1
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Erenso D, Tran L, Abualrob I, Bushra M, Hengstenberg J, Muhammed E, Endale I, Endale N, Endale E, Mayhut S, Torres N, Sheffield P, Vazquez C, Crogman H, Nichols C, Dang T, Hach EE. Observation of magnet-induced star-like radiation of a plasma created from cancer cells in a laser trap. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2024; 53:123-131. [PMID: 38451329 DOI: 10.1007/s00249-024-01701-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 10/06/2023] [Accepted: 01/20/2024] [Indexed: 03/08/2024]
Abstract
We present a new phenomenon resulting from the interaction of magnetic beads with cancer cells in a laser trap formed on a slide containing a depression 16.5 mm in diameter and 0.78 mm of maximum depth. This phenomenon includes the apparent formation and expansion of a dark bubble that attracts and incinerates surrounding matter when it explodes, which leads to a plasma emitting intense radiation that has the appearance of a star on a microscopic scale. We have observed the star-like phenomenon for more than 4 years, and the intensity depends on the laser's power. Measuring the laser power of the dark bubble shows the entrapment of electromagnetic energy as it expands.
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Affiliation(s)
- D Erenso
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA.
| | - L Tran
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - I Abualrob
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - M Bushra
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - J Hengstenberg
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - E Muhammed
- Department of Physics, Addis Ababa University, Addis Ababa, Ethiopia
| | - I Endale
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - N Endale
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - E Endale
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - S Mayhut
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - N Torres
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - P Sheffield
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - C Vazquez
- Department of Physics, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - H Crogman
- Department of Physics, California State University Dominguez Hills, Carson, CA, 90747, USA
| | - C Nichols
- Department of Physics, California State University Dominguez Hills, Carson, CA, 90747, USA
| | - T Dang
- Department of Physics, California State University Dominguez Hills, Carson, CA, 90747, USA
| | - E E Hach
- School of Physics and Astronomy, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY, 14623, USA
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2
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Al Masri C, Wan B, Yu J. Nonspecific vs. specific DNA binding free energetics of a transcription factor domain protein. Biophys J 2023; 122:4476-4487. [PMID: 37897044 PMCID: PMC10722393 DOI: 10.1016/j.bpj.2023.10.025] [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: 03/06/2023] [Revised: 07/06/2023] [Accepted: 10/20/2023] [Indexed: 10/29/2023] Open
Abstract
Transcription factor (TF) proteins regulate gene expression by binding to specific sites on the genome. In the facilitated diffusion model, an optimized search process is achieved by the TF alternating between 3D diffusion in the bulk and 1D diffusion along DNA. While undergoing 1D diffusion, the protein can switch from a search mode for fast diffusion along nonspecific DNA to a recognition mode for stable binding to specific DNA. It was recently noticed that, for a small TF domain protein, reorientations on DNA happen between the nonspecific and specific DNA binding. We here conducted all-atom molecular dynamics simulations with steering forces to reveal the protein-DNA binding free energetics, confirming that the search and recognition modes are distinguished primarily by protein orientations on the DNA. As the binding free energy difference between the specific and nonspecific DNA system slightly deviates from that being estimated directly from dissociation constants on 15-bp DNA constructs, we hypothesize that the discrepancy can come from DNA sequences flanking the 6-bp central binding sites that impact on the dissociation kinetics measurements. The hypothesis is supported by a simplified spherical protein-DNA model along with stochastic simulations and kinetic modeling.
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Affiliation(s)
- Carmen Al Masri
- Department of Physics and Astronomy, University of California, Irvine, California
| | - Biao Wan
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China
| | - Jin Yu
- Department of Physics and Astronomy, University of California, Irvine, California; Department of Physics and Astronomy, Department of Chemistry, NSF-Simons Center for Multiscale Cell Fate Research, University of California, Irvine, California.
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3
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Kamagata K, Kusano R, Kanbayashi S, Banerjee T, Takahashi H. Single-molecule characterization of target search dynamics of DNA-binding proteins in DNA-condensed droplets. Nucleic Acids Res 2023; 51:6654-6667. [PMID: 37283050 PMCID: PMC10359612 DOI: 10.1093/nar/gkad471] [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: 03/20/2023] [Revised: 05/05/2023] [Accepted: 05/14/2023] [Indexed: 06/08/2023] Open
Abstract
Target search models of DNA-binding proteins in cells typically consider search mechanisms that include 3D diffusion and 1D sliding, which can be characterized by single-molecule tracking on DNA. However, the finding of liquid droplets of DNA and nuclear components in cells cast doubt on extrapolation from the behavior in ideal non-condensed DNA conditions to those in cells. In this study, we investigate the target search behavior of DNA-binding proteins in reconstituted DNA-condensed droplets using single-molecule fluorescence microscopy. To mimic nuclear condensates, we reconstituted DNA-condensed droplets using dextran and PEG polymers. In the DNA-condensed droplets, we measured the translational movement of four DNA-binding proteins (p53, Nhp6A, Fis and Cas9) and p53 mutants possessing different structures, sizes, and oligomeric states. Our results demonstrate the presence of fast and slow mobility modes in DNA-condensed droplets for the four DNA-binding proteins. The slow mobility mode capability is correlated strongly to the molecular size and the number of DNA-binding domains on DNA-binding proteins, but only moderately to the affinity to single DNA segments in non-condensed conditions. The slow mobility mode in DNA-condensed droplets is interpreted as a multivalent interaction mode of the DNA-binding protein to multiple DNA segments.
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Affiliation(s)
- Kiyoto Kamagata
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Ryo Kusano
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Saori Kanbayashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Trishit Banerjee
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Hiroto Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
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4
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Ivanovaitė ŠRN, Paksaitė J, Kopu Stas A, Karzaitė G, Rutkauskas D, Silanskas A, Sasnauskas G, Zaremba M, Jones SK, Tutkus M. smFRET Detection of Cis and Trans DNA Interactions by the BfiI Restriction Endonuclease. J Phys Chem B 2023. [PMID: 37452775 PMCID: PMC10388346 DOI: 10.1021/acs.jpcb.3c03269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
Protein-DNA interactions are fundamental to many biological processes. Proteins must find their target site on a DNA molecule to perform their function, and mechanisms for target search differ across proteins. Especially challenging phenomena to monitor and understand are transient binding events that occur across two DNA target sites, whether occurring in cis or trans. Type IIS restriction endonucleases rely on such interactions. They play a crucial role in safeguarding bacteria against foreign DNA, including viral genetic material. BfiI, a type IIS restriction endonuclease, acts upon a specific asymmetric sequence, 5-ACTGGG-3, and precisely cuts both upper and lower DNA strands at fixed locations downstream of this sequence. Here, we present two single-molecule Förster resonance energy-transfer-based assays to study such interactions in a BfiI-DNA system. The first assay focuses on DNA looping, detecting both "Phi"- and "U"-shaped DNA looping events. The second assay only allows in trans BfiI-target DNA interactions, improving the specificity and reducing the limits on observation time. With total internal reflection fluorescence microscopy, we directly observe on- and off-target binding events and characterize BfiI binding events. Our results show that BfiI binds longer to target sites and that BfiI rarely changes conformations during binding. This newly developed assay could be employed for other DNA-interacting proteins that bind two targets and for the dsDNA substrate BfiI-PAINT, a useful strategy for DNA stretch assays and other super-resolution fluorescence microscopy studies.
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Affiliation(s)
- Ša Ru Nė Ivanovaitė
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Savanorių 231, Vilnius LT-02300, Lithuania
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
| | - Justė Paksaitė
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
| | - Aurimas Kopu Stas
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Savanorių 231, Vilnius LT-02300, Lithuania
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
| | - Giedrė Karzaitė
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Savanorių 231, Vilnius LT-02300, Lithuania
| | - Danielis Rutkauskas
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Savanorių 231, Vilnius LT-02300, Lithuania
| | - Arunas Silanskas
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
| | - Giedrius Sasnauskas
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
| | - Mindaugas Zaremba
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
| | - Stephen K Jones
- VU LSC-EMBL Partnership for Genome Editing Technologies, Life Sciences Center, Vilnius University, Vilnius LT-10257, Lithuania
| | - Marijonas Tutkus
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Savanorių 231, Vilnius LT-02300, Lithuania
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Saulėtekio av. 7, Vilnius LT-10257, Lithuania
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5
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Punia B, Chaudhury S. Theoretical insights into the full description of DNA target search by subdiffusing proteins. Phys Chem Chem Phys 2022; 24:29074-29083. [PMID: 36440504 DOI: 10.1039/d2cp04934a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
DNA binding proteins (DBPs) diffuse in the cytoplasm to recognise and bind with their respective target sites on the DNA to initiate several biologically important processes. The first passage time distributions (FPTDs) of DBPs are useful in quantifying the timescales of the most-probable search paths in addition to the mean value of the distribution which, strikingly, are decades of order apart in time. However, extremely crowded in vivo conditions or the viscoelasticity of the cellular medium among other factors causes biomolecules to exhibit anomalous diffusion which is usually overlooked in most theoretical studies. We have obtained approximate analytical expressions of a general FPTD and the two characteristic timescales that are valid for any single subdiffusing protein searching for its target in vivo. Our results can be applied to single-particle tracking experiments of target search.
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Affiliation(s)
- Bhawakshi Punia
- Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pune, Maharashtra, India.
| | - Srabanti Chaudhury
- Department of Chemistry, Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pune, Maharashtra, India.
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6
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D'Acunto M. Quantum biology. π-π entanglement signatures in Protein-DNA interactions. Phys Biol 2022; 19. [PMID: 35263721 DOI: 10.1088/1478-3975/ac5bda] [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: 12/23/2021] [Accepted: 03/09/2022] [Indexed: 11/11/2022]
Abstract
DNA biological functions are carried out by individual proteins that interact with specific sequences along DNA to prime molecular processes required by cellular metabolism. Protein-DNA interactions include DNA replication, gene expression and its regulation, DNA repair, DNA restriction and modification by endonucleases, generally classified as enzymatic functions, or transcription factors functions. To find specific binding target sequences and finalize their activities, proteins must operate in symbiosis with cellular crowded environment identifying extremely small cognate sequences along the DNA chain, ranging from 15-20 bps for repressors to 4-6 bps for restriction enzymes in less than one second.
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Affiliation(s)
- Mario D'Acunto
- Istituto di Biofisica, Via Moruzzi 1, Pisa, 56124, ITALY
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7
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Cognate DNA Recognition by Engrailed Homeodomain Involves a Conformational Change Controlled via an Electrostatic-Spring-Loaded Latch. Int J Mol Sci 2022; 23:ijms23052412. [PMID: 35269555 PMCID: PMC8910618 DOI: 10.3390/ijms23052412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/11/2022] [Accepted: 02/11/2022] [Indexed: 02/01/2023] Open
Abstract
Transcription factors must scan genomic DNA, recognize the cognate sequence of their control element(s), and bind tightly to them. The DNA recognition process is primarily carried out by their DNA binding domains (DBD), which interact with the cognate site with high affinity and more weakly with any other DNA sequence. DBDs are generally thought to bind to their cognate DNA without changing conformation (lock-and-key). Here, we used nuclear magnetic resonance and circular dichroism to investigate the interplay between DNA recognition and DBD conformation in the engrailed homeodomain (enHD), as a model case for the homeodomain family of eukaryotic DBDs. We found that the conformational ensemble of enHD is rather flexible and becomes gradually more disordered as ionic strength decreases following a Debye–Hückel’s dependence. Our analysis indicates that enHD’s response to ionic strength is mediated by a built-in electrostatic spring-loaded latch that operates as a conformational transducer. We also found that, at moderate ionic strengths, enHD changes conformation upon binding to cognate DNA. This change is of larger amplitude and somewhat orthogonal to the response to ionic strength. As a consequence, very high ionic strengths (e.g., 700 mM) block the electrostatic-spring-loaded latch and binding to cognate DNA becomes lock-and-key. However, the interplay between enHD conformation and cognate DNA binding is robust across a range of ionic strengths (i.e., 45 to 300 mM) that covers the physiologically-relevant conditions. Therefore, our results demonstrate the presence of a mechanism for the conformational control of cognate DNA recognition on a eukaryotic DBD. This mechanism can function as a signal transducer that locks the DBD in place upon encountering the cognate site during active DNA scanning. The electrostatic-spring-loaded latch of enHD can also enable the fine control of DNA recognition in response to transient changes in local ionic strength induced by variate physiological processes.
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8
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Kamagata K, Itoh Y, Tan C, Mano E, Wu Y, Mandali S, Takada S, Johnson RC. Testing mechanisms of DNA sliding by architectural DNA-binding proteins: dynamics of single wild-type and mutant protein molecules in vitro and in vivo. Nucleic Acids Res 2021; 49:8642-8664. [PMID: 34352099 PMCID: PMC8421229 DOI: 10.1093/nar/gkab658] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 07/10/2021] [Accepted: 07/22/2021] [Indexed: 01/06/2023] Open
Abstract
Architectural DNA-binding proteins (ADBPs) are abundant constituents of eukaryotic or bacterial chromosomes that bind DNA promiscuously and function in diverse DNA reactions. They generate large conformational changes in DNA upon binding yet can slide along DNA when searching for functional binding sites. Here we investigate the mechanism by which ADBPs diffuse on DNA by single-molecule analyses of mutant proteins rationally chosen to distinguish between rotation-coupled diffusion and DNA surface sliding after transient unbinding from the groove(s). The properties of yeast Nhp6A mutant proteins, combined with molecular dynamics simulations, suggest Nhp6A switches between two binding modes: a static state, in which the HMGB domain is bound within the minor groove with the DNA highly bent, and a mobile state, where the protein is traveling along the DNA surface by means of its flexible N-terminal basic arm. The behaviors of Fis mutants, a bacterial nucleoid-associated helix-turn-helix dimer, are best explained by mobile proteins unbinding from the major groove and diffusing along the DNA surface. Nhp6A, Fis, and bacterial HU are all near exclusively associated with the chromosome, as packaged within the bacterial nucleoid, and can be modeled by three diffusion modes where HU exhibits the fastest and Fis the slowest diffusion.
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Affiliation(s)
- Kiyoto Kamagata
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Yuji Itoh
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Cheng Tan
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Eriko Mano
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Yining Wu
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Sridhar Mandali
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA
| | - Shoji Takada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Reid C Johnson
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA.,Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
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9
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Recognition and repair of oxidatively generated DNA lesions in plasmid DNA by a facilitated diffusion mechanism. Biochem J 2021; 478:2359-2370. [PMID: 34060590 DOI: 10.1042/bcj20210095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 05/27/2021] [Accepted: 06/01/2021] [Indexed: 11/17/2022]
Abstract
The oxidatively generated genotoxic spiroiminodihydantoin (Sp) lesions are well-known substrates of the base excision repair (BER) pathway initiated by the bifunctional DNA glycosylase NEIL1. In this work, we reported that the excision kinetics of the single Sp lesions site-specifically embedded in the covalently closed circular DNA plasmids (contour length 2686 base pairs) by NEIL1 are biphasic under single-turnover conditions ([NEIL1] ≫ [SpDNApl]) in contrast with monophasic excision kinetics of the same lesions embedded in147-mer Sp-modified DNA duplexes. Under conditions of a large excess of plasmid DNA base pairs over NEIL1 molecules, the kinetics of excision of Sp lesions are biphasic in nature, exhibiting an initial burst phase, followed by a slower rate of formation of excision products The burst phase is associated with NEIL1-DNA plasmid complexes, while the slow kinetic phase is attributed to the dissociation of non-specific NEIL1-DNA complexes. The amplitude of the burst phase is limited because of the competing non-specific binding of NEIL1 to unmodified DNA sequences flanking the lesion. A numerical analysis of the incision kinetics yielded a value of φ ≍ 0.03 for the fraction of NEIL1 encounters with plasmid molecules that result in the excision of the Sp lesion, and a characteristic dissociation time of non-specific NEIL1-DNA complexes (τ-ns ≍ 8 s). The estimated average DNA translocation distance of NEIL1 is ∼80 base pairs. This estimate suggests that facilitated diffusion enhances the probability that NEIL1 can locate its substrate embedded in an excess of unmodified plasmid DNA nucleotides by a factor of ∼10.
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10
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Kopu̅stas A, Ivanovaitė Š, Rakickas T, Pocevičiu̅tė E, Paksaitė J, Karvelis T, Zaremba M, Manakova E, Tutkus M. Oriented Soft DNA Curtains for Single-Molecule Imaging. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3428-3437. [PMID: 33689355 PMCID: PMC8280724 DOI: 10.1021/acs.langmuir.1c00066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Over the past 20 years, single-molecule methods have become extremely important for biophysical studies. These methods, in combination with new nanotechnological platforms, can significantly facilitate experimental design and enable faster data acquisition. A nanotechnological platform, which utilizes a flow-stretch of immobilized DNA molecules, called DNA Curtains, is one of the best examples of such combinations. Here, we employed new strategies to fabricate a flow-stretch assay of stably immobilized and oriented DNA molecules using a protein template-directed assembly. In our assay, a protein template patterned on a glass coverslip served for directional assembly of biotinylated DNA molecules. In these arrays, DNA molecules were oriented to one another and maintained extended by either single- or both-end immobilization to the protein templates. For oriented both-end DNA immobilization, we employed heterologous DNA labeling and protein template coverage with the antidigoxigenin antibody. In contrast to single-end immobilization, both-end immobilization does not require constant buffer flow for keeping DNAs in an extended configuration, allowing us to study protein-DNA interactions at more controllable reaction conditions. Additionally, we increased the immobilization stability of the biotinylated DNA molecules using protein templates fabricated from traptavidin. Finally, we demonstrated that double-tethered Soft DNA Curtains can be used in nucleic acid-interacting protein (e.g., CRISPR-Cas9) binding assay that monitors the binding location and position of individual fluorescently labeled proteins on DNA.
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Affiliation(s)
- Aurimas Kopu̅stas
- Departments
of Molecular Compound Physics, Nanoengineering, and Functional Materials and Electronics, Center for Physical Sciences and Technology, Savanoriu 231, Vilnius LT-02300, Lithuania
- Life
Sciences Center, Institute of Biotechnology, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Šaru̅nė Ivanovaitė
- Departments
of Molecular Compound Physics, Nanoengineering, and Functional Materials and Electronics, Center for Physical Sciences and Technology, Savanoriu 231, Vilnius LT-02300, Lithuania
| | - Tomas Rakickas
- Departments
of Molecular Compound Physics, Nanoengineering, and Functional Materials and Electronics, Center for Physical Sciences and Technology, Savanoriu 231, Vilnius LT-02300, Lithuania
| | - Ernesta Pocevičiu̅tė
- Departments
of Molecular Compound Physics, Nanoengineering, and Functional Materials and Electronics, Center for Physical Sciences and Technology, Savanoriu 231, Vilnius LT-02300, Lithuania
- Life
Sciences Center, Institute of Biotechnology, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Justė Paksaitė
- Life
Sciences Center, Institute of Biotechnology, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Tautvydas Karvelis
- Life
Sciences Center, Institute of Biotechnology, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Mindaugas Zaremba
- Life
Sciences Center, Institute of Biotechnology, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Elena Manakova
- Life
Sciences Center, Institute of Biotechnology, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
| | - Marijonas Tutkus
- Departments
of Molecular Compound Physics, Nanoengineering, and Functional Materials and Electronics, Center for Physical Sciences and Technology, Savanoriu 231, Vilnius LT-02300, Lithuania
- Life
Sciences Center, Institute of Biotechnology, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania
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11
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D'Acunto M. Protein-DNA target search relies on quantum walk. Biosystems 2020; 201:104340. [PMID: 33387562 DOI: 10.1016/j.biosystems.2020.104340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/21/2020] [Accepted: 12/21/2020] [Indexed: 01/25/2023]
Abstract
Protein-DNA interactions play a fundamental role in all life systems. A critical issue of such interactions is given by the strategy of protein search for specific targets on DNA. The mechanisms by which the protein are able to find relatively small cognate sequences, typically 15-20 base pairs (bps) for repressors, and 4-6 bps for restriction enzymes among the millions of bp of non-specific chromosomal DNA have hardly engaged researchers for decades. Recent experimental studies have generated new insights on the basic processes of protein-DNA interactions evidencing the underlying complex dynamic phenomena involved, which combine three-dimensional and one-dimensional motion along the DNA chain. It has been demonstrated that protein molecules have an extraordinary ability to find the target very quickly on the DNA chain, in some cases, with two orders of magnitude faster than the diffusion limit. This unique property of protein-DNA search mechanism is known as facilitated diffusion. Several theoretical mechanisms have been suggested to describe the origin of facilitated diffusion. However, none of such models currently has the ability to fully describe the protein search strategy. In this paper, we suggest that the ability of proteins to identify consensus sequences on DNA is based on the entanglement of π-π electrons between DNA nucleotides and protein amino acids. The π-π entanglement is based on Quantum Walk (QW), through Coin-position entanglement (CPE). First, the protein identifies a dimer belonging to the consensus sequence, and localize a π on such dimer, hence, the other π electron scans the DNA chain until the sequence is identified. Focusing on the example of recognition of consensus sequences of EcoRV or EcoRI, we will describe the quantum features of QW on protein-DNA complexes during the search strategy, such as walker quadratic spreading on a coherent superposition of different vertices and environment-supported long-time survival probability of the walker. We will employ both discrete- or continuous-time versions of QW. Biased and unbiased classical Random Walk (CRW) have been used for a long time to describe the Protein-DNA search strategy. QW, the quantum version of CRW, has been widely studied for its applications in quantum information applications. In our biological application, the walker (the protein) resides at a vertex in a graph (the DNA structural topology). Differently to CRW, where the walker moves randomly, the quantum walker can hop along the edges in the graph to reach other vertices entering coherently a superposition across different vertices spreading quadratically faster than CRW analogous evidencing the typical speed up features of the QW. When applied to a protein-DNA target search problem, QW gives the possibility to achieve the experimental diffusional motion of proteins over diffusion classical limits experienced along DNA chains exploiting quantum features such as CPE and long-time survival probability supported by the environment. In turn, we come to the conclusion that, under quantum picture, the protein search strategy does not distinguish between one-dimensional (1D) and three-dimensional (3D) cases.
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Affiliation(s)
- Mario D'Acunto
- CNR-IBF, Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Via Moruzzi 1, 56124, Pisa, Italy.
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12
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Iwahara J, Kolomeisky AB. Discrete-state stochastic kinetic models for target DNA search by proteins: Theory and experimental applications. Biophys Chem 2020; 269:106521. [PMID: 33338872 PMCID: PMC7855466 DOI: 10.1016/j.bpc.2020.106521] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/03/2020] [Accepted: 12/03/2020] [Indexed: 12/15/2022]
Abstract
To perform their functions, transcription factors and DNA-repair/modifying enzymes randomly search DNA in order to locate their specific targets on DNA. Discrete-state stochastic kinetic models have been developed to explain how the efficiency of the search process is influenced by the molecular properties of proteins and DNA as well as by other factors such as molecular crowding. These theoretical models not only offer explanations on the relation of microscopic processes to macroscopic behavior of proteins, but also facilitate the analysis and interpretation of experimental data. In this review article, we provide an overview on discrete-state stochastic kinetic models and explain how these models can be applied to experimental investigations using stopped-flow, single-molecule, nuclear magnetic resonance (NMR), and other biophysical and biochemical methods.
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Affiliation(s)
- Junji Iwahara
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Anatoly B Kolomeisky
- Department of Chemistry, Department of Chemical and Biomolecular Engineering, Department of Physics and Astronomy and Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
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Monico C, Tempestini A, Gardini L, Pavone FS, Capitanio M. Data on the target search by a single protein on DNA measured with ultrafast force-clamp spectroscopy. Data Brief 2019; 24:103918. [PMID: 31193354 PMCID: PMC6526245 DOI: 10.1016/j.dib.2019.103918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/05/2019] [Accepted: 04/08/2019] [Indexed: 01/28/2023] Open
Abstract
The mechanism by which proteins are able to find small cognate sequences in the range from few to few tens of base pairs amongst the millions of non-specific chromosomal DNA has been puzzling researchers for decades. Single molecule techniques based on fluorescence have been successfully applied to investigate this process but are inherently limited in terms of spatial and temporal resolution. We previously showed that ultrafast force-clamp spectroscopy, a single molecule technique based on laser tweezers, can be applied to the study of protein-DNA interaction attaining sub-millisecond and few base-pair resolution. Here, we share experimental records of interactions between a single lactose repressor protein and DNA collected under different forces using our technique [1]. The data can be valuable for researchers interested in the study of protein-DNA interaction and the mechanism of DNA target search, both from an experimental and modeling point of view. The data is related to the research article "Sliding of a single lac repressor protein along DNA is tuned by DNA sequence and molecular switching" [2].
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Affiliation(s)
- Carina Monico
- LENS – European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy
| | - Alessia Tempestini
- LENS – European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy
| | - Lucia Gardini
- LENS – European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy
- National Institute of Optics–National Research Council, Largo Fermi 6, 50125, Florence, Italy
| | - Francesco Saverio Pavone
- LENS – European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Via Sansone 1, 50019, Sesto Fiorentino, Italy
- National Institute of Optics–National Research Council, Largo Fermi 6, 50125, Florence, Italy
| | - Marco Capitanio
- LENS – European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019, Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Via Sansone 1, 50019, Sesto Fiorentino, Italy
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Esadze A, Stivers JT. Facilitated Diffusion Mechanisms in DNA Base Excision Repair and Transcriptional Activation. Chem Rev 2018; 118:11298-11323. [PMID: 30379068 DOI: 10.1021/acs.chemrev.8b00513] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Preservation of the coding potential of the genome and highly regulated gene expression over the life span of a human are two fundamental requirements of life. These processes require the action of repair enzymes or transcription factors that efficiently recognize specific sites of DNA damage or transcriptional regulation within a restricted time frame of the cell cycle or metabolism. A failure of these systems to act results in accumulated mutations, metabolic dysfunction, and disease. Despite the multifactorial complexity of cellular DNA repair and transcriptional regulation, both processes share a fundamental physical requirement that the proteins must rapidly diffuse to their specific DNA-binding sites that are embedded within the context of a vastly greater number of nonspecific DNA-binding sites. Superimposed on the needle-in-the-haystack problem is the complex nature of the cellular environment, which contains such high concentrations of macromolecules that the time frame for diffusion is expected to be severely extended as compared to dilute solution. Here we critically review the mechanisms for how these proteins solve the needle-in-the-haystack problem and how the effects of cellular macromolecular crowding can enhance facilitated diffusion processes. We restrict the review to human proteins that use stochastic, thermally driven site-recognition mechanisms, and we specifically exclude systems involving energy cofactors or circular DNA clamps. Our scope includes ensemble and single-molecule studies of the past decade or so, with an emphasis on connecting experimental observations to biological function.
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Affiliation(s)
- Alexandre Esadze
- Department of Pharmacology and Molecular Sciences , Johns Hopkins University School of Medicine , 725 North Wolfe Street , WBSB 314, Baltimore , Maryland 21205 , United States
| | - James T Stivers
- Department of Pharmacology and Molecular Sciences , Johns Hopkins University School of Medicine , 725 North Wolfe Street , WBSB 314, Baltimore , Maryland 21205 , United States
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Tempestini A, Monico C, Gardini L, Vanzi F, Pavone FS, Capitanio M. Sliding of a single lac repressor protein along DNA is tuned by DNA sequence and molecular switching. Nucleic Acids Res 2018; 46:5001-5011. [PMID: 29584872 PMCID: PMC6007606 DOI: 10.1093/nar/gky208] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 03/06/2018] [Accepted: 03/09/2018] [Indexed: 01/12/2023] Open
Abstract
In any living cell, genome maintenance is carried out by DNA-binding proteins that recognize specific sequences among a vast amount of DNA. This includes fundamental processes such as DNA replication, DNA repair, and gene expression and regulation. Here, we study the mechanism of DNA target search by a single lac repressor protein (LacI) with ultrafast force-clamp spectroscopy, a sub-millisecond and few base-pair resolution technique based on laser tweezers. We measure 1D-diffusion of proteins on DNA at physiological salt concentrations with 20 bp resolution and find that sliding of LacI along DNA is sequence dependent. We show that only allosterically activated LacI slides along non-specific DNA sequences during target search, whereas the inhibited conformation does not support sliding and weakly interacts with DNA. Moreover, we find that LacI undergoes a load-dependent conformational change when it switches between sliding and strong binding to the target sequence. Our data reveal how DNA sequence and molecular switching regulate LacI target search process and provide a comprehensive model of facilitated diffusion for LacI.
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Affiliation(s)
- Alessia Tempestini
- LENS—European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Via Sansone 1, 50019 Sesto Fiorentino, Italy
| | - Carina Monico
- LENS—European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy
| | - Lucia Gardini
- LENS—European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy
- National Institute of Optics—National Research Council, Largo Fermi 6, 50125 Florence, Italy
| | - Francesco Vanzi
- LENS—European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy
- Department of Biology, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy
| | - Francesco S Pavone
- LENS—European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Via Sansone 1, 50019 Sesto Fiorentino, Italy
- National Institute of Optics—National Research Council, Largo Fermi 6, 50125 Florence, Italy
- International Center of Computational Neurophotonics, Via Nello Carrara 1, 50019 Sesto Fiorentino (FI), Italy
| | - Marco Capitanio
- LENS—European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Via Sansone 1, 50019 Sesto Fiorentino, Italy
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Abstract
Here, we describe protocols for three-dimensional tracking of single quantum dot-conjugated molecules with nanometer accuracy in living cells using conventional fluorescence microscopy. The technique exploits out-of-focus images of single emitters combined with an automated pattern-recognition open-source software that fits the images with proper model functions to extract the emitter coordinates. We describe protocols for targeting quantum dots to both membrane components and cytosolic proteins.
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Abstract
The three-dimensional structure of DNA is highly susceptible to changes by mechanical and biochemical cues in vivo and in vitro. In particular, large increases in base pair spacing compared to regular B-DNA are effected by mechanical (over)stretching and by intercalation of compounds that are widely used in biophysical/chemical assays and drug treatments. We present single-molecule experiments and a three-state statistical mechanical model that provide a quantitative understanding of the interplay between B-DNA, overstretched DNA and intercalated DNA. The predictions of this model include a hitherto unconfirmed hyperstretched state, twice the length of B-DNA. Our force-fluorescence experiments confirm this hyperstretched state and reveal its sequence dependence. These results pin down the physical principles that govern DNA mechanics under the influence of tension and biochemical reactions. A predictive understanding of the possibilities and limitations of DNA extension can guide refined exploitation of DNA in, e.g., programmable soft materials and DNA origami applications. The mechanics and structural transitions of DNA are important to many essential processes inside living cells. Here the authors combine theory and single-molecule experiments to show that intercalator binding stabilises a new structural state of DNA: hyperstretched DNA.
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Kamagata K, Murata A, Itoh Y, Takahashi S. Characterization of facilitated diffusion of tumor suppressor p53 along DNA using single-molecule fluorescence imaging. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2017. [DOI: 10.1016/j.jphotochemrev.2017.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Kittiravechote A, Usman A, Masuhara H, Liau I. Enhanced optical confinement of dielectric nanoparticles by two-photon resonance transition. RSC Adv 2017. [DOI: 10.1039/c7ra06031a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Two-photon resonance enhances optical confinement of nanoparticles.
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Affiliation(s)
- Aungtinee Kittiravechote
- Department of Applied Chemistry
- Institute of Molecular Science
- National Chiao Tung University
- Hsinchu
- Taiwan
| | - Anwar Usman
- Department of Applied Chemistry
- Institute of Molecular Science
- National Chiao Tung University
- Hsinchu
- Taiwan
| | - Hiroshi Masuhara
- Department of Applied Chemistry
- Institute of Molecular Science
- National Chiao Tung University
- Hsinchu
- Taiwan
| | - Ian Liau
- Department of Applied Chemistry
- Institute of Molecular Science
- National Chiao Tung University
- Hsinchu
- Taiwan
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20
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Ordu O, Lusser A, Dekker NH. Recent insights from in vitro single-molecule studies into nucleosome structure and dynamics. Biophys Rev 2016; 8:33-49. [PMID: 28058066 PMCID: PMC5167136 DOI: 10.1007/s12551-016-0212-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/17/2016] [Indexed: 01/04/2023] Open
Abstract
Eukaryotic DNA is tightly packed into a hierarchically ordered structure called chromatin in order to fit into the micron-scaled nucleus. The basic unit of chromatin is the nucleosome, which consists of a short piece of DNA wrapped around a core of eight histone proteins. In addition to their role in packaging DNA, nucleosomes impact the regulation of essential nuclear processes such as replication, transcription, and repair by controlling the accessibility of DNA. Thus, knowledge of this fundamental DNA-protein complex is crucial for understanding the mechanisms of gene control. While structural and biochemical studies over the past few decades have provided key insights into both the molecular composition and functional aspects of nucleosomes, these approaches necessarily average over large populations and times. In contrast, single-molecule methods are capable of revealing features of subpopulations and dynamic changes in the structure or function of biomolecules, rendering them a powerful complementary tool for probing mechanistic aspects of DNA-protein interactions. In this review, we highlight how these single-molecule approaches have recently yielded new insights into nucleosomal and subnucleosomal structures and dynamics.
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Affiliation(s)
- Orkide Ordu
- Bionanoscience Department, Kavli Institute of Nanoscience,, Delft University of Technology, Van der Maasweg 9,, 2629 HZ Delft, The Netherlands
| | - Alexandra Lusser
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Nynke H. Dekker
- Bionanoscience Department, Kavli Institute of Nanoscience,, Delft University of Technology, Van der Maasweg 9,, 2629 HZ Delft, The Netherlands
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21
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22
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Künne T, Westra ER, Brouns SJJ. Electrophoretic Mobility Shift Assay of DNA and CRISPR-Cas Ribonucleoprotein Complexes. Methods Mol Biol 2016; 1311:171-84. [PMID: 25981473 DOI: 10.1007/978-1-4939-2687-9_11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The Electrophoretic Mobility Shift Assay is a straightforward and inexpensive method for the determination and quantification of protein-nucleic acid interactions. It relies on the different mobility of free and protein-bound nucleic acid in a gel matrix during electrophoresis. Nucleic acid affinities of crRNA-Cas complexes can be quantified by calculating the dissociation constant (Kd). Here, we describe how two types of EMSA assays are performed using the Cascade ribonucleoprotein complex from Escherichia coli as an example.
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Affiliation(s)
- Tim Künne
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands
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24
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Mechetin GV, Zharkov DO. Mechanisms of diffusional search for specific targets by DNA-dependent proteins. BIOCHEMISTRY (MOSCOW) 2015; 79:496-505. [PMID: 25100007 DOI: 10.1134/s0006297914060029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
To perform their functions, many DNA-dependent proteins have to quickly locate specific targets against the vast excess of nonspecific DNA. Although this problem was first formulated over 40 years ago, the mechanism of such search remains one of the unsolved fundamental problems in the field of protein-DNA interactions. Several complementary mechanisms have been suggested: sliding, based on one-dimensional random diffusion along the DNA contour; hopping, in which the protein "jumps" between the closely located DNA fragments; macroscopic association-dissociation of the protein-DNA complex; and intersegmental transfer. This review covers the modern state of the problem of target DNA search, theoretical descriptions, and methods of research at the macroscopic (molecule ensembles) and microscopic (individual molecules) levels. Almost all studied DNA-dependent proteins search for specific targets by combined three-dimensional diffusion and one-dimensional diffusion along the DNA contour.
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Affiliation(s)
- G V Mechetin
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
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25
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Perez-Gonzalez DC, Penedo JC. Single-Molecule Strategies for DNA and RNA Diagnostics. RNA TECHNOLOGIES 2015. [DOI: 10.1007/978-3-319-17305-4_15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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26
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Monico C, Belcastro G, Vanzi F, Pavone FS, Capitanio M. Combining single-molecule manipulation and imaging for the study of protein-DNA interactions. J Vis Exp 2014. [PMID: 25226304 DOI: 10.3791/51446] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The paper describes the combination of optical tweezers and single molecule fluorescence detection for the study of protein-DNA interaction. The method offers the opportunity of investigating interactions occurring in solution (thus avoiding problems due to closeby surfaces as in other single molecule methods), controlling the DNA extension and tracking interaction dynamics as a function of both mechanical parameters and DNA sequence. The methods for establishing successful optical trapping and nanometer localization of single molecules are illustrated. We illustrate the experimental conditions allowing the study of interaction of lactose repressor (lacI), labeled with Atto532, with a DNA molecule containing specific target sequences (operators) for LacI binding. The method allows the observation of specific interactions at the operators, as well as one-dimensional diffusion of the protein during the process of target search. The method is broadly applicable to the study of protein-DNA interactions but also to molecular motors, where control of the tension applied to the partner track polymer (for example actin or microtubules) is desirable.
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Affiliation(s)
- Carina Monico
- LENS - European Laboratory for Non-linear Spectroscopy, University of Florence; Chemistry Research Laboratory, University of Oxford
| | - Gionata Belcastro
- LENS - European Laboratory for Non-linear Spectroscopy, University of Florence
| | - Francesco Vanzi
- LENS - European Laboratory for Non-linear Spectroscopy, University of Florence; Department of Biology, University of Florence
| | - Francesco S Pavone
- LENS - European Laboratory for Non-linear Spectroscopy, University of Florence; Department of Physics and Astronomy, University of Florence; National Institute of Optics-National Research Council, Italy; International Center of Computational Neurophotonics
| | - Marco Capitanio
- LENS - European Laboratory for Non-linear Spectroscopy, University of Florence; Department of Physics and Astronomy, University of Florence;
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27
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Esadze A, Kemme CA, Kolomeisky AB, Iwahara J. Positive and negative impacts of nonspecific sites during target location by a sequence-specific DNA-binding protein: origin of the optimal search at physiological ionic strength. Nucleic Acids Res 2014; 42:7039-46. [PMID: 24838572 PMCID: PMC4066804 DOI: 10.1093/nar/gku418] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The inducible transcription factor Egr-1, which recognizes a 9-bp target DNA sequence via three zinc-finger domains, rapidly activates particular genes upon cellular stimuli such as neuronal signals and vascular stresses. Here, using the stopped-flow fluorescence method, we measured the target search kinetics of the Egr-1 zinc-finger protein at various ionic strengths between 40 and 400 mM KCl and found the most efficient search at 150 mM KCl. We further investigated the kinetics of intersegment transfer, dissociation, and sliding of this protein on DNA at distinct concentrations of KCl. Our data suggest that Egr-1's kinetic properties are well suited for efficient scanning of chromosomal DNA in vivo. Based on a newly developed theory, we analyzed the origin of the optimal search efficiency at physiological ionic strength. Target association is accelerated by nonspecific binding to nearby sites and subsequent sliding to the target as well as by intersegment transfer. Although these effects are stronger at lower ionic strengths, such conditions also favor trapping of the protein at distant nonspecific sites, decelerating the target association. Our data demonstrate that Egr-1 achieves the optimal search at physiological ionic strength through a compromise between the positive and negative impacts of nonspecific interactions with DNA.
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Affiliation(s)
- Alexandre Esadze
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Catherine A Kemme
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Anatoly B Kolomeisky
- Department of Chemistry and Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
| | - Junji Iwahara
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
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28
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Hughes CD, Simons M, Mackenzie CE, Van Houten B, Kad NM. Single molecule techniques in DNA repair: a primer. DNA Repair (Amst) 2014; 20:2-13. [PMID: 24819596 DOI: 10.1016/j.dnarep.2014.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 02/03/2014] [Indexed: 10/25/2022]
Abstract
A powerful new approach has become much more widespread and offers insights into aspects of DNA repair unattainable with billions of molecules. Single molecule techniques can be used to image, manipulate or characterize the action of a single repair protein on a single strand of DNA. This allows search mechanisms to be probed, and the effects of force to be understood. These physical aspects can dominate a biochemical reaction, where at the ensemble level their nuances are obscured. In this paper we discuss some of the many technical advances that permit study at the single molecule level. We focus on DNA repair to which these techniques are actively being applied. DNA repair is also a process that encompasses so much of what single molecule studies benefit--searching for targets, complex formation, sequential biochemical reactions and substrate hand-off to name just a few. We discuss how single molecule biophysics is poised to transform our understanding of biological systems, in particular DNA repair.
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Affiliation(s)
- Craig D Hughes
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Michelle Simons
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Cassidy E Mackenzie
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Bennett Van Houten
- Department of Pharmacology and Chemical Biology, University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Neil M Kad
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.
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29
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Erie DA, Weninger KR. Single molecule studies of DNA mismatch repair. DNA Repair (Amst) 2014; 20:71-81. [PMID: 24746644 DOI: 10.1016/j.dnarep.2014.03.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 03/21/2014] [Accepted: 03/22/2014] [Indexed: 11/30/2022]
Abstract
DNA mismatch repair, which involves is a widely conserved set of proteins, is essential to limit genetic drift in all organisms. The same system of proteins plays key roles in many cancer related cellular transactions in humans. Although the basic process has been reconstituted in vitro using purified components, many fundamental aspects of DNA mismatch repair remain hidden due in part to the complexity and transient nature of the interactions between the mismatch repair proteins and DNA substrates. Single molecule methods offer the capability to uncover these transient but complex interactions and allow novel insights into mechanisms that underlie DNA mismatch repair. In this review, we discuss applications of single molecule methodology including electron microscopy, atomic force microscopy, particle tracking, FRET, and optical trapping to studies of DNA mismatch repair. These studies have led to formulation of mechanistic models of how proteins identify single base mismatches in the vast background of matched DNA and signal for their repair.
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Affiliation(s)
- Dorothy A Erie
- Department of Chemistry and Curriculum in Applied Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States.
| | - Keith R Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695, United States
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30
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Interrogating biology with force: single molecule high-resolution measurements with optical tweezers. Biophys J 2014; 105:1293-303. [PMID: 24047980 DOI: 10.1016/j.bpj.2013.08.007] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 07/26/2013] [Accepted: 08/07/2013] [Indexed: 11/20/2022] Open
Abstract
Single molecule force spectroscopy methods, such as optical and magnetic tweezers and atomic force microscopy, have opened up the possibility to study biological processes regulated by force, dynamics of structural conformations of proteins and nucleic acids, and load-dependent kinetics of molecular interactions. Among the various tools available today, optical tweezers have recently seen great progress in terms of spatial resolution, which now allows the measurement of atomic-scale conformational changes, and temporal resolution, which has reached the limit of the microsecond-scale relaxation times of biological molecules bound to a force probe. Here, we review different strategies and experimental configurations recently developed to apply and measure force using optical tweezers. We present the latest progress that has pushed optical tweezers' spatial and temporal resolution down to today's values, discussing the experimental variables and constraints that are influencing measurement resolution and how these can be optimized depending on the biological molecule under study.
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31
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SANCHEZ-OSORIO ISMAEL, RAMOS FERNANDO, MAYORGA PEDRO, DANTAN EDGAR. FOUNDATIONS FOR MODELING THE DYNAMICS OF GENE REGULATORY NETWORKS: A MULTILEVEL-PERSPECTIVE REVIEW. J Bioinform Comput Biol 2014; 12:1330003. [DOI: 10.1142/s0219720013300037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A promising alternative for unraveling the principles under which the dynamic interactions among genes lead to cellular phenotypes relies on mathematical and computational models at different levels of abstraction, from the molecular level of protein-DNA interactions to the system level of functional relationships among genes. This review article presents, under a bottom–up perspective, a hierarchy of approaches to modeling gene regulatory network dynamics, from microscopic descriptions at the single-molecule level in the spatial context of an individual cell to macroscopic models providing phenomenological descriptions at the population-average level. The reviewed modeling approaches include Molecular Dynamics, Particle-Based Brownian Dynamics, the Master Equation approach, Ordinary Differential Equations, and the Boolean logic abstraction. Each of these frameworks is motivated by a particular biological context and the nature of the insight being pursued. The setting of gene network dynamic models from such frameworks involves assumptions and mathematical artifacts often ignored by the non-specialist. This article aims at providing an entry point for biologists new to the field and computer scientists not acquainted with some recent biophysically-inspired models of gene regulation. The connections promoting intuition between different abstraction levels and the role that approximations play in the modeling process are highlighted throughout the paper.
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Affiliation(s)
- ISMAEL SANCHEZ-OSORIO
- Department of Computer Science, Monterrey Institute of Technology and Higher Education Campus Cuernavaca, Autopista del Sol km 104, Xochitepec, Morelos 62790, Mexico
| | - FERNANDO RAMOS
- Department of Computer Science, Monterrey Institute of Technology and Higher Education Campus Cuernavaca, Autopista del Sol km 104, Xochitepec, Morelos 62790, Mexico
| | - PEDRO MAYORGA
- Department of Computer Science, Monterrey Institute of Technology and Higher Education Campus Cuernavaca, Autopista del Sol km 104, Xochitepec, Morelos 62790, Mexico
| | - EDGAR DANTAN
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Cuernavaca, Morelos 62209, Mexico
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Levy-Sakin M, Grunwald A, Kim S, Gassman NR, Gottfried A, Antelman J, Kim Y, Ho S, Samuel R, Michalet X, Lin RR, Dertinger T, Kim AS, Chung S, Colyer RA, Weinhold E, Weiss S, Ebenstein Y. Toward single-molecule optical mapping of the epigenome. ACS NANO 2014; 8:14-26. [PMID: 24328256 PMCID: PMC4022788 DOI: 10.1021/nn4050694] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The past decade has seen an explosive growth in the utilization of single-molecule techniques for the study of complex systems. The ability to resolve phenomena otherwise masked by ensemble averaging has made these approaches especially attractive for the study of biological systems, where stochastic events lead to inherent inhomogeneity at the population level. The complex composition of the genome has made it an ideal system to study at the single-molecule level, and methods aimed at resolving genetic information from long, individual, genomic DNA molecules have been in use for the last 30 years. These methods, and particularly optical-based mapping of DNA, have been instrumental in highlighting genomic variation and contributed significantly to the assembly of many genomes including the human genome. Nanotechnology and nanoscopy have been a strong driving force for advancing genomic mapping approaches, allowing both better manipulation of DNA on the nanoscale and enhanced optical resolving power for analysis of genomic information. During the past few years, these developments have been adopted also for epigenetic studies. The common principle for these studies is the use of advanced optical microscopy for the detection of fluorescently labeled epigenetic marks on long, extended DNA molecules. Here we will discuss recent single-molecule studies for the mapping of chromatin composition and epigenetic DNA modifications, such as DNA methylation.
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Affiliation(s)
- Michal Levy-Sakin
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, Israel
| | - Assaf Grunwald
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, Israel
| | - Soohong Kim
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Natalie R. Gassman
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Anna Gottfried
- Institute of Organic Chemistry, RWTH Aachen University, Aachen, Germany
| | - Josh Antelman
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Younggyu Kim
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Sam Ho
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Robin Samuel
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Xavier Michalet
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Ron R. Lin
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Thomas Dertinger
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Andrew S. Kim
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Sangyoon Chung
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Ryan A. Colyer
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Elmar Weinhold
- Institute of Organic Chemistry, RWTH Aachen University, Aachen, Germany
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
- Corresponding authors: (Y. Ebenstein), (S. Weiss)
| | - Yuval Ebenstein
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, Israel
- Corresponding authors: (Y. Ebenstein), (S. Weiss)
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Liyanage R, Krylova SM, Krylov SN. Minimizing adsorption of histidine-tagged proteins for the study of protein–deoxyribonucleic acid interactions by kinetic capillary electrophoresis. J Chromatogr A 2013; 1322:90-6. [DOI: 10.1016/j.chroma.2013.11.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/31/2013] [Accepted: 11/01/2013] [Indexed: 01/24/2023]
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