtsK then dissociated, rather than reversing. Infrequently, FtsK activated XerCD-dif recombination when it encountered a preformed synaptic complex, and dissociated before the completion of recombination, consistent with each FtsK-XerCD-dif encounter activating only one round of recombination.
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Evans GW, Hohlbein J, Craggs T, Aigrain L, Kapanidis AN. Real-time single-molecule studies of the motions of DNA polymerase fingers illuminate DNA synthesis mechanisms. Nucleic Acids Res 2015; 43:5998-6008. [PMID: 26013816 PMCID: PMC4499156 DOI: 10.1093/nar/gkv547] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 05/13/2015] [Indexed: 12/30/2022] Open
Abstract
DNA polymerases maintain genomic integrity by copying DNA with high fidelity. A conformational change important for fidelity is the motion of the polymerase fingers subdomain from an open to a closed conformation upon binding of a complementary nucleotide. We previously employed intra-protein single-molecule FRET on diffusing molecules to observe fingers conformations in polymerase-DNA complexes. Here, we used the same FRET ruler on surface-immobilized complexes to observe fingers-opening and closing of individual polymerase molecules in real time. Our results revealed the presence of intrinsic dynamics in the binary complex, characterized by slow fingers-closing and fast fingers-opening. When binary complexes were incubated with increasing concentrations of complementary nucleotide, the fingers-closing rate increased, strongly supporting an induced-fit model for nucleotide recognition. Meanwhile, the opening rate in ternary complexes with complementary nucleotide was 6 s(-1), much slower than either fingers closing or the rate-limiting step in the forward direction; this rate balance ensures that, after nucleotide binding and fingers-closing, nucleotide incorporation is overwhelmingly likely to occur. Our results for ternary complexes with a non-complementary dNTP confirmed the presence of a state corresponding to partially closed fingers and suggested a radically different rate balance regarding fingers transitions, which allows polymerase to achieve high fidelity.
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Affiliation(s)
- Geraint W Evans
- Department of Physics and Biological Physics Research Group, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Johannes Hohlbein
- Department of Physics and Biological Physics Research Group, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Timothy Craggs
- Department of Physics and Biological Physics Research Group, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Louise Aigrain
- Department of Physics and Biological Physics Research Group, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Achillefs N Kapanidis
- Department of Physics and Biological Physics Research Group, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
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