1
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Balakrishnan S, Adolph M, Tsai MS, Akizuki T, Gallagher K, Cortez D, Chazin WJ. Structure of RADX and mechanism for regulation of RAD51 nucleofilaments. Proc Natl Acad Sci U S A 2024; 121:e2316491121. [PMID: 38466836 PMCID: PMC10962997 DOI: 10.1073/pnas.2316491121] [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: 09/27/2023] [Accepted: 02/07/2024] [Indexed: 03/13/2024] Open
Abstract
Replication fork reversal is a fundamental process required for resolution of encounters with DNA damage. A key step in the stabilization and eventual resolution of reversed forks is formation of RAD51 nucleoprotein filaments on exposed single strand DNA (ssDNA). To avoid genome instability, RAD51 filaments are tightly controlled by a variety of positive and negative regulators. RADX (RPA-related RAD51-antagonist on the X chromosome) is a recently discovered negative regulator that binds tightly to ssDNA, directly interacts with RAD51, and regulates replication fork reversal and stabilization in a context-dependent manner. Here, we present a structure-based investigation of RADX's mechanism of action. Mass photometry experiments showed that RADX forms multiple oligomeric states in a concentration-dependent manner, with a predominance of trimers in the presence of ssDNA. The structure of RADX, which has no structurally characterized orthologs, was determined ab initio by cryo-electron microscopy (cryo-EM) from maps in the 2 to 4 Å range. The structure reveals the molecular basis for RADX oligomerization and the coupled multi-valent binding of ssDNA binding. The interaction of RADX with RAD51 filaments was imaged by negative stain EM, which showed a RADX oligomer at the end of filaments. Based on these results, we propose a model in which RADX functions by capping and restricting the end of RAD51 filaments.
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Affiliation(s)
- Swati Balakrishnan
- Center for Structural Biology, Vanderbilt University, Nashville, TN37240
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN37237
| | - Madison Adolph
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN37237
| | - Miaw-Sheue Tsai
- Biological Systems and Bioengineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA94720
| | - Tae Akizuki
- Center for Structural Biology, Vanderbilt University, Nashville, TN37240
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN37237
| | - Kaitlyn Gallagher
- Center for Structural Biology, Vanderbilt University, Nashville, TN37240
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN37237
| | - David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN37237
| | - Walter J. Chazin
- Center for Structural Biology, Vanderbilt University, Nashville, TN37240
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN37237
- Department of Chemistry, Vanderbilt University, Nashville, TN37235
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2
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Vermeer B, van Ossenbruggen J, Schmid S. Single-Molecule FRET-Resolved Protein Dynamics - from Plasmid to Data in Six Steps. Methods Mol Biol 2024; 2694:267-291. [PMID: 37824009 DOI: 10.1007/978-1-0716-3377-9_13] [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
Single-molecule Förster resonance energy transfer (smFRET) is a powerful technique for the detection of conformational dynamics of biomolecules. While many smFRET experiments are performed using dye-labeled DNA, here we describe a comprehensive protocol to resolve the conformational dynamics of a protein system - notably from plasmid to data. Using the example of the heat-shock protein Hsp90, we describe the protein production and threefold site-specific bioconjugation, the smFRET measurement using total internal reflection fluorescence microscopy (TIRFM), and raw data processing to reveal time-resolved protein dynamics. The described smFRET approach is readily transferrable to the study of many more all-protein systems and their conformational energy landscape.
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Affiliation(s)
- Benjamin Vermeer
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, The Netherlands
| | | | - Sonja Schmid
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, The Netherlands.
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3
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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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4
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Kümmerlin M, Mazumder A, Kapanidis AN. Bleaching-resistant, Near-continuous Single-molecule Fluorescence and FRET Based on Fluorogenic and Transient DNA Binding. Chemphyschem 2023; 24:e202300175. [PMID: 37043705 PMCID: PMC10946581 DOI: 10.1002/cphc.202300175] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 03/16/2023] [Indexed: 04/14/2023]
Abstract
Photobleaching of fluorescent probes limits the observation span of typical single-molecule fluorescence measurements and hinders observation of dynamics at long timescales. Here, we present a general strategy to circumvent photobleaching by replenishing fluorescent probes via transient binding of fluorogenic DNAs to complementary DNA strands attached to a target molecule. Our strategy allows observation of near-continuous single-molecule fluorescence for more than an hour, a timescale two orders of magnitude longer than the typical photobleaching time of single fluorophores under our conditions. Using two orthogonal sequences, we show that our method is adaptable to Förster Resonance Energy Transfer (FRET) and that can be used to study the conformational dynamics of dynamic structures, such as DNA Holliday junctions, for extended periods. By adjusting the temporal resolution and observation span, our approach enables capturing the conformational dynamics of proteins and nucleic acids over a wide range of timescales.
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Affiliation(s)
- Mirjam Kümmerlin
- Department of PhysicsUniversity of OxfordOxfordOX1 3PUUK
- Kavli Institute for Nanoscience DiscoveryUniversity of OxfordDorothy Crowfoot Hodgkin BuildingOxfordOX1 3QUUK
| | - Abhishek Mazumder
- Department of PhysicsUniversity of OxfordOxfordOX1 3PUUK
- Kavli Institute for Nanoscience DiscoveryUniversity of OxfordDorothy Crowfoot Hodgkin BuildingOxfordOX1 3QUUK
- Structural Biology and Bioinformatics DivisionCSIR-Indian Institute of Chemical Biology4, Raja S. C. Mullick RoadKolkata700 032India
| | - Achillefs N. Kapanidis
- Department of PhysicsUniversity of OxfordOxfordOX1 3PUUK
- Kavli Institute for Nanoscience DiscoveryUniversity of OxfordDorothy Crowfoot Hodgkin BuildingOxfordOX1 3QUUK
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5
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Fan H. Single‐molecule tethered particle motion to study
protein‐DNA
interaction. J CHIN CHEM SOC-TAIP 2023. [DOI: 10.1002/jccs.202300051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
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6
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Torres R, Carrasco B, Alonso JC. Bacillus subtilis RadA/Sms-Mediated Nascent Lagging-Strand Unwinding at Stalled or Reversed Forks Is a Two-Step Process: RadA/Sms Assists RecA Nucleation, and RecA Loads RadA/Sms. Int J Mol Sci 2023; 24:ijms24054536. [PMID: 36901969 PMCID: PMC10003422 DOI: 10.3390/ijms24054536] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 02/14/2023] [Accepted: 02/23/2023] [Indexed: 03/02/2023] Open
Abstract
Replication fork rescue requires Bacillus subtilis RecA, its negative (SsbA) and positive (RecO) mediators, and fork-processing (RadA/Sms). To understand how they work to promote fork remodeling, reconstituted branched replication intermediates were used. We show that RadA/Sms (or its variant, RadA/Sms C13A) binds to the 5'-tail of a reversed fork with longer nascent lagging-strand and unwinds it in the 5'→3' direction, but RecA and its mediators limit unwinding. RadA/Sms cannot unwind a reversed fork with a longer nascent leading-strand, or a gapped stalled fork, but RecA interacts with and activates unwinding. Here, the molecular mechanism by which RadA/Sms, in concert with RecA, in a two-step reaction, unwinds the nascent lagging-strand of reversed or stalled forks is unveiled. First, RadA/Sms, as a mediator, contributes to SsbA displacement from the forks and nucleates RecA onto single-stranded DNA. Then, RecA, as a loader, interacts with and recruits RadA/Sms onto the nascent lagging strand of these DNA substrates to unwind them. Within this process, RecA limits RadA/Sms self-assembly to control fork processing, and RadA/Sms prevents RecA from provoking unnecessary recombination.
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7
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Xu L, Halma MTJ, Wuite GJL. Unravelling How Single-Stranded DNA Binding Protein Coordinates DNA Metabolism Using Single-Molecule Approaches. Int J Mol Sci 2023; 24:ijms24032806. [PMID: 36769124 PMCID: PMC9917605 DOI: 10.3390/ijms24032806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 01/23/2023] [Accepted: 01/28/2023] [Indexed: 02/05/2023] Open
Abstract
Single-stranded DNA-binding proteins (SSBs) play vital roles in DNA metabolism. Proteins of the SSB family exclusively and transiently bind to ssDNA, preventing the DNA double helix from re-annealing and maintaining genome integrity. In the meantime, they interact and coordinate with various proteins vital for DNA replication, recombination, and repair. Although SSB is essential for DNA metabolism, proteins of the SSB family have been long described as accessory players, primarily due to their unclear dynamics and mechanistic interaction with DNA and its partners. Recently-developed single-molecule tools, together with biochemical ensemble techniques and structural methods, have enhanced our understanding of the different coordination roles that SSB plays during DNA metabolism. In this review, we discuss how single-molecule assays, such as optical tweezers, magnetic tweezers, Förster resonance energy transfer, and their combinations, have advanced our understanding of the binding dynamics of SSBs to ssDNA and their interaction with other proteins partners. We highlight the central coordination role that the SSB protein plays by directly modulating other proteins' activities, rather than as an accessory player. Many possible modes of SSB interaction with protein partners are discussed, which together provide a bigger picture of the interaction network shaped by SSB.
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8
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ATPase Activity of Bacillus subtilis RecA Affects the Dynamic Formation of RecA Filaments at DNA Double Strand Breaks. mSphere 2022; 7:e0041222. [PMID: 36321831 PMCID: PMC9769622 DOI: 10.1128/msphere.00412-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
RecA plays a central role in DNA repair and is a main actor involved in homologous recombination (HR). In vivo, RecA forms filamentous structures termed "threads," which are essential for HR, but whose nature is still ill defined. We show that RecA from Bacillus subtilis having lower ATP binding activity can still form nucleoprotein filaments in vitro, features lower dsDNA binding activity, but still retains most of wild type RecA activity in vivo. Contrarily, loss of ATPase activity strongly reduced formation of nucleoprotein filaments in vitro, and effectivity to repair double strand breaks (DSBs) in vivo. In the presence of wild type RecA protein, additionally expressed RecA with lowered ATPbinding activity only moderately affected RecA dynamics, while loss of ATPase activity leads to a large reduction of the formation of threads, as well as of their dynamic changes observed in a seconds-scale. Single molecule tracking of RecA revealed incorporation of freely diffusing and nonspecifically DNA-bound molecules into threads upon induction of a single DSB. This change of dynamics was highly perturbed in the absence of ATPase activity, revealing that filamentous forms of RecA as well as their dynamics depend on ATPase activity. Based on the idea that ATPase activity of RecA is most important for DNA strand exchange activity, our data suggest that extension and retraction of threads due is to many local strand invasion events during the search for sequences homologous to the induced DNA break site. IMPORTANCE Single-strand (ss) DNA binding ATPase RecA is the central recombinase in homologous recombination, and therefore essential for DNA repair pathways involving DNA strand exchange reactions. In several bacterial, RecA forms filamentous structures along the long axis of cells after induction of double strand breaks (DSBs) in the chromosome. These striking assemblies likely reflect RecA/ssDNA nucleoprotein filaments, which can extend and remodel within a time frame of few minutes. We show that ATPase activity of RecA is pivotal for these dynamic rearrangements, which include recruitment of freely diffusing molecules into low-mobile molecules within filaments. Our data suggest that ssDNA binding- and unbinding reactions are at the heart of RecA dynamics that power the dynamics of subcellular filamentous assemblies, leading to strand exchange reactions over a distance of several micrometers.
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9
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Kang Y, An S, Min D, Lee JY. Single-molecule fluorescence imaging techniques reveal molecular mechanisms underlying deoxyribonucleic acid damage repair. Front Bioeng Biotechnol 2022; 10:973314. [PMID: 36185427 PMCID: PMC9520083 DOI: 10.3389/fbioe.2022.973314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/25/2022] [Indexed: 11/13/2022] Open
Abstract
Advances in single-molecule techniques have uncovered numerous biological secrets that cannot be disclosed by traditional methods. Among a variety of single-molecule methods, single-molecule fluorescence imaging techniques enable real-time visualization of biomolecular interactions and have allowed the accumulation of convincing evidence. These techniques have been broadly utilized for studying DNA metabolic events such as replication, transcription, and DNA repair, which are fundamental biological reactions. In particular, DNA repair has received much attention because it maintains genomic integrity and is associated with diverse human diseases. In this review, we introduce representative single-molecule fluorescence imaging techniques and survey how each technique has been employed for investigating the detailed mechanisms underlying DNA repair pathways. In addition, we briefly show how live-cell imaging at the single-molecule level contributes to understanding DNA repair processes inside cells.
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Affiliation(s)
- Yujin Kang
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Soyeong An
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Duyoung Min
- Department of Chemistry, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Ja Yil Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
- Center for Genomic Integrity, Institute of Basic Sciences, Ulsan, South Korea
- *Correspondence: Ja Yil Lee,
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10
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Purkait D, Islam F, Mishra PP. A single-molecule approach to unravel the molecular mechanism of the action of Deinococcus radiodurans RecD2 and its interaction with SSB and RecA in DNA repair. Int J Biol Macromol 2022; 221:653-664. [PMID: 36096248 DOI: 10.1016/j.ijbiomac.2022.09.043] [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: 06/01/2022] [Revised: 09/02/2022] [Accepted: 09/06/2022] [Indexed: 11/28/2022]
Abstract
Helicases are ATP-driven molecular machines that directionally remodel nucleic acid polymers in all three domains of life. They are responsible for resolving double-stranded DNA (dsDNA) into single-strands, which is essential for DNA replication, nucleotide excision repair, and homologous recombination. RecD2 from Deinococcus radiodurans (DrRecD2) has important contributions to the organism's unusually high tolerance to gamma radiation and hydrogen peroxide. Although the results from X-ray Crystallography studies have revealed the structural characteristics of the protein, direct experimental evidence regarding the dynamics of the DNA unwinding process by DrRecD2 in the context of other accessory proteins is yet to be found. In this study, we have probed the exact binding event and processivity of DrRecD2 at single-molecule resolution using Protein-induced fluorescence enhancement (smPIFE) and Forster resonance energy transfer (smFRET). We have found that the protein prefers to bind at the 5' terminal end of the single-stranded DNA (ssDNA) by Drift and has helicase activity even in absence of ATP. However, a faster and iterative mode of DNA unwinding was evident in presence of ATP. The rate of translocation of the protein was found to be slower on dsDNA compared to ssDNA. We also showed that DrRecD2 is recruited at the binding site by the single-strand binding protein (SSB) and during the unwinding, it can displace RecA from ssDNA.
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Affiliation(s)
- Debayan Purkait
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhaba National Institute, Mumbai, India
| | - Farhana Islam
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhaba National Institute, Mumbai, India
| | - Padmaja P Mishra
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhaba National Institute, Mumbai, India.
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11
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Vermeer B, Schmid S. Can DyeCycling break the photobleaching limit in single-molecule FRET? NANO RESEARCH 2022; 15:9818-9830. [PMID: 35582137 PMCID: PMC9101981 DOI: 10.1007/s12274-022-4420-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 05/03/2023]
Abstract
Biomolecular systems, such as proteins, crucially rely on dynamic processes at the nanoscale. Detecting biomolecular nanodynamics is therefore key to obtaining a mechanistic understanding of the energies and molecular driving forces that control biomolecular systems. Single-molecule fluorescence resonance energy transfer (smFRET) is a powerful technique to observe in real-time how a single biomolecule proceeds through its functional cycle involving a sequence of distinct structural states. Currently, this technique is fundamentally limited by irreversible photobleaching, causing the untimely end of the experiment and thus, a narrow temporal bandwidth of ≤ 3 orders of magnitude. Here, we introduce "DyeCycling", a measurement scheme with which we aim to break the photobleaching limit in smFRET. We introduce the concept of spontaneous dye replacement by simulations, and as an experimental proof-of-concept, we demonstrate the intermittent observation of a single biomolecule for one hour with a time resolution of milliseconds. Theoretically, DyeCycling can provide > 100-fold more information per single molecule than conventional smFRET. We discuss the experimental implementation of DyeCycling, its current and fundamental limitations, and specific biological use cases. Given its general simplicity and versatility, DyeCycling has the potential to revolutionize the field of time-resolved smFRET, where it may serve to unravel a wealth of biomolecular dynamics by bridging from milliseconds to the hour range. Electronic Supplementary Material Supplementary material is available for this article at 10.1007/s12274-022-4420-5 and is accessible for authorized users.
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Affiliation(s)
- Benjamin Vermeer
- NanoDynamicsLab, Laboratory of Biophysics, Wageningen University, Stippeneng 4, 6708WE Wageningen, The Netherlands
| | - Sonja Schmid
- NanoDynamicsLab, Laboratory of Biophysics, Wageningen University, Stippeneng 4, 6708WE Wageningen, The Netherlands
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12
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Study of cholesterol phase effect on the dynamics of DOPC and DPPC small vesicle membranes using single-molecule fluorescence correlation spectroscopy. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Carrasco B, Moreno-del Álamo M, Torres R, Alonso JC. PcrA Dissociates RecA Filaments and the SsbA and RecO Mediators Counterbalance Such Activity. Front Mol Biosci 2022; 9:836211. [PMID: 35223992 PMCID: PMC8865920 DOI: 10.3389/fmolb.2022.836211] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 01/05/2022] [Indexed: 11/24/2022] Open
Abstract
PcrA depletion is lethal in wild-type Bacillus subtilis cells. The PcrA DNA helicase contributes to unwinding RNA from the template strand, backtracking the RNA polymerase, rescuing replication-transcription conflicts, and disassembling RecA from single-stranded DNA (ssDNA) by poorly understood mechanisms. We show that, in the presence of RecA, circa one PcrA/plasmid-size circular ssDNA (cssDNA) molecule hydrolyzes ATP at a rate similar to that on the isolated cssDNA. PcrA K37A, which poorly hydrolyses ATP, fails to displace RecA from cssDNA. SsbA inhibits and blocks the ATPase activities of PcrA and RecA, respectively. RecO partially antagonizes and counteracts the negative effect of SsbA on PcrA- and RecA-mediated ATP hydrolysis, respectively. Conversely, multiple PcrA molecules are required to inhibit RecA·ATP-mediated DNA strand exchange (DSE). RecO and SsbA poorly antagonize the PcrA inhibitory effect on RecA·ATP-mediated DSE. We propose that two separable PcrA functions exist: an iterative translocating PcrA monomer strips RecA from cssDNA to prevent unnecessary recombination with the mediators SsbA and RecO balancing such activity; and a PcrA cluster that disrupts DNA transactions, as RecA-mediated DSE.
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14
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Rad54 and Rdh54 prevent Srs2-mediated disruption of Rad51 presynaptic filaments. Proc Natl Acad Sci U S A 2022; 119:2113871119. [PMID: 35042797 PMCID: PMC8795549 DOI: 10.1073/pnas.2113871119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2021] [Indexed: 11/18/2022] Open
Abstract
Homologous DNA recombination is an essential pathway necessary for the repair of double-stranded DNA breaks. Defects in this pathway are associated with hereditary breast cancer, ovarian cancer, and cancer-prone syndromes. Although essential, too much recombination is also bad and can lead to genetic mutations. Thus, cells have evolved “antirecombinase” enzymes that can actively dismantle recombination intermediates to prevent excessive recombination. However, our current understanding of how antirecombinases are themselves regulated remains very limited. Here, we study the antirecombinase Srs2 and its regulation by the recombination accessory factors Rad54 and Rdh54. Our data suggest that Rad54 and Rdh54 act synergistically to function as key regulators of Srs2, thus serving as “licensing factors” that enable timely progression of DNA repair. Srs2 is a superfamily 1 (SF1) helicase that participates in several pathways necessary for the repair of damaged DNA. Srs2 regulates formation of early homologous recombination (HR) intermediates by actively removing the recombinase Rad51 from single-stranded DNA (ssDNA). It is not known whether and how Srs2 itself is down-regulated to allow for timely HR progression. Rad54 and Rdh54 are two closely related superfamily 2 (SF2) motor proteins that promote the formation of Rad51-dependent recombination intermediates. Rad54 and Rdh54 bind tightly to Rad51-ssDNA and act downstream of Srs2, suggesting that they may affect the ability of Srs2 to dismantle Rad51 filaments. Here, we used DNA curtains to determine whether Rad54 and Rdh54 alter the ability of Srs2 to disrupt Rad51 filaments. We show that Rad54 and Rdh54 act synergistically to greatly restrict the antirecombinase activity of Srs2. Our findings suggest that Srs2 may be accorded only a limited time window to act and that Rad54 and Rdh54 fulfill a role of prorecombinogenic licensing factors.
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15
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Małecka EM, Hua B, Woodson SA. Single-Molecule FRET Studies of RNA Structural Rearrangements and RNA-RNA Interactions. Methods Mol Biol 2022; 2518:271-289. [PMID: 35666451 PMCID: PMC10052914 DOI: 10.1007/978-1-0716-2421-0_16] [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: 06/15/2023]
Abstract
RNA-guided regulation of gene expression is found in all cell types. In this mode of regulation, antisense interactions between the regulatory RNA and its target are typically facilitated by a protein partner. Single-molecule fluorescence microscopy is a powerful tool for dissecting the conformational states and intermediates that contribute to target recognition. This chapter describes protocols for studying target recognition by bacterial small RNAs and their chaperone Hfq on the single-molecule level, using a total internal reflection fluorescence microscope. The sections cover the design of suitable RNA substrates for sRNA-mRNA annealing reactions, preparation of internally labeled mRNA for detecting conformational changes in the target, and key steps of the data analysis. These protocols can be adapted to other RNA-binding proteins that chaperone RNA interactions.
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Affiliation(s)
- Ewelina M Małecka
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Boyang Hua
- Department of Molecular Biology and Genetics, Johns Hopkins Medical School, Baltimore, MD, USA
| | - Sarah A Woodson
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA.
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16
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Paul T, Liou W, Cai X, Opresko PL, Myong S. TRF2 promotes dynamic and stepwise looping of POT1 bound telomeric overhang. Nucleic Acids Res 2021; 49:12377-12393. [PMID: 34850123 PMCID: PMC8643667 DOI: 10.1093/nar/gkab1123] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/20/2021] [Accepted: 11/18/2021] [Indexed: 11/12/2022] Open
Abstract
Human telomeres are protected by shelterin proteins, but how telomeres maintain a dynamic structure remains elusive. Here, we report an unexpected activity of POT1 in imparting conformational dynamics of the telomere overhang, even at a monomer level. Strikingly, such POT1-induced overhang dynamics is greatly enhanced when TRF2 engages with the telomere duplex. Interestingly, TRF2, but not TRF2ΔB, recruits POT1-bound overhangs to the telomere ds/ss junction and induces a discrete stepwise movement up and down the axis of telomere duplex. The same steps are observed regardless of the length of the POT1-bound overhang, suggesting a tightly regulated conformational dynamic coordinated by TRF2 and POT1. TPP1 and TIN2 which physically connect POT1 and TRF2 act to generate a smooth movement along the axis of the telomere duplex. Our results suggest a plausible mechanism wherein telomeres maintain a dynamic structure orchestrated by shelterin.
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Affiliation(s)
- Tapas Paul
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Wilson Liou
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Xinyi Cai
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh, Hillman Cancer Center, 5117 Centre Avenue, Suite 2.6a, Pittsburgh, PA 15213, USA
| | - Sua Myong
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.,Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA
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17
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2D fluorescence correlation to visualize influence of size curvature and phase structure of silica nanoparticle-supported small unilamellar vesicle membrane. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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18
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Kong M, Greene EC. Mechanistic Insights From Single-Molecule Studies of Repair of Double Strand Breaks. Front Cell Dev Biol 2021; 9:745311. [PMID: 34869333 PMCID: PMC8636147 DOI: 10.3389/fcell.2021.745311] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/28/2021] [Indexed: 01/01/2023] Open
Abstract
DNA double strand breaks (DSBs) are among some of the most deleterious forms of DNA damage. Left unrepaired, they are detrimental to genome stability, leading to high risk of cancer. Two major mechanisms are responsible for the repair of DSBs, homologous recombination (HR) and nonhomologous end joining (NHEJ). The complex nature of both pathways, involving a myriad of protein factors functioning in a highly coordinated manner at distinct stages of repair, lend themselves to detailed mechanistic studies using the latest single-molecule techniques. In avoiding ensemble averaging effects inherent to traditional biochemical or genetic methods, single-molecule studies have painted an increasingly detailed picture for every step of the DSB repair processes.
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Affiliation(s)
| | - Eric C. Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, United States
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19
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Sobhy MA, Tehseen M, Takahashi M, Bralić A, De Biasio A, Hamdan SM. Implementing fluorescence enhancement, quenching, and FRET for investigating flap endonuclease 1 enzymatic reaction at the single-molecule level. Comput Struct Biotechnol J 2021; 19:4456-4471. [PMID: 34471492 PMCID: PMC8385120 DOI: 10.1016/j.csbj.2021.07.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 07/23/2021] [Accepted: 07/25/2021] [Indexed: 11/24/2022] Open
Abstract
Flap endonuclease 1 (FEN1) is an important component of the intricate molecular machinery for DNA replication and repair. FEN1 is a structure-specific 5' nuclease that cleaves nascent single-stranded 5' flaps during the maturation of Okazaki fragments. Here, we review our research primarily applying single-molecule fluorescence to resolve important mechanistic aspects of human FEN1 enzymatic reaction. The methodology presented in this review is aimed as a guide for tackling other biomolecular enzymatic reactions by fluorescence enhancement, quenching, and FRET and their combinations. Using these methods, we followed in real-time the structures of the substrate and product and 5' flap cleavage during catalysis. We illustrate that FEN1 actively bends the substrate to verify its features and continues to mold it to induce a protein disorder-to-order transitioning that controls active site assembly. This mechanism suppresses off-target cleavage of non-cognate substrates and promotes their dissociation with an accuracy that was underestimated from bulk assays. We determined that product release in FEN1 after the 5' flap release occurs in two steps; a brief binding to the bent nicked-product followed by longer binding to the unbent nicked-product before dissociation. Based on our cryo-electron microscopy structure of the human lagging strand replicase bound to FEN1, we propose how this two-step product release mechanism may regulate the final steps during the maturation of Okazaki fragments.
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Affiliation(s)
- Mohamed A Sobhy
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Muhammad Tehseen
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Masateru Takahashi
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Amer Bralić
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Alfredo De Biasio
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester LE1 7HB, UK
| | - Samir M Hamdan
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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20
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Israels B, Albrecht CS, Dang A, Barney M, von Hippel PH, Marcus AH. Submillisecond Conformational Transitions of Short Single-Stranded DNA Lattices by Photon Correlation Single-Molecule Förster Resonance Energy Transfer. J Phys Chem B 2021; 125:9426-9440. [PMID: 34379430 DOI: 10.1021/acs.jpcb.1c04119] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Thermally driven conformational fluctuations (or "breathing") of DNA play important roles in the function and regulation of the "macromolecular machinery of genome expression." Fluctuations in double-stranded (ds) DNA are involved in the transient exposure of pathways to protein binding sites within the DNA framework, leading to the binding of regulatory proteins to single-stranded (ss) DNA templates. These interactions often require that the ssDNA sequences, as well as the proteins involved, assume transient conformations critical for successful binding. Here, we use microsecond-resolved single-molecule Förster resonance energy transfer (smFRET) experiments to investigate the backbone fluctuations of short [oligo(dT)n] templates within DNA constructs that also serve as models for ss-dsDNA junctions. Such junctions, together with the attached ssDNA sequences, are involved in interactions with the ssDNA binding (ssb) proteins that control and integrate the functions of DNA replication complexes. We analyze these data using a chemical network model based on multiorder time-correlation functions and probability distribution functions that characterize the kinetic and thermodynamic behavior of the system. We find that the oligo(dT)n tails of ss-dsDNA constructs interconvert, on submillisecond time scales, between three macrostates with distinctly different end-to-end distances. These are (i) a "compact" macrostate that represents the dominant species at equilibrium; (ii) a "partially extended" macrostate that exists as minority species; and (iii) a "highly extended" macrostate that is present in trace amounts. We propose a model for ssDNA secondary structure that advances our understanding of how spontaneously formed nucleic acid conformations may facilitate the activities of ssDNA-associating proteins.
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Affiliation(s)
- Brett Israels
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States.,Department of Chemistry and Biochemistry, Center for Optical, Molecular and Quantum Science, University of Oregon, Eugene, Oregon 97403, United States
| | - Claire S Albrecht
- Department of Physics, Center for Optical, Molecular and Quantum Science, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States
| | - Anson Dang
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States
| | - Megan Barney
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States
| | - Peter H von Hippel
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States
| | - Andrew H Marcus
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States.,Department of Chemistry and Biochemistry, Center for Optical, Molecular and Quantum Science, University of Oregon, Eugene, Oregon 97403, United States.,Department of Physics, Center for Optical, Molecular and Quantum Science, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States
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21
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Wilson H, Wang Q. ABEL-FRET: tether-free single-molecule FRET with hydrodynamic profiling. Nat Methods 2021; 18:816-820. [PMID: 34127856 DOI: 10.1038/s41592-021-01173-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 05/04/2021] [Indexed: 02/03/2023]
Abstract
Single-molecule Förster resonance energy transfer (smFRET) has become a versatile and widespread method to probe nanoscale conformation and dynamics. However, current experimental modalities often resort to molecule immobilization for long observation times and do not always approach the resolution limit of FRET-based nanoscale metrology. Here we present ABEL-FRET, an immobilization-free platform for smFRET measurements with ultrahigh resolving power in FRET efficiency. Importantly, single-molecule diffusivity is used to provide additional size and shape information for hydrodynamic profiling of individual molecules, which, together with the concurrently measured intramolecular conformation through FRET, enables a holistic and dynamic view of biomolecules and their complexes.
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Affiliation(s)
- Hugh Wilson
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Quan Wang
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.
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22
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Fan HF, Su S. The regulation mechanism of the C-terminus of RecA proteins during DNA strand-exchange process. Biophys J 2021; 120:3166-3179. [PMID: 34197804 DOI: 10.1016/j.bpj.2021.06.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 04/21/2021] [Accepted: 06/03/2021] [Indexed: 12/14/2022] Open
Abstract
The C-terminus of Escherichia coli RecA protein can affect the DNA binding affinity, interact with accessory proteins, and regulate the RecA activity. A substantial upward shift in the pH-reaction profile of RecA-mediated DNA strand-exchange reactions was observed for C-terminal-truncated E. coli ΔC17 RecA, Deinococcus radiodurans RecA, and Deinococcus ficus RecA. Here, the process of RecA-mediated strand exchange from the beginning to the end was investigated with florescence resonance energy transfer and tethered particle motion experiments to determine the detailed regulation mechanism. RecA proteins with a shorter C-terminus possess more stable nuclei, higher DNA binding affinities, and lower protonation requirements for the formation of nucleoprotein filaments. Moreover, more stable synaptic complexes in the homologous sequence searching process were also observed for RecA proteins with a shorter C-terminus. Our results suggest that the C-terminus of RecA proteins regulates not only the formation of RecA nucleoprotein filaments but also the entrance of secondary DNA into RecA nucleoprotein filaments.
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Affiliation(s)
- Hsiu-Fang Fan
- Institute of Medical Science and Technology, Kaohsiung, Taiwan; Department of Chemistry, Kaohsiung, Taiwan; Aerosol Science Research Center, National Sun Yat-sen University, Kaohsiung, Taiwan.
| | - Shu Su
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
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23
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Fairlamb MS, Whitaker AM, Bain FE, Spies M, Freudenthal BD. Construction of a Three-Color Prism-Based TIRF Microscope to Study the Interactions and Dynamics of Macromolecules. BIOLOGY 2021; 10:biology10070571. [PMID: 34201434 PMCID: PMC8301196 DOI: 10.3390/biology10070571] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/08/2021] [Accepted: 06/15/2021] [Indexed: 02/05/2023]
Abstract
Simple Summary Prism-based single-molecule total internal reflection fluorescence (prismTIRF) microscopes are excellent tools for studying macromolecular dynamics and interactions. Here, we provide an easy-to-follow guide for the design, assembly, and operation of a three-color prismTIRF microscope using commercially available components with the hope of assisting those who aim to implement TIRF imaging techniques in their laboratory. Abstract Single-molecule total internal reflection fluorescence (TIRF) microscopy allows for the real-time visualization of macromolecular dynamics and complex assembly. Prism-based TIRF microscopes (prismTIRF) are relatively simple to operate and can be easily modulated to fit the needs of a wide variety of experimental applications. While building a prismTIRF microscope without expert assistance can pose a significant challenge, the components needed to build a prismTIRF microscope are relatively affordable and, with some guidance, the assembly can be completed by a determined novice. Here, we provide an easy-to-follow guide for the design, assembly, and operation of a three-color prismTIRF microscope which can be utilized for the study of macromolecular complexes, including the multi-component protein–DNA complexes responsible for DNA repair, replication, and transcription. Our hope is that this article can assist laboratories that aspire to implement single-molecule TIRF techniques, and consequently expand the application of this technology.
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Affiliation(s)
- Max S. Fairlamb
- Department of Biochemistry and Molecular Biology and Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA; (M.S.F.); (A.M.W.)
| | - Amy M. Whitaker
- Department of Biochemistry and Molecular Biology and Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA; (M.S.F.); (A.M.W.)
| | - Fletcher E. Bain
- Department of Biochemistry and Molecular Biology, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA; (F.E.B.); (M.S.)
| | - Maria Spies
- Department of Biochemistry and Molecular Biology, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA; (F.E.B.); (M.S.)
| | - Bret D. Freudenthal
- Department of Biochemistry and Molecular Biology and Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA; (M.S.F.); (A.M.W.)
- Correspondence:
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24
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Bianco PR, Lu Y. Single-molecule insight into stalled replication fork rescue in Escherichia coli. Nucleic Acids Res 2021; 49:4220-4238. [PMID: 33744948 PMCID: PMC8096234 DOI: 10.1093/nar/gkab142] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/15/2021] [Accepted: 02/22/2021] [Indexed: 01/05/2023] Open
Abstract
DNA replication forks stall at least once per cell cycle in Escherichia coli. DNA replication must be restarted if the cell is to survive. Restart is a multi-step process requiring the sequential action of several proteins whose actions are dictated by the nature of the impediment to fork progression. When fork progress is impeded, the sequential actions of SSB, RecG and the RuvABC complex are required for rescue. In contrast, when a template discontinuity results in the forked DNA breaking apart, the actions of the RecBCD pathway enzymes are required to resurrect the fork so that replication can resume. In this review, we focus primarily on the significant insight gained from single-molecule studies of individual proteins, protein complexes, and also, partially reconstituted regression and RecBCD pathways. This insight is related to the bulk-phase biochemical data to provide a comprehensive review of each protein or protein complex as it relates to stalled DNA replication fork rescue.
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Affiliation(s)
- Piero R Bianco
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA
| | - Yue Lu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA
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25
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Ren Z, Zhang Y, Wu T, Xue Q, Wang S. Simple and sensitive detection of deoxyribonucleic acid using a RecA-GFP fusion protein-DNA filament as probe. LUMINESCENCE 2021; 36:1272-1276. [PMID: 33837604 DOI: 10.1002/bio.4053] [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: 10/23/2020] [Revised: 02/27/2021] [Accepted: 04/06/2021] [Indexed: 11/06/2022]
Abstract
A simple, rapid and highly sensitive method for detection of double-stranded DNA (dsDNA) was developed using a novel fluorescence probe composed of a RecA-GFP fusion protein that had specific recognition of ssDNA complexes (RecA-GFP-DNA filament). The RecA-GFP fusion protein not only had strong fluorescence, but could also occur by homologous recombination. In the presence of the target dsDNA, the complementary ssDNA of the RecA-GFP-DNA filaments invaded one end of the dsDNA chain. In addition, the other end of the ssDNA dissociated the RecA-GFP filaments. An assay of the probe showed a linear relationship with dsDNA concentration in the range 1-11 nM, with a correlation coefficient of 0.9923. The limit of detection for dsDNA was determined experimentally to be 0.3 nM (3δ). Compared with conventional methods, this method has the advantages of simple operation, high specificity, and high sensitivity.
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Affiliation(s)
- Zijing Ren
- Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, China
| | - Yuanfu Zhang
- Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, China
| | - Tao Wu
- Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, China
| | - Qingwang Xue
- Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, China
| | - Shuhao Wang
- Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, China
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26
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Maman N, Kumar P, Yadav A, Feingold M. Single Molecule Study of the Polymerization of RecA on dsDNA: The Dynamics of Individual Domains. Front Mol Biosci 2021; 8:609076. [PMID: 33842536 PMCID: PMC8025788 DOI: 10.3389/fmolb.2021.609076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 02/02/2021] [Indexed: 11/13/2022] Open
Abstract
In the Escherichia coli, RecA plays a central role in the recombination and repair of the DNA. For homologous recombination, RecA binds to ssDNA forming a nucleoprotein filament. The RecA-ssDNA filament searches for a homologous sequence on a dsDNA and, subsequently, RecA mediates strand exchange between the ssDNA and the dsDNA. In vitro, RecA binds to both ssDNA and dsDNA. Despite a wide range of studies of the polymerization of RecA on dsDNA, both at the single molecule level and by means of biochemical methods, important aspects of this process are still awaiting a better understanding. Specifically, a detailed, quantitative description of the nucleation and growth dynamics of the RecA-dsDNA filaments is still lacking. Here, we use Optical Tweezers together with a single molecule analysis approach to measure the dynamics of the individual RecA domains on dsDNA and the corresponding growth rates for each of their fronts. We focus on the regime where the nucleation and growth rate constants, kn and kg, are comparable, leading to a coverage of the dsDNA molecule that consists of a small number of RecA domains. For the case of essentially irreversible binding (using ATPγS instead of ATP), we find that domain growth is highly asymmetric with a ratio of about 10:1 between the fast and slow fronts growth rates.
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Affiliation(s)
- Nitzan Maman
- Department of Physics, Ben Gurion University of the Negev, Beer Sheva, Israel.,The Ilse Katz Center for Nanotechnology, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Pramod Kumar
- Department of Physics, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Amarjeet Yadav
- Department of Physics, Ben Gurion University of the Negev, Beer Sheva, Israel.,Department of Applied Physics, Babasaheb Bhimrao Ambedkar University, Lucknow, India
| | - Mario Feingold
- Department of Physics, Ben Gurion University of the Negev, Beer Sheva, Israel.,The Ilse Katz Center for Nanotechnology, Ben Gurion University of the Negev, Beer Sheva, Israel
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27
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Paul T, Ha T, Myong S. Regeneration of PEG slide for multiple rounds of single-molecule measurements. Biophys J 2021; 120:1788-1799. [PMID: 33675764 DOI: 10.1016/j.bpj.2021.02.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/10/2021] [Accepted: 02/23/2021] [Indexed: 10/22/2022] Open
Abstract
Single-molecule fluorescence detection of protein and other biomolecules requires a polyethylene glycol (PEG)-passivated surface. Individual channels on a PEG-passivated slide are typically used only a few times, limiting the number of experiments per slide. Here, we report several strategies for regenerating PEG surfaces for multiple rounds of experiments. First, we show regeneration of DNA- or RNA-tethered surfaces by washing out the bound protein by 0.1% sodium dodecyl sulfate, which is significantly more effective than 6 M urea, 6 M GdmCl, or 100 μM proteinase K. Strikingly, 10 consecutive experiments in five different systems produced indistinguishable results both in molecule count and protein activity. Second, duplexed DNA unwound by helicase or denatured by 50 mM NaOH was reannealed with a complementary strand to regenerate the duplexed substrate with an exceptionally high recovery rate. Third, the biotin-PEG layer was regenerated by using 7 M NaOH to strip off NeutrAvidin, which can be reapplied for additional experiments. We demonstrate five cycles of regenerating antibody immobilized surface by which three different protein activity was measured. Altogether, our methods represent reliable and reproducible yet simple and rapid strategies that will enhance the efficiency of single-molecule experiments.
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Affiliation(s)
- Tapas Paul
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Taekjip Ha
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland; Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, Urbana, Illinois; Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, Maryland
| | - Sua Myong
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland; Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, Urbana, Illinois.
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28
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Single-molecule analysis reveals cooperative stimulation of Rad51 filament nucleation and growth by mediator proteins. Mol Cell 2021; 81:1058-1073.e7. [PMID: 33421363 PMCID: PMC7941204 DOI: 10.1016/j.molcel.2020.12.020] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/02/2020] [Accepted: 12/10/2020] [Indexed: 12/16/2022]
Abstract
Homologous recombination (HR) is an essential DNA double-strand break (DSB) repair mechanism, which is frequently inactivated in cancer. During HR, RAD51 forms nucleoprotein filaments on RPA-coated, resected DNA and catalyzes strand invasion into homologous duplex DNA. How RAD51 displaces RPA and assembles into long HR-proficient filaments remains uncertain. Here, we employed single-molecule imaging to investigate the mechanism of nematode RAD-51 filament growth in the presence of BRC-2 (BRCA2) and RAD-51 paralogs, RFS-1/RIP-1. BRC-2 nucleates RAD-51 on RPA-coated DNA, whereas RFS-1/RIP-1 acts as a "chaperone" to promote 3' to 5' filament growth via highly dynamic engagement with 5' filament ends. Inhibiting ATPase or mutation in the RFS-1 Walker box leads to RFS-1/RIP-1 retention on RAD-51 filaments and hinders growth. The rfs-1 Walker box mutants display sensitivity to DNA damage and accumulate RAD-51 complexes non-functional for HR in vivo. Our work reveals the mechanism of RAD-51 nucleation and filament growth in the presence of recombination mediators.
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29
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Naufer MN, Morse M, Möller GB, McIsaac J, Rouzina I, Beuning PJ, Williams MC. Multiprotein E. coli SSB-ssDNA complex shows both stable binding and rapid dissociation due to interprotein interactions. Nucleic Acids Res 2021; 49:1532-1549. [PMID: 33434279 PMCID: PMC7897507 DOI: 10.1093/nar/gkaa1267] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 12/10/2020] [Accepted: 12/21/2020] [Indexed: 11/14/2022] Open
Abstract
Escherichia coli SSB (EcSSB) is a model single-stranded DNA (ssDNA) binding protein critical in genome maintenance. EcSSB forms homotetramers that wrap ssDNA in multiple conformations to facilitate DNA replication and repair. Here we measure the binding and wrapping of many EcSSB proteins to a single long ssDNA substrate held at fixed tensions. We show EcSSB binds in a biphasic manner, where initial wrapping events are followed by unwrapping events as ssDNA-bound protein density passes critical saturation and high free protein concentration increases the fraction of EcSSBs in less-wrapped conformations. By destabilizing EcSSB wrapping through increased substrate tension, decreased substrate length, and protein mutation, we also directly observe an unstable bound but unwrapped state in which ∼8 nucleotides of ssDNA are bound by a single domain, which could act as a transition state through which rapid reorganization of the EcSSB-ssDNA complex occurs. When ssDNA is over-saturated, stimulated dissociation rapidly removes excess EcSSB, leaving an array of stably-wrapped complexes. These results provide a mechanism through which otherwise stably bound and wrapped EcSSB tetramers are rapidly removed from ssDNA to allow for DNA maintenance and replication functions, while still fully protecting ssDNA over a wide range of protein concentrations.
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Affiliation(s)
- M Nabuan Naufer
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Michael Morse
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | | | - James McIsaac
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
| | - Ioulia Rouzina
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA
| | - Penny J Beuning
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
| | - Mark C Williams
- Department of Physics, Northeastern University, Boston, MA 02115, USA
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30
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Kilic Z, Sgouralis I, Pressé S. Generalizing HMMs to Continuous Time for Fast Kinetics: Hidden Markov Jump Processes. Biophys J 2021; 120:409-423. [PMID: 33421415 PMCID: PMC7896036 DOI: 10.1016/j.bpj.2020.12.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 12/25/2020] [Accepted: 12/30/2020] [Indexed: 12/18/2022] Open
Abstract
The hidden Markov model (HMM) is a framework for time series analysis widely applied to single-molecule experiments. Although initially developed for applications outside the natural sciences, the HMM has traditionally been used to interpret signals generated by physical systems, such as single molecules, evolving in a discrete state space observed at discrete time levels dictated by the data acquisition rate. Within the HMM framework, transitions between states are modeled as occurring at the end of each data acquisition period and are described using transition probabilities. Yet, whereas measurements are often performed at discrete time levels in the natural sciences, physical systems evolve in continuous time according to transition rates. It then follows that the modeling assumptions underlying the HMM are justified if the transition rates of a physical process from state to state are small as compared to the data acquisition rate. In other words, HMMs apply to slow kinetics. The problem is, because the transition rates are unknown in principle, it is unclear, a priori, whether the HMM applies to a particular system. For this reason, we must generalize HMMs for physical systems, such as single molecules, because these switch between discrete states in "continuous time". We do so by exploiting recent mathematical tools developed in the context of inferring Markov jump processes and propose the hidden Markov jump process. We explicitly show in what limit the hidden Markov jump process reduces to the HMM. Resolving the discrete time discrepancy of the HMM has clear implications: we no longer need to assume that processes, such as molecular events, must occur on timescales slower than data acquisition and can learn transition rates even if these are on the same timescale or otherwise exceed data acquisition rates.
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Affiliation(s)
- Zeliha Kilic
- Center for Biological Physics, Department of Physics, Arizona State University, Tempe, Arizona
| | - Ioannis Sgouralis
- Department of Mathematics, University of Tennessee, Knoxville, Tennessee
| | - Steve Pressé
- Center for Biological Physics, Department of Physics, Arizona State University, Tempe, Arizona; School of Molecular Sciences, Arizona State University, Tempe, Arizona.
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Kuang Y, Guo X, Guo A, Ran X, He Y, Zhang Y, Guo L. Single-molecule enzymatic reaction dynamics and mechanisms of GPX3 and TRXh9 from Arabidopsis thaliana. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 243:118778. [PMID: 32810779 DOI: 10.1016/j.saa.2020.118778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 07/16/2020] [Accepted: 07/19/2020] [Indexed: 06/11/2023]
Abstract
Glutathione peroxidases (GPXs) regulate the levels of reactive oxygen species in cells and tissues. During the redox cycling, the plant GPX is regenerated by thioredoxins (TRXs) as reductant rather than glutathione as the electron donor. However, the direct experimental observation on the interaction dynamics between GPXs and TRXs has not been reported, and the redox mechanism is unclear. In this work, the protein interactions between oxidized AtGPX3 and reduced AtTRXh9 have been studied using single-molecule fluorescence resonance energy transfer (smFRET). The obtained results indicate there are four processes in these two protein interaction, including biological recognition, binding, intermediate and unbinding state. Two enzymatic reaction intermediate states have been identified in the dissociation of AtGPX3-AtTRXh9 complex from binding to unbinding state, suggesting two types of interaction pathways and intermediate complexes. In particular, the dynamical study reveals that the redox reaction between oxidized AtGPX3 and reduced AtTRXh9 is realized through the forming and breaking of disulfide bonds via the active sites of Cys4 and Cys57 in AtTRXh9. These findings are of significant for deep understanding the redox reaction and mechanism between GPXs and TRXs enzymes, and studying other protein dynamics at single-molecule level.
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Affiliation(s)
- Yanmin Kuang
- State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475004, China; School of Physics and Electronics, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, China
| | - Xing Guo
- School of Physics and Electronics, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, China
| | - Aiyu Guo
- State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475004, China
| | - Xia Ran
- State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475004, China; School of Physics and Electronics, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, China
| | - Yulu He
- School of Physics and Electronics, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, China
| | - Yu Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475004, China
| | - Lijun Guo
- State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475004, China; School of Physics and Electronics, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, China.
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32
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The PafBC-mediated response sensitizes a bistable DNA damage response in Mycobacteria. J Theor Biol 2020; 508:110462. [PMID: 32890555 DOI: 10.1016/j.jtbi.2020.110462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 08/05/2020] [Accepted: 08/24/2020] [Indexed: 01/03/2023]
Abstract
Due to the genotoxically challenging environments in which they live in, Mycobacteria have a complex DNA damage repair system that is governed by two major DNA damage responses, namely, the LexA/RecA-dependent response and the newly characterized PafBC-mediated response (Müller et al., 2018). The LexA/RecA-dependent response is a well-known bistable response found in different types of bacteria, and the Mycobacteria-specific PafBC-mediated response interacts with and modifies the LexA/RecA-dependent response (Müller et al., 2018). The interaction between the LexA/RecA-dependent response and the PafBC-mediated response has not been characterized mathematically. Our analysis shows that the addition of the PafBC-mediated response sensitizes the overall DNA damage response, effectively lowering the DNA damage rate threshold for activation.
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33
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Myka KK, Marians KJ. Two components of DNA replication-dependent LexA cleavage. J Biol Chem 2020; 295:10368-10379. [PMID: 32513870 PMCID: PMC7383369 DOI: 10.1074/jbc.ra120.014224] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/04/2020] [Indexed: 12/19/2022] Open
Abstract
Induction of the SOS response, a cellular system triggered by DNA damage in bacteria, depends on DNA replication for the generation of the SOS signal, ssDNA. RecA binds to ssDNA, forming filaments that stimulate proteolytic cleavage of the LexA transcriptional repressor, allowing expression of > 40 gene products involved in DNA repair and cell cycle regulation. Here, using a DNA replication system reconstituted in vitro in tandem with a LexA cleavage assay, we studied LexA cleavage during DNA replication of both undamaged and base-damaged templates. Only a ssDNA-RecA filament supported LexA cleavage. Surprisingly, replication of an undamaged template supported levels of LexA cleavage like that induced by a template carrying two site-specific cyclobutane pyrimidine dimers. We found that two processes generate ssDNA that could support LexA cleavage. 1) During unperturbed replication, single-stranded regions formed because of stochastic uncoupling of the leading-strand DNA polymerase from the replication fork DNA helicase, and 2) on the damaged template, nascent leading-strand gaps were generated by replisome lesion skipping. The two pathways differed in that RecF stimulated LexA cleavage during replication of the damaged template, but not normal replication. RecF appears to facilitate RecA filament formation on the leading-strand ssDNA gaps generated by replisome lesion skipping.
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Affiliation(s)
- Kamila K Myka
- Molecular Biology Program, Sloan Kettering Institute Memorial Sloan Kettering Cancer Center, New York, New York USA
| | - Kenneth J Marians
- Molecular Biology Program, Sloan Kettering Institute Memorial Sloan Kettering Cancer Center, New York, New York USA
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Mäeots ME, Lee B, Nans A, Jeong SG, Esfahani MMN, Ding S, Smith DJ, Lee CS, Lee SS, Peter M, Enchev RI. Modular microfluidics enables kinetic insight from time-resolved cryo-EM. Nat Commun 2020; 11:3465. [PMID: 32651368 PMCID: PMC7351747 DOI: 10.1038/s41467-020-17230-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/18/2020] [Indexed: 11/09/2022] Open
Abstract
Mechanistic understanding of biochemical reactions requires structural and kinetic characterization of the underlying chemical processes. However, no single experimental technique can provide this information in a broadly applicable manner and thus structural studies of static macromolecules are often complemented by biophysical analysis. Moreover, the common strategy of utilizing mutants or crosslinking probes to stabilize intermediates is prone to trapping off-pathway artefacts and precludes determining the order of molecular events. Here we report a time-resolved sample preparation method for cryo-electron microscopy (trEM) using a modular microfluidic device, featuring a 3D-mixing unit and variable delay lines that enables automated, fast, and blot-free sample vitrification. This approach not only preserves high-resolution structural detail but also substantially improves sample integrity and protein distribution across the vitreous ice. We validate the method by visualising reaction intermediates of early RecA filament growth across three orders of magnitude on sub-second timescales. The trEM method reported here is versatile, reproducible, and readily adaptable to a broad spectrum of fundamental questions in biology.
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Affiliation(s)
- Märt-Erik Mäeots
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093, Zurich, Switzerland
- The Visual Biochemistry Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Byungjin Lee
- Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Yuseong-Gu, Daejeon, 305-764, Republic of Korea
| | - Andrea Nans
- Structural Biology Scientific Technology Platform, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Seung-Geun Jeong
- Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Yuseong-Gu, Daejeon, 305-764, Republic of Korea
| | - Mohammad M N Esfahani
- The Visual Biochemistry Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Shan Ding
- The Visual Biochemistry Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Daniel J Smith
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093, Zurich, Switzerland
- Scientific Center for Optical and Electron Microscopy, ETH Zurich, Otto-Stern-Weg 3, 8093, Zurich, Switzerland
| | - Chang-Soo Lee
- Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Yuseong-Gu, Daejeon, 305-764, Republic of Korea.
| | - Sung Sik Lee
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093, Zurich, Switzerland.
- Scientific Center for Optical and Electron Microscopy, ETH Zurich, Otto-Stern-Weg 3, 8093, Zurich, Switzerland.
| | - Matthias Peter
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093, Zurich, Switzerland.
| | - Radoslav I Enchev
- Institute of Biochemistry, Department of Biology, ETH Zurich, Otto-Stern-Weg 3, 8093, Zurich, Switzerland.
- The Visual Biochemistry Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK.
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Paul T, Voter AF, Cueny RR, Gavrilov M, Ha T, Keck J, Myong S. E. coli Rep helicase and RecA recombinase unwind G4 DNA and are important for resistance to G4-stabilizing ligands. Nucleic Acids Res 2020; 48:6640-6653. [PMID: 32449930 PMCID: PMC7337899 DOI: 10.1093/nar/gkaa442] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/24/2020] [Accepted: 05/21/2020] [Indexed: 11/30/2022] Open
Abstract
G-quadruplex (G4) DNA structures can form physical barriers within the genome that must be unwound to ensure cellular genomic integrity. Here, we report unanticipated roles for the Escherichia coli Rep helicase and RecA recombinase in tolerating toxicity induced by G4-stabilizing ligands in vivo. We demonstrate that Rep and Rep-X (an enhanced version of Rep) display G4 unwinding activities in vitro that are significantly higher than the closely related UvrD helicase. G4 unwinding mediated by Rep involves repetitive cycles of G4 unfolding and refolding fueled by ATP hydrolysis. Rep-X and Rep also dislodge G4-stabilizing ligands, in agreement with our in vivo G4-ligand sensitivity result. We further demonstrate that RecA filaments disrupt G4 structures and remove G4 ligands in vitro, consistent with its role in countering cellular toxicity of G4-stabilizing ligands. Together, our study reveals novel genome caretaking functions for Rep and RecA in resolving deleterious G4 structures.
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Affiliation(s)
- Tapas Paul
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Andrew F Voter
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
| | - Rachel R Cueny
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
| | - Momčilo Gavrilov
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Taekjip Ha
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
- Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA
- Howard Hughes Medical Institute, Johns Hopkins University, USA
| | - James L Keck
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
| | - Sua Myong
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
- Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA
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36
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A Comprehensive View of Translesion Synthesis in Escherichia coli. Microbiol Mol Biol Rev 2020; 84:84/3/e00002-20. [PMID: 32554755 DOI: 10.1128/mmbr.00002-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The lesion bypass pathway, translesion synthesis (TLS), exists in essentially all organisms and is considered a pathway for postreplicative gap repair and, at the same time, for lesion tolerance. As with the saying "a trip is not over until you get back home," studying TLS only at the site of the lesion is not enough to understand the whole process of TLS. Recently, a genetic study uncovered that polymerase V (Pol V), a poorly expressed Escherichia coli TLS polymerase, is not only involved in the TLS step per se but also participates in the gap-filling reaction over several hundred nucleotides. The same study revealed that in contrast, Pol IV, another highly expressed TLS polymerase, essentially stays away from the gap-filling reaction. These observations imply fundamentally different ways these polymerases are recruited to DNA in cells. While access of Pol IV appears to be governed by mass action, efficient recruitment of Pol V involves a chaperone-like action of the RecA filament. We present a model of Pol V activation: the 3' tip of the RecA filament initially stabilizes Pol V to allow stable complex formation with a sliding β-clamp, followed by the capture of the terminal RecA monomer by Pol V, thus forming a functional Pol V complex. This activation process likely determines higher accessibility of Pol V than of Pol IV to normal DNA. Finally, we discuss the biological significance of TLS polymerases during gap-filling reactions: error-prone gap-filling synthesis may contribute as a driving force for genetic diversity, adaptive mutation, and evolution.
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37
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Li Y, Zhao L, Yao Y, Guo X. Single-Molecule Nanotechnologies: An Evolution in Biological Dynamics Detection. ACS APPLIED BIO MATERIALS 2019; 3:68-85. [DOI: 10.1021/acsabm.9b00840] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yu Li
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Lihua Zhao
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Yuan Yao
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Xuefeng Guo
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
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38
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Müller AU, Imkamp F, Weber-Ban E. The Mycobacterial LexA/RecA-Independent DNA Damage Response Is Controlled by PafBC and the Pup-Proteasome System. Cell Rep 2019; 23:3551-3564. [PMID: 29924998 DOI: 10.1016/j.celrep.2018.05.073] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/16/2018] [Accepted: 05/22/2018] [Indexed: 12/11/2022] Open
Abstract
Mycobacteria exhibit two DNA damage response pathways: the LexA/RecA-dependent SOS response and a LexA/RecA-independent pathway. Using a combination of transcriptomics and genome-wide binding site analysis, we demonstrate that PafBC (proteasome accessory factor B and C), encoded in the Pup-proteasome system (PPS) gene locus, is the transcriptional regulator of the predominant LexA/RecA-independent pathway. Comparison of the resulting PafBC regulon with the DNA damage response of Mycobacterium smegmatis reveals that the majority of induced DNA repair genes are upregulated by PafBC. We further demonstrate that RecA, a member of the PafBC regulon and principal regulator of the SOS response, is degraded by the PPS when DNA damage stress has been overcome. Our results suggest a model for the regulation of the mycobacterial DNA damage response that employs the concerted action of PafBC as master transcriptional activator and the PPS for removal of DNA repair proteins to maintain a temporally controlled stress response.
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Affiliation(s)
- Andreas U Müller
- ETH Zurich, Institute of Molecular Biology and Biophysics, 8093 Zurich, Switzerland
| | - Frank Imkamp
- University of Zurich, Institute of Medical Microbiology, 8006 Zurich, Switzerland
| | - Eilika Weber-Ban
- ETH Zurich, Institute of Molecular Biology and Biophysics, 8093 Zurich, Switzerland.
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39
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Homologous Recombination under the Single-Molecule Fluorescence Microscope. Int J Mol Sci 2019; 20:ijms20236102. [PMID: 31816946 PMCID: PMC6929127 DOI: 10.3390/ijms20236102] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/26/2019] [Accepted: 11/30/2019] [Indexed: 11/16/2022] Open
Abstract
Homologous recombination (HR) is a complex biological process and is central to meiosis and for repair of DNA double-strand breaks. Although the HR process has been the subject of intensive study for more than three decades, the complex protein–protein and protein–DNA interactions during HR present a significant challenge for determining the molecular mechanism(s) of the process. This knowledge gap is largely because of the dynamic interactions between HR proteins and DNA which is difficult to capture by routine biochemical or structural biology methods. In recent years, single-molecule fluorescence microscopy has been a popular method in the field of HR to visualize these complex and dynamic interactions at high spatiotemporal resolution, revealing mechanistic insights of the process. In this review, we describe recent efforts that employ single-molecule fluorescence microscopy to investigate protein–protein and protein–DNA interactions operating on three key DNA-substrates: single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), and four-way DNA called Holliday junction (HJ). We also outline the technological advances and several key insights revealed by these studies in terms of protein assembly on these DNA substrates and highlight the foreseeable promise of single-molecule fluorescence microscopy in advancing our understanding of homologous recombination.
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40
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Lin YH, Chu CC, Fan HF, Wang PY, Cox MM, Li HW. A 5'-to-3' strand exchange polarity is intrinsic to RecA nucleoprotein filaments in the absence of ATP hydrolysis. Nucleic Acids Res 2019; 47:5126-5140. [PMID: 30916331 PMCID: PMC6547424 DOI: 10.1093/nar/gkz189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 03/08/2019] [Accepted: 03/11/2019] [Indexed: 01/13/2023] Open
Abstract
RecA is essential to recombinational DNA repair in which RecA filaments mediate the homologous DNA pairing and strand exchange. Both RecA filament assembly and the subsequent DNA strand exchange are directional. Here, we demonstrate that the polarity of DNA strand exchange is embedded within RecA filaments even in the absence of ATP hydrolysis, at least over short DNA segments. Using single-molecule tethered particle motion, we show that successful strand exchange in the presence of ATP proceeds with a 5′-to-3′ polarity, as demonstrated previously. RecA filaments prepared with ATPγS also exhibit a 5′-to-3′ progress of strand exchange, suggesting that the polarity is not determined by RecA disassembly and/or ATP hydrolysis. RecAΔC17 mutants, lacking a C-terminal autoregulatory flap, also promote strand exchange in a 5′-to-3′ polarity in ATPγS, a polarity that is largely lost with this RecA variant when ATP is hydrolyzed. We propose that there is an inherent strand exchange polarity mediated by the structure of the RecA filament groove, associated by conformation changes propagated in a polar manner as DNA is progressively exchanged. ATP hydrolysis is coupled to polar strand exchange over longer distances, and its contribution to the polarity requires an intact RecA C-terminus.
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Affiliation(s)
- Yu-Hsuan Lin
- Department of Chemistry, National Taiwan University, 10617, Taiwan
| | - Chia-Chieh Chu
- Department of Chemistry, National Taiwan University, 10617, Taiwan
| | - Hsiu-Fang Fan
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, 11221 Taiwan
| | - Pang-Yen Wang
- Department of Chemistry, National Taiwan University, 10617, Taiwan
| | - Michael M Cox
- Department of Biochemistry, University of Wisconsin, Madison, 53706, USA
| | - Hung-Wen Li
- Department of Chemistry, National Taiwan University, 10617, Taiwan
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41
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Keyamura K, Hishida T. Topological DNA-binding of structural maintenance of chromosomes-like RecN promotes DNA double-strand break repair in Escherichia coli. Commun Biol 2019; 2:413. [PMID: 31754643 PMCID: PMC6856136 DOI: 10.1038/s42003-019-0655-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 10/16/2019] [Indexed: 12/21/2022] Open
Abstract
Bacterial RecN, closely related to the structural maintenance of chromosomes (SMC) family of proteins, functions in the repair of DNA double-strand breaks (DSBs) by homologous recombination. Here we show that the purified Escherichia coli RecN protein topologically loads onto both single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) that has a preference for ssDNA. RecN topologically bound to dsDNA slides off the end of linear dsDNA, but this is prevented by RecA nucleoprotein filaments on ssDNA, thereby allowing RecN to translocate to DSBs. Furthermore, we found that, once RecN is recruited onto ssDNA, it can topologically capture a second dsDNA substrate in an ATP-dependent manner, suggesting a role in synapsis. Indeed, RecN stimulates RecA-mediated D-loop formation and subsequent strand exchange activities. Our findings provide mechanistic insights into the recruitment of RecN to DSBs and sister chromatid interactions by RecN, both of which function in RecA-mediated DSB repair.
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Affiliation(s)
- Kenji Keyamura
- Department of Molecular Biology, Graduate School of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588 Japan
| | - Takashi Hishida
- Department of Molecular Biology, Graduate School of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588 Japan
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42
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Schärfen L, Schlierf M. Real-time monitoring of protein-induced DNA conformational changes using single-molecule FRET. Methods 2019; 169:11-20. [DOI: 10.1016/j.ymeth.2019.02.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 12/21/2018] [Accepted: 02/11/2019] [Indexed: 12/11/2022] Open
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Amundsen SK, Smith GR. The RecB helicase-nuclease tether mediates Chi hotspot control of RecBCD enzyme. Nucleic Acids Res 2019; 47:197-209. [PMID: 30445486 PMCID: PMC6326792 DOI: 10.1093/nar/gky1132] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 10/29/2018] [Indexed: 11/25/2022] Open
Abstract
In bacteria, repair of DNA double-strand breaks uses a highly conserved helicase–nuclease complex to unwind DNA from a broken end and cut it at specific DNA sequences called Chi. In Escherichia coli the RecBCD enzyme also loads the DNA strand-exchange protein RecA onto the newly formed end, resulting in a recombination hotspot at Chi. Chi hotspots regulate multiple RecBCD activities by altering RecBCD’s conformation, which is proposed to include the swinging of the RecB nuclease domain on the 19-amino-acid tether connecting the helicase and nuclease domains. Here, we altered the tether and tested multiple RecBCD activities, genetically in cells and enzymatically in cell-free extracts. Randomizing the amino-acid sequence or lengthening it had little effect. However, shortening it by as little as two residues or making substitutions of ≥10 proline or ≥9 glycine residues dramatically lowered Chi-dependent activities. These results indicate that proper control of RecBCD by Chi requires that the tether be long enough and appropriately flexible. We discuss a model in which the swing-time of the nuclease domain determines the position of Chi-dependent and Chi-independent cuts and Chi hotspot activity.
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Affiliation(s)
- Susan K Amundsen
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109 USA
| | - Gerald R Smith
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109 USA
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44
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Yokota H. Fluorescence microscopy for visualizing single-molecule protein dynamics. Biochim Biophys Acta Gen Subj 2019; 1864:129362. [PMID: 31078674 DOI: 10.1016/j.bbagen.2019.05.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 04/26/2019] [Accepted: 05/07/2019] [Indexed: 01/06/2023]
Abstract
BACKGROUND Single-molecule fluorescence imaging (smFI) has evolved into a valuable method used in biophysical and biochemical studies as it can observe the real-time behavior of individual protein molecules, enabling understanding of their detailed dynamic features. smFI is also closely related to other state-of-the-art microscopic methods, optics, and nanomaterials in that smFI and these technologies have developed synergistically. SCOPE OF REVIEW This paper provides an overview of the recently developed single-molecule fluorescence microscopy methods, focusing on critical techniques employed in higher-precision measurements in vitro and fluorescent nanodiamond, an emerging promising fluorophore that will improve single-molecule fluorescence microscopy. MAJOR CONCLUSIONS smFI will continue to improve regarding the photostability of fluorophores and will develop via combination with other techniques based on nanofabrication, single-molecule manipulation, and so on. GENERAL SIGNIFICANCE Quantitative, high-resolution single-molecule studies will help establish an understanding of protein dynamics and complex biomolecular systems.
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Affiliation(s)
- Hiroaki Yokota
- Biophotonics Laboratory, Graduate School for the Creation of New Photonics Industries, Kurematsu-cho, Nishi-ku, Hamamatsu, Shizuoka 431-1202, Japan.
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45
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Tutkus M, Rakickas T, Kopu Stas A, Ivanovaitė ŠN, Venckus O, Navikas V, Zaremba M, Manakova E, Valiokas RN. Fixed DNA Molecule Arrays for High-Throughput Single DNA-Protein Interaction Studies. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5921-5930. [PMID: 30955328 DOI: 10.1021/acs.langmuir.8b03424] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The DNA Curtains assay is a recently developed experimental platform for protein-DNA interaction studies at the single-molecule level that is based on anchoring and alignment of DNA fragments. The DNA Curtains so far have been made by using chromium barriers and fluid lipid bilayer membranes, which makes such a specialized assay technically challenging and relatively unstable. Herein, we report on an alternative strategy for DNA arraying for analysis of individual DNA-protein interactions. It relies on stable DNA tethering onto nanopatterned protein templates via high affinity molecular recognition. We describe fabrication of streptavidin templates (line features as narrow as 200 nm) onto modified glass coverslips by combining surface chemistry, atomic force microscopy (AFM), and soft lithography techniques with affinity-driven assembly. We have employed such chips for arraying single- and double-tethered DNA strands, and we characterized the obtained molecular architecture: we evaluated the structural characteristics and specific versus nonspecific binding of fluorescence-labeled DNA using AFM and total internal reflection fluorescence microscopy. We demonstrate the feasibility of our DNA molecule arrays for short single-tethered as well as for lambda single- and double-tethered DNA. The latter type of arrays proved very suitable for localization of single DNA-protein interactions employing restriction endonucleases. The presented molecular architecture and facile method of fabrication of our nanoscale platform does not require clean room equipment, and it offers advanced functional studies of DNA machineries and the development of future nanodevices.
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Affiliation(s)
| | | | - Aurimas Kopu Stas
- Vilnius University, Life Sciences Center, Institute of Biotechnology , Sauletekio av. 7 , Vilnius LT-10257 , Lithuania
| | | | | | | | - Mindaugas Zaremba
- Vilnius University, Life Sciences Center, Institute of Biotechnology , Sauletekio av. 7 , Vilnius LT-10257 , Lithuania
| | - Elena Manakova
- Vilnius University, Life Sciences Center, Institute of Biotechnology , Sauletekio av. 7 , Vilnius LT-10257 , Lithuania
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46
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Ma D, Xu C, Hou W, Zhao C, Ma J, Huang X, Jia Q, Ma L, Diao J, Liu C, Li M, Lu Y. Detecting Single‐Molecule Dynamics on Lipid Membranes with Quenchers‐in‐a‐Liposome FRET. Angew Chem Int Ed Engl 2019; 58:5577-5581. [DOI: 10.1002/anie.201813888] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 02/11/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Dong‐Fei Ma
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Chun‐Hua Xu
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Wen‐Qing Hou
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Chun‐Yu Zhao
- Interdisciplinary Research Center on Biology and ChemistryShanghai Institute of Organic ChemistryChinese Academy of Sciences Shanghai 200032 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jian‐Bing Ma
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Xing‐Yuan Huang
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Qi Jia
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Lu Ma
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jiajie Diao
- Department of Cancer BiologyUniversity of Cincinnati School of Medicine Cincinnati OH 45267 USA
| | - Cong Liu
- Interdisciplinary Research Center on Biology and ChemistryShanghai Institute of Organic ChemistryChinese Academy of Sciences Shanghai 200032 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Ming Li
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
- Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China
| | - Ying Lu
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
- Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China
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47
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Ma D, Xu C, Hou W, Zhao C, Ma J, Huang X, Jia Q, Ma L, Diao J, Liu C, Li M, Lu Y. Detecting Single‐Molecule Dynamics on Lipid Membranes with Quenchers‐in‐a‐Liposome FRET. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201813888] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Dong‐Fei Ma
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Chun‐Hua Xu
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Wen‐Qing Hou
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Chun‐Yu Zhao
- Interdisciplinary Research Center on Biology and ChemistryShanghai Institute of Organic ChemistryChinese Academy of Sciences Shanghai 200032 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jian‐Bing Ma
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Xing‐Yuan Huang
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Qi Jia
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Lu Ma
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jiajie Diao
- Department of Cancer BiologyUniversity of Cincinnati School of Medicine Cincinnati OH 45267 USA
| | - Cong Liu
- Interdisciplinary Research Center on Biology and ChemistryShanghai Institute of Organic ChemistryChinese Academy of Sciences Shanghai 200032 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Ming Li
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
- Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China
| | - Ying Lu
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 China
- Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China
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48
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Okamoto K, Sako Y. Single-Molecule Förster Resonance Energy Transfer Measurement Reveals the Dynamic Partially Ordered Structure of the Epidermal Growth Factor Receptor C-Tail Domain. J Phys Chem B 2019; 123:571-581. [PMID: 30571124 DOI: 10.1021/acs.jpcb.8b10066] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Intrinsically disordered proteins (IDPs) or regions (IDRs) are thought to exhibit unique functionalities without forming ordered structures. However, these molecular mechanisms are not easily elucidated, partly because of the difficultly of measuring structural information. In this study, we applied the alternative laser excitation (ALEX) method and circular dichroism (CD) spectroscopy to investigate the structure of the C-terminal tail (CTT) domain of the human epidermal growth factor receptor (EGFR). The single-molecule distributions of Förster resonance energy transfer (FRET) obtained by ALEX under solution conditions modified by the addition of potassium chloride (KCl), urea, or guanidinium chloride (GdmCl) allowed us to separately examine the influences of charge interactions and secondary structure formation. The CD spectrum analyses indicated the types of included secondary structure. The results suggested that the structure of the CTT is influenced by secondary structure formation, which is a principally antiparallel β-sheet, rather than by charge interactions and that phosphorylation of the major Grb2-binding sites partially denatures that secondary structure. Our findings suggest that the EGFR CTT might regulate ligand binding kinetics by local β-sheet formation or by the disruption associated with phosphorylation states.
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Affiliation(s)
- Kenji Okamoto
- Cellular Informatics Laboratory , RIKEN , 2-1 Hirosawa , Wako , Saitama 351-0198 Japan
| | - Yasushi Sako
- Cellular Informatics Laboratory , RIKEN , 2-1 Hirosawa , Wako , Saitama 351-0198 Japan
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49
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Schmid S, Hugel T. Efficient use of single molecule time traces to resolve kinetic rates, models and uncertainties. J Chem Phys 2018; 148:123312. [PMID: 29604821 DOI: 10.1063/1.5006604] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Single molecule time traces reveal the time evolution of unsynchronized kinetic systems. Especially single molecule Förster resonance energy transfer (smFRET) provides access to enzymatically important time scales, combined with molecular distance resolution and minimal interference with the sample. Yet the kinetic analysis of smFRET time traces is complicated by experimental shortcomings-such as photo-bleaching and noise. Here we recapitulate the fundamental limits of single molecule fluorescence that render the classic, dwell-time based kinetic analysis unsuitable. In contrast, our Single Molecule Analysis of Complex Kinetic Sequences (SMACKS) considers every data point and combines the information of many short traces in one global kinetic rate model. We demonstrate the potential of SMACKS by resolving the small kinetic effects caused by different ionic strengths in the chaperone protein Hsp90. These results show an unexpected interrelation between conformational dynamics and ATPase activity in Hsp90.
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Affiliation(s)
- Sonja Schmid
- Institute of Physical Chemistry II, University of Freiburg, Albertstr. 23 a, 79104 Freiburg, Germany
| | - Thorsten Hugel
- Institute of Physical Chemistry II, University of Freiburg, Albertstr. 23 a, 79104 Freiburg, Germany
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50
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Swi5-Sfr1 stimulates Rad51 recombinase filament assembly by modulating Rad51 dissociation. Proc Natl Acad Sci U S A 2018; 115:E10059-E10068. [PMID: 30297419 DOI: 10.1073/pnas.1812753115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic Rad51 protein is essential for homologous-recombination repair of DNA double-strand breaks. Rad51 recombinases first assemble onto single-stranded DNA to form a nucleoprotein filament, required for function in homology pairing and strand exchange. This filament assembly is the first regulation step in homologous recombination. Rad51 nucleation is kinetically slow, and several accessory factors have been identified to regulate this step. Swi5-Sfr1 (S5S1) stimulates Rad51-mediated homologous recombination by stabilizing Rad51 nucleoprotein filaments, but the mechanism of stabilization is unclear. We used single-molecule tethered particle motion experiments to show that mouse S5S1 (mS5S1) efficiently stimulates mouse RAD51 (mRAD51) nucleus formation and inhibits mRAD51 dissociation from filaments. We also used single-molecule fluorescence resonance energy transfer experiments to show that mS5S1 promotes stable nucleus formation by specifically preventing mRAD51 dissociation. This leads to a reduction of nucleation size from three mRAD51 to two mRAD51 molecules in the presence of mS5S1. Compared with mRAD51, fission yeast Rad51 (SpRad51) exhibits fast nucleation but quickly dissociates from the filament. SpS5S1 specifically reduces SpRad51 disassembly to maintain a stable filament. These results clearly demonstrate the conserved function of S5S1 by primarily stabilizing Rad51 on DNA, allowing both the formation of the stable nucleus and the maintenance of filament length.
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