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Takahashi M, Ito K, Iwasaki H, Norden B. Linear dichroism reveals the perpendicular orientation of DNA bases in the RecA and Rad51 recombinase filaments: A possible mechanism for the strand exchange reaction. Chirality 2024; 36:e23664. [PMID: 38561319 DOI: 10.1002/chir.23664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 02/26/2024] [Accepted: 03/06/2024] [Indexed: 04/04/2024]
Abstract
Linear dichroism spectroscopy is used to investigate the structure of RecA family recombinase filaments (RecA and Rad51 proteins) with DNA for clarifying the molecular mechanism of DNA strand exchange promoted by these proteins and its activation. The measurements show that the recombinases promote the perpendicular base orientation of single-stranded DNA only in the presence of activators, indicating the importance of base orientation in the reaction. We summarize the results and discuss the role of DNA base orientation.
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Affiliation(s)
- Masayuki Takahashi
- School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Kentaro Ito
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Hiroshi Iwasaki
- School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
- Innovative Science Institute, Tokyo Institute of Technology, Yokohama, Japan
| | - Bengt Norden
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
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2
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Shioi T, Hatazawa S, Oya E, Hosoya N, Kobayashi W, Ogasawara M, Kobayashi T, Takizawa Y, Kurumizaka H. Cryo-EM structures of RAD51 assembled on nucleosomes containing a DSB site. Nature 2024; 628:212-220. [PMID: 38509361 PMCID: PMC10990931 DOI: 10.1038/s41586-024-07196-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 02/13/2024] [Indexed: 03/22/2024]
Abstract
RAD51 is the central eukaryotic recombinase required for meiotic recombination and mitotic repair of double-strand DNA breaks (DSBs)1,2. However, the mechanism by which RAD51 functions at DSB sites in chromatin has remained elusive. Here we report the cryo-electron microscopy structures of human RAD51-nucleosome complexes, in which RAD51 forms ring and filament conformations. In the ring forms, the N-terminal lobe domains (NLDs) of RAD51 protomers are aligned on the outside of the RAD51 ring, and directly bind to the nucleosomal DNA. The nucleosomal linker DNA that contains the DSB site is recognized by the L1 and L2 loops-active centres that face the central hole of the RAD51 ring. In the filament form, the nucleosomal DNA is peeled by the RAD51 filament extension, and the NLDs of RAD51 protomers proximal to the nucleosome bind to the remaining nucleosomal DNA and histones. Mutations that affect nucleosome-binding residues of the RAD51 NLD decrease nucleosome binding, but barely affect DNA binding in vitro. Consistently, yeast Rad51 mutants with the corresponding mutations are substantially defective in DNA repair in vivo. These results reveal an unexpected function of the RAD51 NLD, and explain the mechanism by which RAD51 associates with nucleosomes, recognizes DSBs and forms the active filament in chromatin.
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Affiliation(s)
- Takuro Shioi
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Suguru Hatazawa
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan
| | - Eriko Oya
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan
| | - Noriko Hosoya
- Laboratory of Molecular Radiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Wataru Kobayashi
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan
| | - Mitsuo Ogasawara
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan
| | - Takehiko Kobayashi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan
| | - Yoshimasa Takizawa
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan.
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
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3
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Takahashi M, Norden B. Linear Dichroism Measurements for the Study of Protein-DNA Interactions. Int J Mol Sci 2023; 24:16092. [PMID: 38003280 PMCID: PMC10671323 DOI: 10.3390/ijms242216092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 11/04/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
Linear dichroism (LD) is a differential polarized light absorption spectroscopy used for studying filamentous molecules such as DNA and protein filaments. In this study, we review the applications of LD for the analysis of DNA-protein interactions. LD signals can be measured in a solution by aligning the sample using flow-induced shear force or a strong electric field. The signal generated is related to the local orientation of chromophores, such as DNA bases, relative to the filament axis. LD can thus assess the tilt and roll of DNA bases and distinguish intercalating from groove-binding ligands. The intensity of the LD signal depends upon the degree of macroscopic orientation. Therefore, DNA shortening and bending can be detected by a decrease in LD signal intensity. As examples of LD applications, we present a kinetic study of DNA digestion by restriction enzymes and structural analyses of homologous recombination intermediates, i.e., RecA and Rad51 recombinase complexes with single-stranded DNA. LD shows that the DNA bases in these complexes are preferentially oriented perpendicular to the filament axis only in the presence of activators, suggesting the importance of organized base orientation for the reaction. LD measurements detect DNA bending by the CRP transcription activator protein, as well as by the UvrB DNA repair protein. LD can thus provide information about the structures of protein-DNA complexes under various conditions and in real time.
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Affiliation(s)
- Masayuki Takahashi
- School of Life Science and Technology, Tokyo Institute of Technology, Oookayama, Meguro, Tokyo 152-8550, Japan
| | - Bengt Norden
- Department of Chemical and Biological Engineering, Chemistry, Chalmers University of Technology, 412 96 Gothenburg, Sweden;
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4
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The Development of Single Molecule Force Spectroscopy: From Polymer Biophysics to Molecular Machines. Q Rev Biophys 2022; 55:e9. [PMID: 35916314 DOI: 10.1017/s0033583522000087] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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5
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García-Lepe UO, Torres-Dimas E, Espinal-Centeno A, Cruz-Ramírez A, Bermúdez-Cruz RM. Evidence of requirement for homologous-mediated DNA repair during Ambystoma mexicanum limb regeneration. Dev Dyn 2022; 251:1035-1053. [PMID: 35040539 DOI: 10.1002/dvdy.455] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 12/22/2021] [Accepted: 01/06/2022] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Limb regeneration in the axolotl is achieved by epimorphosis, thus depending on the blastema formation, a mass of progenitor cells capable of proliferating and differentiating to recover all lost structures functionally. During regeneration, the blastema cells accelerate the cell cycle and duplicate its genome, which is inherently difficult to replicate because of its length and composition, thus being prone to suffer double-strand breaks. RESULTS We identified and characterized two remarkable components of the homologous recombination repair pathway (Amex.RAD51 and Amex.MRE11), which were heterologously expressed, biochemically characterized, and inhibited by specific chemicals. These same inhibitors were applied at different time points after amputation to study their effects during limb regeneration. We observed an increase in cellular senescent accompanied by a slight delay in regeneration at 28 days post-amputation regenerated tissues; moreover, inhibitors caused a rise in the double-strand break signaling as a response to the inhibition of the repair mechanisms. CONCLUSIONS We confirmed the participation and importance of homologous recombination during limb regeneration. Where the chemical inhibition induces double-strand breaks that lead to DNA damage associated senescence, or in an alternatively way, this damage could be possibly repaired by a different DNA repair pathway, permitting proper regeneration and avoiding senescence. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Ulises Omar García-Lepe
- Genetics and Molecular Biology Department, Centro de Investigación y Estudios Avanzados del IPN Mexico city, Mexico
| | - Esteban Torres-Dimas
- Genetics and Molecular Biology Department, Centro de Investigación y Estudios Avanzados del IPN Mexico city, Mexico
| | - Annie Espinal-Centeno
- Molecular and Developmental Complexity Group, Unidad de Genómica Avanzada (LANGEBIO), Centro de Investigación y de Estudios Avanzados del IPN, Guanajuato, Mexico
| | - Alfredo Cruz-Ramírez
- Molecular and Developmental Complexity Group, Unidad de Genómica Avanzada (LANGEBIO), Centro de Investigación y de Estudios Avanzados del IPN, Guanajuato, Mexico
| | - Rosa María Bermúdez-Cruz
- Genetics and Molecular Biology Department, Centro de Investigación y Estudios Avanzados del IPN Mexico city, Mexico
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6
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Inhibiting homologous recombination by targeting RAD51 protein. Biochim Biophys Acta Rev Cancer 2021; 1876:188597. [PMID: 34332021 DOI: 10.1016/j.bbcan.2021.188597] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 07/09/2021] [Accepted: 07/24/2021] [Indexed: 02/06/2023]
Abstract
Homologous recombination (HR) is involved in repairing DNA double-strand breaks (DSB), the most harmful for the cell. Regulating HR is essential for maintaining genomic stability. In many forms of cancer, overactivation of HR increases tumor resistance to DNA-damaging treatments. RAD51, HR's core protein, is very often over-expressed in these cancers and plays a critical role in cancer cell development and survival. Targeting RAD51 directly to reduce its activity and its expression is therefore one strategy to sensitize and overcome resistance cancer cells to existing DNA-damaging therapies which remains the limiting factor for the success of targeted therapy. This review describes the structure and biological roles of RAD51, summarizes the different targeted sites of RAD51 and its inhibitory compounds discovered and described in the last decade.
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7
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Nordén B, Brown T, Feng B. Mismatch detection in homologous strand exchange amplified by hydrophobic effects. Biopolymers 2021; 112:e23426. [PMID: 33780001 DOI: 10.1002/bip.23426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 02/16/2021] [Accepted: 03/10/2021] [Indexed: 12/19/2022]
Abstract
In contrast to DNA replication and transcription where nucleotides are added and matched one by one, homologous recombination by DNA strand exchange tests whole sequences for complementarity, which requires elimination of mismatched yet thermodynamically stable intermediates. To understand the remarkable sequence specificity of homologous recombination, we have studied strand exchange between a 20-mer duplex containing one single mismatch (placed at varied positions) with the matching single strand in presence of poly(ethylene glycol) representing a semi-hydrophobic environment. A FRET-based assay shows that rates and yields of strand exchange from mismatched to matched strands rapidly increase with semi-hydrophobic co-solute concentration, contrasting previously observed general strand exchange accelerating effect of ethyl glycol ethers. We argue that this effect is not caused simply by DNA melting or solvent-induced changes of DNA conformation but is more complex involving several mechanisms. The catalytic effects, we propose, involve strand invasion facilitated by reduced duplex stability due to weakened base stacking ("longitudinal breathing"). Secondly, decreased water activity makes base-pair hydrogen bonds stronger, increasing the relative energy penalty per mismatch. Finally, unstacked mismatched bases (gaps) are stabilized through partly intercalated hydrophobic co-solvent molecules, assisting nucleation of strand invasion at the point of mismatch. We speculate that nature long ago discovered, and now exploits in various enzymes, that sequence recognition power of nucleic acids may be modulated in a hydrophobic environment.
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Affiliation(s)
- Bengt Nordén
- Department of Chemistry & Chemical Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Tom Brown
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Bobo Feng
- Department of Chemistry & Chemical Engineering, Chalmers University of Technology, Gothenburg, Sweden
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8
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Abstract
AbstractThe human protein Rad51 is double-edged in cancer contexts: on one hand, preventing tumourigenesis by eliminating potentially carcinogenic DNA damage and, on the other, promoting tumours by introducing new mutations. Understanding mechanistic details of Rad51 in homologous recombination (HR) and repair could facilitate design of novel methods, including CRISPR, for Rad51-targeted cancer treatment. Despite extensive research, however, we do not yet understand the mechanism of HR in sufficient detail, partly due to complexity, a large number of Rad51 protein units being involved in the exchange of long DNA segments. Another reason for lack of understanding could be that current recognition models of DNA interactions focus only on hydrogen bond-directed base pair formation. A more complete model may need to include, for example, the kinetic effects of DNA base stacking and unstacking (‘longitudinal breathing’). These might explain how Rad51 can recognize sequence identity of DNA over several bases long stretches with high accuracy, despite the fact that a single base mismatch could be tolerated if we consider only the hydrogen bond energy. We here propose that certain specific hydrophobic effects, recently discovered destabilizing stacking of nucleobases, may play a central role in this context for the function of Rad51.
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9
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Atwell SX, Migliozzi D, Dupont A, Viovy JL, Cappello G. Structural transitions and mechanochemical coupling in the nucleoprotein filament explain homology selectivity and Rad51 protein cooperativity in cellular DNA repair. Phys Rev E 2020; 101:032407. [PMID: 32289957 DOI: 10.1103/physreve.101.032407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 02/17/2020] [Indexed: 11/07/2022]
Abstract
The nucleoprotein filament (NPF) is the fundamental element of homologous recombination (HR), a major mechanism for the repair of double-strand DNA breaks in the cell. The NPF is made of the damaged DNA strand surrounded by recombinase proteins, and its sensitivity to base-pairing mismatches is a crucial feature that guarantees the fidelity of the repair. The concurrent recombinases are also essential for several steps of HR. In this work, we used torque-sensitive magnetic tweezers to probe and apply mechanical constraints to single nucleoprotein filaments (NPFs). We demonstrated that the NPF undergoes structural transitions from a stretched to a compact state, and we measured the corresponding mechanochemical signatures. Using an active two-state model, we proposed a free-energy landscape for the NPF transition. Using this quantitative model, we explained both how the sensitivity of the NPF to the homology length is regulated by its structural transition and how the cooperativity of Rad51 favors selectivity to relatively long homologous sequences.
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Affiliation(s)
- Scott X Atwell
- Institut Curie, PSL Research University, Centre National de la Recherche Scientifique, Sorbonne Universités, UPMC Univ Paris 06, Unité Mixte de Recherche 168, 75005 Paris, France
| | - Daniel Migliozzi
- Institut Curie, PSL Research University, Centre National de la Recherche Scientifique, Sorbonne Universités, UPMC Univ Paris 06, Unité Mixte de Recherche 168, 75005 Paris, France.,Laboratory of Microsystems, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland
| | - Aurélie Dupont
- Institut Curie, PSL Research University, Centre National de la Recherche Scientifique, Sorbonne Universités, UPMC Univ Paris 06, Unité Mixte de Recherche 168, 75005 Paris, France.,Université Grenoble Alpes, Laboratoire Interdisciplinaire de Physique, CNRS, F-38000 Grenoble, France
| | - Jean-Louis Viovy
- Institut Curie, PSL Research University, Centre National de la Recherche Scientifique, Sorbonne Universités, UPMC Univ Paris 06, Unité Mixte de Recherche 168, Institut Pierre Gilles de Gennes, MMBM Group, 75005 Paris, France
| | - Giovanni Cappello
- Institut Curie, PSL Research University, Centre National de la Recherche Scientifique, Sorbonne Universités, UPMC Univ Paris 06, Unité Mixte de Recherche 168, 75005 Paris, France.,Université Grenoble Alpes, Laboratoire Interdisciplinaire de Physique, CNRS, F-38000 Grenoble, France
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10
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Role of Rad51 and DNA repair in cancer: A molecular perspective. Pharmacol Ther 2020; 208:107492. [PMID: 32001312 DOI: 10.1016/j.pharmthera.2020.107492] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/13/2020] [Accepted: 01/22/2020] [Indexed: 12/24/2022]
Abstract
The maintenance of genome integrity is essential for any organism survival and for the inheritance of traits to offspring. To the purpose, cells have developed a complex DNA repair system to defend the genetic information against both endogenous and exogenous sources of damage. Accordingly, multiple repair pathways can be aroused from the diverse forms of DNA lesions, which can be effective per se or via crosstalk with others to complete the whole DNA repair process. Deficiencies in DNA healing resulting in faulty repair and/or prolonged DNA damage can lead to genes mutations, chromosome rearrangements, genomic instability, and finally carcinogenesis and/or cancer progression. Although it might seem paradoxical, at the same time such defects in DNA repair pathways may have therapeutic implications for potential clinical practice. Here we provide an overview of the main DNA repair pathways, with special focus on the role played by homologous repair and the RAD51 recombinase protein in the cellular DNA damage response. We next discuss the recombinase structure and function per se and in combination with all its principal mediators and regulators. Finally, we conclude with an analysis of the manifold roles that RAD51 plays in carcinogenesis, cancer progression and anticancer drug resistance, and conclude this work with a survey of the most promising therapeutic strategies aimed at targeting RAD51 in experimental oncology.
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11
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Hydrophobic catalysis and a potential biological role of DNA unstacking induced by environment effects. Proc Natl Acad Sci U S A 2019; 116:17169-17174. [PMID: 31413203 PMCID: PMC6717297 DOI: 10.1073/pnas.1909122116] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The main stabilizer of the DNA double helix is not the base-pair hydrogen bonds but coin-pile stacking of base pairs, whose hydrophobic cohesion, requiring abundant water, indirectly makes the DNA interior dry so that hydrogen bonds can exert full recognition power. We report that certain semihydrophobic agents depress the stacking energy (measurable in single-molecule experiments), leading to transiently occurring holes in the base-pair stack (monitorable via binding of threading intercalators). Similar structures observed in DNA complexes with RecA and Rad51, and previous observations of spontaneous strand exchange catalyzed in semihydrophobic model systems, make us propose that some hydrophobic protein residues may have roles in catalyzing homologous recombination. We speculate that hydrophobic catalysis is a general phenomenon in DNA enzymes. Hydrophobic base stacking is a major contributor to DNA double-helix stability. We report the discovery of specific unstacking effects in certain semihydrophobic environments. Water-miscible ethylene glycol ethers are found to modify structure, dynamics, and reactivity of DNA by mechanisms possibly related to a biologically relevant hydrophobic catalysis. Spectroscopic data and optical tweezers experiments show that base-stacking energies are reduced while base-pair hydrogen bonds are strengthened. We propose that a modulated chemical potential of water can promote “longitudinal breathing” and the formation of unstacked holes while base unpairing is suppressed. Flow linear dichroism in 20% diglyme indicates a 20 to 30% decrease in persistence length of DNA, supported by an increased flexibility in single-molecule nanochannel experiments in poly(ethylene glycol). A limited (3 to 6%) hyperchromicity but unaffected circular dichroism is consistent with transient unstacking events while maintaining an overall average B-DNA conformation. Further information about unstacking dynamics is obtained from the binding kinetics of large thread-intercalating ruthenium complexes, indicating that the hydrophobic effect provides a 10 to 100 times increased DNA unstacking frequency and an “open hole” population on the order of 10−2 compared to 10−4 in normal aqueous solution. Spontaneous DNA strand exchange catalyzed by poly(ethylene glycol) makes us propose that hydrophobic residues in the L2 loop of recombination enzymes RecA and Rad51 may assist gene recombination via modulation of water activity near the DNA helix by hydrophobic interactions, in the manner described here. We speculate that such hydrophobic interactions may have catalytic roles also in other biological contexts, such as in polymerases.
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12
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Haas KT, Lee M, Esposito A, Venkitaraman AR. Single-molecule localization microscopy reveals molecular transactions during RAD51 filament assembly at cellular DNA damage sites. Nucleic Acids Res 2019; 46:2398-2416. [PMID: 29309696 PMCID: PMC5861458 DOI: 10.1093/nar/gkx1303] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 12/19/2017] [Indexed: 11/14/2022] Open
Abstract
RAD51 recombinase assembles on single-stranded (ss)DNA substrates exposed by DNA end-resection to initiate homologous recombination (HR), a process fundamental to genome integrity. RAD51 assembly has been characterized using purified proteins, but its ultrastructural topography in the cell nucleus is unexplored. Here, we combine cell genetics with single-molecule localization microscopy and a palette of bespoke analytical tools, to visualize molecular transactions during RAD51 assembly in the cellular milieu at resolutions approaching 30-40 nm. In several human cell types, RAD51 focalizes in clusters that progressively extend into long filaments, which abut-but do not overlap-with globular bundles of replication protein A (RPA). Extended filaments alter topographically over time, suggestive of succeeding steps in HR. In cells depleted of the tumor suppressor protein BRCA2, or overexpressing its RAD51-binding BRC repeats, RAD51 fails to assemble at damage sites, although RPA accumulates unhindered. By contrast, in cells lacking a BRCA2 carboxyl (C)-terminal region targeted by cancer-causing mutations, damage-induced RAD51 assemblies initiate but do not extend into filaments. We suggest a model wherein RAD51 assembly proceeds concurrently with end-resection at adjacent sites, via an initiation step dependent on the BRC repeats, followed by filament extension through the C-terminal region of BRCA2.
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Affiliation(s)
- Kalina T Haas
- The Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - MiYoung Lee
- The Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Alessandro Esposito
- The Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Ashok R Venkitaraman
- The Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
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13
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Abstract
The behavior of benzoic acid in polyethylene inspired me to reflect on why water is a unique molecule that all living organisms depend upon. From properties of DNA in aqueous solution a seemingly counter-intuitive conjecture emerges: water is needed for the creation of certain dry low-dielectric nm-size environments where hydrogen bonding exerts strong recognition power. Such environments seem to be functionally crucial, and their interactions with other hydrophobic environments, or with hydrophobic agents that modulate the chemical potential of water, can cause structural transformations via ‘hydrophobic catalysis’. Possibly combined with an excluded volume osmosis effect (EVO), hydrophobic catalysis may have important biological roles, e.g., in genetic recombination. Hydrophobic agents are found to strongly accelerate spontaneous DNA strand exchange as well as certain other DNA rearrangement reactions. It is hypothesized that hydrophobic catalysis be involved in gene recognition and gene recombination mediated by bacterial RecA (one of the oldest proteins we know of) as well as in sexual recombination in higher organisms, by Rad51. Hydrophobically catalyzed unstacking fluctuations of DNA bases can favor elongated conformations, such as the recently proposed [Formula: see text]-DNA, with potential regulatory roles. That living cells can survive as dormant spores, with very low water content and in principle as such travel far in space is reflected upon: a random walk model with solar photon pressure as driving force indicates our life on earth could not have originated outside our galaxy but possibly from many solar systems within it — at some place, though, where there was plenty of liquid water.
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Affiliation(s)
- Bengt Nordén
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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14
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Zhao XC, Fu H, Song L, Yang YJ, Zhou EC, Liu GX, Chen XF, Li Z, Wu WQ, Zhang XH. S-DNA and RecA/RAD51-Mediated Strand Exchange in Vitro. Biochemistry 2019; 58:2009-2016. [PMID: 30900876 DOI: 10.1021/acs.biochem.8b01125] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
S-DNA (stretched DNA) is an elongated base-paired DNA conformation under high tension. Because the RecA/Rad51 family DNA recombinases form helical filaments on DNA and mediate the formation of the DNA triplex (D-loop), in which the DNA is stretched, and because the extension of these nucleoprotein filaments is similar to the extension of S-DNA, S-DNA has long been hypothesized as a possible state of DNA that participants in RecA/Rad51-mediated DNA strand exchange in homologous recombination. Such a hypothesis, however, is still lacking direct experimental studies. In this work, we have studied the polymerization and strand exchange on S-DNA mediated by Escherichia coli RecA, human Rad51, and Saccharomyces cerevisiae Rad51 by single-molecule magnetic tweezers. We report that RecA/Rad51 polymerizes faster on S-DNA than on B-DNA with the same buffer conditions. Furthermore, the RecA/Rad51-mediated DNA triplex forms faster from S-DNA than from B-DNA together with the homologous single-stranded DNA. These results provide evidence that S-DNA can interact with RecA and Rad51 and shed light on the possible functions of S-DNA.
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Affiliation(s)
- Xiao-Cong Zhao
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Hang Fu
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Lun Song
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Ya-Jun Yang
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Er-Chi Zhou
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Guang-Xue Liu
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Xue-Feng Chen
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
| | - Zhuo Li
- Third Institute of Oceanography , State Oceanic Administration , Xiamen 361005 , China
| | - Wen-Qiang Wu
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, Department of Biology , Henan University , Kaifeng 475001 , China
| | - Xing-Hua Zhang
- College of Life Sciences, The Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis , Wuhan University , Wuhan 430072 , China
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15
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Abstract
We have discovered a well-defined extended conformation of double-stranded DNA, which we call Σ-DNA, using laser-tweezers force-spectroscopy experiments. At a transition force corresponding to free energy change ΔG = 1·57 ± 0·12 kcal (mol base pair)-1 60 or 122 base-pair long synthetic GC-rich sequences, when pulled by the 3'-3' strands, undergo a sharp transition to the 1·52 ± 0·04 times longer Σ-DNA. Intriguingly, the same degree of extension is also found in DNA complexes with recombinase proteins, such as bacterial RecA and eukaryotic Rad51. Despite vital importance to all biological organisms for survival, genome maintenance and evolution, the recombination reaction is not yet understood at atomic level. We here propose that the structural distortion represented by Σ-DNA, which is thus physically inherent to the nucleic acid, is related to how recombination proteins mediate recognition of sequence homology and execute strand exchange. Our hypothesis is that a homogeneously stretched DNA undergoes a 'disproportionation' into an inhomogeneous Σ-form consisting of triplets of locally B-like perpendicularly stacked bases. This structure may ensure improved fidelity of base-pair recognition and promote rejection in case of mismatch during homologous recombination reaction. Because a triplet is the length of a gene codon, we speculate that the structural physics of nucleic acids may have biased the evolution of recombinase proteins to exploit triplet base stacks and also the genetic code.
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16
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Szigyártó IC, Deák R, Mihály J, Rocha S, Zsila F, Varga Z, Beke-Somfai T. Flow Alignment of Extracellular Vesicles: Structure and Orientation of Membrane-Associated Bio-macromolecules Studied with Polarized Light. Chembiochem 2018; 19:545-551. [PMID: 29237098 DOI: 10.1002/cbic.201700378] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 11/17/2017] [Indexed: 12/26/2022]
Abstract
Extracellular vesicles (EVs) are currently in scientific focus, as they have great potential to revolutionize the diagnosis and therapy of various diseases. However, numerous aspects of these species are still poorly understood, and thus, additional insight into their molecular-level properties, membrane-protein interactions, and membrane rigidity is still needed. We here demonstrate the use of red-blood-cell-derived EVs (REVs) that polarized light spectroscopy techniques, linear and circular dichroism, can provide molecular-level structural information on these systems. Flow-linear dichroism (flow-LD) measurements show that EVs can be oriented by shear force and indicate that hemoglobin molecules are associated to the lipid bilayer in freshly released REVs. During storage, this interaction ceases; this is coupled to major protein conformational changes relative to the initial state. Further on, the degree of orientation gives insight into vesicle rigidity, which decreases in time parallel to changes in protein conformation. Overall, we propose that both linear dichroism and circular dichroism spectroscopy can provide simple, rapid, yet efficient ways to track changes in the membrane-protein interactions of EV components at the molecular level, which may also give insight into processes occurring during vesiculation.
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Affiliation(s)
- Imola Cs Szigyártó
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P. O. Box 286, 1519, Budapest, Hungary
| | - Róbert Deák
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P. O. Box 286, 1519, Budapest, Hungary
| | - Judith Mihály
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P. O. Box 286, 1519, Budapest, Hungary
| | - Sandra Rocha
- Department of Biology and Biological Engineering, Chalmers University of Technology, Chemical Biology, Kemigården 4, 41296, Göteborg, Sweden
| | - Ferenc Zsila
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P. O. Box 286, 1519, Budapest, Hungary
| | - Zoltán Varga
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P. O. Box 286, 1519, Budapest, Hungary.,Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó u. 37-47, 1094, Budapest, Hungary
| | - Tamás Beke-Somfai
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P. O. Box 286, 1519, Budapest, Hungary.,Department of Chemistry and Chemical Engineering, Chemistry and Biochemistry, Chalmers University of Technology, Kemigården 4, 41296, Göteborg, Sweden
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17
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Zhao L, Xu J, Zhao W, Sung P, Wang HW. Determining the RAD51-DNA Nucleoprotein Filament Structure and Function by Cryo-Electron Microscopy. Methods Enzymol 2018; 600:179-199. [PMID: 29458758 DOI: 10.1016/bs.mie.2017.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Homologous recombination is a universal tool for DNA double-strand break and replication fork repair, and it is catalyzed by a highly conserved family of recombinases. In eukaryotes, Rad51 is the recombinase that catalyzes the pairing of homologous DNA molecules and the exchange of strands between the paired molecules. Rad51 assembles on single-stranded DNA (ssDNA) stemming from lesion processing to form a right-handed helical polymer that engages then samples double-stranded DNA (dsDNA) for homology. Upon matching with a homologous sequence, the Rad51-bound ssDNA invades the dsDNA, leading to the formation of a DNA joint with concomitant displacement of the strand of like polarity. The Rad51-DNA filaments are amenable to structural studies using cryo-electron microscopy (cryo-EM). In particular, recent technical breakthroughs in cryo-EM have made it possible to define the structure and function of human RAD51 at near-atomic resolution. In this chapter, we describe our cryo-EM approach to capture the human RAD51 filament structures in various stages of catalysis. The approach may also be useful for related recombinases and other helical assemblies.
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Affiliation(s)
- Lingyun Zhao
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Jingfei Xu
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | | | | | - Hong-Wei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
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18
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Lindberg DJ, Wenger A, Sundin E, Wesén E, Westerlund F, Esbjörner EK. Binding of Thioflavin-T to Amyloid Fibrils Leads to Fluorescence Self-Quenching and Fibril Compaction. Biochemistry 2017; 56:2170-2174. [DOI: 10.1021/acs.biochem.7b00035] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- David J. Lindberg
- Division
of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
| | - Anna Wenger
- Division
of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
| | - Elin Sundin
- Division
of Chemistry and Biochemistry, Department of Chemistry and Chemical
Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
| | - Emelie Wesén
- Division
of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
| | - Fredrik Westerlund
- Division
of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
| | - Elin K. Esbjörner
- Division
of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Gothenburg, Sweden
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19
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Xu J, Zhao L, Xu Y, Zhao W, Sung P, Wang HW. Cryo-EM structures of human RAD51 recombinase filaments during catalysis of DNA-strand exchange. Nat Struct Mol Biol 2016; 24:40-46. [PMID: 27941862 DOI: 10.1038/nsmb.3336] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 11/07/2016] [Indexed: 01/16/2023]
Abstract
The central step in eukaryotic homologous recombination (HR) is ATP-dependent DNA-strand exchange mediated by the Rad51 recombinase. In this process, Rad51 assembles on single-stranded DNA (ssDNA) and generates a helical filament that is able to search for and invade homologous double-stranded DNA (dsDNA), thus leading to strand separation and formation of new base pairs between the initiating ssDNA and the complementary strand within the duplex. Here, we used cryo-EM to solve the structures of human RAD51 in complex with DNA molecules, in presynaptic and postsynaptic states, at near-atomic resolution. Our structures reveal both conserved and distinct structural features of the human RAD51-DNA complexes compared with their prokaryotic counterpart. Notably, we also captured the structure of an arrested synaptic complex. Our results provide new insight into the molecular mechanisms of the DNA homology search and strand-exchange processes.
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Affiliation(s)
- Jingfei Xu
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lingyun Zhao
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yuanyuan Xu
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Weixing Zhao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Hong-Wei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
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20
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Short JM, Liu Y, Chen S, Soni N, Madhusudhan MS, Shivji MKK, Venkitaraman AR. High-resolution structure of the presynaptic RAD51 filament on single-stranded DNA by electron cryo-microscopy. Nucleic Acids Res 2016; 44:9017-9030. [PMID: 27596592 PMCID: PMC5100573 DOI: 10.1093/nar/gkw783] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 08/24/2016] [Indexed: 12/21/2022] Open
Abstract
Homologous DNA recombination (HR) by the RAD51 recombinase enables error-free DNA break repair. To execute HR, RAD51 first forms a presynaptic filament on single-stranded (ss) DNA, which catalyses pairing with homologous double-stranded (ds) DNA. Here, we report a structure for the presynaptic human RAD51 filament at 3.5–5.0Å resolution using electron cryo-microscopy. RAD51 encases ssDNA in a helical filament of 103Å pitch, comprising 6.4 protomers per turn, with a rise of 16.1Å and a twist of 56.2°. Inter-protomer distance correlates with rotation of an α-helical region in the core catalytic domain that is juxtaposed to ssDNA, suggesting how the RAD51–DNA interaction modulates protomer spacing and filament pitch. We map Fanconi anaemia-like disease-associated RAD51 mutations, clarifying potential phenotypes. We predict binding sites on the presynaptic filament for two modules present in each BRC repeat of the BRCA2 tumour suppressor, a critical HR mediator. Structural modelling suggests that changes in filament pitch mask or expose one binding site with filament-inhibitory potential, rationalizing the paradoxical ability of the BRC repeats to either stabilize or inhibit filament formation at different steps during HR. Collectively, our findings provide fresh insight into the structural mechanism of HR and its dysregulation in human disease.
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Affiliation(s)
- Judith M Short
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Yang Liu
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Shaoxia Chen
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Neelesh Soni
- Indian Institute of Science, Education & Research, Dr Homi Babha Road, Pune 411 008, India
| | - Mallur S Madhusudhan
- Indian Institute of Science, Education & Research, Dr Homi Babha Road, Pune 411 008, India.,Bioinformatics Institute, A*STAR, 30 Biopolis Drive, 138671 Singapore
| | - Mahmud K K Shivji
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Ashok R Venkitaraman
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
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21
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Volodin AA, Bocharova TN, Smirnova EA. Polycationic ligands of different chemical classes stimulate DNA strand displacement between short oligonucleotides in a protein-free system. Biopolymers 2016; 105:633-41. [DOI: 10.1002/bip.22859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 03/26/2016] [Accepted: 04/19/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Alexander A. Volodin
- Institute of Molecular Genetics of the Russian Academy of Sciences; Kurchatov Sq, 2 Moscow 123182 Russia
| | - Tatiana N. Bocharova
- Institute of Molecular Genetics of the Russian Academy of Sciences; Kurchatov Sq, 2 Moscow 123182 Russia
| | - Elena A. Smirnova
- Institute of Molecular Genetics of the Russian Academy of Sciences; Kurchatov Sq, 2 Moscow 123182 Russia
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22
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Antosiewicz JM, Shugar D. UV-Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 1: basic principles and properties of tyrosine chromophore. Biophys Rev 2016; 8:151-161. [PMID: 28510058 PMCID: PMC4884207 DOI: 10.1007/s12551-016-0198-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 03/17/2016] [Indexed: 11/08/2022] Open
Abstract
Spectroscopic properties of tyrosine residues may be employed in structural studies of proteins. Here we discuss several different types of UV–Vis spectroscopy, like normal, difference and second-derivative UV absorption spectroscopy, fluorescence spectroscopy, linear and circular dichroism spectroscopy, and Raman spectroscopy, and corresponding optical properties of the tyrosine chromophore, phenol, which are used to study protein structure.
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Affiliation(s)
- Jan M Antosiewicz
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Żwirki i Wigury 93, 02-089, Warsaw, Poland.
| | - David Shugar
- Institute of Biochemistry & Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106, Warsaw, Poland
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23
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UV-Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 2: selected applications. Biophys Rev 2016; 8:163-177. [PMID: 28510057 PMCID: PMC4884208 DOI: 10.1007/s12551-016-0197-7] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 03/14/2016] [Indexed: 11/07/2022] Open
Abstract
In Part 2 we discuss application of several different types of UV–Vis spectroscopy, such as normal, difference, and second-derivative UV absorption spectroscopy, fluorescence spectroscopy, linear and circular dichroism spectroscopy, and Raman spectroscopy, of the side-chain of tyrosine residues in different molecular environments. We review the ways these spectroscopies can be used to probe complex protein structures.
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24
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Schay G, Borka B, Kernya L, Bulyáki É, Kardos J, Fekete M, Fidy J. Without Binding ATP, Human Rad51 Does Not Form Helical Filaments on ssDNA. J Phys Chem B 2016; 120:2165-78. [PMID: 26890079 DOI: 10.1021/acs.jpcb.5b12220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Construction of the presynaptic filament (PSF) of proper helical structure by Rad51 recombinases is a prerequisite of the progress of homologous recombination repair. We studied the contribution of ATP-binding to this structure of wt human Rad51 (hRad51). We exploited the protein-dissociation effect of high hydrostatic pressure to determine the free energy of dissociation of the protomer interfaces in hRad51 oligomer states and used electron microscopy to obtain topological parameters. Without cofactors ATP and Ca(2+) and template DNA, hRad51 did not exist in monomer form, but it formed rodlike long filaments without helical order. ΔG(diss) indicated a strong inherent tendency of aggregation. Binding solely ssDNA left the filament unstructured with slightly increased ΔG(diss). Adding only ATP and Ca(2+) to the buffer disintegrated the self-associated rods into rings and short helices of further increased ΔG(diss). Rad51 binding to ssDNA only with ATP and Ca bound could lead to ordered helical filament formation of proper pitch size with interface contacts of K(d) ∼ 2 × 10(-11) M, indicating a structure of outstanding stability. ATP/Ca binding increased the ΔG(diss) of protomer contacts in the filament by 16 kJ/mol. The results emphasize that ATP-binding in the PSF of hRad51 has an essential, yet purely structural, role.
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Affiliation(s)
- Gusztáv Schay
- Department of Biophysics and Radiation Biology, Semmelweis University , Tűzoltó utca 37-47, Budapest H-1094, Hungary
| | - Bálint Borka
- Department of Biophysics and Radiation Biology, Semmelweis University , Tűzoltó utca 37-47, Budapest H-1094, Hungary
| | - Linda Kernya
- MTA-ELTE NAP B Neuroimmunology Research Group, Department of Biochemistry, Eötvös Loránd University , Pázmány P. sétány 1/C, Budapest H-1117, Hungary
| | - Éva Bulyáki
- MTA-ELTE NAP B Neuroimmunology Research Group, Department of Biochemistry, Eötvös Loránd University , Pázmány P. sétány 1/C, Budapest H-1117, Hungary
| | - József Kardos
- MTA-ELTE NAP B Neuroimmunology Research Group, Department of Biochemistry, Eötvös Loránd University , Pázmány P. sétány 1/C, Budapest H-1117, Hungary
| | - Melinda Fekete
- Department of Biophysics and Radiation Biology, Semmelweis University , Tűzoltó utca 37-47, Budapest H-1094, Hungary
| | - Judit Fidy
- Department of Biophysics and Radiation Biology, Semmelweis University , Tűzoltó utca 37-47, Budapest H-1094, Hungary
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25
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Feng B, Westerlund F, Nordén B. Evidence for hydrophobic catalysis of DNA strand exchange. Chem Commun (Camb) 2015; 51:7390-2. [DOI: 10.1039/c5cc01515d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
DNA strand exchange is catalysed by a hydrophobic environment which destabilises base stacking and promotes DNA breathing.
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Affiliation(s)
- B. Feng
- Department of Chemistry and Chemical Engineering
- Chalmers University of Technology
- SE-412 96 Gothenburg
- Sweden
| | - F. Westerlund
- Department of Biology and Biological Engineering
- Chalmers University of Technology
- SE-412 96 Gothenburg
- Sweden
| | - B. Nordén
- Department of Chemistry and Chemical Engineering
- Chalmers University of Technology
- SE-412 96 Gothenburg
- Sweden
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26
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Sun L, Frykholm K, Fornander LH, Svedhem S, Westerlund F, Akerman B. Sensing conformational changes in DNA upon ligand binding using QCM-D. Polyamine condensation and Rad51 extension of DNA layers. J Phys Chem B 2014; 118:11895-904. [PMID: 25197950 DOI: 10.1021/jp506733w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Biosensors, in which binding of ligands is detected through changes in the optical or electrochemical properties of a DNA layer confined to the sensor surface, are important tools for investigating DNA interactions. Here, we investigate if conformational changes induced in surface-attached DNA molecules upon ligand binding can be monitored by the quartz crystal microbalance with dissipation (QCM-D) technique. DNA duplexes containing 59-184 base pairs were formed on QCM-D crystals by stepwise assembly of synthetic oligonucleotides of designed base sequences. The DNA films were exposed to the cationic polyamines spermidine and spermine, known to condense DNA molecules in bulk experiments, or to the recombination protein Rad51, known to extend the DNA helix. The binding and dissociation of the ligands to the DNA films were monitored in real time by measurements of the shifts in resonance frequency (Δf) and in dissipation (ΔD). The QCM-D data were analyzed using a Voigt-based model for the viscoelastic properties of polymer films in order to evaluate how the ligands affect thickness and shear viscosity of the DNA layer. Binding of spermine shrinks all DNA layers and increases their viscosity in a reversible fashion, and so does spermidine, but to a smaller extent, in agreement with its lower positive charge. SPR was used to measure the amount of bound polyamines, and when combined with QCM-D, the data indicate that the layer condensation leads to a small release of water from the highly hydrated DNA films. The binding of Rad51 increases the effective layer thickness of a 59 bp film, more than expected from the know 50% DNA helix extension. The combined results provide guidelines for a QCM-D biosensor based on ligand-induced structural changes in DNA films. The QCM-D approach provides high discrimination between ligands affecting the thickness and the structural properties of the DNA layer differently. The reversibility of the film deformation allows comparative studies of two or more analytes using the same DNA layer as demonstrated here by spermine and spermidine.
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Affiliation(s)
- Lu Sun
- Department of Chemical and Biological Engineering and ‡Department of Applied Physics, Chalmers University of Technology , SE-412 96 Gothenburg, Sweden
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27
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Fornander LH, Feng B, Beke-Somfai T, Nordén B. UV Transition Moments of Tyrosine. J Phys Chem B 2014; 118:9247-57. [DOI: 10.1021/jp5065352] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Louise H. Fornander
- Department of Chemical and
Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Bobo Feng
- Department of Chemical and
Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Tamás Beke-Somfai
- Department of Chemical and
Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Bengt Nordén
- Department of Chemical and
Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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28
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Renkawitz J, Lademann CA, Jentsch S. Mechanisms and principles of homology search during recombination. Nat Rev Mol Cell Biol 2014; 15:369-83. [PMID: 24824069 DOI: 10.1038/nrm3805] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Homologous recombination is crucial for genome stability and for genetic exchange. Although our knowledge of the principle steps in recombination and its machinery is well advanced, homology search, the critical step of exploring the genome for homologous sequences to enable recombination, has remained mostly enigmatic. However, recent methodological advances have provided considerable new insights into this fundamental step in recombination that can be integrated into a mechanistic model. These advances emphasize the importance of genomic proximity and nuclear organization for homology search and the critical role of homology search mediators in this process. They also aid our understanding of how homology search might lead to unwanted and potentially disease-promoting recombination events.
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Affiliation(s)
- Jörg Renkawitz
- 1] Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany. [2] Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria. [3]
| | - Claudio A Lademann
- 1] Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany. [2]
| | - Stefan Jentsch
- Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
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29
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Fornander LH, Renodon-Cornière A, Kuwabara N, Ito K, Tsutsui Y, Shimizu T, Iwasaki H, Nordén B, Takahashi M. Swi5-Sfr1 protein stimulates Rad51-mediated DNA strand exchange reaction through organization of DNA bases in the presynaptic filament. Nucleic Acids Res 2013; 42:2358-65. [PMID: 24304898 PMCID: PMC3936755 DOI: 10.1093/nar/gkt1257] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Swi5-Sfr1 heterodimer protein stimulates the Rad51-promoted DNA strand exchange reaction, a crucial step in homologous recombination. To clarify how this accessory protein acts on the strand exchange reaction, we have analyzed how the structure of the primary reaction intermediate, the Rad51/single-stranded DNA (ssDNA) complex filament formed in the presence of ATP, is affected by Swi5-Sfr1. Using flow linear dichroism spectroscopy, we observe that the nucleobases of the ssDNA are more perpendicularly aligned to the filament axis in the presence of Swi5-Sfr1, whereas the bases are more randomly oriented in the absence of Swi5-Sfr1. When using a modified version of the natural protein where the N-terminal part of Sfr1 is deleted, which has no affinity for DNA but maintained ability to stimulate the strand exchange reaction, we still observe the improved perpendicular DNA base orientation. This indicates that Swi5-Sfr1 exerts its activating effect through interaction with the Rad51 filament mainly and not with the DNA. We propose that the role of a coplanar alignment of nucleobases induced by Swi5-Sfr1 in the presynaptic Rad51/ssDNA complex is to facilitate the critical matching with an invading double-stranded DNA, hence stimulating the strand exchange reaction.
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Affiliation(s)
- Louise H Fornander
- Department of Chemical and Biological Engineering, Chalmers University of Technology, S-41296 Gothenburg, Sweden, Research Unit FRE3478, Centre National de la Recherche Scientifique & University of Nantes, F-44322 Nantes cedex 3, France, Graduate School of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan, Structural Biology Research Center, Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, KEK, Tsukuba, 305-0801, Japan and Department of Life Science, Graduate School of Bioscience & Biotechnology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
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30
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Molecular modeling and molecular dynamics simulations of recombinase Rad51. Biophys J 2013; 104:1556-65. [PMID: 23561532 DOI: 10.1016/j.bpj.2013.02.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 01/29/2013] [Accepted: 02/07/2013] [Indexed: 11/24/2022] Open
Abstract
The Rad51 ATPase plays central roles in DNA homologous recombination. Yeast Rad51 dimer structure in the active form of the filament was constructed using homology modeling techniques, and all-atom molecular dynamics (MD) simulations were performed using the modeled structure. We found two crucial interaction networks involving ATP: one is among the γ-phosphate of ATP, K(+) ions, H352, and D374; the other is among the adenine ring of ATP, R228, and P379. Multiple MD simulations were performed in which the number of bound K(+) ions was changed. The simulated structures suggested that K(+) ions are indispensable for the stabilization of the active dimer and resemble the arginine and lysine fingers of other P-loop containing ATPases and GTPases. MD simulations also showed that the adenine ring of ATP mediates interactions between adjacent protomers. Furthermore, in MD simulations starting from a structure just after ATP hydrolysis, the opening motion corresponding to dissociation from DNA was observed. These results support the hypothesis that ATP and K(+) ions function as glue between protomers.
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31
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Abstract
All organisms need homologous recombination (HR) to repair DNA double-strand breaks. Defects in recombination are linked to genetic instability and to elevated risks in developing cancers. The central catalyst of HR is a nucleoprotein filament, consisting of recombinase proteins (human RAD51 or bacterial RecA) bound around single-stranded DNA. Over the last two decades, single-molecule techniques have provided substantial new insights into the dynamics of homologous recombination. Here, we survey important recent developments in this field of research and provide an outlook on future developments.
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32
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Kogan M, Nordén B, Beke-Somfai T. High anisotropy of flow-aligned bicellar membrane systems. Chem Phys Lipids 2013; 175-176:105-15. [PMID: 23999012 DOI: 10.1016/j.chemphyslip.2013.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 08/17/2013] [Accepted: 08/19/2013] [Indexed: 10/26/2022]
Abstract
In recent years, multi-lipid bicellar systems have emerged as promising membrane models. The fast orientational diffusion and magnetic alignability made these systems very attractive for NMR investigations. However, their alignment was so far achieved with a strong magnetic field, which limited their use with other methods that require macroscopic orientation. Recently, it was shown that bicelles could be aligned also by shear flow in a Couette flow cell, making it applicable to structural and biophysical studies by polarized light spectroscopy. Considering the sensitivity of this lipid system to small variations in composition and physicochemical parameters, efficient use of such a flow-cell method with coupled techniques will critically depend on the detailed understanding of how the lipid systems behave under flow conditions. In the present study we have characterized the flow alignment behavior of the commonly used dimyristoyl phosphatidylcholine/dicaproyl phosphatidylcholine (DMPC/DHPC) bicelle system, for various temperatures, lipid compositions, and lipid concentrations. We conclude that at optimal flow conditions the selected bicellar systems can produce the most efficient flow alignment out of any lipid systems used so far. The highest degree of orientation of DMPC/DHPC samples is noticed in a narrow temperature interval, at a practical temperature around 25 °C, most likely in the phase transition region characterized by maximum sample viscosity. The change of macroscopic orientation factor as function of the above conditions is now described in detail. The increase in macroscopic alignment observed for bicelles will most likely allow recording of higher resolution spectra on membrane systems, which provide deeper structural insight and analysis into properties of biomolecules interacting with solution phase lipid membranes.
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Affiliation(s)
- Maxim Kogan
- Department of Chemical and Biological Engineering, Physical Chemistry, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
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Subramanyam S, Jones WT, Spies M, Spies MA. Contributions of the RAD51 N-terminal domain to BRCA2-RAD51 interaction. Nucleic Acids Res 2013; 41:9020-32. [PMID: 23935068 PMCID: PMC3799448 DOI: 10.1093/nar/gkt691] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
RAD51 DNA strand exchange protein catalyzes the central step in homologous recombination, a cellular process fundamentally important for accurate repair of damaged chromosomes, preservation of the genetic integrity, restart of collapsed replication forks and telomere maintenance. BRCA2 protein, a product of the breast cancer susceptibility gene, is a key recombination mediator that interacts with RAD51 and facilitates RAD51 nucleoprotein filament formation on single-stranded DNA generated at the sites of DNA damage. An accurate atomistic level description of this interaction, however, is limited to a partial crystal structure of the RAD51 core fused to BRC4 peptide. Here, by integrating homology modeling and molecular dynamics, we generated a structure of the full-length RAD51 in complex with BRC4 peptide. Our model predicted previously unknown hydrogen bonding patterns involving the N-terminal domain (NTD) of RAD51. These interactions guide positioning of the BRC4 peptide within a cavity between the core and the NTDs; the peptide binding separates the two domains and restricts internal dynamics of RAD51 protomers. The model’s depiction of the RAD51-BRC4 complex was validated by free energy calculations and in vitro functional analysis of rationally designed mutants. All generated mutants, RAD51E42A, RAD51E59A, RAD51E237A, RAD51E59A/E237A and RAD51E42A/E59A/E237A maintained basic biochemical activities of the wild-type RAD51, but displayed reduced affinities for the BRC4 peptide. Strong correlation between the calculated and experimental binding energies confirmed the predicted structure of the RAD51-BRC4 complex and highlighted the importance of RAD51 NTD in RAD51-BRCA2 interaction.
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Affiliation(s)
- Shyamal Subramanyam
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA, Center for the Physics of Living Cells, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA, Department of Biochemistry, Carver College of Medicine, College of Pharmacy, University of Iowa, Iowa City, IA 52242, USA and Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA 52242, USA
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Lee M, Lipfert J, Sanchez H, Wyman C, Dekker NH. Structural and torsional properties of the RAD51-dsDNA nucleoprotein filament. Nucleic Acids Res 2013; 41:7023-30. [PMID: 23703213 PMCID: PMC3737536 DOI: 10.1093/nar/gkt425] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Human RAD51 is a key protein in the repair of DNA by homologous recombination. Its assembly onto DNA, which induces changes in DNA structure, results in the formation of a nucleoprotein filament that forms the basis of strand exchange. Here, we determine the structural and mechanical properties of RAD51-dsDNA filaments. Our measurements use two recently developed magnetic tweezers assays, freely orbiting magnetic tweezers and magnetic torque tweezers, designed to measure the twist and torque of individual molecules. By directly monitoring changes in DNA twist on RAD51 binding, we determine the unwinding angle per RAD51 monomer to be 45°, in quantitative agreement with that of its bacterial homolog, RecA. Measurements of the torque that is built up when RAD51-dsDNA filaments are twisted show that under conditions that suppress ATP hydrolysis the torsional persistence length of the RAD51-dsDNA filament exceeds that of its RecA counterpart by a factor of three. Examination of the filament’s torsional stiffness for different combinations of divalent ions and nucleotide cofactors reveals that the Ca2+ ion, apart from suppressing ATPase activity, plays a key role in increasing the torsional stiffness of the filament. These quantitative measurements of RAD51-imposed DNA distortions and accumulated mechanical stress suggest a finely tuned interplay between chemical and mechanical interactions within the RAD51 nucleoprotein filament.
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Affiliation(s)
- Mina Lee
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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Revealing the competition between peeled ssDNA, melting bubbles, and S-DNA during DNA overstretching by single-molecule calorimetry. Proc Natl Acad Sci U S A 2013; 110:3865-70. [PMID: 23431154 DOI: 10.1073/pnas.1213740110] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Double-stranded DNA (dsDNA) unconstrained by torsion undergoes an overstretching transition at about 65 pN, elongating the DNA to about 1.7-fold. Three possible structural transitions have been debated for the nature of DNA overstretching: (i) "peeling" apart of dsDNA to produce a peeled ssDNA strand under tension while the other strand coils, (ii) "inside-strand separation" of dsDNA to two parallel ssDNA strands that share tension (melting bubbles), and (iii) "B-to-S" transition to a novel dsDNA, termed S-DNA. Here we overstretched an end-opened DNA (with one open end to allow peeling) and an end-closed (i.e., both ends of the linear DNA are covalently closed to prohibit peeling) and torsion-unconstrained DNA. We report that all three structural transitions exist depending on experimental conditions. For the end-opened DNA, the peeling transition and the B-to-S transition were observed; for the end-closed DNA, the inside-strand separation and the B-to-S transition were observed. The peeling transition and the inside-strand separation are hysteretic and have an entropy change of approximately 17 cal/(K⋅mol), whereas the B-to-S transition is nonhysteretic and has an entropy change of approximately -2 cal/(K⋅mol). The force-extension curves of peeled ssDNA, melting bubbles, and S-DNA were characterized by experiments. Our results provide experimental evidence for the formation of DNA melting bubbles driven by high tension and prove the existence of nonmelted S-DNA. Our findings afford a full understanding of three possible force-driven structural transitions of torsion-unconstrained DNA and the resulting three overstretched DNA structures.
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Atwell S, Disseau L, Stasiak AZ, Stasiak A, Renodon-Cornière A, Takahashi M, Viovy JL, Cappello G. Probing Rad51-DNA interactions by changing DNA twist. Nucleic Acids Res 2012. [PMID: 23180779 PMCID: PMC3526263 DOI: 10.1093/nar/gks1131] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In eukaryotes, Rad51 protein is responsible for the recombinational repair of double-strand DNA breaks. Rad51 monomers cooperatively assemble on exonuclease-processed broken ends forming helical nucleo-protein filaments that can pair with homologous regions of sister chromatids. Homologous pairing allows the broken ends to be reunited in a complex but error-free repair process. Rad51 protein has ATPase activity but its role is poorly understood, as homologous pairing is independent of adenosine triphosphate (ATP) hydrolysis. Here we use magnetic tweezers and electron microscopy to investigate how changes of DNA twist affect the structure of Rad51-DNA complexes and how ATP hydrolysis participates in this process. We show that Rad51 protein can bind to double-stranded DNA in two different modes depending on the enforced DNA twist. The stretching mode is observed when DNA is unwound towards a helical repeat of 18.6 bp/turn, whereas a non-stretching mode is observed when DNA molecules are not permitted to change their native helical repeat. We also show that the two forms of complexes are interconvertible and that by enforcing changes of DNA twist one can induce transitions between the two forms. Our observations permit a better understanding of the role of ATP hydrolysis in Rad51-mediated homologous pairing and strand exchange.
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Affiliation(s)
- Scott Atwell
- Institut Curie, Centre de Recherche-Physico-Chimie-Curie, CNRS UMR168, Université Pierre et Marie Curie, Paris F-75231, France, Centre Intégratif de Génomique, Faculté de Biologie et de Médecine, Université de Lausanne, CH-1015 Lausanne, Switzerland and Unité Fonctionnalité et Ingénierie des Protéines, FRE CNRS 3478, Université de Nantes, Nantes F-44322 Cedex 03, France
| | - Ludovic Disseau
- Institut Curie, Centre de Recherche-Physico-Chimie-Curie, CNRS UMR168, Université Pierre et Marie Curie, Paris F-75231, France, Centre Intégratif de Génomique, Faculté de Biologie et de Médecine, Université de Lausanne, CH-1015 Lausanne, Switzerland and Unité Fonctionnalité et Ingénierie des Protéines, FRE CNRS 3478, Université de Nantes, Nantes F-44322 Cedex 03, France
| | - Alicja Z. Stasiak
- Institut Curie, Centre de Recherche-Physico-Chimie-Curie, CNRS UMR168, Université Pierre et Marie Curie, Paris F-75231, France, Centre Intégratif de Génomique, Faculté de Biologie et de Médecine, Université de Lausanne, CH-1015 Lausanne, Switzerland and Unité Fonctionnalité et Ingénierie des Protéines, FRE CNRS 3478, Université de Nantes, Nantes F-44322 Cedex 03, France
| | - Andrzej Stasiak
- Institut Curie, Centre de Recherche-Physico-Chimie-Curie, CNRS UMR168, Université Pierre et Marie Curie, Paris F-75231, France, Centre Intégratif de Génomique, Faculté de Biologie et de Médecine, Université de Lausanne, CH-1015 Lausanne, Switzerland and Unité Fonctionnalité et Ingénierie des Protéines, FRE CNRS 3478, Université de Nantes, Nantes F-44322 Cedex 03, France
- *To whom correspondence should be addressed. Tel: +41 21 692 4282; Fax: +41 21 692 4115;
| | - Axelle Renodon-Cornière
- Institut Curie, Centre de Recherche-Physico-Chimie-Curie, CNRS UMR168, Université Pierre et Marie Curie, Paris F-75231, France, Centre Intégratif de Génomique, Faculté de Biologie et de Médecine, Université de Lausanne, CH-1015 Lausanne, Switzerland and Unité Fonctionnalité et Ingénierie des Protéines, FRE CNRS 3478, Université de Nantes, Nantes F-44322 Cedex 03, France
| | - Masayuki Takahashi
- Institut Curie, Centre de Recherche-Physico-Chimie-Curie, CNRS UMR168, Université Pierre et Marie Curie, Paris F-75231, France, Centre Intégratif de Génomique, Faculté de Biologie et de Médecine, Université de Lausanne, CH-1015 Lausanne, Switzerland and Unité Fonctionnalité et Ingénierie des Protéines, FRE CNRS 3478, Université de Nantes, Nantes F-44322 Cedex 03, France
| | - Jean-Louis Viovy
- Institut Curie, Centre de Recherche-Physico-Chimie-Curie, CNRS UMR168, Université Pierre et Marie Curie, Paris F-75231, France, Centre Intégratif de Génomique, Faculté de Biologie et de Médecine, Université de Lausanne, CH-1015 Lausanne, Switzerland and Unité Fonctionnalité et Ingénierie des Protéines, FRE CNRS 3478, Université de Nantes, Nantes F-44322 Cedex 03, France
| | - Giovanni Cappello
- Institut Curie, Centre de Recherche-Physico-Chimie-Curie, CNRS UMR168, Université Pierre et Marie Curie, Paris F-75231, France, Centre Intégratif de Génomique, Faculté de Biologie et de Médecine, Université de Lausanne, CH-1015 Lausanne, Switzerland and Unité Fonctionnalité et Ingénierie des Protéines, FRE CNRS 3478, Université de Nantes, Nantes F-44322 Cedex 03, France
- Correspondence may also be addressed to Giovanni Cappello. Tel: +33 1 56 24 64 68; Fax: +33 1 40 51 06 36;
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Abstract
Mixed-sequence DNA molecules undergo mechanical overstretching by approximately 70% at 60-70 pN. Since its initial discovery 15 y ago, a debate has arisen as to whether the molecule adopts a new form [Cluzel P, et al. (1996) Science 271:792-794; Smith SB, Cui Y, Bustamante C (1996) Science 271:795-799], or simply denatures under tension [van Mameren J, et al. (2009) Proc Natl Acad Sci USA 106:18231-18236]. Here, we resolve this controversy by using optical tweezers to extend small 60-64 bp single DNA duplex molecules whose base content can be designed at will. We show that when AT content is high (70%), a force-induced denaturation of the DNA helix ensues at 62 pN that is accompanied by an extension of the molecule of approximately 70%. By contrast, GC-rich sequences (60% GC) are found to undergo a reversible overstretching transition into a distinct form that is characterized by a 51% extension and that remains base-paired. For the first time, results proving the existence of a stretched basepaired form of DNA can be presented. The extension observed in the reversible transition coincides with that produced on DNA by binding of bacterial RecA and human Rad51, pointing to its possible relevance in homologous recombination.
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Fornander LH, Frykholm K, Reymer A, Renodon-Cornière A, Takahashi M, Nordén B. Ca2+ improves organization of single-stranded DNA bases in human Rad51 filament, explaining stimulatory effect on gene recombination. Nucleic Acids Res 2012; 40:4904-13. [PMID: 22362735 PMCID: PMC3367181 DOI: 10.1093/nar/gks140] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Human RAD51 protein (HsRad51) catalyses the DNA strand exchange reaction for homologous recombination. To clarify the molecular mechanism of the reaction in vitro being more effective in the presence of Ca2+ than of Mg2+, we have investigated the effect of these ions on the structure of HsRad51 filament complexes with single- and double-stranded DNA, the reaction intermediates. Flow linear dichroism spectroscopy shows that the two ionic conditions induce significantly different structures in the HsRad51/single-stranded DNA complex, while the HsRad51/double-stranded DNA complex does not demonstrate this ionic dependence. In the HsRad51/single-stranded DNA filament, the primary intermediate of the strand exchange reaction, ATP/Ca2+ induces an ordered conformation of DNA, with preferentially perpendicular orientation of nucleobases relative to the filament axis, while the presence of ATP/Mg2+, ADP/Mg2+ or ADP/Ca2+ does not. A high strand exchange activity is observed for the filament formed with ATP/Ca2+, whereas the other filaments exhibit lower activity. Molecular modelling suggests that the structural variation is caused by the divalent cation interfering with the L2 loop close to the DNA-binding site. It is proposed that the larger Ca2+ stabilizes the loop conformation and thereby the protein–DNA interaction. A tight binding of DNA, with bases perpendicularly oriented, could facilitate strand exchange.
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Affiliation(s)
- Louise H Fornander
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
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Amunugama R, Fishel R. Homologous Recombination in Eukaryotes. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 110:155-206. [DOI: 10.1016/b978-0-12-387665-2.00007-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Cerasoli E, Ravi J, Gregor C, Hussain R, Siligardi G, Martyna G, Crain J, Ryadnov MG. Membrane mediated regulation in free peptides of HIV-1 gp41: minimal modulation of the hemifusion phase. Phys Chem Chem Phys 2012; 14:1277-85. [DOI: 10.1039/c1cp23155c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ragunathan K, Joo C, Ha T. Real-time observation of strand exchange reaction with high spatiotemporal resolution. Structure 2011; 19:1064-73. [PMID: 21827943 DOI: 10.1016/j.str.2011.06.009] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 05/23/2011] [Accepted: 06/07/2011] [Indexed: 11/25/2022]
Abstract
RecA binds to single-stranded (ss) DNA to form a helical filament that catalyzes strand exchange with a homologous double-stranded (ds) DNA. The study of strand exchange in ensemble assays is limited by the diffusion limited homology search process, which masks the subsequent strand exchange reaction. We developed a single-molecule fluorescence assay with a few base-pair and millisecond resolution that can separate initial docking from the subsequent propagation of joint molecule formation. Our data suggest that propagation occurs in 3 bp increments with destabilization of the incoming dsDNA and concomitant pairing with the reference ssDNA. Unexpectedly, we discovered the formation of a dynamic complex between RecA and the displaced DNA that remains bound transiently after joint molecule formation. This finding could have important implications for the irreversibility of strand exchange. Our model for strand exchange links structural models of RecA to its catalytic function.
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Affiliation(s)
- Kaushik Ragunathan
- Center for Biophysics and Computational Biology, Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Amunugama R, Fishel R. Subunit interface residues F129 and H294 of human RAD51 are essential for recombinase function. PLoS One 2011; 6:e23071. [PMID: 21857994 PMCID: PMC3155514 DOI: 10.1371/journal.pone.0023071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Accepted: 07/05/2011] [Indexed: 11/30/2022] Open
Abstract
RAD51 mediated homologous recombinational repair (HRR) of DNA double-strand breaks (DSBs) is essential to maintain genomic integrity. RAD51 forms a nucleoprotein filament (NPF) that catalyzes the fundamental homologous pairing and strand exchange reaction (recombinase) required for HRR. Based on structural and functional homology with archaeal and yeast RAD51, we have identified the human RAD51 (HsRAD51) subunit interface residues HsRad51(F129) in the Walker A box and HsRad51(H294) in the L2 ssDNA binding region as potentially important participants in salt-induced conformational transitions essential for recombinase activity. We demonstrate that the HsRad51(F129V) and HsRad51(H294V) substitution mutations reduce DNA dependent ATPase activity and are largely defective in the formation of a functional NPF, which ultimately eliminates recombinase catalytic functions. Our data are consistent with the conclusion that the HsRAD51(F129) and HsRAD51(H294) residues are important participants in the cation-induced allosteric activation of HsRAD51.
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Affiliation(s)
- Ravindra Amunugama
- Biophysics Graduate Program, The Ohio State University Medical Center and Comprehensive Cancer Center, Columbus, Ohio, United States of America
- Department of Molecular Virology, Immunology, and Medical Genetics, Human Cancer Genetics, The Ohio State University Medical Center and Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Richard Fishel
- Department of Molecular Virology, Immunology, and Medical Genetics, Human Cancer Genetics, The Ohio State University Medical Center and Comprehensive Cancer Center, Columbus, Ohio, United States of America
- Physics Department, The Ohio State University Columbus, Columbus, Ohio, United States of America
- * E-mail:
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Kogan M, Beke-Somfai T, Nordén B. Flow-alignment of bicellar lipid mixtures: orientations of probe molecules and membrane-associated biomacromolecules in lipid membranes studied with polarized light. Chem Commun (Camb) 2011; 47:7356-8. [PMID: 21637893 DOI: 10.1039/c1cc12313k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bicelles are excellent membrane-mimicking hosts for a dynamic and structural study of solutes with NMR, but the magnetic fields required for their alignment are hard to apply to optical conditions. Here we demonstrate that bicellar mixtures can be aligned by shear forces in a Couette flow cell, to provide orientation of membrane-bound retinoic acid, pyrene and cytochrome c (cyt c) protein, conveniently studied with linear dichroism spectroscopy.
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Affiliation(s)
- Maxim Kogan
- Department of Chemical and Biological Engineering, Physical Chemistry, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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Tsai YC, Wang Y, Urena DE, Kumar S, Chen J. Heterology tolerance and recognition of mismatched base pairs by human Rad51 protein. DNA Repair (Amst) 2011; 10:363-72. [PMID: 21239234 DOI: 10.1016/j.dnarep.2010.12.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 12/17/2010] [Accepted: 12/20/2010] [Indexed: 12/15/2022]
Abstract
Human Rad51 (hRad51) promoted homology recognition and subsequent strand exchange are the key steps in human homologous recombination mediated repair of DNA double-strand breaks. However, it is still not clear how hRad51 deals with sequence heterology between the two homologous chromosomes in eukaryotic cells, which would lead to mismatched base pairs after strand exchange. Excessive tolerance of sequence heterology may compromise the fidelity of repair of DNA double-strand breaks. In this study, fluorescence resonance energy transfer (FRET) was used to monitor the heterology tolerance of human Rad51 mediated strand exchange reactions, in real time, by introducing either G-T or I-C mismatched base pairs between the two homologous DNA strands. The strand exchange reactions were much more sensitive to G-T than to I-C base pairs. These results imply that the recognition of homology and the tolerance of heterology by hRad51 may depend on the local structural motif adopted by the base pairs participating in strand exchange. AnhRad51 mutant protein (hRad51K133R), deficient in ATP hydrolysis, showed greater heterology tolerance to both types of mismatch base pairing, suggesting that ATPase activity may be important for maintenance of high fidelity homologous recombination DNA repair.
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Affiliation(s)
- Yu-Cheng Tsai
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
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45
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RecA-Mediated Homology Search as a Nearly Optimal Signal Detection System. Mol Cell 2010; 40:388-96. [DOI: 10.1016/j.molcel.2010.10.020] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 02/18/2010] [Accepted: 09/08/2010] [Indexed: 11/18/2022]
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46
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Feng B, Frykholm K, Nordén B, Westerlund F. DNA strand exchange catalyzed by molecular crowding in PEG solutions. Chem Commun (Camb) 2010; 46:8231-3. [DOI: 10.1039/c0cc03117h] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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