1
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Reginato G, Dello Stritto MR, Wang Y, Hao J, Pavani R, Schmitz M, Halder S, Morin V, Cannavo E, Ceppi I, Braunshier S, Acharya A, Ropars V, Charbonnier JB, Jinek M, Nussenzweig A, Ha T, Cejka P. HLTF disrupts Cas9-DNA post-cleavage complexes to allow DNA break processing. Nat Commun 2024; 15:5789. [PMID: 38987539 PMCID: PMC11237066 DOI: 10.1038/s41467-024-50080-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 06/28/2024] [Indexed: 07/12/2024] Open
Abstract
The outcome of CRISPR-Cas-mediated genome modifications is dependent on DNA double-strand break (DSB) processing and repair pathway choice. Homology-directed repair (HDR) of protein-blocked DSBs requires DNA end resection that is initiated by the endonuclease activity of the MRE11 complex. Using reconstituted reactions, we show that Cas9 breaks are unexpectedly not directly resectable by the MRE11 complex. In contrast, breaks catalyzed by Cas12a are readily processed. Cas9, unlike Cas12a, bridges the broken ends, preventing DSB detection and processing by MRE11. We demonstrate that Cas9 must be dislocated after DNA cleavage to allow DNA end resection and repair. Using single molecule and bulk biochemical assays, we next find that the HLTF translocase directly removes Cas9 from broken ends, which allows DSB processing by DNA end resection or non-homologous end-joining machineries. Mechanistically, the activity of HLTF requires its HIRAN domain and the release of the 3'-end generated by the cleavage of the non-target DNA strand by the Cas9 RuvC domain. Consequently, HLTF removes the H840A but not the D10A Cas9 nickase. The removal of Cas9 H840A by HLTF explains the different cellular impact of the two Cas9 nickase variants in human cells, with potential implications for gene editing.
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Affiliation(s)
- Giordano Reginato
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Maria Rosaria Dello Stritto
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Yanbo Wang
- Department of Biophysics & Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, 21205, USA
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Jingzhou Hao
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Raphael Pavani
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Michael Schmitz
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Swagata Halder
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
- Biological Systems Engineering, Plaksha University, Mohali, Punjab, 140306, India
| | - Vincent Morin
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Elda Cannavo
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Ilaria Ceppi
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Stefan Braunshier
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Ananya Acharya
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland
| | - Virginie Ropars
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Jean-Baptiste Charbonnier
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Martin Jinek
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Andrè Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Taekjip Ha
- Department of Biophysics & Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, 21205, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
- Howard Hughes Medical Institute, Boston, MA, 02115, USA
| | - Petr Cejka
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), 6500, Bellinzona, Switzerland.
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2
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Sülzle J, Elfeky L, Manley S. Surface passivation and functionalisation for mass photometry. J Microsc 2024; 295:14-20. [PMID: 38606461 DOI: 10.1111/jmi.13302] [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: 11/30/2023] [Revised: 03/30/2024] [Accepted: 04/02/2024] [Indexed: 04/13/2024]
Abstract
Interferometric scattering (iSCAT) microscopy enables the label-free observation of biomolecules. Consequently, single-particle imaging and tracking with the iSCAT-based method known as mass photometry (MP) is a growing area of study. However, establishing reliable cover glass passivation and functionalisation methods is crucial to reduce nonspecific binding and prepare surfaces for in vitro single-molecule binding experiments. Existing protocols for fluorescence microscopy can contain strongly scattering or mobile components, which make them impractical for MP-based microscopy. In this study, we characterise several different surface coatings using MP. We present approaches for cover glass passivation using 3-aminopropyltriethoxysilane (APTES) and polyethylene glycol (PEG, 2k) along with functionalisation via a maleimide-thiol linker. These coatings are compatible with water or salt buffers, and show low background scattering; thus, we are able to measure proteins as small as 60 kDa. In this technical note, we offer a surface preparation suitable for in vitro experiments with MP.
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Affiliation(s)
- Jenny Sülzle
- Laboratory of Experimental Biophysics (LEB), Institute of Physics and Institute of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Laila Elfeky
- Laboratory of Experimental Biophysics (LEB), Institute of Physics and Institute of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Suliana Manley
- Laboratory of Experimental Biophysics (LEB), Institute of Physics and Institute of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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3
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Nicolas Y, Bret H, Cannavo E, Acharya A, Cejka P, Borde V, Guerois R. Molecular insights into the activation of Mre11-Rad50 endonuclease activity by Sae2/CtIP. Mol Cell 2024; 84:2223-2237.e4. [PMID: 38870937 DOI: 10.1016/j.molcel.2024.05.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 02/25/2024] [Accepted: 05/20/2024] [Indexed: 06/15/2024]
Abstract
In Saccharomyces cerevisiae (S. cerevisiae), Mre11-Rad50-Xrs2 (MRX)-Sae2 nuclease activity is required for the resection of DNA breaks with secondary structures or protein blocks, while in humans, the MRE11-RAD50-NBS1 (MRN) homolog with CtIP is needed to initiate DNA end resection of all breaks. Phosphorylated Sae2/CtIP stimulates the endonuclease activity of MRX/N. Structural insights into the activation of the Mre11 nuclease are available only for organisms lacking Sae2/CtIP, so little is known about how Sae2/CtIP activates the nuclease ensemble. Here, we uncover the mechanism of Mre11 activation by Sae2 using a combination of AlphaFold2 structural modeling of biochemical and genetic assays. We show that Sae2 stabilizes the Mre11 nuclease in a conformation poised to cleave substrate DNA. Several designs of compensatory mutations establish how Sae2 activates MRX in vitro and in vivo, supporting the structural model. Finally, our study uncovers how human CtIP, despite considerable sequence divergence, employs a similar mechanism to activate MRN.
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Affiliation(s)
- Yoann Nicolas
- Institut Curie, PSL University, Sorbonne Université, CNRS UMR3244, Dynamics of Genetic Information, 75005 Paris, France
| | - Hélène Bret
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Elda Cannavo
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland
| | - Ananya Acharya
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland.
| | - Valérie Borde
- Institut Curie, PSL University, Sorbonne Université, CNRS UMR3244, Dynamics of Genetic Information, 75005 Paris, France.
| | - Raphaël Guerois
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
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4
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Zheng Y, Zhao Y, Dong K, Miao L, Zhou X, Gong Y, Zhang L. A novel Mre11 protein from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5 possesses 5'-3' exonuclease and endonuclease activities. Int J Biol Macromol 2024; 272:132654. [PMID: 38810854 DOI: 10.1016/j.ijbiomac.2024.132654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 05/21/2024] [Accepted: 05/23/2024] [Indexed: 05/31/2024]
Abstract
Mre11 is one of important proteins that are involved in DNA repair and recombination by processing DNA ends to produce 3'-single stranded DNA, thus providing a platform for other DNA repair and recombination proteins. In this work, we characterized the Mre11 protein from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5 (Tba-Mre11) biochemically and dissected the roles of its four conserved residues, which is the first report on Mre11 proteins from Thermococcus. Tba-Mre11 possesses exonuclease activity for degrading ssDNA and dsDNA in the 5'-3' direction, which contrasts with other reported Mre11 homologs. Maximum degradation efficiency was observed with Mn2+ at 80 °C and at pH 7.5-9.5. In addition to possessing 5'-3' exonuclease activity, Tba-Mre11 has endonuclease activity that nicks plasmid DNA and circular ssDNA. Mutational data show that residues D10, D51 and N86 in Tba-Mre11 are essential for DNA degradation since almost no activity was observed for the D10A, D51A and N86A mutants. By comparison, residue D44 in Tba-Mre11 is not responsible for DNA degradation since the D44A mutant possessed the similar WT protein activity. Notably, the D44A mutant almost completely abolished the ability to bind DNA, suggesting that residue D44 is essential for binding DNA.
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Affiliation(s)
- Yaqi Zheng
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Yang Zhao
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Kunming Dong
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Li Miao
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Xiaojian Zhou
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Yong Gong
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, China
| | - Likui Zhang
- College of Environmental Science and Engineering, Yangzhou University, China.
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5
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Möller C, Sharma R, Öz R, Reginato G, Cannavo E, Ceppi I, Sriram KK, Cejka P, Westerlund F. Xrs2/NBS1 promote end-bridging activity of the MRE11-RAD50 complex. Biochem Biophys Res Commun 2024; 695:149464. [PMID: 38217957 DOI: 10.1016/j.bbrc.2023.149464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/04/2023] [Accepted: 12/29/2023] [Indexed: 01/15/2024]
Abstract
DNA double strand breaks (DSBs) can be detrimental to the cell and need to be efficiently repaired. A first step in DSB repair is to bring the free ends in close proximity to enable ligation by non-homologous end-joining (NHEJ), while the more precise, but less available, repair by homologous recombination (HR) requires close proximity of a sister chromatid. The human MRE11-RAD50-NBS1 (MRN) complex, Mre11-Rad50-Xrs2 (MRX) in yeast, is involved in both repair pathways. Here we use nanofluidic channels to study, on the single DNA molecule level, how MRN, MRX and their constituents interact with long DNA and promote DNA bridging. Nanofluidics is a suitable method to study reactions on DNA ends since no anchoring of the DNA end(s) is required. We demonstrate that NBS1 and Xrs2 play important, but differing, roles in the DNA tethering by MRN and MRX. NBS1 promotes DNA bridging by MRN consistent with tethering of a repair template. MRX shows a "synapsis-like" DNA end-bridging, stimulated by the Xrs2 subunit. Our results highlight the different ways MRN and MRX bridge DNA, and the results are in agreement with their key roles in HR and NHEJ, respectively, and contribute to the understanding of the roles of NBS1 and Xrs2 in DSB repair.
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Affiliation(s)
- Carl Möller
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE, 41296, Sweden
| | - Rajhans Sharma
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE, 41296, Sweden
| | - Robin Öz
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE, 41296, Sweden
| | - Giordano Reginato
- Institute for Research in Biomedicine, Universitá della Svizzera Italiana, Bellinzona, CH 6500, Switzerland
| | - Elda Cannavo
- Institute for Research in Biomedicine, Universitá della Svizzera Italiana, Bellinzona, CH 6500, Switzerland
| | - Ilaria Ceppi
- Institute for Research in Biomedicine, Universitá della Svizzera Italiana, Bellinzona, CH 6500, Switzerland
| | - K K Sriram
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE, 41296, Sweden
| | - Petr Cejka
- Institute for Research in Biomedicine, Universitá della Svizzera Italiana, Bellinzona, CH 6500, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH) Zürich, Switzerland
| | - Fredrik Westerlund
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE, 41296, Sweden.
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6
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De Bragança S, Dillingham MS, Moreno-Herrero F. Recent insights into eukaryotic double-strand DNA break repair unveiled by single-molecule methods. Trends Genet 2023; 39:924-940. [PMID: 37806853 DOI: 10.1016/j.tig.2023.09.004] [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: 06/14/2023] [Revised: 09/04/2023] [Accepted: 09/07/2023] [Indexed: 10/10/2023]
Abstract
Genome integrity and maintenance are essential for the viability of all organisms. A wide variety of DNA damage types have been described, but double-strand breaks (DSBs) stand out as one of the most toxic DNA lesions. Two major pathways account for the repair of DSBs: homologous recombination (HR) and non-homologous end joining (NHEJ). Both pathways involve complex DNA transactions catalyzed by proteins that sequentially or cooperatively work to repair the damage. Single-molecule methods allow visualization of these complex transactions and characterization of the protein:DNA intermediates of DNA repair, ultimately allowing a comprehensive breakdown of the mechanisms underlying each pathway. We review current understanding of the HR and NHEJ responses to DSBs in eukaryotic cells, with a particular emphasis on recent advances through the use of single-molecule techniques.
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Affiliation(s)
- Sara De Bragança
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB), CSIC, Madrid, Spain
| | - Mark S Dillingham
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnología (CNB), CSIC, Madrid, Spain.
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7
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Vertemara J, Tisi R. Dynamic Properties of the DNA Damage Response Mre11/Rad50 Complex. Int J Mol Sci 2023; 24:12377. [PMID: 37569756 PMCID: PMC10418313 DOI: 10.3390/ijms241512377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 07/28/2023] [Accepted: 08/01/2023] [Indexed: 08/13/2023] Open
Abstract
DNA double-strand breaks (DSBs) are a significant threat to cell viability due to the induction of genome instability and the potential loss of genetic information. One of the key players for early DNA damage response is the conserved Mre11/Rad50 Nbs1/Xrs2 (MRN/X) complex, which is quickly recruited to the DNA's ruptured ends and is required for their tethering and their subsequent repair via different pathways. The MRN/X complex associates with several other proteins to exert its functions, but it also exploits sophisticated internal dynamic properties to orchestrate the several steps required to address the damage. In this review, we summarize the intrinsic molecular features of the MRN/X complex through biophysical, structural, and computational analyses in order to describe the conformational transitions that allow for this complex to accomplish its multiple functions.
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Affiliation(s)
| | - Renata Tisi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy;
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8
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Gnügge R, Reginato G, Cejka P, Symington LS. Sequence and chromatin features guide DNA double-strand break resection initiation. Mol Cell 2023; 83:1237-1250.e15. [PMID: 36917982 PMCID: PMC10131398 DOI: 10.1016/j.molcel.2023.02.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 01/09/2023] [Accepted: 02/09/2023] [Indexed: 03/14/2023]
Abstract
DNA double-strand breaks (DSBs) are cytotoxic genome lesions that must be accurately and efficiently repaired to ensure genome integrity. In yeast, the Mre11-Rad50-Xrs2 (MRX) complex nicks 5'-terminated DSB ends to initiate nucleolytic processing of DSBs for repair by homologous recombination. How MRX-DNA interactions support 5' strand-specific nicking and how nicking is influenced by the chromatin context have remained elusive. Using a deep sequencing-based assay, we mapped MRX nicks at single-nucleotide resolution next to multiple DSBs in the yeast genome. We observed that the DNA end-binding Ku70-Ku80 complex directed DSB-proximal nicks and that repetitive MRX cleavage extended the length of resection tracts. We identified a sequence motif and a DNA meltability profile that is preferentially nicked by MRX. Furthermore, we found that nucleosomes as well as transcription impeded MRX incisions. Our findings suggest that local DNA sequence and chromatin features shape the activity of this central DSB repair complex.
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Affiliation(s)
- Robert Gnügge
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Giordano Reginato
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093 Zürich, Switzerland; Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland
| | - Petr Cejka
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093 Zürich, Switzerland; Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, 6500 Bellinzona, Switzerland
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA; Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY 10032, USA.
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9
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Azatian SB, Canny MD, Latham MP. Three segment ligation of a 104 kDa multi-domain protein by SrtA and OaAEP1. JOURNAL OF BIOMOLECULAR NMR 2023; 77:25-37. [PMID: 36539644 PMCID: PMC10149453 DOI: 10.1007/s10858-022-00409-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 11/28/2022] [Indexed: 05/03/2023]
Abstract
NMR spectroscopy is an excellent tool for studying protein structure and dynamics which provides a deeper understanding of biological function. As the size of the biomolecule of interest increases, it can become advantageous to dilute the number of observed signals in the NMR spectrum to decrease spectral overlap and increase resolution. One way to limit the number of resonances in the NMR data is by selectively labeling a smaller domain within the larger macromolecule, a process called segmental isotopic labeling. Many examples of segmental isotopic labeling have been described where two segments of a protein are ligated together by chemical or enzymatic means, but there are far fewer descriptions of a three or more segment ligation reaction. Herein, we describe an enzymatic segmental labeling scheme that combines the widely used Sortase A and more recently described OaAEP1 for a two site ligation strategy. In preparation to study proposed long-range allostery in the 104 kDa DNA damage repair protein Rad50, we ligated side-chain methyl group labeled Zn Hook domain between two long segments of otherwise unlabeled P.furiosus Rad50. Enzymatic activity data demonstrated that the scars resulting from the ligation reactions did not affect Rad50 function within the Mre11-Rad50 DNA double strand break repair complex. Finally, methyl-based NMR spectroscopy confirmed the formation of the full-length ligated protein. Our strategy highlights the strengths of OaAEP1 for segmental labeling, namely faster reaction times and a smaller recognition sequence, and provides a straightforward template for using these two enzymes in multisite segmental labeling reactions.
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Affiliation(s)
- Stephan B Azatian
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Marella D Canny
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Michael P Latham
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA.
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10
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Mre11-Rad50: the DNA end game. Biochem Soc Trans 2023; 51:527-538. [PMID: 36892213 DOI: 10.1042/bst20220754] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/09/2023] [Accepted: 02/17/2023] [Indexed: 03/10/2023]
Abstract
The Mre11-Rad50-(Nbs1/Xrs2) complex is an evolutionarily conserved factor for the repair of DNA double-strand breaks and other DNA termini in all kingdoms of life. It is an intricate DNA associated molecular machine that cuts, among other functions, a large variety of free and obstructed DNA termini for DNA repair by end joining or homologous recombination, yet leaves undamaged DNA intact. Recent years have brought progress in both the structural and functional analyses of Mre11-Rad50 orthologs, revealing mechanisms of DNA end recognition, endo/exonuclease activities, nuclease regulation and DNA scaffolding. Here, I review our current understanding and recent progress on the functional architecture Mre11-Rad50 and how this chromosome associated coiled-coil ABC ATPase acts as DNA topology specific endo-/exonuclease.
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11
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Rotheneder M, Stakyte K, van de Logt E, Bartho JD, Lammens K, Fan Y, Alt A, Kessler B, Jung C, Roos WP, Steigenberger B, Hopfner KP. Cryo-EM structure of the Mre11-Rad50-Nbs1 complex reveals the molecular mechanism of scaffolding functions. Mol Cell 2023; 83:167-185.e9. [PMID: 36577401 DOI: 10.1016/j.molcel.2022.12.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 10/14/2022] [Accepted: 12/03/2022] [Indexed: 12/28/2022]
Abstract
The DNA double-strand break repair complex Mre11-Rad50-Nbs1 (MRN) detects and nucleolytically processes DNA ends, activates the ATM kinase, and tethers DNA at break sites. How MRN can act both as nuclease and scaffold protein is not well understood. The cryo-EM structure of MRN from Chaetomium thermophilum reveals a 2:2:1 complex with a single Nbs1 wrapping around the autoinhibited Mre11 nuclease dimer. MRN has two DNA-binding modes, one ATP-dependent mode for loading onto DNA ends and one ATP-independent mode through Mre11's C terminus, suggesting how it may interact with DSBs and intact DNA. MRNs two 60-nm-long coiled-coil domains form a linear rod structure, the apex of which is assembled by the two joined zinc-hook motifs. Apices from two MRN complexes can further dimerize, forming 120-nm spanning MRN-MRN structures. Our results illustrate the architecture of MRN and suggest how it mechanistically integrates catalytic and tethering functions.
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Affiliation(s)
- Matthias Rotheneder
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Kristina Stakyte
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Erik van de Logt
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Joseph D Bartho
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Katja Lammens
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Yilan Fan
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Aaron Alt
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Brigitte Kessler
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Christophe Jung
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Wynand P Roos
- Institute for Toxicology, Johannes-Gutenberg-Universität, Mainz, Germany
| | - Barbara Steigenberger
- Mass Spectrometry Core Facility, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Karl-Peter Hopfner
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany.
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12
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Stabilization of DNA fork junctions by Smc5/6 complexes revealed by single-molecule imaging. Cell Rep 2022; 41:111778. [PMID: 36476856 PMCID: PMC9756111 DOI: 10.1016/j.celrep.2022.111778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 09/15/2022] [Accepted: 11/11/2022] [Indexed: 12/12/2022] Open
Abstract
SMC complexes play key roles in genome maintenance, where they ensure efficient genome replication and segregation. The SMC complex Smc5/6 is a crucial player in DNA replication and repair, yet many molecular features that determine its roles are unclear. Here, we use single-molecule microscopy to investigate Smc5/6's interaction with DNA. We find that Smc5/6 forms oligomers that dynamically redistribute on dsDNA by 1D diffusion and statically bind to ssDNA. Using combined force manipulation and single-molecule microscopy, we generate ssDNA-dsDNA junctions that mimic structures present in DNA repair intermediates or replication forks. We show that Smc5/6 accumulates at these junction sites, stabilizes the fork, and promotes the retention of RPA. Our observations provide a model for the complex's enrichment at sites of replication stress and DNA lesions from where it coordinates the recruitment and activation of downstream repair proteins.
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Kim H, Kim D, Choi H, Shin G, Lee JK. Deubiquitinase USP2 stabilizes the MRE11-RAD50-NBS1 complex at DNA double-strand break sites by counteracting the ubiquitination of NBS1. J Biol Chem 2022; 299:102752. [PMID: 36436562 PMCID: PMC9758435 DOI: 10.1016/j.jbc.2022.102752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 11/26/2022] Open
Abstract
The MRE11-RAD50-NBS1 (MRN) complex plays essential roles in the cellular response to DNA double-strand breaks (DSBs), which are the most cytotoxic DNA lesions, and is a target of various modifications and controls. Recently, lysine 48-linked ubiquitination of NBS1, resulting in premature disassembly of the MRN complex from DSB sites, was observed in cells lacking RECQL4 helicase activity. However, the role and control of this ubiquitination during the DSB response in cells with intact RECQL4 remain unknown. Here, we showed that USP2 counteracts this ubiquitination and stabilizes the MRN complex during the DSB response. By screening deubiquitinases that increase the stability of the MRN complex in RECQL4-deficient cells, USP2 was identified as a new deubiquitinase that acts at DSB sites to counteract NBS1 ubiquitination. We determined that USP2 is recruited to DSB sites in a manner dependent on ATM, a major checkpoint kinase against DSBs, and stably interacts with NBS1 and RECQL4 in immunoprecipitation experiments. Phosphorylation of two critical residues in the N terminus of USP2 by ATM is required for its recruitment to DSBs and its interaction with RECQL4. While inactivation of USP2 alone does not substantially influence the DSB response, we found that inactivation of USP2 and USP28, another deubiquitinase influencing NBS1 ubiquitination, results in premature disassembly of the MRN complex from DSB sites as well as defects in ATM activation and homologous recombination repair abilities. These results suggest that deubiquitinases counteracting NBS1 ubiquitination are essential for the stable maintenance of the MRN complex and proper cellular response to DSBs.
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Affiliation(s)
- Hyunsup Kim
- Interdisciplinary Graduate Program in Genetic Engineering, Seoul National University, Seoul, Korea
| | - Dongmin Kim
- Department of Biology Education, Seoul National University, Seoul, Korea
| | - Hyemin Choi
- Department of Biology Education, Seoul National University, Seoul, Korea
| | - Gwangsu Shin
- Interdisciplinary Graduate Program in Genetic Engineering, Seoul National University, Seoul, Korea
| | - Joon-Kyu Lee
- Interdisciplinary Graduate Program in Genetic Engineering, Seoul National University, Seoul, Korea; Department of Biology Education, Seoul National University, Seoul, Korea.
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Saccharomyces cerevisiae as a Model System for Eukaryotic Cell Biology, from Cell Cycle Control to DNA Damage Response. Int J Mol Sci 2022; 23:ijms231911665. [PMID: 36232965 PMCID: PMC9570374 DOI: 10.3390/ijms231911665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/26/2022] [Accepted: 09/28/2022] [Indexed: 11/08/2022] Open
Abstract
The yeast Saccharomyces cerevisiae has been used for bread making and beer brewing for thousands of years. In addition, its ease of manipulation, well-annotated genome, expansive molecular toolbox, and its strong conservation of basic eukaryotic biology also make it a prime model for eukaryotic cell biology and genetics. In this review, we discuss the characteristics that made yeast such an extensively used model organism and specifically focus on the DNA damage response pathway as a prime example of how research in S. cerevisiae helped elucidate a highly conserved biological process. In addition, we also highlight differences in the DNA damage response of S. cerevisiae and humans and discuss the challenges of using S. cerevisiae as a model system.
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Structural mechanism of endonucleolytic processing of blocked DNA ends and hairpins by Mre11-Rad50. Mol Cell 2022; 82:3513-3522.e6. [DOI: 10.1016/j.molcel.2022.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 06/10/2022] [Accepted: 07/23/2022] [Indexed: 11/17/2022]
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