1
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Li Y, Liu C, Jia X, Bi L, Ren Z, Zhao Y, Zhang X, Guo L, Bao Y, Liu C, Li W, Sun B. RPA transforms RNase H1 to a bidirectional exoribonuclease for processive RNA-DNA hybrid cleavage. Nat Commun 2024; 15:7464. [PMID: 39198528 PMCID: PMC11358518 DOI: 10.1038/s41467-024-51984-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 08/21/2024] [Indexed: 09/01/2024] Open
Abstract
RNase H1 has been acknowledged as an endoribonuclease specializing in the internal degradation of the RNA moiety within RNA-DNA hybrids, and its ribonuclease activity is indispensable in multifaceted aspects of nucleic acid metabolism. However, the molecular mechanism underlying RNase H1-mediated hybrid cleavage remains inadequately elucidated. Herein, using single-molecule approaches, we probe the dynamics of the hybrid cleavage by Saccharomyces cerevisiae RNase H1. Remarkably, a single RNase H1 enzyme displays 3'-to-5' exoribonuclease activity. The directional RNA degradation proceeds processively and yet discretely, wherein unwinding approximately 6-bp hybrids as a prerequisite for two consecutive 3-nt RNA excisions limits the overall rate within each catalytic cycle. Moreover, Replication Protein A (RPA) reinforces RNase H1's 3'-to-5' nucleolytic rate and processivity and stimulates its 5'-to-3' exoribonuclease activity. This stimulation is primarily realized through the pre-separation of the hybrids and consequently transfers RNase H1 to a bidirectional exoribonuclease, further potentiating its cleavage efficiency. These findings unveil unprecedented characteristics of an RNase and provide a dynamic view of RPA-enhanced processive hybrid cleavage by RNase H1.
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Affiliation(s)
- Yanan Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Chao Liu
- Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xinshuo Jia
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Lulu Bi
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Zhiyun Ren
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yilin Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Xia Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Lijuan Guo
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yanling Bao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Cong Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Wei Li
- Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China.
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
| | - Bo Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
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2
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Belan O, Greenhough L, Kuhlen L, Anand R, Kaczmarczyk A, Gruszka DT, Yardimci H, Zhang X, Rueda DS, West SC, Boulton SJ. Visualization of direct and diffusion-assisted RAD51 nucleation by full-length human BRCA2 protein. Mol Cell 2023; 83:2925-2940.e8. [PMID: 37499663 PMCID: PMC7615647 DOI: 10.1016/j.molcel.2023.06.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 06/09/2023] [Accepted: 06/26/2023] [Indexed: 07/29/2023]
Abstract
Homologous recombination (HR) is essential for error-free repair of DNA double-strand breaks, perturbed replication forks (RFs), and post-replicative single-stranded DNA (ssDNA) gaps. To initiate HR, the recombination mediator and tumor suppressor protein BRCA2 facilitates nucleation of RAD51 on ssDNA prior to stimulation of RAD51 filament growth by RAD51 paralogs. Although ssDNA binding by BRCA2 has been implicated in RAD51 nucleation, the function of double-stranded DNA (dsDNA) binding by BRCA2 remains unclear. Here, we exploit single-molecule (SM) imaging to visualize BRCA2-mediated RAD51 nucleation in real time using purified proteins. We report that BRCA2 nucleates and stabilizes RAD51 on ssDNA either directly or through an unappreciated diffusion-assisted delivery mechanism involving binding to and sliding along dsDNA, which requires the cooperative action of multiple dsDNA-binding modules in BRCA2. Collectively, our work reveals two distinct mechanisms of BRCA2-dependent RAD51 loading onto ssDNA, which we propose are critical for its diverse functions in maintaining genome stability and cancer suppression.
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Affiliation(s)
- Ondrej Belan
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Luke Greenhough
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Lucas Kuhlen
- Section of Structural Biology, Faculty of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London SW7 2AZ, UK
| | - Roopesh Anand
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Artur Kaczmarczyk
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London W12 0NN, UK; Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London W12 0NN, UK
| | - Dominika T Gruszka
- Single Molecule Imaging of Genome Duplication and Maintenance Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Hasan Yardimci
- Single Molecule Imaging of Genome Duplication and Maintenance Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Faculty of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London SW7 2AZ, UK
| | - David S Rueda
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London W12 0NN, UK; Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London W12 0NN, UK
| | - Stephen C West
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Simon J Boulton
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
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3
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Liu C, Wang L, Li Y, Guo M, Hu J, Wang T, Li M, Yang Z, Lin R, Xu W, Chen Y, Luo M, Gao F, Chen JY, Sun Q, Liu H, Sun B, Li W. RNase H1 facilitates recombinase recruitment by degrading DNA-RNA hybrids during meiosis. Nucleic Acids Res 2023; 51:7357-7375. [PMID: 37378420 PMCID: PMC10415156 DOI: 10.1093/nar/gkad524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 05/29/2023] [Accepted: 06/05/2023] [Indexed: 06/29/2023] Open
Abstract
DNA-RNA hybrids play various roles in many physiological progresses, but how this chromatin structure is dynamically regulated during spermatogenesis remains largely unknown. Here, we show that germ cell-specific knockout of Rnaseh1, a specialized enzyme that degrades the RNA within DNA-RNA hybrids, impairs spermatogenesis and causes male infertility. Notably, Rnaseh1 knockout results in incomplete DNA repair and meiotic prophase I arrest. These defects arise from the altered RAD51 and DMC1 recruitment in zygotene spermatocytes. Furthermore, single-molecule experiments show that RNase H1 promotes recombinase recruitment to DNA by degrading RNA within DNA-RNA hybrids and allows nucleoprotein filaments formation. Overall, we uncover a function of RNase H1 in meiotic recombination, during which it processes DNA-RNA hybrids and facilitates recombinase recruitment.
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Affiliation(s)
- Chao Liu
- Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou 510623, China
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Stem Cell and Regenerative Medicine Innovation Institute, Chinese Academy of Sciences, Beijing 100101, China
| | - Liying Wang
- Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou 510623, China
| | - Yanan Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Mengmeng Guo
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Stem Cell and Regenerative Medicine Innovation Institute, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jun Hu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Teng Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Mengjing Li
- Center for Reproductive Medicine, Shandong University, Jinan 250012, China
| | - Zhuo Yang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ruoyao Lin
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Wei Xu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yinghong Chen
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Stem Cell and Regenerative Medicine Innovation Institute, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mengcheng Luo
- Department of Tissue and Embryology, School of Basic Medical Sciences, Wuhan University, Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan 430072, China
| | - Fei Gao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Stem Cell and Regenerative Medicine Innovation Institute, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jia-Yu Chen
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China
| | - Qianwen Sun
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing 100084, China
| | - Hongbin Liu
- Center for Reproductive Medicine, Shandong University, Jinan 250012, China
| | - Bo Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Wei Li
- Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou 510623, China
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Stem Cell and Regenerative Medicine Innovation Institute, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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4
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The convergence of head-on DNA unwinding forks induces helicase oligomerization and activity transition. Proc Natl Acad Sci U S A 2022; 119:e2116462119. [PMID: 35658074 DOI: 10.1073/pnas.2116462119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
SignificanceBloom syndrome helicase (BLM) is a multifunctional helicase that primarily catalyzes the separation of two single strands of DNA. Here, using a single-molecule optical tweezers approach combined with confocal microscopy, we monitored both the enzymatic activity and oligomeric status of BLM at the same time. Strikingly, a head-on collision of BLM-medicated DNA unwinding forks was found to effectively switch their oligomeric state and activity. Specifically, BLMs, upon collision, immediately fuse across the fork junctions and covert their activities from dsDNA unwinding to ssDNA translocation and protein displacement. These findings explain how BLM plays multiple functional roles in homologous recombination (HR). The single-molecule approach used here provides a reference model for investigating the relationship between protein oligomeric state and function.
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5
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Eustáquio R, Ramalho JPP, Caldeira AT, Pereira A. New Red-Shifted 4-Styrylcoumarin Derivatives as Potential Fluorescent Labels for Biomolecules. Molecules 2022; 27:1461. [PMID: 35268562 PMCID: PMC8912076 DOI: 10.3390/molecules27051461] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 11/30/2022] Open
Abstract
Important scientific areas, such as cellular biology, medicine, pharmacy, and environmental sciences, are dependent on very sensitive analytical techniques to track and detect biomolecules. In this work, we develop a simple, low-cost and effective synthetic strategy to produce new red-shifted 4-styrylcoumarin derivatives as promising inexpensive fluorescent labels for biomolecules. The extension of the delocalized π-electron system results in bathochromic shifts in these new coumarin derivatives, which also present large Stokes shifts. In addition, density functional theory and time-dependent density functional theory calculations helped to rationalize the photophysical properties observed by the experimental results.
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Affiliation(s)
- Raquel Eustáquio
- Hercules Laboratory, University of Évora, Largo Marquês de Marialva 8, 7000-809 Évora, Portugal; (R.E.); (A.T.C.)
| | - João P. Prates Ramalho
- Chemistry Department, School of Sciences and Technology, University of Évora, Rua Romão Ramalho 59, 7000-671 Évora, Portugal;
- Laqv-Requimte, University of Évora, Rua Romão Ramalho 59, 7000-671 Évora, Portugal
| | - Ana T. Caldeira
- Hercules Laboratory, University of Évora, Largo Marquês de Marialva 8, 7000-809 Évora, Portugal; (R.E.); (A.T.C.)
- Chemistry Department, School of Sciences and Technology, University of Évora, Rua Romão Ramalho 59, 7000-671 Évora, Portugal;
| | - António Pereira
- Hercules Laboratory, University of Évora, Largo Marquês de Marialva 8, 7000-809 Évora, Portugal; (R.E.); (A.T.C.)
- Chemistry Department, School of Sciences and Technology, University of Évora, Rua Romão Ramalho 59, 7000-671 Évora, Portugal;
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6
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Bi L, Qin Z, Hou XM, Modesti M, Sun B. Simultaneous Mechanical and Fluorescence Detection of Helicase-Catalyzed DNA Unwinding. Methods Mol Biol 2022; 2478:329-347. [PMID: 36063326 DOI: 10.1007/978-1-0716-2229-2_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Helicases are ubiquitous molecular motor proteins that utilize the energy derived from the hydrolysis of nucleoside triphosphates (NTPs) to transiently convert the duplex form of nucleic acids to single-stranded intermediates for many biological processes. These enzymes play vital roles in nearly all aspects of nucleic acid metabolism, such as DNA repair and RNA splicing. Understanding helicase's functional roles requires methods to dissect the mechanisms of motor proteins at the molecular level. In the past three decades, there has been a large increase in the application of single-molecule approaches to investigate helicases. These techniques, such as optical tweezers and single-molecule fluorescence, offer capabilities to monitor helicase motions with unprecedented spatiotemporal resolution, to apply quantitative forces to probe the chemo-mechanical activities of these motors and to resolve helicase heterogeneity at the single-molecule level. In this chapter, we describe a single-molecule method that combines optical tweezers with confocal fluorescence microscopy to study helicase-catalyzed DNA unwinding. Using Bloom syndrome protein (BLM), a multifunctional helicase that maintains genome stability, as an example, we show that this method allows for the simultaneous detection of displacement, force and fluorescence signals of a single DNA molecule during unwinding in real time, leading to the discovery of a distinct bidirectional unwinding mode of BLM that is activated by a single-stranded DNA binding protein called replication protein A (RPA). We provide detailed instructions on how to prepare two DNA templates to be used in the assays, purify the BLM and RPA proteins, perform single-molecule experiments, and acquire and analyse the data.
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Affiliation(s)
- Lulu Bi
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Zhenheng Qin
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Xi-Miao Hou
- College of Life Sciences, Northwest A&F University, Yangling, China
| | - Mauro Modesti
- Cancer Research Center of Marseille, Marseille, France
| | - Bo Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
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7
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Anand R, Buechelmaier E, Belan O, Newton M, Vancevska A, Kaczmarczyk A, Takaki T, Rueda DS, Powell SN, Boulton SJ. HELQ is a dual-function DSB repair enzyme modulated by RPA and RAD51. Nature 2022; 601:268-273. [PMID: 34937945 PMCID: PMC8755542 DOI: 10.1038/s41586-021-04261-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 11/17/2021] [Indexed: 02/04/2023]
Abstract
DNA double-stranded breaks (DSBs) are deleterious lesions, and their incorrect repair can drive cancer development1. HELQ is a superfamily 2 helicase with 3' to 5' polarity, and its disruption in mice confers germ cells loss, infertility and increased predisposition to ovarian and pituitary tumours2-4. At the cellular level, defects in HELQ result in hypersensitivity to cisplatin and mitomycin C, and persistence of RAD51 foci after DNA damage3,5. Notably, HELQ binds to RPA and the RAD51-paralogue BCDX2 complex, but the relevance of these interactions and how HELQ functions in DSB repair remains unclear3,5,6. Here we show that HELQ helicase activity and a previously unappreciated DNA strand annealing function are differentially regulated by RPA and RAD51. Using biochemistry analyses and single-molecule imaging, we establish that RAD51 forms a complex with and strongly stimulates HELQ as it translocates during DNA unwinding. By contrast, RPA inhibits DNA unwinding by HELQ but strongly stimulates DNA strand annealing. Mechanistically, we show that HELQ possesses an intrinsic ability to capture RPA-bound DNA strands and then displace RPA to facilitate annealing of complementary sequences. Finally, we show that HELQ deficiency in cells compromises single-strand annealing and microhomology-mediated end-joining pathways and leads to bias towards long-tract gene conversion tracts during homologous recombination. Thus, our results implicate HELQ in multiple arms of DSB repair through co-factor-dependent modulation of intrinsic translocase and DNA strand annealing activities.
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Affiliation(s)
- Roopesh Anand
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London, UK
| | - Erika Buechelmaier
- Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Graduate School of Medical Sciences, Weill Cornell Medicine, New York, NY, USA
| | - Ondrej Belan
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London, UK
| | - Matthew Newton
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London, UK
| | | | - Artur Kaczmarczyk
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK
- Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, UK
| | - Tohru Takaki
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London, UK
| | - David S Rueda
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK.
- Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, UK.
| | - Simon N Powell
- Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | - Simon J Boulton
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London, UK.
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8
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Belan O, Moore G, Kaczmarczyk A, Newton MD, Anand R, Boulton SJ, Rueda DS. Generation of versatile ss-dsDNA hybrid substrates for single-molecule analysis. STAR Protoc 2021; 2:100588. [PMID: 34169285 PMCID: PMC8209646 DOI: 10.1016/j.xpro.2021.100588] [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] [Indexed: 11/29/2022] Open
Abstract
Here, we describe a rapid and versatile protocol to generate gapped DNA substrates for single-molecule (SM) analysis using optical tweezers via site-specific Cas9 nicking and force-induced melting. We provide examples of single-stranded (ss) DNA gaps of different length and position. We outline protocols to visualize these substrates by replication protein A-enhanced Green Fluorescent Protein (RPA-eGFP) and SYTOX Orange staining using commercially available optical tweezers (C-TRAP). Finally, we demonstrate the utility of these substrates for SM analysis of bidirectional growth of RAD-51-ssDNA filaments. For complete details on the use and execution of this protocol, please refer to Belan et al. (2021).
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Affiliation(s)
- Ondrej Belan
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - George Moore
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London W12 0NN, UK
- Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London W12 0NN, UK
| | - Artur Kaczmarczyk
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London W12 0NN, UK
- Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London W12 0NN, UK
| | - Matthew D. Newton
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London W12 0NN, UK
- Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London W12 0NN, UK
| | - Roopesh Anand
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Simon J. Boulton
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - David S. Rueda
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London W12 0NN, UK
- Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London W12 0NN, UK
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9
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Single-molecule imaging reveals replication fork coupled formation of G-quadruplex structures hinders local replication stress signaling. Nat Commun 2021; 12:2525. [PMID: 33953191 PMCID: PMC8099879 DOI: 10.1038/s41467-021-22830-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 03/30/2021] [Indexed: 12/19/2022] Open
Abstract
Guanine-rich DNA sequences occur throughout the human genome and can transiently form G-quadruplex (G4) structures that may obstruct DNA replication, leading to genomic instability. Here, we apply multi-color single-molecule localization microscopy (SMLM) coupled with robust data-mining algorithms to quantitatively visualize replication fork (RF)-coupled formation and spatial-association of endogenous G4s. Using this data, we investigate the effects of G4s on replisome dynamics and organization. We show that a small fraction of active replication forks spontaneously form G4s at newly unwound DNA immediately behind the MCM helicase and before nascent DNA synthesis. These G4s locally perturb replisome dynamics and organization by reducing DNA synthesis and limiting the binding of the single-strand DNA-binding protein RPA. We find that the resolution of RF-coupled G4s is mediated by an interplay between RPA and the FANCJ helicase. FANCJ deficiency leads to G4 accumulation, DNA damage at G4-associated replication forks, and silencing of the RPA-mediated replication stress response. Our study provides first-hand evidence of the intrinsic, RF-coupled formation of G4 structures, offering unique mechanistic insights into the interference and regulation of stable G4s at replication forks and their effect on RPA-associated fork signaling and genomic instability.
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10
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Handzlik D, Larson ET, Munschy E, Obmolova G, Collin D, Craig TK. Inexpensive robotic system for standard and fluorescent imaging of protein crystals. Acta Crystallogr F Struct Biol Commun 2019; 75:673-686. [PMID: 31702581 PMCID: PMC6839817 DOI: 10.1107/s2053230x19014730] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 10/31/2019] [Indexed: 11/10/2022] Open
Abstract
Protein-crystallization imaging and classification is a labor-intensive process typically performed either by humans or by instruments that currently cost well over $100 000. This cost puts the use of crystallization-trial imaging outside the reach of most academic laboratories, and also start-up biotechnology firms, where resources are scarce. An imaging system has been designed and prototyped which automatically captures images from multi-well protein-crystallization experiments using both standard and fluorescent imaging techniques at a cost 28 times lower than current market rates. The machine uses a Panowin F1 3D printer as a base and controls it using G-code commands sent from a Python script running on a desktop computer. A graphical user interface (GUI) was developed to enable users to control the machine and facilitate image capture, classification and editing. A 488 nm laser diode and a 525 nm filter were incorporated to allow in situ fluorescent imaging of proteins trace-labeled with a fluorophore, Alexa Fluor 488. The instrument was primarily designed using a 3D printer and augmented using commercially available parts, and this publication aims to serve as a guide for comparable in-laboratory robotics projects.
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Affiliation(s)
| | - Eric T. Larson
- HarkerBIO LLC, 700 Ellicott Street, Buffalo, NY 14203, USA
| | - Erika Munschy
- HarkerBIO LLC, 700 Ellicott Street, Buffalo, NY 14203, USA
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11
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Panicker RC, Chattopadhaya S, Coyne AG, Srinivasan R. Allosteric Small-Molecule Serine/Threonine Kinase Inhibitors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1163:253-278. [PMID: 31707707 DOI: 10.1007/978-981-13-8719-7_11] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Deregulation of protein kinase activity has been linked to many diseases ranging from cancer to AIDS and neurodegenerative diseases. Not surprisingly, drugging the human kinome - the complete set of kinases encoded by the human genome - has been one of the major drug discovery pipelines. Majority of the approved clinical kinase inhibitors target the ATP binding site of kinases. However, the remarkable sequence and structural similarity of ATP binding pockets of kinases make selective inhibition of kinases a daunting task. To circumvent these issues, allosteric inhibitors that target sites other than the orthosteric ATP binding pocket have been developed. The structural diversity of the allosteric sites allows these inhibitors to have higher selectivity, lower toxicity and improved physiochemical properties and overcome drug resistance associated with the use of conventional kinase inhibitors. In this chapter, we will focus on the allosteric inhibitors of selected serine/threonine kinases, outline the benefits of using these inhibitors and discuss the challenges and future opportunities.
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Affiliation(s)
- Resmi C Panicker
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, People's Republic of China
| | | | - Anthony G Coyne
- University Chemical Laboratory, University of Cambridge, Cambridge, UK
| | - Rajavel Srinivasan
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, People's Republic of China.
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