1
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Shen J, Qiao L. Proteomic and metabolic analysis of Moorella thermoacetica-g-C 3N 4 nanocomposite system for artificial photosynthesis. Talanta 2024; 278:126479. [PMID: 38941811 DOI: 10.1016/j.talanta.2024.126479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 06/18/2024] [Accepted: 06/24/2024] [Indexed: 06/30/2024]
Abstract
Artificial photosynthesis by microbe-semiconductor biohybrid systems has been demonstrated as a valuable strategy in providing sustainable energy and in carbon fixation. However, most of the developed biohybrid systems for light harvesting employ heavy metal materials, especially cadmium sulfide (CdS), which normally cause environmental pollution and restrict the widespread of the systems. Herein, we constructed an environmentally friendly biohybirid system based on a typical acetogenic bacteria, Moorella thermoacetica, coupling with a carbon-based semiconductor, graphitic carbon nitride (g-C3N4), to realize light-driven carbon fixation. The proposed biohybrid system displayed outstanding acetate productivity with a quantum yield of 2.66 ± 0.43 %. Non-targeted proteomic analysis indicated that the physiological activity of the bacteria was improved, coupling with the non-toxic material. We further proposed the mechanisms of energy generation, electron transfer and CO2 fixation of the irradiated biohybrid system by proteomic and metabolomic characterization. With the photoelectron generated in g-C3N4 under illumination, CO2 is finally converted to acetate via the Wood-Ljungdahl pathway (WLP). Other associated pathways were also proved to be activated, providing extra energy or substrates for acetate production. The study reveals that the future focus of the development of biohybrid systems for light harvesting can be on the metal-free biocompatible material, which can activate the expression of the key enzymes involved in the electron transfer and carbon metabolism under light irradiation.
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Affiliation(s)
- Jiayuan Shen
- Department of Chemistry, and Minhang Hospital, Fudan University, Shanghai, 200000, China
| | - Liang Qiao
- Department of Chemistry, and Minhang Hospital, Fudan University, Shanghai, 200000, China.
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2
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Muhammad AA, Basto C, Peterlini T, Guirouilh-Barbat J, Thomas M, Veaute X, Busso D, Lopez B, Mazon G, Le Cam E, Masson JY, Dupaigne P. Human RAD52 stimulates the RAD51-mediated homology search. Life Sci Alliance 2024; 7:e202201751. [PMID: 38081641 PMCID: PMC10713436 DOI: 10.26508/lsa.202201751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/01/2023] [Accepted: 12/01/2023] [Indexed: 12/18/2023] Open
Abstract
Homologous recombination (HR) is a DNA repair mechanism of double-strand breaks and blocked replication forks, involving a process of homology search leading to the formation of synaptic intermediates that are regulated to ensure genome integrity. RAD51 recombinase plays a central role in this mechanism, supported by its RAD52 and BRCA2 partners. If the mediator function of BRCA2 to load RAD51 on RPA-ssDNA is well established, the role of RAD52 in HR is still far from understood. We used transmission electron microscopy combined with biochemistry to characterize the sequential participation of RPA, RAD52, and BRCA2 in the assembly of the RAD51 filament and its activity. Although our results confirm that RAD52 lacks a mediator activity, RAD52 can tightly bind to RPA-coated ssDNA, inhibit the mediator activity of BRCA2, and form shorter RAD51-RAD52 mixed filaments that are more efficient in the formation of synaptic complexes and D-loops, resulting in more frequent multi-invasions as well. We confirm the in situ interaction between RAD51 and RAD52 after double-strand break induction in vivo. This study provides new molecular insights into the formation and regulation of presynaptic and synaptic intermediates by BRCA2 and RAD52 during human HR.
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Affiliation(s)
- Ali Akbar Muhammad
- Genome Integrity and Cancers UMR 9019 CNRS, Université Paris- Saclay, Gustave Roussy, Villejuif Cedex, France
| | - Clara Basto
- Genome Integrity and Cancers UMR 9019 CNRS, Université Paris- Saclay, Gustave Roussy, Villejuif Cedex, France
| | - Thibaut Peterlini
- Genome Stability Laboratory, CHU de Quebec Research Center, HDQ Pavilion, Oncology Axis, Quebec City, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Quebec City, Canada
| | - Josée Guirouilh-Barbat
- https://ror.org/02vjkv261 INSERM U1016, UMR 8104 CNRS, Institut Cochin, Equipe Labellisée Ligue Contre le Cancer, Université de Paris, Paris, France
| | - Melissa Thomas
- Genome Stability Laboratory, CHU de Quebec Research Center, HDQ Pavilion, Oncology Axis, Quebec City, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Quebec City, Canada
| | - Xavier Veaute
- https://ror.org/02vjkv261 CIGEx Platform, INSERM, IRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, Université de Paris and Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Didier Busso
- https://ror.org/02vjkv261 CIGEx Platform, INSERM, IRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, Université de Paris and Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Bernard Lopez
- https://ror.org/02vjkv261 INSERM U1016, UMR 8104 CNRS, Institut Cochin, Equipe Labellisée Ligue Contre le Cancer, Université de Paris, Paris, France
| | - Gerard Mazon
- Genome Integrity and Cancers UMR 9019 CNRS, Université Paris- Saclay, Gustave Roussy, Villejuif Cedex, France
| | - Eric Le Cam
- Genome Integrity and Cancers UMR 9019 CNRS, Université Paris- Saclay, Gustave Roussy, Villejuif Cedex, France
| | - Jean-Yves Masson
- Genome Stability Laboratory, CHU de Quebec Research Center, HDQ Pavilion, Oncology Axis, Quebec City, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Quebec City, Canada
| | - Pauline Dupaigne
- Genome Integrity and Cancers UMR 9019 CNRS, Université Paris- Saclay, Gustave Roussy, Villejuif Cedex, France
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3
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Nevinsky GA. How Enzymes, Proteins, and Antibodies Recognize Extended DNAs; General Regularities. Int J Mol Sci 2021; 22:1369. [PMID: 33573045 PMCID: PMC7866405 DOI: 10.3390/ijms22031369] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 11/17/2022] Open
Abstract
X-ray analysis cannot provide quantitative estimates of the relative contribution of non-specific, specific, strong, and weak contacts of extended DNA molecules to their total affinity for enzymes and proteins. The interaction of different enzymes and proteins with long DNA and RNA at the quantitative molecular level can be successfully analyzed using the method of the stepwise increase in ligand complexity (SILC). The present review summarizes the data on stepwise increase in ligand complexity (SILC) analysis of nucleic acid recognition by various enzymes-replication, restriction, integration, topoisomerization, six different repair enzymes (uracil DNA glycosylase, Fpg protein from Escherichia coli, human 8-oxoguanine-DNA glycosylase, human apurinic/apyrimidinic endonuclease, RecA protein, and DNA-ligase), and five DNA-recognizing proteins (RNA helicase, human lactoferrin, alfa-lactalbumin, human blood albumin, and IgGs against DNA). The relative contributions of structural elements of DNA fragments "covered" by globules of enzymes and proteins to the total affinity of DNA have been evaluated. Thermodynamic and catalytic factors providing discrimination of unspecific and specific DNAs by these enzymes on the stages of primary complex formation following changes in enzymes and DNAs or RNAs conformations and direct processing of the catalysis of the reactions were found. General regularities of recognition of nucleic acid by DNA-dependent enzymes, proteins, and antibodies were established.
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Affiliation(s)
- Georgy A Nevinsky
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, 63009 Novosibirsk, Russia
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4
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Serrano E, Ramos C, Alonso JC, Ayora S. Recombination proteins differently control the acquisition of homeologous DNA during Bacillus subtilis natural chromosomal transformation. Environ Microbiol 2020; 23:512-524. [PMID: 33264457 DOI: 10.1111/1462-2920.15342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 11/30/2020] [Indexed: 12/23/2022]
Abstract
Natural chromosomal transformation (CT) plays a major role in prokaryote evolution, yet factors that govern the integration of DNA from related species remain poorly understood. We show that in naturally competent Bacillus subtilis cells the acquisition of homeologous sequences is governed by sequence divergence (SD). Integration initiates in a minimal efficient processing segment via homology-directed CT, and its frequency decreases log-linearly with increased SD up to 15%. Beyond this and up to 23% SD the interspecies boundaries prevail, the CT frequency marginally decreases, and short (<10-nucleotides) segments are integrated via homology-facilitated micro-homologous integration. Both mechanisms are RecA dependent. We identify the other recombination proteins required for the acquisition of homeologous DNA. The absence of AddAB, RecF, RecO, RuvAB or RecU, crucial for repair-by-recombination, did not affect CT. However, dprA, radA, recJ, recX or recD2 inactivation strongly decreased intraspecies and interspecies CT. Interspecies CT was not detected beyond ~8% SD in ΔdprA, ~10% in ΔrecJ, ΔradA, ΔrecX and ~14% in ΔrecD2 cells. We propose that DprA, RecX, RadA/Sms, RecJ and RecD2 accessory proteins are important for the generation of genetic diversity. Together with RecA, they facilitate gene acquisition from bacteria of related species.
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Affiliation(s)
- Ester Serrano
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, 28049, Spain
| | - Cristina Ramos
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, 28049, Spain
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, 28049, Spain
| | - Silvia Ayora
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, 28049, Spain
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5
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Real-time tracking reveals catalytic roles for the two DNA binding sites of Rad51. Nat Commun 2020; 11:2950. [PMID: 32528002 PMCID: PMC7289862 DOI: 10.1038/s41467-020-16750-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 05/19/2020] [Indexed: 02/03/2023] Open
Abstract
During homologous recombination, Rad51 forms a nucleoprotein filament on single-stranded DNA to promote DNA strand exchange. This filament binds to double-stranded DNA (dsDNA), searches for homology, and promotes transfer of the complementary strand, producing a new heteroduplex. Strand exchange proceeds via two distinct three-strand intermediates, C1 and C2. C1 contains the intact donor dsDNA whereas C2 contains newly formed heteroduplex DNA. Here, we show that the conserved DNA binding motifs, loop 1 (L1) and loop 2 (L2) in site I of Rad51, play distinct roles in this process. L1 is involved in formation of the C1 complex whereas L2 mediates the C1–C2 transition, producing the heteroduplex. Another DNA binding motif, site II, serves as the DNA entry position for initial Rad51 filament formation, as well as for donor dsDNA incorporation. Our study provides a comprehensive molecular model for the catalytic process of strand exchange mediated by eukaryotic RecA-family recombinases. Rad51 drives DNA strand exchange, the central reaction in recombinational DNA repair. Two sites of Rad51 are responsible for DNA binding, but the function of these sites has proven elusive. Here, the authors employ real-time assays to reveal catalytic roles for the two DNA binding sites of Rad51.
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6
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Tavares EM, Wright WD, Heyer WD, Le Cam E, Dupaigne P. In vitro role of Rad54 in Rad51-ssDNA filament-dependent homology search and synaptic complexes formation. Nat Commun 2019; 10:4058. [PMID: 31492866 PMCID: PMC6731316 DOI: 10.1038/s41467-019-12082-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 08/12/2019] [Indexed: 11/28/2022] Open
Abstract
Homologous recombination (HR) uses a homologous template to accurately repair DNA double-strand breaks and stalled replication forks to maintain genome stability. During homology search, Rad51 nucleoprotein filaments probe and interact with dsDNA, forming the synaptic complex that is stabilized on a homologous sequence. Strand intertwining leads to the formation of a displacement-loop (D-loop). In yeast, Rad54 is essential for HR in vivo and required for D-loop formation in vitro, but its exact role remains to be fully elucidated. Using electron microscopy to visualize the DNA-protein complexes, here we find that Rad54 is crucial for Rad51-mediated synaptic complex formation and homology search. The Rad54−K341R ATPase-deficient mutant protein promotes formation of synaptic complexes but not D-loops and leads to the accumulation of stable heterologous associations, suggesting that the Rad54 ATPase is involved in preventing non-productive intermediates. We propose that Rad51/Rad54 form a functional unit operating in homology search, synaptic complex and D-loop formation. Homologous recombination uses a template to accurately repair DNA double-strand breaks and stalled replication forks to maintain genome stability. Here authors use electron microscopy to investigate the role of Rad54 in homology search and synaptic complex formation.
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Affiliation(s)
- Eliana Moreira Tavares
- Genome Maintenance and Molecular Microscopy UMR8126 CNRS, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy, F-94805, Villejuif Cedex, France
| | - William Douglass Wright
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, 95616-8665, USA
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA, 95616-8665, USA
| | - Eric Le Cam
- Genome Maintenance and Molecular Microscopy UMR8126 CNRS, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy, F-94805, Villejuif Cedex, France
| | - Pauline Dupaigne
- Genome Maintenance and Molecular Microscopy UMR8126 CNRS, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy, F-94805, Villejuif Cedex, France.
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7
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Wright WD, Shah SS, Heyer WD. Homologous recombination and the repair of DNA double-strand breaks. J Biol Chem 2018; 293:10524-10535. [PMID: 29599286 DOI: 10.1074/jbc.tm118.000372] [Citation(s) in RCA: 406] [Impact Index Per Article: 67.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Homologous recombination enables the cell to access and copy intact DNA sequence information in trans, particularly to repair DNA damage affecting both strands of the double helix. Here, we discuss the DNA transactions and enzymatic activities required for this elegantly orchestrated process in the context of the repair of DNA double-strand breaks in somatic cells. This includes homology search, DNA strand invasion, repair DNA synthesis, and restoration of intact chromosomes. Aspects of DNA topology affecting individual steps are highlighted. Overall, recombination is a dynamic pathway with multiple metastable and reversible intermediates designed to achieve DNA repair with high fidelity.
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Affiliation(s)
| | | | - Wolf-Dietrich Heyer
- From the Departments of Microbiology and Molecular Genetics and .,Molecular and Cellular Biology, University of California, Davis, Davis, California 95616-8665
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8
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Chen J, Tang Q, Guo S, Lu C, Le S, Yan J. Parallel triplex structure formed between stretched single-stranded DNA and homologous duplex DNA. Nucleic Acids Res 2017; 45:10032-10041. [PMID: 28973442 PMCID: PMC5622322 DOI: 10.1093/nar/gkx628] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 07/11/2017] [Indexed: 02/01/2023] Open
Abstract
The interaction between the single-stranded DNA and the homologous duplex DNA is essential for DNA homologous repair. Here, we report that parallel triplex structure can form spontaneously between a mechanically extended ssDNA and a homologous dsDNA in protein-free condition. The triplex has a contour length close to that of a B-form DNA duplex and remains stable after force is released. The binding energy between the ssDNA and the homologous dsDNA in the triplex is estimated to be comparable to the basepairing energy in a B-form dsDNA. As ssDNA is in a similar extended conformation within recombinase-coated nucleoprotein filaments, we propose that the parallel triplex may form and serve as an intermediate during recombinase-catalyzed homologous joint formation.
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Affiliation(s)
- Jin Chen
- Mechanobiology Institute, National University of Singapore, 117411, Singapore
| | - Qingnan Tang
- Department of Physics, National University of Singapore, 117542, Singapore
| | - Shiwen Guo
- Mechanobiology Institute, National University of Singapore, 117411, Singapore
| | - Chen Lu
- Mechanobiology Institute, National University of Singapore, 117411, Singapore.,Centre for Bioimaging Sciences, National University of Singapore, 117546, Singapore
| | - Shimin Le
- Mechanobiology Institute, National University of Singapore, 117411, Singapore.,Department of Physics, National University of Singapore, 117542, Singapore
| | - Jie Yan
- Mechanobiology Institute, National University of Singapore, 117411, Singapore.,Department of Physics, National University of Singapore, 117542, Singapore.,Centre for Bioimaging Sciences, National University of Singapore, 117546, Singapore
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9
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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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10
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León SC, Prentiss M, Fyta M. Binding energies of nucleobase complexes: Relevance to homology recognition of DNA. Phys Rev E 2016; 93:062410. [PMID: 27415301 DOI: 10.1103/physreve.93.062410] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Indexed: 06/06/2023]
Abstract
The binding energies of complexes of DNA nucleobase pairs are evaluated using quantum mechanical calculations at the level of dispersion corrected density functional theory. We begin with Watson-Crick base pairs of singlets, duplets, and triplets and calculate their binding energies. At a second step, mismatches are incorporated into the Watson-Crick complexes in order to evaluate the variation in the binding energy with respect to the canonical Watson-Crick pairs. A linear variation of this binding energy with the degree of mismatching is observed. The binding energies for the duplets and triplets containing mismatches are further compared to the energies of the respective singlets in order to assess the degree of collectivity in these complexes. This study also suggests that mismatches do not considerably affect the energetics of canonical base pairs. Our work is highly relevant to the recognition process in DNA promoted through the RecA protein and suggests a clear distinction between recognition in singlets, and recognition in duplets or triplets. Our work assesses the importance of collectivity in the homology recognition of DNA.
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Affiliation(s)
- Sergio Cruz León
- Institute for Computational Physics, Universität Stuttgart, Allmandring 3, 70569 Stuttgart, Germany
- Departamento de Ciencias Naturales, Escuela Colombiana de Ingeniería Julio Garavito, AK 45 205-59, Bogotá, Colombia
| | - Mara Prentiss
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138, USA
| | - Maria Fyta
- Institute for Computational Physics, Universität Stuttgart, Allmandring 3, 70569 Stuttgart, Germany
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11
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Abstract
The bacteriophage λ Red homologous recombination system has been studied over the past 50 years as a model system to define the mechanistic details of how organisms exchange DNA segments that share extended regions of homology. The λ Red system proved useful as a system to study because recombinants could be easily generated by co-infection of genetically marked phages. What emerged from these studies was the recognition that replication of phage DNA was required for substantial Red-promoted recombination in vivo, and the critical role that double-stranded DNA ends play in allowing the Red proteins access to the phage DNA chromosomes. In the past 16 years, however, the λ Red recombination system has gained a new notoriety. When expressed independently of other λ functions, the Red system is able to promote recombination of linear DNA containing limited regions of homology (∼50 bp) with the Escherichia coli chromosome, a process known as recombineering. This review explains how the Red system works during a phage infection, and how it is utilized to make chromosomal modifications of E. coli with such efficiency that it changed the nature and number of genetic manipulations possible, leading to advances in bacterial genomics, metabolic engineering, and eukaryotic genetics.
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Affiliation(s)
- Kenan C Murphy
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605
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12
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Abstract
Homologous recombination allows for the regulated exchange of genetic information between two different DNA molecules of identical or nearly identical sequence composition, and is a major pathway for the repair of double-stranded DNA breaks. A key facet of homologous recombination is the ability of recombination proteins to perfectly align the damaged DNA with homologous sequence located elsewhere in the genome. This reaction is referred to as the homology search and is akin to the target searches conducted by many different DNA-binding proteins. Here I briefly highlight early investigations into the homology search mechanism, and then describe more recent research. Based on these studies, I summarize a model that includes a combination of intersegmental transfer, short-distance one-dimensional sliding, and length-specific microhomology recognition to efficiently align DNA sequences during the homology search. I also suggest some future directions to help further our understanding of the homology search. Where appropriate, I direct the reader to other recent reviews describing various issues related to homologous recombination.
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Affiliation(s)
- Eric C Greene
- From the Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032
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13
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Mismatch repair and homeologous recombination. DNA Repair (Amst) 2015; 38:75-83. [PMID: 26739221 DOI: 10.1016/j.dnarep.2015.11.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 10/26/2015] [Accepted: 11/30/2015] [Indexed: 12/27/2022]
Abstract
DNA mismatch repair influences the outcome of recombination events between diverging DNA sequences. Here we discuss how mismatch repair proteins are active in different homologous recombination subpathways and specific reaction steps, resulting in differential modulation of these recombination events, with a focus on the mechanism of heteroduplex rejection during the inhibition of recombination between slightly diverged (homeologous) DNA sequences.
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14
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Yang D, Boyer B, Prévost C, Danilowicz C, Prentiss M. Integrating multi-scale data on homologous recombination into a new recognition mechanism based on simulations of the RecA-ssDNA/dsDNA structure. Nucleic Acids Res 2015; 43:10251-63. [PMID: 26384422 PMCID: PMC4666392 DOI: 10.1093/nar/gkv883] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 08/23/2015] [Indexed: 12/11/2022] Open
Abstract
RecA protein is the prototypical recombinase. Members of the recombinase family can accurately repair double strand breaks in DNA. They also provide crucial links between pairs of sister chromatids in eukaryotic meiosis. A very broad outline of how these proteins align homologous sequences and promote DNA strand exchange has long been known, as are the crystal structures of the RecA-DNA pre- and postsynaptic complexes; however, little is known about the homology searching conformations and the details of how DNA in bacterial genomes is rapidly searched until homologous alignment is achieved. By integrating a physical model of recognition to new modeling work based on docking exploration and molecular dynamics simulation, we present a detailed structure/function model of homology recognition that reconciles extremely quick searching with the efficient and stringent formation of stable strand exchange products and which is consistent with a vast body of previously unexplained experimental results.
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Affiliation(s)
- Darren Yang
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Benjamin Boyer
- Laboratoire de Biochimie Théorique, CNRS UPR 9080, Univ Paris Diderot, Sorbonne Paris Cité, IBPC, Paris, France
| | - Chantal Prévost
- Laboratoire de Biochimie Théorique, CNRS UPR 9080, Univ Paris Diderot, Sorbonne Paris Cité, IBPC, Paris, France
| | | | - Mara Prentiss
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
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15
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Danilowicz C, Yang D, Kelley C, Prévost C, Prentiss M. The poor homology stringency in the heteroduplex allows strand exchange to incorporate desirable mismatches without sacrificing recognition in vivo. Nucleic Acids Res 2015; 43:6473-85. [PMID: 26089391 PMCID: PMC4513875 DOI: 10.1093/nar/gkv610] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 05/31/2015] [Indexed: 11/15/2022] Open
Abstract
RecA family proteins are responsible for homology search and strand exchange. In bacteria, homology search begins after RecA binds an initiating single-stranded DNA (ssDNA) in the primary DNA-binding site, forming the presynaptic filament. Once the filament is formed, it interrogates double-stranded DNA (dsDNA). During the interrogation, bases in the dsDNA attempt to form Watson–Crick bonds with the corresponding bases in the initiating strand. Mismatch dependent instability in the base pairing in the heteroduplex strand exchange product could provide stringent recognition; however, we present experimental and theoretical results suggesting that the heteroduplex stability is insensitive to mismatches. We also present data suggesting that an initial homology test of 8 contiguous bases rejects most interactions containing more than 1/8 mismatches without forming a detectable 20 bp product. We propose that, in vivo, the sparsity of accidental sequence matches allows an initial 8 bp test to rapidly reject almost all non-homologous sequences. We speculate that once the initial test is passed, the mismatch insensitive binding in the heteroduplex allows short mismatched regions to be incorporated in otherwise homologous strand exchange products even though sequences with less homology are eventually rejected.
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Affiliation(s)
| | - Darren Yang
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Craig Kelley
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Chantal Prévost
- Laboratoire de Biochimie Théorique, CNRS UPR 9080, Univ. Paris Diderot, Sorbonne Paris Cité, IBPC, Paris, France
| | - Mara Prentiss
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
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16
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Sansam CL, Pezza RJ. Connecting by breaking and repairing: mechanisms of DNA strand exchange in meiotic recombination. FEBS J 2015; 282:2444-57. [PMID: 25953379 PMCID: PMC4573575 DOI: 10.1111/febs.13317] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 03/26/2015] [Accepted: 05/06/2015] [Indexed: 01/03/2023]
Abstract
During prophase of meiosis I, homologous chromosomes interact and undergo recombination. Successful completion of these processes is required in order for the homologous chromosomes to mount the meiotic spindle as a pair. The organization of the chromosomes into pairs ensures orderly segregation to opposite poles of the dividing cell, such that each gamete receives one copy of each chromosome. Chiasmata, the cytological manifestation of crossover products of recombination, physically connect the homologs in pairs, providing a linkage that facilitates their segregation. Consequently, mutations that reduce the level of recombination are invariably associated with increased errors in meiotic chromosome segregation. In this review, we focus on recent biochemical and genetic advances in elucidating the mechanisms of meiotic DNA strand exchange catalyzed by the Dmc1 protein. We also discuss the mode by which two recombination mediators, Hop2 and Mnd1, facilitate rate-limiting steps of DNA strand exchange catalyzed by Dmc1.
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Affiliation(s)
- Christopher L Sansam
- Cell Cycle and Cancer Biology Program, Oklahoma Medical Research Foundation and the Department of Cell Biology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Roberto J Pezza
- Cell Cycle and Cancer Biology Program, Oklahoma Medical Research Foundation and the Department of Cell Biology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
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17
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Jiang L, Prentiss M. RecA-mediated sequence homology recognition as an example of how searching speed in self-assembly systems can be optimized by balancing entropic and enthalpic barriers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:022704. [PMID: 25215755 PMCID: PMC4972340 DOI: 10.1103/physreve.90.022704] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Indexed: 06/03/2023]
Abstract
Ideally, self-assembly should rapidly and efficiently produce stable correctly assembled structures. We study the tradeoff between enthalpic and entropic cost in self-assembling systems using RecA-mediated homology search as an example. Earlier work suggested that RecA searches could produce stable final structures with high stringency using a slow testing process that follows an initial rapid search of ∼9-15 bases. In this work, we will show that as a result of entropic and enthalpic barriers, simultaneously testing all ∼9-15 bases as separate individual units results in a longer overall searching time than testing them in groups and stages.
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18
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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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19
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Pezza RJ, Voloshin ON, Volodin AA, Boateng KA, Bellani MA, Mazin AV, Camerini-Otero RD. The dual role of HOP2 in mammalian meiotic homologous recombination. Nucleic Acids Res 2013; 42:2346-57. [PMID: 24304900 PMCID: PMC3936763 DOI: 10.1093/nar/gkt1234] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Deletion of Hop2 in mice eliminates homologous chromosome synapsis and disrupts double-strand break (DSB) repair through homologous recombination. HOP2 in vitro shows two distinctive activities: when it is incorporated into a HOP2–MND1 complex it stimulates DMC1 and RAD51 recombination activities and the purified HOP2 alone is proficient in promoting strand invasion. We observed that a fraction of Mnd1−/− spermatocytes, which express HOP2 but apparently have inactive DMC1 and RAD51 due to lack of the HOP2–MND1 complex, exhibits a high level of chromosome synapsis and that most DSBs in these spermatocytes are repaired. This suggests that DSB repair catalyzed solely by HOP2 supports homologous chromosome pairing and synapsis. In addition, we show that in vitro HOP2 promotes the co-aggregation of ssDNA with duplex DNA, binds to ssDNA leading to unstacking of the bases, and promotes the formation of a three-strand synaptic intermediate. However, HOP2 shows distinctive mechanistic signatures as a recombinase. Namely, HOP2-mediated strand exchange does not require ATP and, in contrast to DMC1, joint molecules formed by HOP2 are more sensitive to mismatches and are efficiently dissociated by RAD54. We propose that HOP2 may act as a recombinase with specific functions in meiosis.
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Affiliation(s)
- Roberto J Pezza
- Oklahoma Medical Research Foundation, Oklahoma City, 73104 OK, USA, Department of Cell Biology, Oklahoma University Health Science Center, Oklahoma City, 73126 OK, USA, Genetics and Biochemistry Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, 20892 MD, USA, Institute of Molecular Genetics of the Russian Academy of Sciences, 123182 Moscow, Russia, Biomedical Research Center, National Institute of Aging, Baltimore, 21224 MA, USA and Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, 19102 PA, USA
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20
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Application of the ASLP technology to a novel platform for rapid and noise-free multiplexed SNP genotyping. Biosens Bioelectron 2013; 54:687-94. [PMID: 24362043 DOI: 10.1016/j.bios.2013.10.071] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/30/2013] [Accepted: 10/30/2013] [Indexed: 11/30/2022]
Abstract
A novel multiplexing method, which relies on universal amplification of separated ligation-dependent probes (ASLP), has been developed to genotype single-nucleotide polymorphisms (SNPs). The ASLP technique employs two allele-specific oligonucleotides (ASO), modified with universal forward primer sequences at the 5'-end and a common locus-specific oligonucleotide (LSO) extended with a universal separation (US) sequence at the 3'-end. In the process, allele-specific ligation first takes place when target genomic DNA is hybridized by perfectly matching the ASO together with the LSO. A separation probe, which consists of a universal reverse primer sequence labeled with biotin at the 5'-end and complementary sequence of US at the 3'-end, is then applied to the resulting ligation product. During the extension reaction of the separation probe, the ligated probes dissociate from target genomic DNA in the form of a double-stranded DNA and are separated from the reaction mixture, which includes genomic DNA and unligated probes, by simply using streptavidin-coated magnetic beads. PCR amplification of the separated ligation products is then carried out by using universal primers and the PCR products are hybridized on a DNA microarray using the RecA protein. The advantageous features of the new method were demonstrated by using it to genotype 15 SNP markers for cultivar identification of pepper in a convenient and correct manner.
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21
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Shechter N, Zaltzman L, Weiner A, Brumfeld V, Shimoni E, Fridmann-Sirkis Y, Minsky A. Stress-induced condensation of bacterial genomes results in re-pairing of sister chromosomes: implications for double strand DNA break repair. J Biol Chem 2013; 288:25659-25667. [PMID: 23884460 DOI: 10.1074/jbc.m113.473025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Genome condensation is increasingly recognized as a generic stress response in bacteria. To better understand the physiological implications of this response, we used fluorescent markers to locate specific sites on Escherichia coli chromosomes following exposure to cytotoxic stress. We find that stress-induced condensation proceeds through a nonrandom, zipper-like convergence of sister chromosomes, which is proposed to rely on the recently demonstrated intrinsic ability of identical double-stranded DNA molecules to specifically identify each other. We further show that this convergence culminates in spatial proximity of homologous sites throughout chromosome arms. We suggest that the resulting apposition of homologous sites can explain how repair of double strand DNA breaks might occur in a mechanism that is independent of the widely accepted yet physiologically improbable genome-wide search for homologous templates. We claim that by inducing genome condensation and orderly convergence of sister chromosomes, diverse stress conditions prime bacteria to effectively cope with severe DNA lesions such as double strand DNA breaks.
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Affiliation(s)
| | | | | | - Vlad Brumfeld
- Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eyal Shimoni
- Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel
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22
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Vlassakis J, Feinstein E, Yang D, Tilloy A, Weiller D, Kates-Harbeck J, Coljee V, Prentiss M. Tension on dsDNA bound to ssDNA-RecA filaments may play an important role in driving efficient and accurate homology recognition and strand exchange. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:032702. [PMID: 27499708 PMCID: PMC4973255 DOI: 10.1103/physreve.87.032702] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
It is well known that during homology recognition and strand exchange the double stranded DNA (dsDNA) in DNA/RecA filaments is highly extended, but the functional role of the extension has been unclear. We present an analytical model that calculates the distribution of tension in the extended dsDNA during strand exchange. The model suggests that the binding of additional dsDNA base pairs to the DNA/RecA filament alters the tension in dsDNA that was already bound to the filament, resulting in a non-linear increase in the mechanical energy as a function of the number of bound base pairs. This collective mechanical response may promote homology stringency and underlie unexplained experimental results.
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Affiliation(s)
- Julea Vlassakis
- Harvard University, Department of Physics, Cambridge, MA, 02138
| | | | - Darren Yang
- Harvard University, Department of Physics, Cambridge, MA, 02138
| | - Antoine Tilloy
- Harvard University, Department of Physics, Cambridge, MA, 02138
| | - Dominic Weiller
- Harvard University, Department of Physics, Cambridge, MA, 02138
| | | | - Vincent Coljee
- Harvard University, Department of Physics, Cambridge, MA, 02138
| | - Mara Prentiss
- Harvard University, Department of Physics, Cambridge, MA, 02138
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23
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Sharma R, Davies AG, Wälti C. Nanoscale programmable sequence-specific patterning of DNA scaffolds using RecA protein. NANOTECHNOLOGY 2012; 23:365301. [PMID: 22910126 DOI: 10.1088/0957-4484/23/36/365301] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Molecular self-assembly inherent to many biological molecules, in conjunction with suitable molecular scaffolds to facilitate programmable positioning of nanoscale objects, offers a promising approach for the integration of functional nanoscale complexes into macroscopic host devices. Here, we report the use of the protein RecA as a means of highly efficient programmable patterning of double-stranded (ds)DNA molecules with molecular-scale precision at specific locations along the DNA strand. RecA proteins form nucleoprotein filaments with single-stranded (ss)DNA molecules, which are chosen to be of sequence homologous to the desired binding region on the dsDNA scaffold. We show that the patterning yield can be in excess of 85% and we demonstrate that concurrent patterning of multiple locations on the same dsDNA scaffold can be achieved with separation between the assembled nucleoprotein filaments of less than 4 nm. This is an important prerequisite for this programmable and flexible DNA scaffold patterning technique to be employed in molecular- and nanoscale assembly applications.
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Affiliation(s)
- R Sharma
- School of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
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24
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Mechanism of homology recognition in DNA recombination from dual-molecule experiments. Mol Cell 2012; 46:616-24. [PMID: 22560720 DOI: 10.1016/j.molcel.2012.03.029] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 02/21/2012] [Accepted: 03/30/2012] [Indexed: 11/24/2022]
Abstract
In E. coli homologous recombination, a filament of RecA protein formed on DNA searches and pairs a homologous sequence within a second DNA molecule with remarkable speed and fidelity. Here, we directly probe the strength of the two-molecule interactions involved in homology search and recognition using dual-molecule manipulation, combining magnetic and optical tweezers. We find that the filament's secondary DNA-binding site interacts with a single strand of the incoming double-stranded DNA during homology sampling. Recognition requires opening of the helix and is strongly promoted by unwinding torsional stress. Recognition is achieved upon binding of both strands of the incoming dsDNA to each of two ssDNA-binding sites in the filament. The data indicate a physical picture for homology recognition in which the fidelity of the search process is governed by the distance between the DNA-binding sites.
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25
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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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26
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Abstract
Cleverly designed single-molecule FRET experiments reported in this issue of Structure by Ragunathan et al. coax RecA to reveal some of its secrets. Observing individual events identifies intermediate steps and provides clues for how to drive strand exchange forward.
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Affiliation(s)
- Claire Wyman
- Department of Radiation Oncology, Erasmus University Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands.
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27
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Danilowicz C, Feinstein E, Conover A, Coljee VW, Vlassakis J, Chan YL, Bishop DK, Prentiss M. RecA homology search is promoted by mechanical stress along the scanned duplex DNA. Nucleic Acids Res 2011; 40:1717-27. [PMID: 22013164 PMCID: PMC3287184 DOI: 10.1093/nar/gkr855] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
A RecA–single-stranded DNA (RecA–ssDNA) filament searches a genome for sequence homology by rapidly binding and unbinding double-stranded DNA (dsDNA) until homology is found. We demonstrate that pulling on the opposite termini (3′ and 5′) of one of the two DNA strands in a dsDNA molecule stabilizes the normally unstable binding of that dsDNA to non-homologous RecA–ssDNA filaments, whereas pulling on the two 3′, the two 5′, or all four termini does not. We propose that the ‘outgoing’ strand in the dsDNA is extended by strong DNA–protein contacts, whereas the ‘complementary’ strand is extended by the tension on the base pairs that connect the ‘complementary’ strand to the ‘outgoing’ strand. The stress resulting from different levels of tension on its constitutive strands causes rapid dsDNA unbinding unless sufficient homology is present.
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28
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Nevinsky GA. Structural, thermodynamic, and kinetic basis for the activities of some nucleic acid repair enzymes. J Mol Recognit 2011; 24:656-77. [PMID: 21584877 DOI: 10.1002/jmr.1096] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
X-ray structural analysis provides no quantitative estimate of the relative contribution of specific and nonspecific or strong and weak interactions to the total affinity of enzymes for nucleic acids. We have shown that the interaction between enzymes and long nucleic acids at the molecular level can be successfully analyzed by the method of stepwise increase in ligand complexity (SILC). In the present review we summarize our studies of human uracil DNA glycosylase and apurinic/apyrimidinic endonuclease, E. coli 8-oxoguanine DNA glycosylase and RecA protein using the SILC approach. The relative contribution of structural (X-ray analysis data), thermodynamic, and catalytic factors to the discrimination of specific and nonspecific DNA by these enzymes at the stages of complex formation, the following changes in DNA and enzyme conformations and especially the catalysis of the reactions is discussed.
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Affiliation(s)
- Georgy A Nevinsky
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Novosibirsk 63009, Russia.
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29
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Conover AJ, Danilowicz C, Gunaratne R, Coljee VW, Kleckner N, Prentiss M. Changes in the tension in dsDNA alter the conformation of RecA bound to dsDNA-RecA filaments. Nucleic Acids Res 2011; 39:8833-43. [PMID: 21768124 PMCID: PMC3203582 DOI: 10.1093/nar/gkr561] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The RecA protein is an ATPase that mediates recombination via strand exchange. In strand exchange a single-stranded DNA (ssDNA) bound to RecA binding site I in a RecA/ssDNA filament pairs with one strand of a double-stranded DNA (dsDNA) and forms heteroduplex dsDNA in site I if homology is encountered. Long sequences are exchanged in a dynamic process in which initially unbound dsDNA binds to the leading end of a RecA/ssDNA filament, while heteroduplex dsDNA unbinds from the lagging end via ATP hydrolysis. ATP hydrolysis is required to convert the active RecA conformation, which cannot unbind, to the inactive conformation, which can unbind. If dsDNA extension due to RecA binding increases the dsDNA tension, then RecA unbinding must decrease tension. We show that in the presence of ATP hydrolysis decreases in tension induce decreases in length whereas in the absence of hydrolysis, changes in tension have no systematic effect. These results suggest that decreases in force enhance dissociation by promoting transitions from the active to the inactive RecA conformation. In contrast, increases in tension reduce dissociation. Thus, the changes in tension inherent to strand exchange may couple with ATP hydrolysis to increase the directionality and stringency of strand exchange.
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Affiliation(s)
- Alyson J Conover
- Department of Physics and Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
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30
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Nevinsky GA. Main factors providing specificity of repair enzymes. BIOCHEMISTRY (MOSCOW) 2011; 76:94-117. [PMID: 21568843 DOI: 10.1134/s0006297911010111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Specific and nonspecific DNA complex formation with human uracil-DNA glycosylase, 8-oxoguanine-DNA glycosylase, and apurine/apyrimidine endonuclease, as well as with E. coli 8-oxoguanine-DNA glycosylase and RecA protein was analyzed using the method of stepwise increase in DNA-ligand complexity. It is shown that high affinity of these enzymes to any DNA (10(-4)-10(-8) M) is provided by a large number of weak additive contacts mainly with DNA internucleoside phosphate groups and in a less degree with bases of nucleotide links "covered" by protein globules. Enzyme interactions with specific DNA links are comparable in efficiency with weak unspecific contacts and provide only for one-two orders of affinity (10(-1)-10(-2) M), but these contacts are extremely important at stages of DNA and enzyme structural adaptation and catalysis proper. Only in the case of specific DNA individual for each enzyme alterations in DNA structure provide for efficient adjustment of reacting enzyme atoms and DNA orbitals with accuracy up to 10-15° and, as a result, for high reaction rate. Upon transition from nonspecific to specific DNA, reaction rate (k(cat)) increases by 4-8 orders of magnitude. Thus, stages of DNA and enzyme structural adaptation as well as catalysis proper are the basis of specificity of repair enzymes.
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Affiliation(s)
- G A Nevinsky
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
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31
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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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32
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Manfredi C, Suzuki Y, Yadav T, Takeyasu K, Alonso JC. RecO-mediated DNA homology search and annealing is facilitated by SsbA. Nucleic Acids Res 2010; 38:6920-9. [PMID: 20581116 PMCID: PMC2978338 DOI: 10.1093/nar/gkq533] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Bacillus subtilis RecO plays a central role in recombinational repair and genetic recombination by (i) stimulating RecA filamentation onto SsbA-coated single-stranded (ss) DNA, (ii) modulating the extent of RecA-mediated DNA strand exchange and (iii) promoting annealing of complementary DNA strands. Here, we report that RecO-mediated strand annealing is facilitated by cognate SsbA, but not by a heterologous one. Analysis of non-productive intermediates reveals that RecO interacts with SsbA-coated ssDNA, resulting in transient ternary complexes. The self-interaction of ternary complexes via RecO led to the formation of large nucleoprotein complexes. In the presence of homology, SsbA, at the nucleoprotein, removes DNA secondary structures, inhibits spontaneous strand annealing and facilitates RecO loading onto SsbA–ssDNA complex. RecO relieves SsbA inhibition of strand annealing and facilitates transient and random interactions between homologous naked ssDNA molecules. Finally, both proteins lose affinity for duplex DNA. Our results provide a mechanistic framework for rationalizing protein release and dsDNA zippering as coordinated events that are crucial for RecA-independent plasmid transformation.
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Affiliation(s)
- Candela Manfredi
- Centro Nacional de Biotecnología, CSIC, C/Darwin 3, 28049 Madrid, Spain
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33
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Saladin A, Amourda C, Poulain P, Férey N, Baaden M, Zacharias M, Delalande O, Prévost C. Modeling the early stage of DNA sequence recognition within RecA nucleoprotein filaments. Nucleic Acids Res 2010; 38:6313-23. [PMID: 20507912 PMCID: PMC2965220 DOI: 10.1093/nar/gkq459] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Homologous recombination is a fundamental process enabling the repair of double-strand breaks with a high degree of fidelity. In prokaryotes, it is carried out by RecA nucleofilaments formed on single-stranded DNA (ssDNA). These filaments incorporate genomic sequences that are homologous to the ssDNA and exchange the homologous strands. Due to the highly dynamic character of this process and its rapid propagation along the filament, the sequence recognition and strand exchange mechanism remains unknown at the structural level. The recently published structure of the RecA/DNA filament active for recombination (Chen et al., Mechanism of homologous recombination from the RecA-ssDNA/dsDNA structure, Nature 2008, 453, 489) provides a starting point for new exploration of the system. Here, we investigate the possible geometries of association of the early encounter complex between RecA/ssDNA filament and double-stranded DNA (dsDNA). Due to the huge size of the system and its dense packing, we use a reduced representation for protein and DNA together with state-of-the-art molecular modeling methods, including systematic docking and virtual reality simulations. The results indicate that it is possible for the double-stranded DNA to access the RecA-bound ssDNA while initially retaining its Watson–Crick pairing. They emphasize the importance of RecA L2 loop mobility for both recognition and strand exchange.
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Affiliation(s)
- Adrien Saladin
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005 Paris, MTI, France
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34
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Mani A, Braslavsky I, Arbel-Goren R, Stavans J. Caught in the act: the lifetime of synaptic intermediates during the search for homology on DNA. Nucleic Acids Res 2009; 38:2036-43. [PMID: 20044347 PMCID: PMC2847238 DOI: 10.1093/nar/gkp1177] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Homologous recombination plays pivotal roles in DNA repair and in the generation of genetic diversity. To locate homologous target sequences at which strand exchange can occur within a timescale that a cell’s biology demands, a single-stranded DNA-recombinase complex must search among a large number of sequences on a genome by forming synapses with chromosomal segments of DNA. A key element in the search is the time it takes for the two sequences of DNA to be compared, i.e. the synapse lifetime. Here, we visualize for the first time fluorescently tagged individual synapses formed by RecA, a prokaryotic recombinase, and measure their lifetime as a function of synapse length and differences in sequence between the participating DNAs. Surprisingly, lifetimes can be ∼10 s long when the DNAs are fully heterologous, and much longer for partial homology, consistently with ensemble FRET measurements. Synapse lifetime increases rapidly as the length of a region of full homology at either the 3′- or 5′-ends of the invading single-stranded DNA increases above 30 bases. A few mismatches can reduce dramatically the lifetime of synapses formed with nearly homologous DNAs. These results suggest the need for facilitated homology search mechanisms to locate homology successfully within the timescales observed in vivo.
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Affiliation(s)
- Adam Mani
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
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35
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Weiner A, Zauberman N, Minsky A. Recombinational DNA repair in a cellular context: a search for the homology search. Nat Rev Microbiol 2009; 7:748-55. [PMID: 19756013 DOI: 10.1038/nrmicro2206] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Double-strand DNA breaks (DSBs) are the most detrimental lesion that can be sustained by the genetic complement, and their inaccurate mending can be just as damaging. According to the consensual view, precise DSB repair relies on homologous recombination. Here, we review studies on DNA repair, chromatin diffusion and chromosome confinement, which collectively imply that a genome-wide search for a homologous template, generally thought to be a pivotal stage in all homologous DSB repair pathways, is improbable. The implications of this assertion for the scope and constraints of DSB repair pathways and for the ability of diverse organisms to cope with DNA damage are discussed.
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Affiliation(s)
- Allon Weiner
- Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
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Li Y, He Y, Luo Y. Conservation of a conformational switch in RadA recombinase from Methanococcus maripaludis. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2009; 65:602-10. [PMID: 19465774 PMCID: PMC2685736 DOI: 10.1107/s0907444909011871] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Accepted: 03/30/2009] [Indexed: 12/26/2022]
Abstract
Archaeal RadAs are close homologues of eukaryal Rad51s ( approximately 40% sequence identity). These recombinases promote ATP hydrolysis and a hallmark strand-exchange reaction between homologous single-stranded and double-stranded DNA substrates. Pairing of the 3'-overhangs located at the damaged DNA with a homologous double-stranded DNA enables the re-synthesis of the damaged region using the homologous DNA as the template. In recent studies, conformational changes in the DNA-interacting regions of Methanococcus voltae RadA have been correlated with the presence of activity-stimulating potassium or calcium ions in the ATPase centre. The series of crystal structures of M. maripaludis RadA presented here further suggest the conservation of an allosteric switch in the ATPase centre which controls the conformational status of DNA-interacting loops. Structural comparison with the distant Escherichia coli RecA homologue supports the notion that the conserved Lys248 and Lys250 residues in RecA play a role similar to that of cations in RadA. The conservation of a cationic bridge between the DNA-interacting L2 region and the terminal phosphate of ATP, together with the apparent stability of the nucleoprotein filament, suggests a gap-displacement model which may explain the advantage of ATP hydrolysis for DNA-strand exchange.
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Affiliation(s)
- Yang Li
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
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Volodin AA, Bocharova TN, Smirnova EA, Camerini-Otero RD. Reversibility, equilibration, and fidelity of strand exchange reaction between short oligonucleotides promoted by RecA protein from escherichia coli and human Rad51 and Dmc1 proteins. J Biol Chem 2009; 284:1495-504. [PMID: 19004837 PMCID: PMC2615514 DOI: 10.1074/jbc.m800612200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 10/21/2008] [Indexed: 11/06/2022] Open
Abstract
We demonstrate the reversibility of RecA-promoted strand exchange reaction between short oligonucleotides in the presence of adenosine 5'-O-(thiotriphosphate). The reverse reaction proceeds without the dissociation of RecA from DNA. The reaction reaches equilibrium and its yield depends on the homology between the reaction substrates. We estimate the tolerance of the RecA-promoted strand exchange to individual base substitutions for a comprehensive set of possible base combinations in a selected position along oligonucleotide substrates for strand exchange and find, in agreement with previously reported estimations, that this tolerance is higher than in the case of free DNA. It is demonstrated that the short oligonucleotide-based approach can be applied to the human recombinases Rad51 and Dmc1 when strand exchange is performed in the presence of calcium ions and ATP. Remarkably, despite the commonly held belief that the eukaryotic recombinases have an inherently lower strand exchange activity, in our system their efficiencies in strand exchange are comparable with that of RecA. Under our experimental conditions, the human recombinases exhibit a significantly higher tolerance to interruptions of homology due to point base substitutions than RecA. Finding conditions where a chemical reaction is reversible and reaches equilibrium is critically important for its thermodynamically correct description. We believe that the experimental system described here will substantially facilitate further studies on different aspects of the mechanisms of homologous recombination.
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Affiliation(s)
- Alexander A Volodin
- Institute of Molecular Genetics of the Russian Academy of Sciences, Kurchatov Square, 123182 Moscow, Russia
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Zhang XP, Galkin VE, Yu X, Egelman EH, Heyer WD. Loop 2 in Saccharomyces cerevisiae Rad51 protein regulates filament formation and ATPase activity. Nucleic Acids Res 2008; 37:158-71. [PMID: 19033358 PMCID: PMC2615628 DOI: 10.1093/nar/gkn914] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Previous studies showed that the K342E substitution in the Saccharomyces cerevisiae Rad51 protein increases the interaction with Rad54 protein in the two-hybrid system, leads to increased sensitivity to the alkylating agent MMS and hyper-recombination in an oligonucleotide-mediated gene targeting assay. K342 localizes in loop 2, a region of Rad51 whose function is not well understood. Here, we show that Rad51-K342E displays DNA-independent and DNA-dependent ATPase activities, owing to its ability to form filaments in the absence of a DNA lattice. These filaments exhibit a compressed pitch of 81 Å, whereas filaments of wild-type Rad51 and Rad51-K342E on DNA form extended filaments with a 97 Å pitch. Rad51-K342E shows near normal binding to ssDNA, but displays a defect in dsDNA binding, resulting in less stable protein-dsDNA complexes. The mutant protein is capable of catalyzing the DNA strand exchange reaction and is insensitive to inhibition by the early addition of dsDNA. Wild-type Rad51 protein is inhibited under such conditions, because of its ability to bind dsDNA. No significant changes in the interaction between Rad51-K342E and Rad54 could be identified. These findings suggest that loop 2 contributes to the primary DNA-binding site in Rad51, controlling filament formation and ATPase activity.
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Affiliation(s)
- Xiao-Ping Zhang
- Department of Microbiology, University of California, Davis, CA 95616-8665, USA
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40
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Sinha M, Peterson CL. A Rad51 presynaptic filament is sufficient to capture nucleosomal homology during recombinational repair of a DNA double-strand break. Mol Cell 2008; 30:803-10. [PMID: 18570881 DOI: 10.1016/j.molcel.2008.04.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 03/05/2008] [Accepted: 04/24/2008] [Indexed: 01/17/2023]
Abstract
Repair of chromosomal DNA double-strand breaks by homologous recombination is essential for cell survival and genome stability. Within eukaryotic cells, this repair pathway requires a search for a homologous donor sequence and a subsequent strand invasion event on chromatin fibers. We employ a biotin-streptavidin minichromosome capture assay to show that yRad51 or hRad51 presynaptic filaments are sufficient to locate a homologous sequence and form initial joints, even on the surface of a nucleosome. Furthermore, we present evidence that the Rad54 chromatin-remodeling enzyme functions to convert these initial metastable products of the homology search to a stable joint molecule that is competent for subsequent steps of the repair process. Thus, contrary to popular belief, nucleosomes do not pose a potent barrier for successful recognition and capture of homology by an invading presynaptic filament.
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Affiliation(s)
- Manisha Sinha
- Program in Molecular Medicine, Interdisciplinary Graduate Program, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA
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41
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Holloman WK, Schirawski J, Holliday R. The homologous recombination system of Ustilago maydis. Fungal Genet Biol 2008; 45 Suppl 1:S31-9. [PMID: 18502156 PMCID: PMC2583931 DOI: 10.1016/j.fgb.2008.04.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 04/09/2008] [Accepted: 04/11/2008] [Indexed: 12/26/2022]
Abstract
Homologous recombination is a high fidelity, template-dependent process that is used in repair of damaged DNA, recovery of broken replication forks, and disjunction of homologous chromosomes in meiosis. Much of what is known about recombination genes and mechanisms comes from studies on baker's yeast. Ustilago maydis, a basidiomycete fungus, is distant evolutionarily from baker's yeast and so offers the possibility of gaining insight into recombination from an alternative perspective. Here we have surveyed the genome of U. maydis to determine the composition of its homologous recombination system. Compared to baker's yeast, there are fundamental differences in the function as well as in the repertoire of dedicated components. These include the use of a BRCA2 homolog and its modifier Dss1 rather than Rad52 as a mediator of Rad51, the presence of only a single Rad51 paralog, and the absence of Dmc1 and auxiliary meiotic proteins.
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Affiliation(s)
- William K Holloman
- Cornell University Weill Medical College, Department of Microbiology and Immunology, NY 10021, USA.
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42
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Homologous recombination in real time: DNA strand exchange by RecA. Mol Cell 2008; 30:530-8. [PMID: 18498754 DOI: 10.1016/j.molcel.2008.03.010] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Revised: 11/02/2007] [Accepted: 03/07/2008] [Indexed: 11/20/2022]
Abstract
Homologous recombination, the exchange of strands between different DNA molecules, is essential for proper maintenance and accurate duplication of the genome. Using magnetic tweezers, we monitor RecA-driven homologous recombination of individual DNA molecules in real time. We resolve several key aspects of DNA structure during and after strand exchange. Changes in DNA length and twist yield helical parameters for the protein-bound three-stranded structure in conditions in which ATP was not hydrolyzed. When strand exchange was completed under ATP hydrolysis conditions that allow protein dissociation, a "D wrap" structure formed. During homologous recombination, strand invasion at one end and RecA dissociation at the other end occurred at the same rate, and our single-molecule analysis indicated that a region of only about 80 bp is actively involved in the synapsis at any time during the entire reaction involving a long ( approximately 1 kb) region of homology.
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43
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Kagawa W, Kagawa A, Saito K, Ikawa S, Shibata T, Kurumizaka H, Yokoyama S. Identification of a second DNA binding site in the human Rad52 protein. J Biol Chem 2008; 283:24264-73. [PMID: 18593704 DOI: 10.1074/jbc.m802204200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rad52 plays essential roles in homology-dependent double-strand break repair. Various studies have established the functions of Rad52 in Rad51-dependent and Rad51-independent repair processes. However, the precise molecular mechanisms of Rad52 in these processes remain unknown. In the present study we have identified a novel DNA binding site within Rad52 by a structure-based alanine scan mutagenesis. This site is closely aligned with the putative single-stranded DNA binding site determined previously. Mutations in this site impaired the ability of the Rad52-single-stranded DNA complex to form a ternary complex with double-stranded DNA and subsequently catalyze the formation of D-loops. We found that Rad52 introduces positive supercoils into double-stranded DNA and that the second DNA binding site is essential for this activity. Our findings suggest that Rad52 aligns two recombining DNA molecules within the first and second DNA binding sites to stimulate the homology search and strand invasion processes.
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Affiliation(s)
- Wataru Kagawa
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Japan
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44
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Abstract
Brh2, the ortholog of the BRCA2 tumor suppressor in Ustilago maydis, works hand in hand with Rad51 to promote repair of DNA by homologous recombination. Previous studies established that Brh2 can stimulate DNA strand exchange by enabling Rad51 nucleoprotein filament formation on replication protein A-coated ssDNA. But, more recently, it was noted that Brh2 has an inherent DNA annealing activity, raising the notion that it might have roles in recombination in addition to or beyond the mediator function. Here, we found that Brh2 can autonomously promote the formation of D-loops in reactions with plasmid DNA and homologous single-stranded oligonucleotides. The reaction differs from that catalyzed by Rad51 in having no requirement for cofactors or preloading phase on ssDNA. D-loop formation was most effective when Brh2 was mixed with plasmid DNA before addition of single-stranded oligomer. D-loop formation catalyzed by Rad51 was also enhanced when Brh2 was premixed with plasmid DNA. Brh2 rendered defective in Rad51 interaction by mutation in the BRC element was still capable of promoting D-loop formation. However, the mutant protein was unable to enhance the Rad51-catalyzed reaction. The results suggest a model in which Brh2 binding to plasmid DNA attracts and helps capture Rad51-coated ssDNA.
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45
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Lanzov VA. RecA homologous DNA transferase: Functional activities and a search for homology by recombining DNA molecules. Mol Biol 2007. [DOI: 10.1134/s0026893307030077] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Lantsov VA. Interaction of single-stranded DNA with the second DNA-binding site of the RecA nucleoprotein filament. Mol Biol 2007; 41:467-77. [PMID: 17685224 DOI: 10.1134/s0026893307030132] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bacterial RecA protein is a prototype of ATP-dependent homologous recombinases found ubiquitously from bacteriophages up to human beings. When RecA filament is forming on single-stranded DNA in the presence of ATP, it initiates the strand exchange reaction with homologous double-stranded DNA. Among three phases of the reaction (the search for homology, the three-stranded structure annealing in conjunction with the switch of pairing, and the strand displacement) the first one is the most enigmatic and least studied. As commonly recognized, this phase is directed by a special (stretched) filament structure and does not required any additional consumption of energy in ATP hydrolysis. The novel approaches in the study of strand exchange reaction, using short oligonucleotides as DNA substrates and sensitive methods for a real-time monitoring of the reaction suggest that all three phases of the reaction depend on the ATP hydrolysis.
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Singleton SF, Roca AI, Lee AM, Xiao J. Probing the structure of RecA-DNA filaments. Advantages of a fluorescent guanine analog. Tetrahedron 2007; 63:3553-3566. [PMID: 17955055 PMCID: PMC2031864 DOI: 10.1016/j.tet.2006.10.092] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The RecA protein of Escherichia coli plays a crucial roles in DNA recombination and repair, as well as various aspects of bacterial pathogenicity. The formation of a RecA-ATP-ssDNA complex initiates all RecA activities and yet a complete structural and mechanistic description of this filament has remained elusive. An analysis of RecA-DNA interactions was performed using fluorescently labeled oligonucleotides. A direct comparison was made between fluorescein and several fluorescent nucleosides. The fluorescent guanine analog 6-methylisoxanthopterin (6MI) demonstrated significant advantages over the other fluorophores and represents an important new tool for characterizing RecA-DNA interactions.
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Affiliation(s)
- Scott F. Singleton
- Division of Medicinal Chemistry & Natural Products, School of Pharmacy, The University of North Carolina at Chapel Hill, CB 7360, Chapel Hill, NC 27599-7360, USA
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48
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Zhang Z, Fan HY, Goldman JA, Kingston RE. Homology-driven chromatin remodeling by human RAD54. Nat Struct Mol Biol 2007; 14:397-405. [PMID: 17417655 DOI: 10.1038/nsmb1223] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Accepted: 02/27/2007] [Indexed: 01/18/2023]
Abstract
Human RAD51 and RAD54 are key players in homologous recombination, a process that requires homology recognition and strand invasion by a RAD51-single-stranded DNA (ssDNA) nucleoprotein filament and chromatin remodeling by RAD54. Here we use in vitro chromatin reconstitution systems to show that RAD51-ssDNA stimulates RAD54-dependent chromatin remodeling in a homology-dependent, polarity-independent manner. This stimulation was not seen with RAD54B or other remodelers. Chromatin remodeling by RAD54 enabled strand invasion by RAD51-ssDNA on nucleosomal templates, which was homology- and polarity-dependent. Three natural RAD54 mutants found in primary cancer cells showed specific defects in remodeling or in the RAD54-RAD51 interaction. We propose that RAD54 is recruited by RAD51-ssDNA filament to the chromatin of the intact chromosome and that it remodels that chromatin to facilitate accessibility for strand exchange.
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Affiliation(s)
- Zhaoqing Zhang
- Department of Molecular Biology, Massachusetts General Hospital and Department of Genetics, Harvard Medical School, 185 Cambridge Street, Boston, Massachusetts 02114, USA
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49
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Egel R. RecA-DNA filament topology: the overlooked alternative of an unconventional syn-syn duplex intermediate. DNA Repair (Amst) 2007; 6:669-75. [PMID: 17317338 DOI: 10.1016/j.dnarep.2006.12.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 12/17/2006] [Accepted: 12/21/2006] [Indexed: 10/23/2022]
Abstract
The helical filaments of RecA protein mediate strand exchange for homologous recombination, but the paths of the interacting DNAs have yet to be determined. Although this interaction is commonly limited to three strands, it is reasoned here that the intrinsic symmetry relationships of quadruplex topology are superior in explaining a range of observations. In particular, this topology suggests the potential of post-exchange base pairing in the unorthodox configuration of syn-syn glycosidic bonds between the nucleotide bases and the pentose rings in the sugar-phosphate backbone, which would transiently be stabilized by the external scaffolding of the RecA protein filament.
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Affiliation(s)
- Richard Egel
- Institute of Molecular Biology and Physiology, University of Copenhagen, Ole Maaløe Vej 5, DK-2100 Copenhagen Ø, Denmark.
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50
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Abstract
The recombinases of the RecA family are often viewed only as DNA-pairing proteins - they bind to one DNA segment, align it with homologous sequences in another DNA segment, promote an exchange of DNA strands and then dissociate. To a first approximation, this description seems to fit the eukaryotic (Rad51 and Dmc1) and archaeal (RadA) RecA homologues. However, the bacterial RecA protein does much more, coupling ATP hydrolysis with DNA-strand exchange in a manner that greatly expands its repertoire of activities. This article explores the protein activities and experimental results that have identified RecA as a motor protein.
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Affiliation(s)
- Michael M Cox
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, Wisconsin 53706-1544, USA.
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