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Lee AJ, Endo M, Hobbs JK, Davies AG, Wälti C. Micro-homology intermediates: RecA's transient sampling revealed at the single molecule level. Nucleic Acids Res 2021; 49:1426-1435. [PMID: 33476368 PMCID: PMC7897476 DOI: 10.1093/nar/gkaa1258] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 12/12/2020] [Accepted: 01/07/2021] [Indexed: 01/21/2023] Open
Abstract
Recombinase A (RecA) is central to homologous recombination. However, despite significant advances, the mechanism with which RecA is able to orchestrate a search for homology remains elusive. DNA nanostructure-augmented high-speed AFM offers the spatial and temporal resolutions required to study the RecA recombination mechanism directly and at the single molecule level. We present the direct in situ observation of RecA-orchestrated alignment of homologous DNA strands to form a stable recombination product within a supporting DNA nanostructure. We show the existence of subtle and short-lived states in the interaction landscape, which suggests that RecA transiently samples micro-homology at the single RecA monomer-level throughout the search for sequence alignment. These transient interactions form the early steps in the search for sequence homology, prior to the formation of stable pairings at >8 nucleotide seeds. The removal of sequence micro-homology results in the loss of the associated transient sampling at that location.
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Affiliation(s)
- Andrew J Lee
- Bioelectronics, The Pollard Institute, School of Electronic and Electrical Engineering, University of Leeds, Woodhouse lane, Leeds LS2 9JT, UK
| | - Masayuki Endo
- Institute for Integrated Cell-Material Sciences, Kyoto University, Yoshida-ushinomiyacho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Jamie K Hobbs
- Department of Physics and Astronomy, University of Sheffield, Houndsfield Road, Sheffield S3 7RH, UK
| | - A Giles Davies
- Bioelectronics, The Pollard Institute, School of Electronic and Electrical Engineering, University of Leeds, Woodhouse lane, Leeds LS2 9JT, UK
| | - Christoph Wälti
- Bioelectronics, The Pollard Institute, School of Electronic and Electrical Engineering, University of Leeds, Woodhouse lane, Leeds LS2 9JT, UK
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Yang H, Zhou C, Dhar A, Pavletich NP. Mechanism of strand exchange from RecA-DNA synaptic and D-loop structures. Nature 2020; 586:801-806. [PMID: 33057191 PMCID: PMC8366275 DOI: 10.1038/s41586-020-2820-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 09/10/2020] [Indexed: 02/08/2023]
Abstract
The strand exchange reaction is central to homologous recombination. It is catalyzed by the RecA family of ATPases that form a helical filament with single-stranded DNA (ssDNA) and ATP. This filament binds to a donor double-stranded DNA (dsDNA) to form synaptic filaments that search for homology, and then catalyze the exchange of the complementary strand to form a new heteroduplex, or a D-loop if homology is limited1,2. Here we report the Cryo-EM analysis of synaptic mini filaments with both non-complementary and partially-complementary dsDNA, and structures of RecA–D-loop complexes containing a 10 or 12 base pair heteroduplex at 2.8 and 2.9 Å, respectively. The RecA C-terminal domain (CTD) binds to dsDNA and directs it to the L2 loop, which inserts into and opens the duplex. The opening propagates through RecA sequestering the homologous strand at a secondary DNA-binding site, freeing the complementary strand to sample pairing with the ssDNA. Duplex opening has a significant probability of stopping at each RecA step, with the as yet unopened dsDNA portion binding to another CTD. Homology suppresses this process through heteroduplex pairing cooperating with secondary site-ssDNA binding to extend dsDNA opening. This mechanism locally limits the length of ssDNA sampled for pairing if homology is not encountered, and it may provide for the formation of multiple synapses separated substantially on the donor dsDNA, increasing the probability of encountering homology.
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Affiliation(s)
- Haijuan Yang
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Chun Zhou
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.,Zhejiang University School of Medicine, Zhejiang, China
| | - Ankita Dhar
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Nikola P Pavletich
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA. .,Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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3
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RecA and DNA recombination: a review of molecular mechanisms. Biochem Soc Trans 2020; 47:1511-1531. [PMID: 31654073 DOI: 10.1042/bst20190558] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 09/18/2019] [Accepted: 09/25/2019] [Indexed: 11/17/2022]
Abstract
Recombinases are responsible for homologous recombination and maintenance of genome integrity. In Escherichia coli, the recombinase RecA forms a nucleoprotein filament with the ssDNA present at a DNA break and searches for a homologous dsDNA to use as a template for break repair. During the first step of this process, the ssDNA is bound to RecA and stretched into a Watson-Crick base-paired triplet conformation. The RecA nucleoprotein filament also contains ATP and Mg2+, two cofactors required for RecA activity. Then, the complex starts a homology search by interacting with and stretching dsDNA. Thanks to supercoiling, intersegment sampling and RecA clustering, a genome-wide homology search takes place at a relevant metabolic timescale. When a region of homology 8-20 base pairs in length is found and stabilized, DNA strand exchange proceeds, forming a heteroduplex complex that is resolved through a combination of DNA synthesis, ligation and resolution. RecA activities can take place without ATP hydrolysis, but this latter activity is necessary to improve and accelerate the process. Protein flexibility and monomer-monomer interactions are fundamental for RecA activity, which functions cooperatively. A structure/function relationship analysis suggests that the recombinogenic activity can be improved and that recombinases have an inherently large recombination potential. Understanding this relationship is essential for designing RecA derivatives with enhanced activity for biotechnology applications. For example, this protein is a major actor in the recombinase polymerase isothermal amplification (RPA) used in point-of-care diagnostics.
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Kim WJ, Higashi D, Goytia M, Rendón MA, Pilligua-Lucas M, Bronnimann M, McLean JA, Duncan J, Trees D, Jerse AE, So M. Commensal Neisseria Kill Neisseria gonorrhoeae through a DNA-Dependent Mechanism. Cell Host Microbe 2019; 26:228-239.e8. [PMID: 31378677 DOI: 10.1016/j.chom.2019.07.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 04/25/2019] [Accepted: 07/11/2019] [Indexed: 12/13/2022]
Abstract
The mucosa is colonized with commensal Neisseria. Some of these niches are sites of infection for the STD pathogen Neisseria gonorrhoeae (Ngo). Given the antagonistic behavior of commensal bacteria toward their pathogenic relatives, we hypothesized that commensal Neisseria may negatively affect Ngo colonization. Here, we report that commensal species of Neisseria kill Ngo through a mechanism based on genetic competence and DNA methylation state. Specifically, commensal-triggered killing occurs when the pathogen takes up commensal DNA containing a methylation pattern that it does not recognize. Indeed, any DNA will kill Ngo if it can enter the cell, is differentially methylated, and has homology to the pathogen genome. Consistent with these findings, commensal Neisseria elongata accelerates Ngo clearance from the mouse in a DNA-uptake-dependent manner. Collectively, we propose that commensal Neisseria antagonizes Ngo infection through a DNA-mediated mechanism and that DNA is a potential microbicide against this highly drug-resistant pathogen.
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Affiliation(s)
- Won Jong Kim
- Department of Immunobiology and the BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA
| | - Dustin Higashi
- Department of Immunobiology and the BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA
| | - Maira Goytia
- Department of Biology, Spelman College, Atlanta, GA 30314, USA
| | - Maria A Rendón
- Department of Immunobiology and the BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA
| | - Michelle Pilligua-Lucas
- Department of Microbiology and Immunology, Uniformed Services University, Bethesda, MD 20814, USA
| | - Matthew Bronnimann
- Department of Immunobiology and the BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA
| | - Jeanine A McLean
- Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Joseph Duncan
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - David Trees
- Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Ann E Jerse
- Department of Microbiology and Immunology, Uniformed Services University, Bethesda, MD 20814, USA
| | - Magdalene So
- Department of Immunobiology and the BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA.
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Lee AJ, Wälti C. DNA nanostructures: A versatile lab-bench for interrogating biological reactions. Comput Struct Biotechnol J 2019; 17:832-842. [PMID: 31316727 PMCID: PMC6611922 DOI: 10.1016/j.csbj.2019.06.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 06/05/2019] [Accepted: 06/11/2019] [Indexed: 01/10/2023] Open
Abstract
At its inception DNA nanotechnology was conceived as a tool for spatially arranging biological molecules in a programmable and deterministic way to improve their interrogation. To date, DNA nanotechnology has provided a versatile toolset of nanostructures and functional devices to augment traditional single molecule investigation approaches - including atomic force microscopy - by isolating, arranging and contextualising biological systems at the single molecule level. This review explores the state-of-the-art of DNA-based nanoscale tools employed to enhance and tune the interrogation of biological reactions, the study of spatially distributed pathways, the visualisation of enzyme interactions, the application and detection of forces to biological systems, and biosensing platforms.
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Affiliation(s)
- Andrew J. Lee
- Bioelectronics, The Pollard Institute, School of Electronic & Electrical Engineering, University of Leeds, LS2 9JT, United Kingdom
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Lee AJ, Endo M, Hobbs JK, Wälti C. Direct Single-Molecule Observation of Mode and Geometry of RecA-Mediated Homology Search. ACS NANO 2018; 12:272-278. [PMID: 29202219 DOI: 10.1021/acsnano.7b06208] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Genomic integrity, when compromised by accrued DNA lesions, is maintained through efficient repair via homologous recombination. For this process the ubiquitous recombinase A (RecA), and its homologues such as the human Rad51, are of central importance, able to align and exchange homologous sequences within single-stranded and double-stranded DNA in order to swap out defective regions. Here, we directly observe the widely debated mechanism of RecA homology searching at a single-molecule level using high-speed atomic force microscopy (HS-AFM) in combination with tailored DNA origami frames to present the reaction targets in a way suitable for AFM-imaging. We show that RecA nucleoprotein filaments move along DNA substrates via short-distance facilitated diffusions, or slides, interspersed with longer-distance random moves, or hops. Importantly, from the specific interaction geometry, we find that the double-stranded substrate DNA resides in the secondary DNA binding-site within the RecA nucleoprotein filament helical groove during the homology search. This work demonstrates that tailored DNA origami, in conjunction with HS-AFM, can be employed to reveal directly conformational and geometrical information on dynamic protein-DNA interactions which was previously inaccessible at an individual single-molecule level.
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Affiliation(s)
- Andrew J Lee
- Bioelectronics, The Pollard Institute, School of Electronic and Electrical Engineering, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Masayuki Endo
- Institute for Integrated Cell-Material Sciences, Kyoto University , Yoshida-ushinomiyacho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Jamie K Hobbs
- Department of Physics and Astronomy, University of Sheffield , Houndsfield Road, Sheffield S3 7RH, United Kingdom
| | - Christoph Wälti
- Bioelectronics, The Pollard Institute, School of Electronic and Electrical Engineering, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, United Kingdom
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