1
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Lin YY, Müller P, Karagianni E, Hepp N, Mueller-Planitz F, Vanderlinden W, Lipfert J. Epigenetic Histone Modifications H3K36me3 and H4K5/8/12/16ac Induce Open Polynucleosome Conformations via Different Mechanisms. J Mol Biol 2024; 436:168671. [PMID: 38908785 DOI: 10.1016/j.jmb.2024.168671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 05/28/2024] [Accepted: 06/16/2024] [Indexed: 06/24/2024]
Abstract
Nucleosomes are the basic compaction unit of chromatin and nucleosome structure and their higher-order assemblies regulate genome accessibility. Many post-translational modifications alter nucleosome dynamics, nucleosome-nucleosome interactions, and ultimately chromatin structure and gene expression. Here, we investigate the role of two post-translational modifications associated with actively transcribed regions, H3K36me3 and H4K5/8/12/16ac, in the contexts of tri-nucleosome arrays that provide a tractable model system for quantitative single-molecule analysis, while enabling us to probe nucleosome-nucleosome interactions. Direct visualization by AFM imaging reveals that H3K36me3 and H4K5/8/12/16ac nucleosomes adopt significantly more open and loose conformations than unmodified nucleosomes. Similarly, magnetic tweezers force spectroscopy shows a reduction in DNA outer turn wrapping and nucleosome-nucleosome interactions for the modified nucleosomes. The results suggest that for H3K36me3 the increased breathing and outer DNA turn unwrapping seen in mononucleosomes propagates to more open conformations in nucleosome arrays. In contrast, the even more open structures of H4K5/8/12/16ac nucleosome arrays do not appear to derive from the dynamics of the constituent mononucleosomes, but are driven by reduced nucleosome-nucleosome interactions, suggesting that stacking interactions can overrule DNA breathing of individual nucleosomes. We anticipate that our methodology will be broadly applicable to reveal the influence of other post-translational modifications and to observe the activity of nucleosome remodelers.
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Affiliation(s)
- Yi-Yun Lin
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Amaliensstrasse 54, 80799 Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, the Netherlands
| | - Peter Müller
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Amaliensstrasse 54, 80799 Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, the Netherlands
| | - Evdoxia Karagianni
- Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, the Netherlands
| | - Nicola Hepp
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany; Current address: Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Felix Mueller-Planitz
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - Willem Vanderlinden
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Amaliensstrasse 54, 80799 Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, the Netherlands; School of Physics and Astronomy, University of Edinburg, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom.
| | - Jan Lipfert
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Amaliensstrasse 54, 80799 Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, the Netherlands.
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2
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Zhao Y, Guo L, Hu J, Ren Z, Li Y, Hu M, Zhang X, Bi L, Li D, Ma H, Liu C, Sun B. Phase-separated ParB enforces diverse DNA compaction modes and stabilizes the parS-centered partition complex. Nucleic Acids Res 2024; 52:8385-8398. [PMID: 38908027 DOI: 10.1093/nar/gkae533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/20/2024] [Accepted: 06/13/2024] [Indexed: 06/24/2024] Open
Abstract
The tripartite ParABS system mediates chromosome segregation in the majority of bacterial species. Typically, DNA-bound ParB proteins around the parS sites condense the chromosomal DNA into a higher-order multimeric nucleoprotein complex for the ParA-driven partition. Despite extensive studies, the molecular mechanism underlying the dynamic assembly of the partition complex remains unclear. Herein, we demonstrate that Bacillus subtilis ParB (Spo0J), through the multimerization of its N-terminal domain, forms phase-separated condensates along a single DNA molecule, leading to the concurrent organization of DNA into a compact structure. Specifically, in addition to the co-condensation of ParB dimers with DNA, the engagement of well-established ParB condensates with DNA allows for the compression of adjacent DNA and the looping of distant DNA. Notably, the presence of CTP promotes the formation of condensates by a low amount of ParB at parS sites, triggering two-step DNA condensation. Remarkably, parS-centered ParB-DNA co-condensate constitutes a robust nucleoprotein architecture capable of withstanding disruptive forces of tens of piconewton. Overall, our findings unveil diverse modes of DNA compaction enabled by phase-separated ParB and offer new insights into the dynamic assembly and maintenance of the bacterial partition complex.
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Affiliation(s)
- Yilin Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Lijuan Guo
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jiaojiao Hu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 201210, China
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zhiyun Ren
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanan Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Meng Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xia Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Lulu Bi
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Dan Li
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China
- Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hanhui Ma
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Cong Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 201210, China
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Bo Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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3
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Kretzer B, Herényi L, Csík G, Supala E, Orosz Á, Tordai H, Kiss B, Kellermayer M. TMPyP binding evokes a complex, tunable nanomechanical response in DNA. Nucleic Acids Res 2024; 52:8399-8418. [PMID: 38943349 DOI: 10.1093/nar/gkae560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 06/06/2024] [Accepted: 06/17/2024] [Indexed: 07/01/2024] Open
Abstract
TMPyP is a porphyrin capable of DNA binding and used in photodynamic therapy and G-quadruplex stabilization. Despite its broad applications, TMPyP's effect on DNA nanomechanics is unknown. Here we investigated, by manipulating λ-phage DNA with optical tweezers combined with microfluidics in equilibrium and perturbation kinetic experiments, how TMPyP influences DNA nanomechanics across wide ranges of TMPyP concentration (5-5120 nM), mechanical force (0-100 pN), NaCl concentration (0.01-1 M) and pulling rate (0.2-20 μm/s). Complex responses were recorded, for the analysis of which we introduced a simple mathematical model. TMPyP binding, which is a highly dynamic process, leads to dsDNA lengthening and softening. dsDNA stability increased at low (<10 nM) TMPyP concentrations, then decreased progressively upon increasing TMPyP concentration. Overstretch cooperativity decreased, due most likely to mechanical roadblocks of ssDNA-bound TMPyP. TMPyP binding increased ssDNA's contour length. The addition of NaCl at high (1 M) concentration competed with the TMPyP-evoked nanomechanical changes. Because the largest amplitude of the changes is induced by the pharmacologically relevant TMPyP concentration range, this porphyrin derivative may be used to tune DNA's structure and properties, hence control the wide array of biomolecular DNA-dependent processes including replication, transcription, condensation and repair.
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Affiliation(s)
- Balázs Kretzer
- Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
- HUNREN-SE Biophysical Virology Group, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
| | - Levente Herényi
- Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
| | - Gabriella Csík
- Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
| | - Eszter Supala
- Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
| | - Ádám Orosz
- Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
| | - Hedvig Tordai
- Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
| | - Bálint Kiss
- Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
- HUNREN-SE Biophysical Virology Group, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
| | - Miklós Kellermayer
- Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
- HUNREN-SE Biophysical Virology Group, Tűzoltó Str. 37-47, H1094 Budapest, Hungary
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4
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Hong Y, Ye F, Qian J, Gao X, Inman JT, Wang MD. Optical torque calculations and measurements for DNA torsional studies. Biophys J 2024:S0006-3495(24)00444-2. [PMID: 38961622 DOI: 10.1016/j.bpj.2024.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 05/20/2024] [Accepted: 07/01/2024] [Indexed: 07/05/2024] Open
Abstract
The angular optical trap (AOT) is a powerful instrument for measuring the torsional and rotational properties of a biological molecule. Thus far, AOT studies of DNA torsional mechanics have been carried out using a high numerical aperture oil-immersion objective, which permits strong trapping but inevitably introduces spherical aberrations due to the glass-aqueous interface. However, the impact of these aberrations on torque measurements is not fully understood experimentally, partly due to a lack of theoretical guidance. Here, we present a numerical platform based on the finite element method to calculate forces and torques on a trapped quartz cylinder. We have also developed a new experimental method to accurately determine the shift in the trapping position due to the spherical aberrations by using a DNA molecule as a distance ruler. We found that the calculated and measured focal shift ratios are in good agreement. We further determined how the angular trap stiffness depends on the trap height and the cylinder displacement from the trap center and found full agreement between predictions and measurements. As a further verification of the methodology, we showed that DNA torsional properties, which are intrinsic to DNA, could be determined robustly under different trap heights and cylinder displacements. Thus, this work has laid both a theoretical and experimental framework that can be readily extended to investigate the trapping forces and torques exerted on particles with arbitrary shapes and optical properties.
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Affiliation(s)
- Yifeng Hong
- Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York
| | - Fan Ye
- Howard Hughes Medical Institute, Cornell University, Ithaca, New York; Department of Physics & LASSP, Cornell University, Ithaca, New York
| | - Jin Qian
- Department of Physics & LASSP, Cornell University, Ithaca, New York
| | - Xiang Gao
- Howard Hughes Medical Institute, Cornell University, Ithaca, New York; Department of Physics & LASSP, Cornell University, Ithaca, New York
| | - James T Inman
- Howard Hughes Medical Institute, Cornell University, Ithaca, New York; Department of Physics & LASSP, Cornell University, Ithaca, New York
| | - Michelle D Wang
- Howard Hughes Medical Institute, Cornell University, Ithaca, New York; Department of Physics & LASSP, Cornell University, Ithaca, New York.
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5
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Xu L, Halma MTJ, Wuite GJL. Mapping fast DNA polymerase exchange during replication. Nat Commun 2024; 15:5328. [PMID: 38909023 PMCID: PMC11193749 DOI: 10.1038/s41467-024-49612-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 06/11/2024] [Indexed: 06/24/2024] Open
Abstract
Despite extensive studies on DNA replication, the exchange mechanisms of DNA polymerase during replication remain unclear. Existing models propose that this exchange is facilitated by protein partners like helicase. Here we present data, employing a combination of mechanical DNA manipulation and single fluorescent protein observation, that reveal DNA polymerase undergoing rapid and autonomous exchange during replication not coordinated by other proteins. The DNA polymerase shows fast unbinding and rebinding dynamics, displaying a preference for either exonuclease or polymerase activity, or pausing events, during each brief binding event. We also observed a 'memory effect' in DNA polymerase rebinding, i.e., the enzyme tends to preserve its prior activity upon reassociation. This effect, potentially linked to the ssDNA/dsDNA junction's conformation, might play a role in regulating binding preference enabling high processivity amidst rapid protein exchange. Taken together, our findings support an autonomous replication model that includes rapid protein exchange, burst of activity, and a 'memory effect' while moving processively forward.
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Affiliation(s)
- Longfu Xu
- Department of Physics and Astronomy and LaserLab, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Matthew T J Halma
- Department of Physics and Astronomy and LaserLab, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Gijs J L Wuite
- Department of Physics and Astronomy and LaserLab, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
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6
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Martucci M, Moretton A, Tarrés-Solé A, Ropars V, Lambert L, Vernet P, Solà M, Falkenberg M, Farge G, van den Wildenberg S. The mutation R107Q alters mtSSB ssDNA compaction ability and binding dynamics. Nucleic Acids Res 2024; 52:5912-5927. [PMID: 38742632 PMCID: PMC11162770 DOI: 10.1093/nar/gkae354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 04/02/2024] [Accepted: 04/22/2024] [Indexed: 05/16/2024] Open
Abstract
Mitochondrial single-stranded DNA-binding protein (mtSSB) is essential for mitochondrial DNA (mtDNA) replication. Recently, several mtSSB variants have been associated with autosomal dominant mitochondrial optic atrophy and retinal dystrophy. Here, we have studied at the molecular level the functional consequences of one of the most severe mtSSB variants, R107Q. We first studied the oligomeric state of this variant and observed that the mtSSBR107Q mutant forms stable tetramers in vitro. On the other hand, we showed, using complementary single-molecule approaches, that mtSSBR107Q displays a lower intramolecular ssDNA compaction ability and a higher ssDNA dissociation rate than the WT protein. Real-time competition experiments for ssDNA-binding showed a marked advantage of mtSSBWT over mtSSBR107Q. Combined, these results show that the R107Q mutation significantly impaired the ssDNA-binding and compacting ability of mtSSB, likely by weakening mtSSB ssDNA wrapping efficiency. These features are in line with our molecular modeling of ssDNA on mtSSB showing that the R107Q mutation may destabilize local interactions and results in an electronegative spot that interrupts an ssDNA-interacting-electropositive patch, thus reducing the potential mtSSB-ssDNA interaction sites.
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Affiliation(s)
- Martial Martucci
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Amandine Moretton
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Aleix Tarrés-Solé
- Structural MitoLab, Molecular Biology Institute Barcelona (IBMB-CSIC), Barcelona Science Park, Barcelona 08028, Spain
| | - Virginie Ropars
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Louise Lambert
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Patrick Vernet
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Maria Solà
- Structural MitoLab, Molecular Biology Institute Barcelona (IBMB-CSIC), Barcelona Science Park, Barcelona 08028, Spain
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Geraldine Farge
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Siet van den Wildenberg
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
- Université Clermont Auvergne, CNRS, IRD, Université Jean Monnet Saint Etienne, LMV, F-63000 Clermont-Ferrand, France
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7
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Rudnizky S, Murray PJ, Wolfe CH, Ha T. Single-Macromolecule Studies of Eukaryotic Genomic Maintenance. Annu Rev Phys Chem 2024; 75:209-230. [PMID: 38382570 DOI: 10.1146/annurev-physchem-090722-010601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Genomes are self-organized and self-maintained as long, complex macromolecules of chromatin. The inherent heterogeneity, stochasticity, phase separation, and chromatin dynamics of genome operation make it challenging to study genomes using ensemble methods. Various single-molecule force-, fluorescent-, and sequencing-based techniques rooted in different disciplines have been developed to fill critical gaps in the capabilities of bulk measurements, each providing unique, otherwise inaccessible, insights into the structure and maintenance of the genome. Capable of capturing molecular-level details about the organization, conformational changes, and packaging of genetic material, as well as processive and stochastic movements of maintenance factors, a single-molecule toolbox provides an excellent opportunity for collaborative research to understand how genetic material functions in health and malfunctions in disease. In this review, we discuss novel insights brought to genomic sciences by single-molecule techniques and their potential to continue to revolutionize the field-one molecule at a time.
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Affiliation(s)
- Sergei Rudnizky
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Peter J Murray
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA;
| | - Clara H Wolfe
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA;
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts, USA
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8
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Vaknin A, Grossman A, Durham ND, Lupovitz I, Goren S, Golani G, Roichman Y, Munro JB, Sorkin R. Ebola Virus Glycoprotein Strongly Binds to Membranes in the Absence of Receptor Engagement. ACS Infect Dis 2024; 10:1590-1601. [PMID: 38684073 PMCID: PMC11091876 DOI: 10.1021/acsinfecdis.3c00622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 04/07/2024] [Accepted: 04/09/2024] [Indexed: 05/02/2024]
Abstract
Ebola virus (EBOV) is an enveloped virus that must fuse with the host cell membrane in order to release its genome and initiate infection. This process requires the action of the EBOV envelope glycoprotein (GP), encoded by the virus, which resides in the viral envelope and consists of a receptor binding subunit, GP1, and a membrane fusion subunit, GP2. Despite extensive research, a mechanistic understanding of the viral fusion process is incomplete. To investigate GP-membrane association, a key step in the fusion process, we used two approaches: high-throughput measurements of single-particle diffusion and single-molecule measurements with optical tweezers. Using these methods, we show that the presence of the endosomal Niemann-Pick C1 (NPC1) receptor is not required for primed GP-membrane binding. In addition, we demonstrate this binding is very strong, likely attributed to the interaction between the GP fusion loop and the membrane's hydrophobic core. Our results also align with previously reported findings, emphasizing the significance of acidic pH in the protein-membrane interaction. Beyond Ebola virus research, our approach provides a powerful toolkit for studying other protein-membrane interactions, opening new avenues for a better understanding of protein-mediated membrane fusion events.
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Affiliation(s)
- Alisa Vaknin
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Center
for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Alon Grossman
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Center
for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Natasha D. Durham
- Department
of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, United States
| | - Inbal Lupovitz
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Center
for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Shahar Goren
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Center
for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Gonen Golani
- Department
of Physics and Haifa Research Center for Theoretical Physics and Astrophysics, University of Haifa, Haifa 3498838, Israel
| | - Yael Roichman
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Center
for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 6997801, Israel
- Raymond
and Beverly Sackler School of Physics & Astronomy, Tel Aviv University, Tel Aviv 6997801, Israel
| | - James B. Munro
- Department
of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, United States
- Department
of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, United States
| | - Raya Sorkin
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Center
for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 6997801, Israel
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9
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Chriss A, Börner GV, Ryan SD. Agent-based modeling of nuclear chromosome ensembles identifies determinants of homolog pairing during meiosis. PLoS Comput Biol 2024; 20:e1011416. [PMID: 38739641 PMCID: PMC11115365 DOI: 10.1371/journal.pcbi.1011416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 05/23/2024] [Accepted: 04/10/2024] [Indexed: 05/16/2024] Open
Abstract
During meiosis, pairing of homologous chromosomes (homologs) ensures the formation of haploid gametes from diploid precursor cells, a prerequisite for sexual reproduction. Pairing during meiotic prophase I facilitates crossover recombination and homolog segregation during the ensuing reductional cell division. Mechanisms that ensure stable homolog alignment in the presence of an excess of non-homologous chromosomes have remained elusive, but rapid chromosome movements appear to play a role in the process. Apart from homolog attraction, provided by early intermediates of homologous recombination, dissociation of non-homologous associations also appears to contribute to homolog pairing, as suggested by the detection of stable non-homologous chromosome associations in pairing-defective mutants. Here, we have developed an agent-based model for homolog pairing derived from the dynamics of a naturally occurring chromosome ensemble. The model simulates unidirectional chromosome movements, as well as collision dynamics determined by attractive and repulsive forces arising from close-range physical interactions. Chromosome number and size as well as movement velocity and repulsive forces are identified as key factors in the kinetics and efficiency of homologous pairing in addition to homolog attraction. Dissociation of interactions between non-homologous chromosomes may contribute to pairing by crowding homologs into a limited nuclear area thus creating preconditions for close-range homolog attraction. Incorporating natural chromosome lengths, the model accurately recapitulates efficiency and kinetics of homolog pairing observed for wild-type and mutant meiosis in budding yeast, and can be adapted to nuclear dimensions and chromosome sets of other organisms.
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Affiliation(s)
- Ariana Chriss
- Department of Mathematics and Statistics, Cleveland State University, Cleveland, Ohio, United States of America
- Department of Biological, Geological, and Environmental Sciences, Cleveland State University, Cleveland, Ohio, United States of America
| | - G. Valentin Börner
- Department of Biological, Geological, and Environmental Sciences, Cleveland State University, Cleveland, Ohio, United States of America
- Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, Ohio, United States of America
| | - Shawn D. Ryan
- Department of Mathematics and Statistics, Cleveland State University, Cleveland, Ohio, United States of America
- Center for Applied Data Analysis and Modeling, Cleveland State University, Cleveland, Ohio, United States of America
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10
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Cashen BA, Morse M, Rouzina I, Karpel RL, Williams MC. C-terminal Domain of T4 gene 32 Protein Enables Rapid Filament Reorganization and Dissociation. J Mol Biol 2024; 436:168544. [PMID: 38508303 DOI: 10.1016/j.jmb.2024.168544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 02/27/2024] [Accepted: 03/14/2024] [Indexed: 03/22/2024]
Abstract
Bacteriophage T4 gene 32 protein (gp32) is a single-stranded DNA (ssDNA) binding protein essential for DNA replication. gp32 forms stable protein filaments on ssDNA through cooperative interactions between its core and N-terminal domain. gp32's C-terminal domain (CTD) is believed to primarily help coordinate DNA replication via direct interactions with constituents of the replisome. However, the exact mechanisms of these interactions are not known, and it is unclear how tightly-bound gp32 filaments are readily displaced from ssDNA as required for genomic processing. Here, we utilized truncated gp32 variants to demonstrate a key role of the CTD in regulating gp32 dissociation. Using optical tweezers, we probed the binding and dissociation dynamics of CTD-truncated gp32, *I, to an 8.1 knt ssDNA molecule and compared these measurements with those for full-length gp32. The *I-ssDNA helical filament becomes progressively unwound with increased protein concentration but remains significantly more stable than that of full-length, wild-type gp32. Protein oversaturation, concomitant with filament unwinding, facilitates rapid dissociation of full-length gp32 from across the entire ssDNA segment. In contrast, *I primarily unbinds slowly from only the ends of the cooperative clusters, regardless of the protein density and degree of DNA unwinding. Our results suggest that the CTD may constrain the relative twist angle of proteins within the ssDNA filament such that upon critical unwinding the cooperative interprotein interactions largely vanish, facilitating prompt removal of gp32. We propose a model of CTD-mediated gp32 displacement via internal restructuring of its filament, providing a mechanism for rapid ssDNA clearing during genomic processing.
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Affiliation(s)
- Ben A Cashen
- Department of Physics, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Michael Morse
- Department of Physics, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Ioulia Rouzina
- Department of Chemistry and Biochemistry, Center for Retroviral Research and Center for RNA Biology, Ohio State University, 281 W Lane Avenue, Columbus, OH 43210, USA
| | - Richard L Karpel
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - Mark C Williams
- Department of Physics, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA.
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11
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Burdick RC, Morse M, Rouzina I, Williams MC, Hu WS, Pathak VK. HIV-1 uncoating requires long double-stranded reverse transcription products. SCIENCE ADVANCES 2024; 10:eadn7033. [PMID: 38657061 PMCID: PMC11042746 DOI: 10.1126/sciadv.adn7033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 03/21/2024] [Indexed: 04/26/2024]
Abstract
HIV-1 cores, which contain the viral genome and replication machinery, must disassemble (uncoat) during viral replication. However, the viral and host factors that trigger uncoating remain unidentified. Recent studies show that infectious cores enter the nucleus and uncoat near the site of integration. Here, we show that efficient uncoating of nuclear cores requires synthesis of a double-stranded DNA (dsDNA) genome >3.5 kb and that the efficiency of uncoating correlates with genome size. Core disruption by capsid inhibitors releases viral DNA, some of which integrates. However, most of the viral DNA is degraded, indicating that the intact core safeguards viral DNA. Atomic force microscopy and core content estimation reveal that synthesis of full-length genomic dsDNA induces substantial internal strain on the core to promote uncoating. We conclude that HIV-1 cores protect viral DNA from degradation by host factors and that synthesis of long double-stranded reverse transcription products is required to trigger efficient HIV-1 uncoating.
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Affiliation(s)
- Ryan C. Burdick
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, 21702, USA
| | - Michael Morse
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Ioulia Rouzina
- Department of Chemistry and Biochemistry, Center for Retroviral Research and Center for RNA Biology, Ohio State University, Columbus, OH 43210, USA
| | - Mark C. Williams
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Wei-Shau Hu
- Viral Recombination Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, 21702, USA
| | - Vinay K. Pathak
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, 21702, USA
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12
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Han Z, Hayes OG, Partridge BE, Huang C, Mirkin CA. Reversible strain-promoted DNA polymerization. SCIENCE ADVANCES 2024; 10:eado8020. [PMID: 38657068 PMCID: PMC11042731 DOI: 10.1126/sciadv.ado8020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 03/20/2024] [Indexed: 04/26/2024]
Abstract
Molecular strain can be introduced to influence the outcome of chemical reactions. Once a thermodynamic product is formed, however, reversing the course of a strain-promoted reaction is challenging. Here, a reversible, strain-promoted polymerization in cyclic DNA is reported. The use of nonhybridizing, single-stranded spacers as short as a single nucleotide in length can promote DNA cyclization. Molecular strain is generated by duplexing the spacers, leading to ring opening and subsequent polymerization. Then, removal of the strain-generating duplexers triggers depolymerization and cyclic dimer recovery via enthalpy-driven cyclization and entropy-mediated ring contraction. This reversibility is retained even when a protein is conjugated to the DNA strands, and the architecture of the protein assemblies can be modulated between bivalent and polyvalent states. This work underscores the utility of using DNA not only as a programmable ligand for assembly but also as a route to access restorable bonds, thus providing a molecular basis for DNA-based materials with shape-memory, self-healing, and stimuli-responsive properties.
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Affiliation(s)
- Zhenyu Han
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Oliver G. Hayes
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Benjamin E. Partridge
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Chi Huang
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
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13
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Wang S, Han Z, Strick TR. Single-molecule characterization of Sen1 translocation properties provides insights into eukaryotic factor-dependent transcription termination. Nucleic Acids Res 2024; 52:3249-3261. [PMID: 38261990 PMCID: PMC11013386 DOI: 10.1093/nar/gkae026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 01/02/2024] [Accepted: 01/04/2024] [Indexed: 01/25/2024] Open
Abstract
Sen1 is an essential helicase for factor-dependent transcription termination in Saccharomyces cerevisiae, whose molecular-motor mechanism has not been well addressed. Here, we use single-molecule experimentation to better understand the molecular-motor determinants of its action on RNA polymerase II (Pol II) complex. We quantify Sen1 translocation activity on single-stranded DNA (ssDNA), finding elevated translocation rates, high levels of processivity and ATP affinities. Upon deleting the N- and C-terminal domains, or further deleting different parts of the prong subdomain, which is an essential element for transcription termination, Sen1 displays changes in its translocation properties, such as slightly reduced translocation processivities, enhanced translocation rates and statistically identical ATP affinities. Although these parameters fulfil the requirements for Sen1 translocating along the RNA transcript to catch up with a stalled Pol II complex, we observe significant reductions in the termination efficiencies as well as the factions of the formation of the previously described topological intermediate prior to termination, suggesting that the prong may preserve an interaction with Pol II complex during factor-dependent termination. Our results underscore a more detailed rho-like mechanism of Sen1 and a critical interaction between Sen1 and Pol II complex for factor-dependent transcription termination in eukaryotes.
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Affiliation(s)
- Shuang Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190 Beijing, China
- Songshan Lake Materials Laboratory, 523808 Dongguan, Guangdong, China
- Molecular Motors and Machines group, Ecole normale supérieure, Institut de Biologie de l’Ecole normale supérieure (IBENS), CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Zhong Han
- Metabolism and Function of RNA in the Nucleus, Institut Jacques Monod, CNRS, University Paris Diderot, Sorbonne Paris Cité F-75205 Paris, France
| | - Terence R Strick
- Molecular Motors and Machines group, Ecole normale supérieure, Institut de Biologie de l’Ecole normale supérieure (IBENS), CNRS, INSERM, PSL Research University, 75005 Paris, France
- Programme Equipe Labellisées, Ligue Contre le Cancer, 75013 Paris, France
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14
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Meroni A, Wells SE, Fonseca C, Ray Chaudhuri A, Caldecott KW, Vindigni A. DNA combing versus DNA spreading and the separation of sister chromatids. J Cell Biol 2024; 223:e202305082. [PMID: 38315097 PMCID: PMC10840220 DOI: 10.1083/jcb.202305082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 12/01/2023] [Accepted: 01/22/2024] [Indexed: 02/07/2024] Open
Abstract
DNA combing and DNA spreading are two central approaches for studying DNA replication fork dynamics genome-wide at single-molecule resolution by distributing labeled genomic DNA on coverslips or slides for immunodetection. Perturbations in DNA replication fork dynamics can differentially affect either leading or lagging strand synthesis, for example, in instances where replication is blocked by a lesion or obstacle on only one of the two strands. Thus, we sought to investigate whether the DNA combing and/or spreading approaches are suitable for resolving adjacent sister chromatids during DNA replication, thereby enabling the detection of DNA replication dynamics within individual nascent strands. To this end, we developed a thymidine labeling scheme that discriminates between these two possibilities. Our data suggests that DNA combing resolves sister chromatids, allowing the detection of strand-specific alterations, whereas DNA spreading typically does not. These findings have important implications when interpreting DNA replication dynamics from data obtained by these two commonly used techniques.
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Affiliation(s)
- Alice Meroni
- Division of Oncology, Department of Medicine, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Sophie E. Wells
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer Brighton, UK
| | - Carmen Fonseca
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Arnab Ray Chaudhuri
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Keith W. Caldecott
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer Brighton, UK
| | - Alessandro Vindigni
- Division of Oncology, Department of Medicine, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
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15
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Shepherd JW, Guilbaud S, Zhou Z, Howard JAL, Burman M, Schaefer C, Kerrigan A, Steele-King C, Noy A, Leake MC. Correlating fluorescence microscopy, optical and magnetic tweezers to study single chiral biopolymers such as DNA. Nat Commun 2024; 15:2748. [PMID: 38553446 PMCID: PMC10980717 DOI: 10.1038/s41467-024-47126-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 03/21/2024] [Indexed: 04/02/2024] Open
Abstract
Biopolymer topology is critical for determining interactions inside cell environments, exemplified by DNA where its response to mechanical perturbation is as important as biochemical properties to its cellular roles. The dynamic structures of chiral biopolymers exhibit complex dependence with extension and torsion, however the physical mechanisms underpinning the emergence of structural motifs upon physiological twisting and stretching are poorly understood due to technological limitations in correlating force, torque and spatial localization information. We present COMBI-Tweez (Combined Optical and Magnetic BIomolecule TWEEZers), a transformative tool that overcomes these challenges by integrating optical trapping, time-resolved electromagnetic tweezers, and fluorescence microscopy, demonstrated on single DNA molecules, that can controllably form and visualise higher order structural motifs including plectonemes. This technology combined with cutting-edge MD simulations provides quantitative insight into complex dynamic structures relevant to DNA cellular processes and can be adapted to study a range of filamentous biopolymers.
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Affiliation(s)
- Jack W Shepherd
- School of Physics, Engineering and Technology, University of York, York, YO10 5DD, England
- Department of Biology, University of York, York, YO10 5DD, England
| | - Sebastien Guilbaud
- School of Physics, Engineering and Technology, University of York, York, YO10 5DD, England
| | - Zhaokun Zhou
- Guangdong Provincial Key Lab of Robotics and Intelligent System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Jamieson A L Howard
- School of Physics, Engineering and Technology, University of York, York, YO10 5DD, England
| | - Matthew Burman
- School of Physics, Engineering and Technology, University of York, York, YO10 5DD, England
| | - Charley Schaefer
- School of Physics, Engineering and Technology, University of York, York, YO10 5DD, England
| | - Adam Kerrigan
- The York-JEOL Nanocentre, University of York, York, YO10 5BR, England
| | - Clare Steele-King
- Bioscience Technology Facility, University of York, York, YO10 5DD, England
| | - Agnes Noy
- School of Physics, Engineering and Technology, University of York, York, YO10 5DD, England
| | - Mark C Leake
- School of Physics, Engineering and Technology, University of York, York, YO10 5DD, England.
- Department of Biology, University of York, York, YO10 5DD, England.
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16
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Jo MH, Meneses P, Yang O, Carcamo CC, Pangeni S, Ha T. Determination of single-molecule loading rate during mechanotransduction in cell adhesion. Science 2024; 383:1374-1379. [PMID: 38513010 PMCID: PMC10977658 DOI: 10.1126/science.adk6921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 02/19/2024] [Indexed: 03/23/2024]
Abstract
Cells connect with their environment through surface receptors and use physical tension in receptor-ligand bonds for various cellular processes. Single-molecule techniques have revealed bond strength by measuring "rupture force," but it has long been recognized that rupture force is dependent on loading rate-how quickly force is ramped up. Thus, the physiological loading rate needs to be measured to reveal the mechanical strength of individual bonds in their functional context. We have developed an overstretching tension sensor (OTS) to allow more accurate force measurement in physiological conditions with single-molecule detection sensitivity even in mechanically active regions. We used serially connected OTSs to show that the integrin loading rate ranged from 0.5 to 4 piconewtons per second and was about three times higher in leukocytes than in epithelial cells.
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Affiliation(s)
- Myung Hyun Jo
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Paul Meneses
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Olivia Yang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Claudia C. Carcamo
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Sushil Pangeni
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Taekjip Ha
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21205, USA
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17
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Pangeni S, Biswas G, Kaushik V, Kuppa S, Yang O, Lin CT, Mishra G, Levy Y, Antony E, Ha T. Rapid Long-distance Migration of RPA on Single Stranded DNA Occurs Through Intersegmental Transfer Utilizing Multivalent Interactions. J Mol Biol 2024; 436:168491. [PMID: 38360091 PMCID: PMC10949852 DOI: 10.1016/j.jmb.2024.168491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/04/2024] [Accepted: 02/08/2024] [Indexed: 02/17/2024]
Abstract
Replication Protein A (RPA) is asingle strandedDNA(ssDNA)binding protein that coordinates diverse DNA metabolic processes including DNA replication, repair, and recombination. RPA is a heterotrimeric protein with six functional oligosaccharide/oligonucleotide (OB) domains and flexible linkers. Flexibility enables RPA to adopt multiple configurations andis thought to modulate its function. Here, usingsingle moleculeconfocal fluorescencemicroscopy combinedwith optical tweezers and coarse-grained molecular dynamics simulations, we investigated the diffusional migration of single RPA molecules on ssDNA undertension.The diffusioncoefficientDis the highest (20,000nucleotides2/s) at 3pNtension and in 100 mMKCl and markedly decreases whentensionor salt concentrationincreases. We attribute the tension effect to intersegmental transfer which is hindered by DNA stretching and the salt effect to an increase in binding site size and interaction energy of RPA-ssDNA. Our integrative study allowed us to estimate the size and frequency of intersegmental transfer events that occur through transient bridging of distant sites on DNA by multiple binding sites on RPA. Interestingly, deletion of RPA trimeric core still allowed significant ssDNA binding although the reduced contact area made RPA 15-fold more mobile. Finally, we characterized the effect of RPA crowding on RPA migration. These findings reveal how the high affinity RPA-ssDNA interactions are remodeled to yield access, a key step in several DNA metabolic processes.
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Affiliation(s)
- Sushil Pangeni
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Gargi Biswas
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Vikas Kaushik
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO, USA
| | - Sahiti Kuppa
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO, USA
| | - Olivia Yang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Chang-Ting Lin
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Garima Mishra
- Department of Physics, Ashoka University, Sonepet, Haryana, India
| | - Yaakov Levy
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Edwin Antony
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO, USA.
| | - Taekjip Ha
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA; Department of Pediatrics, Harvard Medical School, Boston, MA, USA; Howard Hughes Medical Institute, Boston, MA, USA.
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18
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Sandoghdar V. Essay: Exploring the Physics of Basic Medical Research. PHYSICAL REVIEW LETTERS 2024; 132:090001. [PMID: 38489629 DOI: 10.1103/physrevlett.132.090001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Indexed: 03/17/2024]
Abstract
The 20th century witnessed the emergence of many paradigm-shifting technologies from the physics community, which have revolutionized medical diagnostics and patient care. However, fundamental medical research has been mostly guided by methods from areas such as cell biology, biochemistry, and genetics, with fairly small contributions from physicists. In this Essay, I outline some key phenomena in the human body that are based on physical principles and yet govern our health over a vast range of length and time scales. I advocate that research in life sciences can greatly benefit from the methodology, know-how, and mindset of the physics community and that the pursuit of basic research in medicine is compatible with the mission of physics. Part of a series of Essays that concisely present author visions for the future of their field.
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Affiliation(s)
- Vahid Sandoghdar
- Max Planck Institute for the Science of Light, Staudtstr. 2, 91058 Erlangen, Germany; Max-Planck-Zentrum für Physik und Medizin, Kußmaulallee 2, 91054 Erlangen, Germany; and Department of Physics, Friedrich-Alexander University Erlangen-Nuremberg, 91058 Erlangen, Germany
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19
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Croquette V, Orero JV, Rieu M, Allemand JF. Magnetic tweezers principles and promises. Methods Enzymol 2024; 694:1-49. [PMID: 38492947 DOI: 10.1016/bs.mie.2024.01.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2024]
Abstract
Magnetic tweezers have become popular with the outbreak of single molecule micromanipulation: catching a single molecule of DNA, RNA or a single protein and applying mechanical constrains using micron-size magnetic beads and magnets turn out to be easy. Various factors have made this possible: the fact that manufacturers have been preparing these beads to catch various biological entities-the ease of use provided by magnets which apply a force or a torque at a distance thus inside a flow cell-some chance: since the forces so generated are in the right range to stretch a single molecule. This is a little less true for torque. Finally, one feature which also appears very important is the simplicity of their calibration using Brownian motion. Here we start by describing magnetic tweezers used routinely in our laboratory where we have tried to develop a device as simple as possible so that the experimentalist can really focus on the biological aspect of the biomolecules that he/she is interested in. We discuss the implications of the various components and their important features. Next, we summarize what is easy to achieve and what is less easy. Then we refer to contributions by other groups who have brought valuable insights to improve magnetic tweezers.
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Affiliation(s)
- Vincent Croquette
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France; ESPCI Paris, Université PSL, Paris, France.
| | - Jessica Valle Orero
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France; The American University of Paris, Paris, France
| | - Martin Rieu
- Department of Physics, New Biochemistry Building, University of Oxford, South Parks Road, Oxford, United Kingdom
| | - Jean-François Allemand
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
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20
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Hu T, Zhang Z, Reches M. A self-standing superhydrophobic material formed by the self-assembly of an individual amino acid. J Colloid Interface Sci 2024; 655:899-908. [PMID: 37979295 DOI: 10.1016/j.jcis.2023.11.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/03/2023] [Accepted: 11/09/2023] [Indexed: 11/20/2023]
Abstract
HYPOTHESIS There is a growing interest in designing superhydrophobic materials for many applications including self-clean surfaces, separation systems, and antifouling solutions. Peptides and amino acids offer attractive building blocks for these materials since they are biocompatible and biodegradable and can self-assemble into complex ordered structures. EXPERIMENTS AND SIMULATIONS We designed a self-standing superhydrophobic material through the self-assembly of an individual functionalized aromatic amino acid, Cbz-Phe(4F). The self-assembly of Cbz-Phe(4F) was investigated by experimental and computational methods. Moreover, when drop-casted three times on a solid support, it formed a self-standing superhydrophobic material. The mechanical properties and chemical stability of this self-standing superhydrophobic material were demonstrated. FINDINGS The designed Cbz-Phe(4F) self-assembled into fibrous structures in solution. Molecular dynamics (MD) simulations revealed that the fibrous backbone of Cbz-Phe(4F) aggregations was stabilized through hydrogen bonds, whereas the isotropic growth of the aggregates was driven by hydrophobic interactions. Importantly, when drop-casted three times on a solid support, it formed a self-standing superhydrophobic material. Moreover, this material had a high mechanical strength, with a Young's modulus of 53 GPa, resistance to enzymatic degradation, and thermal stability up to 200 ℃. This study provides a simple strategy to generate smart and functional materials by the simple self-assembly of functional individual amino acids.
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Affiliation(s)
- Tan Hu
- Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Zhuo Zhang
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Environment Correlative Dietology (Huazhong Agricultural University), Ministry of Education, Wuhan 430070, China.
| | - Meital Reches
- Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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21
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Yu M, Jiang C, Lai B, Zhang K. Exploring Novel Sensor Design Ideas through Concentration-Induced Conformational Changes in PEG Single Chains. SENSORS (BASEL, SWITZERLAND) 2024; 24:883. [PMID: 38339600 PMCID: PMC10856974 DOI: 10.3390/s24030883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 01/16/2024] [Accepted: 01/24/2024] [Indexed: 02/12/2024]
Abstract
Polyethylene glycol (PEG) is an artificial polymer with good biocompatibility and a low cost, which has a wide range of applications. In this study, the dynamic response of PEG single chains to different ion concentrations was investigated from a microscopic point of view based on single-molecule force spectroscopy, revealing unique interactions that go beyond the traditional sensor-design paradigm. Under low concentrations of potassium chloride, PEG single chains exhibit a gradual reduction in rigidity, while, conversely, high concentrations induce a progressive increase in rigidity. This dichotomy serves as the cornerstone for a profound understanding of PEG conformational dynamics under diverse ion environments. Capitalizing on the remarkable sensitivity of PEG single chains to ion concentration shifts, we introduce innovative sensor-design ideas. Rooted in the adaptive nature of PEG single chains, these sensor designs extend beyond the traditional applications, promising advancements in environmental monitoring, healthcare, and materials science.
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Affiliation(s)
- Miao Yu
- School of Mechanical Engineering, Sichuan University, Chengdu 610065, China; (M.Y.); (C.J.); (B.L.)
- Yibin Industrial Technology Research Institute, Sichuan University, Yibin 644000, China
| | - Chong Jiang
- School of Mechanical Engineering, Sichuan University, Chengdu 610065, China; (M.Y.); (C.J.); (B.L.)
- Yibin Industrial Technology Research Institute, Sichuan University, Yibin 644000, China
| | - Bing Lai
- School of Mechanical Engineering, Sichuan University, Chengdu 610065, China; (M.Y.); (C.J.); (B.L.)
- Yibin Industrial Technology Research Institute, Sichuan University, Yibin 644000, China
| | - Kai Zhang
- School of Mechanical Engineering, Sichuan University, Chengdu 610065, China; (M.Y.); (C.J.); (B.L.)
- Yibin Industrial Technology Research Institute, Sichuan University, Yibin 644000, China
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22
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Jung J, Kim S, Rah SH, Lee J, Shon MJ. Force-fluorescence setup for observing protein-DNA interactions under load. Methods Enzymol 2024; 694:137-165. [PMID: 38492949 DOI: 10.1016/bs.mie.2024.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2024]
Abstract
This chapter explores advanced single-molecule techniques for studying protein-DNA interactions, particularly focusing on Replication Protein A (RPA) using a force-fluorescence setup. It combines magnetic tweezers (MT) with total internal reflection fluorescence (TIRF) microscopy, enabling detailed observation of DNA behavior under mechanical stress. The chapter details the use of DNA hairpins and bare DNA to examine RPA's binding dynamics and its influence on DNA's mechanical properties. This approach provides deeper insights into RPA's role in DNA replication, repair, and recombination, highlighting its significance in maintaining genomic stability.
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Affiliation(s)
- Jaehun Jung
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Subin Kim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Sang-Hyun Rah
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Jayil Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea; Institute of Basic Science Center for Genomic Integrity, Ulsan, Republic of Korea
| | - Min Ju Shon
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea; School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea.
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23
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Horst M, Meisner J, Yang J, Kouznetsova TB, Craig SL, Martínez TJ, Xia Y. Mechanochemistry of Pterodactylane. J Am Chem Soc 2024; 146:884-891. [PMID: 38131266 DOI: 10.1021/jacs.3c11293] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Pterodactylane is a [4]-ladderane with substituents on the central rung. Comparing the mechanochemistry of the [4]-ladderane structure when pulled from the central rung versus the end rung revealed a striking difference in the threshold force of mechanoactivation: the threshold force is dramatically lowered from 1.9 nN when pulled on the end rung to 0.7 nN when pulled on the central rung. We investigated the bicyclic products formed from the mechanochemical activation of pterodactylane experimentally and computationally, which are distinct from the mechanochemical products of ladderanes being activated from the end rung. We compared the products of pterodactylane's mechanochemical and thermal activation to reveal differences and similarities in the mechanochemical and thermal pathways of pterodactylane transformation. Interestingly, we also discovered the presence of elementary steps that are accelerated or suppressed by force within the same mechanochemical reaction of pterodactylane, suggesting rich mechanochemical manifolds of multicyclic structures. We rationalized the greatly enhanced mechanochemical reactivity of the central rung of pterodactylane and discovered force-free ground state bond length to be a good low-cost predictor of the threshold force for cyclobutane-based mechanophores. These findings advance our understanding of mechanochemical reactivities and pathways, and they will guide future designs of mechanophores with low threshold forces to facilitate their applications in force-responsive materials.
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Affiliation(s)
- Matías Horst
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jan Meisner
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Institute for Physical Chemistry, Department of Chemistry, Heinrich-Heine-Universität Düsseldorf, Düsseldorf D-40225, Germany
| | - Jinghui Yang
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Tatiana B Kouznetsova
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Todd J Martínez
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Yan Xia
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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24
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Sun H, Le S, Guo Z, Chen H. Exploring the free energy landscape of proteins using magnetic tweezers. Methods Enzymol 2024; 694:237-261. [PMID: 38492953 DOI: 10.1016/bs.mie.2023.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2024]
Abstract
Proteins fold to their native states by searching through the free energy landscapes. As single-domain proteins are the basic building block of multiple-domain proteins or protein complexes composed of subunits, the free energy landscapes of single-domain proteins are of critical importance to understand the folding and unfolding processes of proteins. To explore the free energy landscapes of proteins over large conformational space, the stability of native structure is perturbed by biochemical or mechanical means, and the conformational transition process is measured. In single molecular manipulation experiments, stretching force is applied to proteins, and the folding and unfolding transitions are recorded by the extension time course. Due to the broad force range and long-time stability of magnetic tweezers, the free energy landscape over large conformational space can be obtained. In this article, we describe the magnetic tweezers instrument design, protein construct design and preparation, fluid chamber preparation, common-used measuring protocols including force-ramp and force-jump measurements, and data analysis methods to construct the free energy landscape. Single-domain cold shock protein is introduced as an example to build its free energy landscape by magnetic tweezers measurements.
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Affiliation(s)
- Hao Sun
- Center of Biomedical Physics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, P.R. China
| | - Shimin Le
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, P.R. China
| | - Zilong Guo
- Center of Biomedical Physics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, P.R. China.
| | - Hu Chen
- Center of Biomedical Physics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, P.R. China; Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Xiamen University, Xiamen, P.R. China.
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25
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McCauley MJ, Joshi J, Becker N, Hu Q, Botuyan MV, Rouzina I, Mer G, James Maher L, Williams MC. Quantifying ATP-Independent Nucleosome Chaperone Activity with Single-Molecule Methods. Methods Mol Biol 2024; 2694:29-55. [PMID: 37823998 DOI: 10.1007/978-1-0716-3377-9_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
The dynamics of histone-DNA interactions govern chromosome organization and regulates the processes of transcription, replication, and repair. Accurate measurements of the energies and the kinetics of DNA binding to component histones of the nucleosome under a variety of conditions are essential to understand these processes at the molecular level. To accomplish this, we employ three specific single-molecule techniques: force disruption (FD) with optical tweezers, confocal imaging (CI) in a combined fluorescence plus optical trap, and survival probability (SP) measurements of disrupted and reformed nucleosomes. Short arrays of positioned nucleosomes serve as a template for study, facilitating rapid quantification of kinetic parameters. These arrays are then exposed to FACT (FAcilitates Chromatin Transcription), a non-ATP-driven heterodimeric nuclear chaperone known to both disrupt and tether histones during transcription. FACT binding drives off the outer wrap of DNA and destabilizes the histone-DNA interactions of the inner wrap as well. This reorganization is driven by two key domains with distinct function. FD experiments show the SPT16 MD domain stabilizes DNA-histone contacts, while the HMGB box of SSRP1 binds DNA, destabilizing the nucleosome. Surprisingly, CI experiments do not show tethering of disrupted histones, but increased rates of histone release from the DNA. SI experiments resolve this, showing that the two active domains of FACT combine to chaperone nucleosome reassembly after the timely release of force. These combinations of single-molecule approaches show FACT is a true nucleosome catalyst, lowering the barrier to both disruption and reformation.
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Affiliation(s)
| | - Joha Joshi
- Department of Physics, Northeastern University, Boston, MA, USA
| | - Nicole Becker
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - Qi Hu
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - Maria Victoria Botuyan
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - Ioulia Rouzina
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, USA
| | - Georges Mer
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - L James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - Mark C Williams
- Department of Physics, Northeastern University, Boston, MA, USA.
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26
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Brouwer TB, Kaczmarczyk A, Zarguit I, Pham C, Dame RT, van Noort J. Unravelling DNA Organization with Single-Molecule Force Spectroscopy Using Magnetic Tweezers. Methods Mol Biol 2024; 2819:535-572. [PMID: 39028523 DOI: 10.1007/978-1-0716-3930-6_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Genomes carry the genetic blueprint of all living organisms. Their organization requires strong condensation as well as carefully regulated accessibility to specific genes for proper functioning of their hosts. The study of the structure and dynamics of the proteins that organize the genome has benefited tremendously from the development of single-molecule force spectroscopy techniques that allow for real-time, nanometer accuracy measurements of the compaction of DNA and manipulation with pico-Newton scale forces. Magnetic tweezers, in particular, have the unique ability to complement such force spectroscopy with the control over the linking number of the DNA molecule, which plays an important role when DNA-organizing proteins form or release wraps, loops, and bends in DNA. Here, we describe all the necessary steps to prepare DNA substrates for magnetic tweezers experiments, assemble flow cells, tether DNA to a magnetic bead inside a flow cell, and manipulate and record the extension of such DNA tethers. Furthermore, we explain how mechanical parameters of nucleoprotein filaments can be extracted from the data.
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Affiliation(s)
- Thomas B Brouwer
- Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - Artur Kaczmarczyk
- Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - Ilias Zarguit
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Chi Pham
- Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - Remus T Dame
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
- Centre for Interdisciplinary Genome Research, Leiden University, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - John van Noort
- Leiden Institute of Physics, Leiden University, Leiden, The Netherlands.
- Centre for Interdisciplinary Genome Research, Leiden University, Leiden, The Netherlands.
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27
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Malinowska AM, van Mameren J, Peterman EJG, Wuite GJL, Heller I. Introduction to Optical Tweezers: Background, System Designs, and Applications. Methods Mol Biol 2024; 2694:3-28. [PMID: 37823997 DOI: 10.1007/978-1-0716-3377-9_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Optical tweezers are a means to manipulate objects with light. With the technique, microscopically small objects can be held and steered, allowing for accurate measurement of the forces applied to these objects. Optical tweezers can typically obtain a nanometer spatial resolution, a picoNewton force resolution, and a millisecond time resolution, which makes the technique well suited for the study of biological processes from the single-cell down to the single-molecule level. In this chapter, we aim to provide an introduction to the use of optical tweezers for single-molecule analyses. We start from the basic principles and methodology involved in optical trapping, force calibration, and force measurements. Next, we describe the components of an optical tweezers setup and their experimental relevance. Finally, we will provide an overview of the broad applications in context of biological research, with the emphasis on the measurement modes, experimental assays, and possible combinations with fluorescence microscopy techniques.
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Affiliation(s)
- Agata M Malinowska
- LaserLaB Amsterdam and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Joost van Mameren
- Institute of Physics, University of Amsterdam, Amsterdam, The Netherlands
| | - Erwin J G Peterman
- LaserLaB Amsterdam and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Gijs J L Wuite
- LaserLaB Amsterdam and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Iddo Heller
- LaserLaB Amsterdam and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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28
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Richeldi M, Pobegalov G, Higashi TL, Gmurczyk K, Uhlmann F, Molodtsov MI. Mechanical disengagement of the cohesin ring. Nat Struct Mol Biol 2024; 31:23-31. [PMID: 37872232 DOI: 10.1038/s41594-023-01122-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 09/11/2023] [Indexed: 10/25/2023]
Abstract
Cohesin forms a proteinaceous ring that is thought to link sister chromatids by entrapping DNA and counteracting the forces generated by the mitotic spindle. Whether individual cohesins encircle both sister DNAs and how cohesin opposes spindle-generated forces remains unknown. Here we perform force measurements on individual yeast cohesin complexes either bound to DNA or holding together two DNAs. By covalently closing the hinge and Smc3Psm3-kleisin interfaces we find that the mechanical stability of the cohesin ring entrapping DNA is determined by the hinge domain. Forces of ~20 pN disengage cohesin at the hinge and release DNA, indicating that ~40 cohesin molecules are sufficient to counteract known spindle forces. Our findings provide a mechanical framework for understanding how cohesin interacts with sister chromatids and opposes the spindle-generated tension during mitosis, with implications for other force-generating chromosomal processes including transcription and DNA replication.
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Affiliation(s)
- Martina Richeldi
- Biophysics and Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Chromosome Segregation Laboratory, The Francis Crick Institute, London, UK
- Department of Physics and Astronomy, University College London, London, UK
| | - Georgii Pobegalov
- Biophysics and Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics and Astronomy, University College London, London, UK
| | - Torahiko L Higashi
- Chromosome Segregation Laboratory, The Francis Crick Institute, London, UK
- Kamakura Research Laboratories, Chugai Pharmaceutical Co., Kamakura City, Japan
| | - Karolina Gmurczyk
- Chromosome Segregation Laboratory, The Francis Crick Institute, London, UK
| | - Frank Uhlmann
- Chromosome Segregation Laboratory, The Francis Crick Institute, London, UK.
| | - Maxim I Molodtsov
- Biophysics and Mechanobiology Laboratory, The Francis Crick Institute, London, UK.
- Department of Physics and Astronomy, University College London, London, UK.
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29
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Kramm K, Schröder T, Vera AM, Grabenhorst L, Tinnefeld P, Grohmann D. DNA Origami-Based Single-Molecule Force Spectroscopy and Applications. Methods Mol Biol 2024; 2694:479-507. [PMID: 37824019 DOI: 10.1007/978-1-0716-3377-9_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Over the last years, single-molecule force spectroscopy provided insights into the intricate connection between mechanical stimuli and biochemical signaling. The underlying molecular mechanisms were uncovered and explored using techniques such as atomic force microscopy and force spectroscopy using optical or magnetic tweezers. These experimental approaches are limited by thermal noise resulting from a physical connection of the studied biological system to the macroscopic world. To overcome this limitation, we recently introduced the DNA origami force clamp (FC) which is a freely diffusing nanodevice that generates piconewton forces on a DNA sequence of interest. Binding of a protein to the DNA under tension can be detected employing fluorescence resonance energy transfer (FRET) as a sensitive readout.This protocol introduces the reader to the working principles of the FC and provides instructions to design and generate a DNA origami FC customized for a protein of interest. Molecular cloning techniques are employed to modify, produce, and purify a custom DNA scaffold. A fluorescently labeled DNA suitable to detect protein binding via FRET is generated via enzymatic ligation of commercial DNA oligonucleotides. After thermal annealing of all components, the DNA origami FC is purified using agarose gel electrophoresis. The final section covers the interrogation of the FC using confocal single-molecule FRET measurements and subsequent data analysis to quantify the binding of a DNA-binding protein to its cognate recognition site under a range of forces. Using this approach, force-dependent DNA-protein interactions can be studied on the single-molecule level on thousands of molecules in a parallelized fashion.
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Affiliation(s)
- Kevin Kramm
- University of Regensburg, Department of Microbiology and Archaea Centre, Regensburg, Germany
| | - Tim Schröder
- Ludwig-Maximilians-Universität München, Department of Chemistry and Center for NanoScience (CeNS), Munich, Germany
| | - Andrés Manuel Vera
- Ludwig-Maximilians-Universität München, Department of Chemistry and Center for NanoScience (CeNS), Munich, Germany
| | - Lennart Grabenhorst
- Ludwig-Maximilians-Universität München, Department of Chemistry and Center for NanoScience (CeNS), Munich, Germany
| | - Philip Tinnefeld
- Ludwig-Maximilians-Universität München, Department of Chemistry and Center for NanoScience (CeNS), Munich, Germany
| | - Dina Grohmann
- University of Regensburg, Department of Microbiology and Archaea Centre, Regensburg, Germany.
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30
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Deng B, Wang S, Hartquist C, Zhao X. Nonlocal Intrinsic Fracture Energy of Polymerlike Networks. PHYSICAL REVIEW LETTERS 2023; 131:228102. [PMID: 38101371 DOI: 10.1103/physrevlett.131.228102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 09/28/2023] [Indexed: 12/17/2023]
Abstract
Connecting polymer network fracture to molecular-level chain scission remains a quandary. While the Lake-Thomas model predicts the intrinsic fracture energy of a polymer network is the energy to rupture a layer of chains, it underestimates recent experiments by ∼1-2 orders of magnitude. Here we show that the intrinsic fracture energy of polymerlike networks stems from nonlocal energy dissipation by relaxing chains far from the crack tip using experiments and simulations of 2D and 3D networks with varying defects, dispersity, topologies, and length scales. Our findings not only provide physical insights into polymer network fracture but offer design principles for tough architected materials.
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Affiliation(s)
- Bolei Deng
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Shu Wang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Chase Hartquist
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Xuanhe Zhao
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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31
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Scalvini B, Heling LWHJ, Sheikhhassani V, Sunderlikova V, Tans SJ, Mashaghi A. Cytosolic Interactome Protects Against Protein Unfolding in a Single Molecule Experiment. Adv Biol (Weinh) 2023; 7:e2300105. [PMID: 37409427 DOI: 10.1002/adbi.202300105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/13/2023] [Indexed: 07/07/2023]
Abstract
Single molecule techniques are particularly well suited for investigating the processes of protein folding and chaperone assistance. However, current assays provide only a limited perspective on the various ways in which the cellular environment can influence the folding pathway of a protein. In this study, a single molecule mechanical interrogation assay is developed and used to monitor protein unfolding and refolding within a cytosolic solution. This allows to test the cumulative topological effect of the cytoplasmic interactome on the folding process. The results reveal a stabilization against forced unfolding for partial folds, which are attributed to the protective effect of the cytoplasmic environment against unfolding and aggregation. This research opens the possibility of conducting single molecule molecular folding experiments in quasi-biological environments.
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Affiliation(s)
- Barbara Scalvini
- Medical Systems Biophysics and Bioengineering, Leiden Academic Centre for Drug Research, Faculty of Science, Leiden University, Einsteinweg 55, Leiden, 2333CC, The Netherlands
- Centre for Interdisciplinary Genome Research, Faculty of Science, Leiden University, Einsteinweg 55, Leiden, 2333CC, The Netherlands
| | - Laurens W H J Heling
- Medical Systems Biophysics and Bioengineering, Leiden Academic Centre for Drug Research, Faculty of Science, Leiden University, Einsteinweg 55, Leiden, 2333CC, The Netherlands
- Centre for Interdisciplinary Genome Research, Faculty of Science, Leiden University, Einsteinweg 55, Leiden, 2333CC, The Netherlands
| | - Vahid Sheikhhassani
- Medical Systems Biophysics and Bioengineering, Leiden Academic Centre for Drug Research, Faculty of Science, Leiden University, Einsteinweg 55, Leiden, 2333CC, The Netherlands
- Centre for Interdisciplinary Genome Research, Faculty of Science, Leiden University, Einsteinweg 55, Leiden, 2333CC, The Netherlands
| | | | - Sander J Tans
- AMOLF, Science Park 104, Amsterdam, 1098 XG, The Netherlands
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, Delft, 2629HZ, The Netherlands
| | - Alireza Mashaghi
- Medical Systems Biophysics and Bioengineering, Leiden Academic Centre for Drug Research, Faculty of Science, Leiden University, Einsteinweg 55, Leiden, 2333CC, The Netherlands
- Centre for Interdisciplinary Genome Research, Faculty of Science, Leiden University, Einsteinweg 55, Leiden, 2333CC, The Netherlands
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32
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Buche MR, Rimsza JM. Modeling single-molecule stretching experiments using statistical thermodynamics. Phys Rev E 2023; 108:064503. [PMID: 38243517 DOI: 10.1103/physreve.108.064503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 11/30/2023] [Indexed: 01/21/2024]
Abstract
Single-molecule stretching experiments are widely utilized within the fields of physics and chemistry to characterize the mechanics of individual bonds or molecules, as well as chemical reactions. Analytic relations describing these experiments are valuable, and these relations can be obtained through the statistical thermodynamics of idealized model systems representing the experiments. Since the specific thermodynamic ensembles manifested by the experiments affect the outcome, primarily for small molecules, the stretching device must be included in the idealized model system. Though the model for the stretched molecule might be exactly solvable, including the device in the model often prevents analytic solutions. In the limit of large or small device stiffness, the isometric or isotensional ensembles can provide effective approximations, but the device effects are missing. Here a dual set of asymptotically correct statistical thermodynamic theories are applied to develop accurate approximations for the full model system that includes both the molecule and the device. The asymptotic theories are first demonstrated to be accurate using the freely jointed chain model and then using molecular dynamics calculations of a single polyethylene chain.
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Affiliation(s)
- Michael R Buche
- Computational Solid Mechanics and Structural Dynamics, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Jessica M Rimsza
- Geochemistry, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
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33
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Zerbetto M, Saint-Pierre C, Piserchia A, Torrengo S, Gambarelli S, Abergel D, Polimeno A, Gasparutto D, Sicoli G. Intrinsic Flexibility beyond the Highly Ordered DNA Tetrahedron: An Integrative Spectroscopic and Molecular Dynamics Approach. J Phys Chem Lett 2023; 14:10032-10038. [PMID: 37906734 DOI: 10.1021/acs.jpclett.3c02383] [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: 11/02/2023]
Abstract
Since the introduction of DNA-based architectures, in the past decade, DNA tetrahedrons have aroused great interest. Applications of such nanostructures require structural control, especially in the perspective of their possible functionalities. In this work, an integrated approach for structural characterization of a tetrahedron structure is proposed with a focus on the fundamental biophysical aspects driving the assembly process. To address such an issue, spin-labeled DNA sequences are chemically synthesized, self-assembled, and then analyzed by Continuous-Wave (CW) and pulsed Electron Paramagnetic Resonance (EPR) spectroscopy. Interspin distance measurements based on PELDOR/DEER techniques combined with molecular dynamics (MD) thus revealed unexpected dynamic heterogeneity and flexibility of the assembled structures. The observation of flexibility in these ordered 3D structures demonstrates the sensitivity of this approach and its effectiveness in accessing the main dynamic and structural features with unprecedented resolution.
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Affiliation(s)
- Mirco Zerbetto
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, I-35131 Padova, Italy
| | - Christine Saint-Pierre
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 17 rue des Martyrs, F-38000 Grenoble, France
| | - Andrea Piserchia
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, I-35131 Padova, Italy
| | - Simona Torrengo
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 17 rue des Martyrs, F-38000 Grenoble, France
| | - Serge Gambarelli
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 17 rue des Martyrs, F-38000 Grenoble, France
| | - Daniel Abergel
- Laboratoire des biomolécules, LBM, Département de chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Antonino Polimeno
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, I-35131 Padova, Italy
| | - Didier Gasparutto
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 17 rue des Martyrs, F-38000 Grenoble, France
| | - Giuseppe Sicoli
- CNRS UMRS 8516, LASIRE, University of Lille, Avenue Paul Langevin - C4 building, F-59655 Villeneuve d'Ascq Cedex, France
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34
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Zou Z, Liang J, Jia Q, Bai D, Xie W, Wu W, Tan C, Ma J. A versatile and high-throughput flow-cell system combined with fluorescence imaging for simultaneous single-molecule force measurement and visualization. NANOSCALE 2023; 15:17443-17454. [PMID: 37859523 DOI: 10.1039/d3nr03214k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
A flow-cell offers many advantages for single-molecule studies. But, its merit as a quantitative single-molecule tool has long been underestimated. In this work, we developed a gas-pumped fully calibrated flow-cell system combined with fluorescence imaging for simultaneous single-molecule force measurement and visualization. Such a flow-cell system has considered the hydrodynamic drags on biomolecules and hence can apply and measure force up to more than 100 pN in sub-pN precision with an ultra-high force stability (force drift <0.01 pN in 10 minutes) and tuning accuracy (∼0.04 pN). Meanwhile, it also allows acquiring force signals and fluorescence images at the same time, parallelly tracking hundreds of protein motors in real time as well as monitoring the conformational changes of biomolecules under a well-controlled force, as demonstrated by a series of single-molecule experiments in this work, including the studies of DNA overstretching dynamics, transcription under force and DNA folding/unfolding dynamics. Interesting findings, such as the very tight association of single-stranded binding (SSB) proteins with ssDNA and the reversed transcription, have also been made. These results together lay down an essential foundation for a flow-cell to be used as a versatile, quantitative and high-throughput tool for single-molecule manipulation and visualization.
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Affiliation(s)
- Zhenyu Zou
- School of Physics, Sun Yat-sen University, Guangzhou 510275, P.R. China.
- State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, P.R. China
| | - Jialun Liang
- School of Physics, Sun Yat-sen University, Guangzhou 510275, P.R. China.
- State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, P.R. China
| | - Qian Jia
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, P.R. China
| | - Di Bai
- School of Life Sciences, State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475001, P.R. China
| | - Wei Xie
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, 510006, P.R. China
| | - Wenqiang Wu
- School of Life Sciences, State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475001, P.R. China
| | - Chuang Tan
- School of Physics, Sun Yat-sen University, Guangzhou 510275, P.R. China.
- State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, P.R. China
| | - Jie Ma
- School of Physics, Sun Yat-sen University, Guangzhou 510275, P.R. China.
- State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, P.R. China
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35
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Dobrynin AV, Tian Y, Jacobs M, Nikitina EA, Ivanov DA, Maw M, Vashahi F, Sheiko SS. Forensics of polymer networks. NATURE MATERIALS 2023; 22:1394-1400. [PMID: 37749314 DOI: 10.1038/s41563-023-01663-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 08/11/2023] [Indexed: 09/27/2023]
Abstract
Our lives cannot be imagined without polymer networks, which range widely, from synthetic rubber to biological tissues. Their properties-elasticity, strain-stiffening and stretchability-are controlled by a convolution of chemical composition, strand conformation and network topology. Yet, since the discovery of rubber vulcanization by Charles Goodyear in 1839, the internal organization of networks has remained a sealed 'black box'. While many studies show how network properties respond to topology variation, no method currently exists that would allow the decoding of the network structure from its properties. We address this problem by analysing networks' nonlinear responses to deformation to quantify their crosslink density, strand flexibility and fraction of stress-supporting strands. The decoded structural information enables the quality control of network synthesis, comparison of targeted to actual architecture and network classification according to the effectiveness of stress distribution. The developed forensic approach is a vital step in future implementation of artificial intelligence principles for soft matter design.
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Affiliation(s)
- Andrey V Dobrynin
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Yuan Tian
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Michael Jacobs
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - Dimitri A Ivanov
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
- Institut de Sciences des Matériaux de Mulhouse (IS2M), CNRS UMR 7361, Université de Haute-Alsace, Mulhouse, France
| | - Mitchell Maw
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Foad Vashahi
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sergei S Sheiko
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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36
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Sarkar A, Niraula G, LeVine D, Zhao Y, Tu Y, Mollaeian K, Ren J, Que L, Wang X. Development of a Ratiometric Tension Sensor Exclusively Responding to Integrin Tension Magnitude in Live Cells. ACS Sens 2023; 8:3701-3712. [PMID: 37738233 PMCID: PMC10788086 DOI: 10.1021/acssensors.3c00606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Abstract
Integrin tensions are critical for cell mechanotransduction. By converting force to fluorescence, molecular tension sensors image integrin tensions in live cells with a high resolution. However, the fluorescence signal intensity results collectively from integrin tension magnitude, tension dwell time, integrin density, sensor accessibility, and so forth, making it highly challenging to specifically monitor the molecular force level of integrin tensions. Here, a ratiometric tension sensor (RTS) was developed to exclusively monitor the integrin tension magnitude. The RTS consists of two tension-sensing units that are coupled in series and always subject to the same integrin tension. These two units are activated by tension to fluoresce in separate spectra and with different activation rates. The ratio of their activation probabilities, reported by fluorescence ratiometric measurement, is solely determined by the local integrin tension magnitude. RTS responded sensitively to the variation of integrin tension magnitude in platelets and focal adhesions due to different cell plating times, actomyosin inhibition, or vinculin knockout. At last, RTS confirmed that integrin tension magnitude in platelets and focal adhesions decreases monotonically with the substrate rigidity, verifying the rigidity dependence of integrin tensions in live cells and suggesting that integrin tension magnitude could be a key biomechanical factor in cell rigidity sensing.
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Affiliation(s)
- Anwesha Sarkar
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States
| | - Gopal Niraula
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States
| | - Dana LeVine
- Department of Veterinary Clinical Sciences, Iowa State University, Ames, Iowa 50011, United States
| | - Yuanchang Zhao
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States
| | - Ying Tu
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States
| | - Keyvan Mollaeian
- Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011, United States
| | - Juan Ren
- Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011, United States
| | - Long Que
- Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011, United States
| | - Xuefeng Wang
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States
- Hoxworth Blood Center, College of Medicine, The University of Cincinnati, Cincinnati, Ohio 45219, United States
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Karna D, Mano E, Ji J, Kawamata I, Suzuki Y, Mao H. Chemo-mechanical forces modulate the topology dynamics of mesoscale DNA assemblies. Nat Commun 2023; 14:6459. [PMID: 37833326 PMCID: PMC10575982 DOI: 10.1038/s41467-023-41604-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 09/06/2023] [Indexed: 10/15/2023] Open
Abstract
The intrinsic complexity of many mesoscale (10-100 nm) cellular machineries makes it challenging to elucidate their topological arrangement and transition dynamics. Here, we exploit DNA origami nanospring as a model system to demonstrate that tens of piconewton linear force can modulate higher-order conformation dynamics of mesoscale molecular assemblies. By switching between two chemical structures (i.e., duplex and tetraplex DNA) in the junctions of adjacent origami modules, the corresponding stretching or compressing chemo-mechanical stress reversibly flips the backbone orientations of the DNA nanosprings. Both coarse-grained molecular dynamics simulations and atomic force microscopy measurements reveal that such a backbone conformational switch does not alter the right-handed chirality of the nanospring helix. This result suggests that mesoscale helical handedness may be governed by the torque, rather than the achiral orientation, of nanospring backbones. It offers a topology-based caging/uncaging concept to present chemicals in response to environmental cues in solution.
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Affiliation(s)
- Deepak Karna
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH, 44242, USA
| | - Eriko Mano
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aramaki-aza Aoba, Aoba-ku, Sendai, 980-8578, Japan
| | - Jiahao Ji
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH, 44242, USA
| | - Ibuki Kawamata
- Department of Robotics, Graduate School of Engineering, Tohoku University, 6-6-01 Aramaki-aza Aoba, Aoba-ku, Sendai, 980-8579, Japan.
| | - Yuki Suzuki
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aramaki-aza Aoba, Aoba-ku, Sendai, 980-8578, Japan.
- Department of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurimamachiya-Cho, Tsu, 514-8507, Japan.
| | - Hanbin Mao
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH, 44242, USA.
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38
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Chauhan K, Mishra G, Kishore V, Kumar S. Appearance of de Gennes length in force-induced transitions. Phys Rev E 2023; 108:L042501. [PMID: 37978702 DOI: 10.1103/physreve.108.l042501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 06/12/2023] [Indexed: 11/19/2023]
Abstract
Using Langevin dynamic simulations, a simple coarse-grained model of a DNA protein construct is used to study the DNA rupture and the protein unfolding. We identify three distinct states: (i) zipped DNA and collapsed protein, (ii) unzipped DNA and stretched protein, and (iii) unzipped DNA and collapsed protein. Here, we find a phase diagram that shows these states depending on the size of the DNA handle and the protein. For a less stable protein, unfolding is solely governed by the size of the linker DNA, whereas if the protein's stability increases, complete unfolding becomes impossible because the rupture force for DNA has reached a saturation regime influenced by the de Gennes length. We show that unfolding occurs via a few intermediate states by monitoring the force-extension curve of the entire protein. We extend our study to a heterogeneous protein system, where similar intermediate states in two systems can lead to different protein unfolding paths.
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Affiliation(s)
- Keerti Chauhan
- Department of Physics, Banaras Hindu University, Varanasi 221 005, India
| | - Garima Mishra
- Department of Physics, Ashoka University, Sonipat 131 029, India
| | - Vimal Kishore
- Department of Physics, Banaras Hindu University, Varanasi 221 005, India
| | - Sanjay Kumar
- Department of Physics, Banaras Hindu University, Varanasi 221 005, India
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39
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Mondal S, Banerjee S, Dey D, Lahiri H, Mana T, Jana SS, Mukhopadhyay R. Impact of HMGB1 binding on the structural alterations of platinum drug-treated single dsDNA molecule. Biochimie 2023; 213:168-175. [PMID: 37211256 DOI: 10.1016/j.biochi.2023.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/24/2023] [Accepted: 05/18/2023] [Indexed: 05/23/2023]
Abstract
High mobility group B1 (HMGB1) is an architectural protein that recognizes the DNA damage sites formed by the platinum anticancer drugs. However, the impact of HMGB1 binding on the structural alterations of the platinum drug-treated single dsDNA molecules has remained largely unknown. Herein, the structural alterations induced by the platinum drugs, the mononuclear cisplatin and it's analog the trinuclear BBR3464, have been probed in presence of HMGB1, by atomic force microscopy (AFM) and AFM-based force spectroscopy. It is observed that the drug-induced DNA loop formation enhanced upon HMGB1 binding, most likely as a result of HMGB1-induced increase in DNA conformational flexibility that allowed the drug-binding sites to come close and form double adducts, thereby resulting in enhanced loop formation via inter-helix cross-linking. Since HMGB1 enhances DNA flexibility, the near-reversible structural transitions as observed in the force-extension curves (for 1 h drug treatment), generally occurred at lower forces in presence of HMGB1. The DNA structural integrity was largely lost after 24 h drug treatment as no reversible transition could be observed. The Young's modulus of the dsDNA molecules, as estimated from the force-extension analysis, increased upon drug treatment, due to formation of the drug-induced covalent cross-links and consequent reduction in DNA flexibility. The Young's modulus increased further in presence of HMGB1 due to HMGB1-induced enhancement in DNA flexibility that could ease formation of the drug-induced covalent cross-links. To our knowledge, this is the first report that shows an increase in the stiffness of the platinum drug-treated DNA molecules in presence of HMGB1.
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Affiliation(s)
- Sourav Mondal
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India
| | - Siddhartha Banerjee
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India
| | - Debapriya Dey
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India
| | - Hiya Lahiri
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India
| | - Tanushree Mana
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India
| | - Siddhartha S Jana
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India
| | - Rupa Mukhopadhyay
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India.
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40
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Lu S, Ma Z, Qin L, Ding M, Wang Z, Liu J, Zhang R, Zhang Y, Dong G. Effect of molecular helical structure on self-growing and damping of single network κ-carrageenan hydrogel. Int J Biol Macromol 2023; 249:126082. [PMID: 37536410 DOI: 10.1016/j.ijbiomac.2023.126082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 07/14/2023] [Accepted: 07/29/2023] [Indexed: 08/05/2023]
Abstract
Molecular helical is ubiquitous in molecular structures, however, the impact of the structure on mechanical properties has yet to be extensively studied. In this study, we synthesized a single network κ-carrageenan (KC) hydrogel with the molecular double helix structure, and elucidated its unique self-enhancing and damping properties from a molecular structural perspective. During cycle tensile tests, the helical structure was stretched and entangled to form a directional arrangement, increasing the elastic modulus and achieving 'self-reinforcement'. Meanwhile, the molecular helices have a spring-like damping effect, allowing the hydrogel to dampen low-frequency noise while transmitting high-frequency signals. By utilizing the hydrogel to create electrodes for electrocardiogram (ECG) detection, we were able to effectively filter out noise generated by movements while retaining necessary signals. Our work thus presents a potential pathway bridging from microscopic molecular structure to macroscopic mechanical properties of materials.
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Affiliation(s)
- Shan Lu
- Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Institute of Design Science and Basic Components, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Zeyu Ma
- Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Institute of Design Science and Basic Components, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Liguo Qin
- Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Institute of Design Science and Basic Components, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Mingwei Ding
- Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Institute of Design Science and Basic Components, Xi'an Jiaotong University, Xi'an 710049, China
| | - Zheng Wang
- Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Institute of Design Science and Basic Components, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Jianbo Liu
- Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Institute of Design Science and Basic Components, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Rui Zhang
- Xi'an Microelectronics Technology Institute, Xi'an 710054, China
| | - Yali Zhang
- Key Laboratory of Biomedical Information of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Guangneng Dong
- Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Institute of Design Science and Basic Components, Xi'an Jiaotong University, Xi'an 710049, China.
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41
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Cashen BA, Morse M, Rouzina I, Karpel R, Williams M. Dynamic structure of T4 gene 32 protein filaments facilitates rapid noncooperative protein dissociation. Nucleic Acids Res 2023; 51:8587-8605. [PMID: 37449435 PMCID: PMC10484735 DOI: 10.1093/nar/gkad595] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 06/26/2023] [Accepted: 07/04/2023] [Indexed: 07/18/2023] Open
Abstract
Bacteriophage T4 gene 32 protein (gp32) is a model single-stranded DNA (ssDNA) binding protein, essential for DNA replication. gp32 forms cooperative filaments on ssDNA through interprotein interactions between its core and N-terminus. However, detailed understanding of gp32 filament structure and organization remains incomplete, particularly for longer, biologically-relevant DNA lengths. Moreover, it is unclear how these tightly-bound filaments dissociate from ssDNA during complementary strand synthesis. We use optical tweezers and atomic force microscopy to probe the structure and binding dynamics of gp32 on long (∼8 knt) ssDNA substrates. We find that cooperative binding of gp32 rigidifies ssDNA while also reducing its contour length, consistent with the ssDNA helically winding around the gp32 filament. While measured rates of gp32 binding and dissociation indicate nM binding affinity, at ∼1000-fold higher protein concentrations gp32 continues to bind into and restructure the gp32-ssDNA filament, leading to an increase in its helical pitch and elongation of the substrate. Furthermore, the oversaturated gp32-ssDNA filament becomes progressively unwound and unstable as observed by the appearance of a rapid, noncooperative protein dissociation phase not seen at lower complex saturation, suggesting a possible mechanism for prompt removal of gp32 from the overcrowded ssDNA in front of the polymerase during replication.
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Affiliation(s)
- Ben A Cashen
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Michael Morse
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Ioulia Rouzina
- Department of Chemistry and Biochemistry, Center for Retroviral Research and Center for RNA Biology, Ohio State University, Columbus, OH 43210, USA
| | - Richard L Karpel
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Mark C Williams
- Department of Physics, Northeastern University, Boston, MA 02115, USA
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42
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Gan F, Yang P, Liang J, Shen C, Crassous J, Qiu H. DNA-induced circularly polarized luminescence of helicene racemates. Chirality 2023; 35:569-576. [PMID: 37051766 DOI: 10.1002/chir.23566] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/22/2023] [Accepted: 03/23/2023] [Indexed: 04/14/2023]
Abstract
Enantiopure helicenes have been extensively investigated due to their outstanding chiroptical properties, while helicene racemates are considered as chiroptically silent. Here, we describe a facile method to produce circularly polarized luminescence (CPL) from helicene racemates via supramolecular association with DNA in aqueous solution. Racemic cationic helicene derivatives are immobilized in the grooves of commercially available double-stranded right-handed DNA, and the discrimination of left- and right-handed helicenes by chiral DNA is monitored by single molecule force spectroscopy. This subsequently leads to the generation of prominent CPL with dissymmetric factor |glum | of close to 0.01, which is approximate to enantiopure helicenes. The strategy developed in this work avoids the tedious and expensive chiral resolution process and provides a distinctive insight into the fabrication of CPL-emitting systems.
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Affiliation(s)
- Fuwei Gan
- School of Chemistry and Chemical Engineering, Zhangjiang Institute for Advanced Study, Frontiers Science Center for Transformative Molecules, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Peng Yang
- School of Chemistry and Chemical Engineering, Zhangjiang Institute for Advanced Study, Frontiers Science Center for Transformative Molecules, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Juncong Liang
- School of Chemistry and Chemical Engineering, Zhangjiang Institute for Advanced Study, Frontiers Science Center for Transformative Molecules, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Chengshuo Shen
- School of Chemistry and Chemical Engineering, Zhangjiang Institute for Advanced Study, Frontiers Science Center for Transformative Molecules, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Jeanne Crassous
- Institut des Sciences Chimiques de Rennes, UMR 6226, Campus de Beaulieu, CNRS-Université de Rennes 1, Rennes Cedex, France
| | - Huibin Qiu
- School of Chemistry and Chemical Engineering, Zhangjiang Institute for Advanced Study, Frontiers Science Center for Transformative Molecules, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, People's Republic of China
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43
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Chen C, Luo X, Kaplan AE, Bawendi MG, Macfarlane RJ, Bathe M. Ultrafast dense DNA functionalization of quantum dots and rods for scalable 2D array fabrication with nanoscale precision. SCIENCE ADVANCES 2023; 9:eadh8508. [PMID: 37566651 PMCID: PMC10421044 DOI: 10.1126/sciadv.adh8508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 07/14/2023] [Indexed: 08/13/2023]
Abstract
Scalable fabrication of two-dimensional (2D) arrays of quantum dots (QDs) and quantum rods (QRs) with nanoscale precision is required for numerous device applications. However, self-assembly-based fabrication of such arrays using DNA origami typically suffers from low yield due to inefficient QD and QR DNA functionalization. In addition, it is challenging to organize solution-assembled DNA origami arrays on 2D device substrates while maintaining their structural fidelity. Here, we reduced manufacturing time from a few days to a few minutes by preparing high-density DNA-conjugated QDs/QRs from organic solution using a dehydration and rehydration process. We used a surface-assisted large-scale assembly (SALSA) method to construct 2D origami lattices directly on solid substrates to template QD and QR 2D arrays with orientational control, with overall loading yields exceeding 90%. Our fabrication approach enables the scalable, high fidelity manufacturing of 2D addressable QDs and QRs with nanoscale orientational and spacing control for functional 2D photonic devices.
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Affiliation(s)
- Chi Chen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Xin Luo
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Alexander E. K. Kaplan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Moungi G. Bawendi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert J. Macfarlane
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Mark Bathe
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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44
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Pokhrel P, Jonchhe S, Pan W, Mao H. Single-Molecular Dissection of Liquid-Liquid Phase Transitions. J Am Chem Soc 2023; 145:17143-17150. [PMID: 37494702 PMCID: PMC10528544 DOI: 10.1021/jacs.3c03812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Interaction between peptides and nucleic acids is a ubiquitous process that drives many cellular functions, such as replications, transcriptions, and translations. Recently, this interaction has been found in liquid-liquid phase separation (LLPS), a process responsible for the formation of newly discovered membraneless organelles with a variety of biological functions inside cells. In this work, we studied the molecular interaction between the poly-l-lysine (PLL) peptide and nucleic acids during the early stage of an LLPS process at the single-molecule level using optical tweezers. By monitoring the mechanical tension of individual nucleic acid templates upon PLL addition, we revealed a multistage LLPS process mediated by the long-range interactions between nucleic acids and polyelectrolytes. By varying different types (ssDNA, ssRNA, and dsDNA) and sequences (A-, T-, G-, or U-rich) of nucleic acids, we pieced together transition diagrams of the PLL-nucleic acid condensates from which we concluded that the propensity to form rigid nucleic acid-PLL complexes reduces the condensate formation during the LLPS process. We anticipate that these results are instrumental in understanding the transition mechanism of LLPS condensates, which allows new strategies to interfere with the biological functions of LLPS condensates inside cells.
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Affiliation(s)
- Pravin Pokhrel
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Sagun Jonchhe
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Wei Pan
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Hanbin Mao
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States
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45
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Li R, Madhvacharyula AS, Du Y, Adepu HK, Choi JH. Mechanics of dynamic and deformable DNA nanostructures. Chem Sci 2023; 14:8018-8046. [PMID: 37538812 PMCID: PMC10395309 DOI: 10.1039/d3sc01793a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 07/05/2023] [Indexed: 08/05/2023] Open
Abstract
In DNA nanotechnology, DNA molecules are designed, engineered, and assembled into arbitrary-shaped architectures with predesigned functions. Static DNA assemblies often have delicate designs with structural rigidity to overcome thermal fluctuations. Dynamic structures reconfigure in response to external cues, which have been explored to create functional nanodevices for environmental sensing and other applications. However, the precise control of reconfiguration dynamics has been a challenge due partly to flexible single-stranded DNA connections between moving parts. Deformable structures are special dynamic constructs with deformation on double-stranded parts and single-stranded hinges during transformation. These structures often have better control in programmed deformation. However, related deformability and mechanics including transformation mechanisms are not well understood or documented. In this review, we summarize the development of dynamic and deformable DNA nanostructures from a mechanical perspective. We present deformation mechanisms such as single-stranded DNA hinges with lock-and-release pairs, jack edges, helicity modulation, and external loading. Theoretical and computational models are discussed for understanding their associated deformations and mechanics. We elucidate the pros and cons of each model and recommend design processes based on the models. The design guidelines should be useful for those who have limited knowledge in mechanics as well as expert DNA designers.
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Affiliation(s)
- Ruixin Li
- School of Mechanical Engineering, Purdue University 585 Purdue Mall West Lafayette Indiana 47907 USA
| | - Anirudh S Madhvacharyula
- School of Mechanical Engineering, Purdue University 585 Purdue Mall West Lafayette Indiana 47907 USA
| | - Yancheng Du
- School of Mechanical Engineering, Purdue University 585 Purdue Mall West Lafayette Indiana 47907 USA
| | - Harshith K Adepu
- School of Mechanical Engineering, Purdue University 585 Purdue Mall West Lafayette Indiana 47907 USA
| | - Jong Hyun Choi
- School of Mechanical Engineering, Purdue University 585 Purdue Mall West Lafayette Indiana 47907 USA
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46
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Lin YY, Brouns T, Kolbeck PJ, Vanderlinden W, Lipfert J. High-yield ligation-free assembly of DNA constructs with nucleosome positioning sequence repeats for single-molecule manipulation assays. J Biol Chem 2023; 299:104874. [PMID: 37257819 PMCID: PMC10404619 DOI: 10.1016/j.jbc.2023.104874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/08/2023] [Accepted: 05/16/2023] [Indexed: 06/02/2023] Open
Abstract
Force and torque spectroscopy have provided unprecedented insights into the mechanical properties, conformational transitions, and dynamics of DNA and DNA-protein complexes, notably nucleosomes. Reliable single-molecule manipulation measurements require, however, specific and stable attachment chemistries to tether the molecules of interest. Here, we present a functionalization strategy for DNA that enables high-yield production of constructs for torsionally constrained and very stable attachment. The method is based on two subsequent PCRs: first ∼380 bp long DNA strands are generated that contain multiple labels, which are used as "megaprimers" in a second PCR to generate ∼kbp long double-stranded DNA constructs with multiple labels at the respective ends. To achieve high-force stability, we use dibenzocyclooctyne-based click chemistry for covalent attachment to the surface and biotin-streptavidin coupling to the bead. The resulting tethers are torsionally constrained and extremely stable under load, with an average lifetime of 70 ± 3 h at 45 pN. The high yield of the approach enables nucleosome reconstitution by salt dialysis on the functionalized DNA, and we demonstrate proof-of-concept measurements on nucleosome assembly statistics and inner turn unwrapping under force. We anticipate that our approach will facilitate a range of studies of DNA interactions and nucleoprotein complexes under forces and torques.
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Affiliation(s)
- Yi-Yun Lin
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands
| | - Tine Brouns
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Division of Molecular Imaging and Photonics, KU Leuven, Leuven, Belgium
| | - Pauline J Kolbeck
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands
| | - Willem Vanderlinden
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands.
| | - Jan Lipfert
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands.
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47
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Blanco PM, Narambuena CF, Madurga S, Mas F, Garcés JL. Unusual Aspects of Charge Regulation in Flexible Weak Polyelectrolytes. Polymers (Basel) 2023; 15:2680. [PMID: 37376324 DOI: 10.3390/polym15122680] [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: 05/22/2023] [Revised: 06/07/2023] [Accepted: 06/10/2023] [Indexed: 06/29/2023] Open
Abstract
This article reviews the state of the art of the studies on charge regulation (CR) effects in flexible weak polyelectrolytes (FWPE). The characteristic of FWPE is the strong coupling of ionization and conformational degrees of freedom. After introducing the necessary fundamental concepts, some unconventional aspects of the the physical chemistry of FWPE are discussed. These aspects are: (i) the extension of statistical mechanics techniques to include ionization equilibria and, in particular, the use of the recently proposed Site Binding-Rotational Isomeric State (SBRIS) model, which allows the calculation of ionization and conformational properties on the same foot; (ii) the recent progresses in the inclusion of proton equilibria in computer simulations; (iii) the possibility of mechanically induced CR in the stretching of FWPE; (iv) the non-trivial adsorption of FWPE on ionized surfaces with the same charge sign as the PE (the so-called "wrong side" of the isoelectric point); (v) the influence of macromolecular crowding on CR.
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Affiliation(s)
- Pablo M Blanco
- Physical Chemistry Unit, Materials Science and Physical Chemistry Department & Research Institute of Theoretical and Computational Chemistry (IQTCUB), Barcelona University (UB), 08028 Barcelona, Catalonia, Spain
| | - Claudio F Narambuena
- Grupo de Bionanotecnologia y Sistemas Complejos, Infap-CONICET & Facultad Regional San Rafael, Universidad Tecnológica Nacional, San Rafael 5600, Argentina
| | - Sergio Madurga
- Physical Chemistry Unit, Materials Science and Physical Chemistry Department & Research Institute of Theoretical and Computational Chemistry (IQTCUB), Barcelona University (UB), 08028 Barcelona, Catalonia, Spain
| | - Francesc Mas
- Physical Chemistry Unit, Materials Science and Physical Chemistry Department & Research Institute of Theoretical and Computational Chemistry (IQTCUB), Barcelona University (UB), 08028 Barcelona, Catalonia, Spain
| | - Josep L Garcés
- Chemistry Department, Technical School of Agricultural Engineering & AGROTECNIO, Lleida University (UdL), 25003 Lleida, Catalonia, Spain
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48
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Torkan E, Salmani-Tehrani M. Conformational dynamics and mechanical properties of biomimetic RNA, DNA, and RNA-DNA hybrid nanotubes: an atomistic molecular dynamics study. Phys Chem Chem Phys 2023. [PMID: 37309220 DOI: 10.1039/d3cp01028g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
With the nanotechnology boom, artificially designed nucleic acid nanotubes have aroused interest due to their practical applications in nanorobotics, vaccine design, membrane channels, drug delivery, and force sensing. In this paper, computational study was performed to investigate the structural dynamics and mechanical properties of RNA nanotubes (RNTs), DNA nanotubes (DNTs), and RNA-DNA hybrid nanotubes (RDHNTs). So far, the structural and mechanical properties of RDHNTs have not been examined in experiments or theoretical calculations, and there is limited knowledge regarding these properties for RNTs. Here, the simulations were carried out using the equilibrium molecular dynamics (MD) and steered molecular dynamics (SMD) approaches. Using in-house scripting, we modeled hexagonal nanotubes composed of six double-stranded molecules connected by four-way Holliday junctions. Classical MD analyses were performed on the collected trajectory data to investigate structural properties. Analyses of the microscopic structural parameters of RDHNT indicated a structural transition from the A-form to a conformation between the A- and B-forms, which may be attributable to the increased rigidity of RNA scaffolds compared to DNA staples. Comprehensive research on the elastic mechanical properties was also conducted based on spontaneous thermal fluctuations of nanotubes and employing the equipartition theorem. The Young's modulus of RDHNT (E = 165 MPa) and RNT (E = 144 MPa) was found to be almost the same and nearly half of that found for DNT (E = 325 MPa). Furthermore, the results showed that RNT was more resistant to bending, torsional, and volumetric deformations than DNT and RDHNT. We also used non-equilibrium SMD simulations to acquire comprehensive knowledge of the mechanical response of nanotubes to tensile stress.
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Affiliation(s)
- Ehsan Torkan
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran.
| | - Mehdi Salmani-Tehrani
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran.
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49
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Tsan VH, Fan D, Caneva S, Smith CS, Verbiest GJ. Low-cost acoustic force trap in a microfluidic channel. HARDWAREX 2023; 14:e00428. [PMID: 37275951 PMCID: PMC10232849 DOI: 10.1016/j.ohx.2023.e00428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A low-cost glass-based microfluidic flow cell with a piezo actuator is built using off-the-shelf parts (total cost €9 per device) to apply acoustophoretic force on polystyrene micro-beads. The main challenge in the fabrication of these devices was to ensure their leak tightness, which we solved using double-sided tape and nail polish. Beads with 1.5 μm diameter flowing in a 100 μm deep channel were trapped at 7.5 MHz using a 23.7 peak-to-peak voltage (Vpp) sinusoidal input. The trap located at 50 ± 0.1 μm depth was measured to have a stiffness of approximately 0.6 pN/μm. With this simple device we can trap and control the axial position of micrometer scale objects, which allows for the manipulation of beads and cells. We intend to use the device for force spectroscopy on micro-bead tethered DNA. This can be combined with super-resolution imaging techniques to study mechanics and binding of protein structures along a DNA strand as a function of induced tension.
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50
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Singh N, Mathur N. Pulling short DNA with mismatch base pairs. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023:10.1007/s00249-023-01659-8. [PMID: 37249617 DOI: 10.1007/s00249-023-01659-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 04/13/2023] [Accepted: 04/30/2023] [Indexed: 05/31/2023]
Abstract
Due to misincorporation during gene replication, the accuracy of the gene expression is often compromised. This results in a mismatch or defective pair in the DNA molecule (James et al. 2016). Here, we present our study of the stability of DNA with defects in the thermal and force ensembles. We consider DNA with a different number of defects from 2to16 and study how the denaturation process differs in both ensembles. Using a statistical model, we calculate the melting point of the DNA chain in both the ensemble. Our findings display different manifestations of DNA denaturation in thermal and force ensembles. While the DNA with defects denatures at a lower temperature than the intact DNA, the point from which the DNA is pulled is important in force ensemble.
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Affiliation(s)
- Navin Singh
- Department of Physics, Birla Institute of Technology and Science, Pilani, Rajasthan, 333 031, India.
| | - Nehal Mathur
- Department of Physics, Birla Institute of Technology and Science, Pilani, Rajasthan, 333 031, India
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