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Wang X, Zhao X, Yu Z, Fan T, Guo Y, Liang J, Wang Y, Zhan J, Chen G, Zhou C, Zhang X, Li X, Chen X. Rtt105 stimulates Rad51-ssDNA assembly and orchestrates Rad51 and RPA actions to promote homologous recombination repair. Proc Natl Acad Sci U S A 2024; 121:e2402262121. [PMID: 39145931 PMCID: PMC11348298 DOI: 10.1073/pnas.2402262121] [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: 02/02/2024] [Accepted: 07/09/2024] [Indexed: 08/16/2024] Open
Abstract
Homologous recombination (HR) is essential for the maintenance of genome stability. During HR, Replication Protein A (RPA) rapidly coats the 3'-tailed single-strand DNA (ssDNA) generated by end resection. Then, the ssDNA-bound RPA must be timely replaced by Rad51 recombinase to form Rad51 nucleoprotein filaments that drive homology search and HR repair. How cells regulate Rad51 assembly dynamics and coordinate RPA and Rad51 actions to ensure proper HR remains poorly understood. Here, we identified that Rtt105, a Ty1 transposon regulator, acts to stimulate Rad51 assembly and orchestrate RPA and Rad51 actions during HR. We found that Rtt105 interacts with Rad51 in vitro and in vivo and restrains the adenosine 5' triphosphate (ATP) hydrolysis activity of Rad51. We showed that Rtt105 directly stimulates dynamic Rad51-ssDNA assembly, strand exchange, and D-loop formation in vitro. Notably, we found that Rtt105 physically regulates the binding of Rad51 and RPA to ssDNA via different motifs and that both regulations are necessary and epistatic in promoting Rad51 nucleation, strand exchange, and HR repair. Consequently, disrupting either of the interactions impaired HR and conferred DNA damage sensitivity, underscoring the importance of Rtt105 in orchestrating the actions of Rad51 and RPA. Our work reveals additional layers of mechanisms regulating Rad51 filament dynamics and the coordination of HR.
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Affiliation(s)
- Xuejie Wang
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Xiaocong Zhao
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Zhengshi Yu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Tianai Fan
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Yunjing Guo
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Jianqiang Liang
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Yanyan Wang
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Jingfei Zhan
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Guifang Chen
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Chun Zhou
- School of Public Health, Zhejiang University School of Medicine, Hangzhou310058, China
| | - Xinghua Zhang
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Xiangpan Li
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
| | - Xuefeng Chen
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Department of Radiation Oncology, Renmin Hospital of Wuhan University, Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan430072, China
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Carver A, Yu TY, Yates LA, White T, Wang R, Lister K, Jasin M, Zhang X. Molecular basis of FIGNL1 in dissociating RAD51 from DNA and chromatin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.16.603765. [PMID: 39071279 PMCID: PMC11275795 DOI: 10.1101/2024.07.16.603765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Maintaining genome integrity is an essential and challenging process. RAD51 recombinase, the central player of several crucial processes in repairing and protecting genome integrity, forms filaments on DNA. RAD51 filaments are tightly regulated. One of these regulators is FIGNL1, that prevents persistent RAD51 foci post-damage and genotoxic chromatin association in cells. The cryogenic electron microscopy structure of FIGNL1 in complex with RAD51 reveals that the FIGNL1 forms a non-planar hexamer and RAD51 N-terminus is enclosed in the FIGNL1 hexamer pore. Mutations in pore loop or catalytic residues of FIGNL1 render it defective in filament disassembly and are lethal in mouse embryonic stem cells. Our study reveals a unique mechanism for removing RAD51 from DNA and provides the molecular basis for FIGNL1 in maintaining genome stability.
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Affiliation(s)
- Alexander Carver
- DNA Processing Machines Laboratory, Francis Crick Institute, London, UK
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, UK
- These authors contributed equally to this study
| | - Tai-Yuan Yu
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center
- These authors contributed equally to this study
| | - Luke A Yates
- DNA Processing Machines Laboratory, Francis Crick Institute, London, UK
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, UK
| | - Travis White
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center
| | - Raymond Wang
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center
| | - Katie Lister
- DNA Processing Machines Laboratory, Francis Crick Institute, London, UK
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, UK
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center
| | - Xiaodong Zhang
- DNA Processing Machines Laboratory, Francis Crick Institute, London, UK
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, UK
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3
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Sridalla K, Woodhouse MV, Hu J, Scheer J, Ferlez B, Crickard JB. The translocation activity of Rad54 reduces crossover outcomes during homologous recombination. Nucleic Acids Res 2024; 52:7031-7048. [PMID: 38828785 PMCID: PMC11229335 DOI: 10.1093/nar/gkae474] [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: 01/29/2024] [Revised: 05/16/2024] [Accepted: 05/21/2024] [Indexed: 06/05/2024] Open
Abstract
Homologous recombination (HR) is a template-based DNA double-strand break repair pathway that requires the selection of an appropriate DNA sequence to facilitate repair. Selection occurs during a homology search that must be executed rapidly and with high fidelity. Failure to efficiently perform the homology search can result in complex intermediates that generate genomic rearrangements, a hallmark of human cancers. Rad54 is an ATP dependent DNA motor protein that functions during the homology search by regulating the recombinase Rad51. How this regulation reduces genomic exchanges is currently unknown. To better understand how Rad54 can reduce these outcomes, we evaluated several amino acid mutations in Rad54 that were identified in the COSMIC database. COSMIC is a collection of amino acid mutations identified in human cancers. These substitutions led to reduced Rad54 function and the discovery of a conserved motif in Rad54. Through genetic, biochemical and single-molecule approaches, we show that disruption of this motif leads to failure in stabilizing early strand invasion intermediates, causing increased crossovers between homologous chromosomes. Our study also suggests that the translocation rate of Rad54 is a determinant in balancing genetic exchange. The latch domain's conservation implies an interaction likely fundamental to eukaryotic biology.
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Affiliation(s)
- Krishay Sridalla
- Deparment of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Mitchell V Woodhouse
- Deparment of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Jingyi Hu
- Deparment of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Jessica Scheer
- Deparment of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Bryan Ferlez
- Deparment of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - J Brooks Crickard
- Deparment of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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4
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Son MY, Belan O, Spirek M, Cibulka J, Nikulenkov F, Kim YY, Hwang S, Myung K, Montagna C, Kim TM, Krejci L, Hasty P. RAD51 separation of function mutation disables replication fork maintenance but preserves DSB repair. iScience 2024; 27:109524. [PMID: 38577109 PMCID: PMC10993188 DOI: 10.1016/j.isci.2024.109524] [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: 11/24/2021] [Revised: 03/01/2023] [Accepted: 03/14/2024] [Indexed: 04/06/2024] Open
Abstract
Homologous recombination (HR) protects replication forks (RFs) and repairs DNA double-strand breaks (DSBs). Within HR, BRCA2 regulates RAD51 via two interaction regions: the BRC repeats to form filaments on single-stranded DNA and exon 27 (Ex27) to stabilize the filament. Here, we identified a RAD51 S181P mutant that selectively disrupted the RAD51-Ex27 association while maintaining interaction with BRC repeat and proficiently forming filaments capable of DNA binding and strand invasion. Interestingly, RAD51 S181P was defective for RF protection/restart but proficient for DSB repair. Our data suggest that Ex27-mediated stabilization of RAD51 filaments is required for the protection of RFs, while it seems dispensable for the repair of DSBs.
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Affiliation(s)
- Mi Young Son
- Department of Molecular Medicine, The Barshop Institute for Longevity and Aging Studies, The Cancer Therapy Research Center, UT Health San Antonio, San Antonio, TX 78229, USA
| | - Ondrej Belan
- Department of Biology, Masaryk University, 625 00 Brno, Czech Republic
| | - Mario Spirek
- Department of Biology, Masaryk University, 625 00 Brno, Czech Republic
- National Centre for Biomolecular Research, Masaryk University, 625 00 Brno, Czech Republic
| | - Jakub Cibulka
- Department of Biology, Masaryk University, 625 00 Brno, Czech Republic
| | - Fedor Nikulenkov
- Department of Biology, Masaryk University, 625 00 Brno, Czech Republic
| | - You Young Kim
- Center for Genomic Integrity Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Sunyoung Hwang
- Center for Genomic Integrity Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Kyungjae Myung
- Center for Genomic Integrity Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Cristina Montagna
- Department of Genetics, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA
| | - Tae Moon Kim
- Department of Molecular Medicine, The Barshop Institute for Longevity and Aging Studies, The Cancer Therapy Research Center, UT Health San Antonio, San Antonio, TX 78229, USA
- Center for Genomic Integrity Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Lumir Krejci
- Department of Biology, Masaryk University, 625 00 Brno, Czech Republic
- National Centre for Biomolecular Research, Masaryk University, 625 00 Brno, Czech Republic
| | - Paul Hasty
- Department of Molecular Medicine, The Barshop Institute for Longevity and Aging Studies, The Cancer Therapy Research Center, UT Health San Antonio, San Antonio, TX 78229, USA
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Fan J, Dhingra N, Yang T, Yang V, Zhao X. Srs2 binding to PCNA and its sumoylation contribute to RPA antagonism during the DNA damage response. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.28.587206. [PMID: 38586001 PMCID: PMC10996639 DOI: 10.1101/2024.03.28.587206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Activation of the DNA damage checkpoint upon genotoxin treatment induces a multitude of cellular changes, such as cell cycle arrest, to cope with genome stress. After prolonged genotoxin treatment, the checkpoint can be downregulated to allow cell cycle and growth resumption. In yeast, downregulation of the DNA damage checkpoint requires the Srs2 DNA helicase, which removes the ssDNA binding complex RPA and the associated Mec1 checkpoint kinase from DNA, thus dampening Mec1 activation. However, it is unclear whether the 'anti-checkpoint' role of Srs2 is temporally and spatially regulated to both allow timely checkpoint termination and to prevent superfluous RPA removal. Here we address this question by examining regulatory elements of Srs2, including its phosphorylation, sumoylation, and protein-interaction sites. Our genetic analyses and checkpoint level assessment suggest that the RPA countering role of Srs2 is promoted by Srs2 binding to PCNA, which is known to recruit Srs2 to subsets of ssDNA regions. RPA antagonism is further fostered by Srs2 sumoylation, which we found depends on the Srs2-PCNA interaction. Srs2 sumoylation is additionally reliant on Mec1 and peaks after Mec1 activity reaches maximal levels. Collectively, our data provide evidence for a two-step model wherein checkpoint downregulation is facilitated by PCNA-mediated Srs2 recruitment to ssDNA-RPA filaments and the subsequent Srs2 sumoylation stimulated upon Mec1 hyperactivation. We propose that this mechanism allows Mec1 hyperactivation to trigger checkpoint recovery.
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Affiliation(s)
- Jiayi Fan
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Nalini Dhingra
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Tammy Yang
- City University of New York Hunter College, New York, NY 10065
| | - Vicki Yang
- City University of New York Hunter College, New York, NY 10065
| | - Xiaolan Zhao
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065
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6
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Hu J, Crickard JB. All who wander are not lost: the search for homology during homologous recombination. Biochem Soc Trans 2024; 52:367-377. [PMID: 38323621 PMCID: PMC10903458 DOI: 10.1042/bst20230705] [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: 11/17/2023] [Revised: 01/10/2024] [Accepted: 01/12/2024] [Indexed: 02/08/2024]
Abstract
Homologous recombination (HR) is a template-based DNA double-strand break repair pathway that functions to maintain genomic integrity. A vital component of the HR reaction is the identification of template DNA to be used during repair. This occurs through a mechanism known as the homology search. The homology search occurs in two steps: a collision step in which two pieces of DNA are forced to collide and a selection step that results in homologous pairing between matching DNA sequences. Selection of a homologous template is facilitated by recombinases of the RecA/Rad51 family of proteins in cooperation with helicases, translocases, and topoisomerases that determine the overall fidelity of the match. This menagerie of molecular machines acts to regulate critical intermediates during the homology search. These intermediates include recombinase filaments that probe for short stretches of homology and early strand invasion intermediates in the form of displacement loops (D-loops) that stabilize paired DNA. Here, we will discuss recent advances in understanding how these specific intermediates are regulated on the molecular level during the HR reaction. We will also discuss how the stability of these intermediates influences the ultimate outcomes of the HR reaction. Finally, we will discuss recent physiological models developed to explain how the homology search protects the genome.
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Affiliation(s)
- Jingyi Hu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, U.S.A
| | - J Brooks Crickard
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, U.S.A
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7
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Ito M, Fujita Y, Shinohara A. Positive and negative regulators of RAD51/DMC1 in homologous recombination and DNA replication. DNA Repair (Amst) 2024; 134:103613. [PMID: 38142595 DOI: 10.1016/j.dnarep.2023.103613] [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: 08/02/2023] [Revised: 12/10/2023] [Accepted: 12/10/2023] [Indexed: 12/26/2023]
Abstract
RAD51 recombinase plays a central role in homologous recombination (HR) by forming a nucleoprotein filament on single-stranded DNA (ssDNA) to catalyze homology search and strand exchange between the ssDNA and a homologous double-stranded DNA (dsDNA). The catalytic activity of RAD51 assembled on ssDNA is critical for the DNA-homology-mediated repair of DNA double-strand breaks in somatic and meiotic cells and restarting stalled replication forks during DNA replication. The RAD51-ssDNA complex also plays a structural role in protecting the regressed/reversed replication fork. Two types of regulators control RAD51 filament formation, stability, and dynamics, namely positive regulators, including mediators, and negative regulators, so-called remodelers. The appropriate balance of action by the two regulators assures genome stability. This review describes the roles of positive and negative RAD51 regulators in HR and DNA replication and its meiosis-specific homolog DMC1 in meiotic recombination. We also provide future study directions for a comprehensive understanding of RAD51/DMC1-mediated regulation in maintaining and inheriting genome integrity.
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Affiliation(s)
- Masaru Ito
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
| | - Yurika Fujita
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
| | - Akira Shinohara
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
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8
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Chadda A, Kozlov AG, Nguyen B, Lohman TM, Galburt EA. Mycobacterium tuberculosis Ku Stimulates Multi-round DNA Unwinding by UvrD1 Monomers. J Mol Biol 2024; 436:168367. [PMID: 37972687 PMCID: PMC10836237 DOI: 10.1016/j.jmb.2023.168367] [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: 09/28/2023] [Revised: 11/07/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
Mycobacterium tuberculosis is the causative agent of Tuberculosis. During the host response to infection, the bacterium is exposed to both reactive oxygen species and nitrogen intermediates that can cause DNA damage. It is becoming clear that the DNA damage response in Mtb and related actinobacteria function via distinct pathways as compared to well-studied model bacteria. For example, we have previously shown that the DNA repair helicase UvrD1 is activated for processive unwinding via redox-dependent dimerization. In addition, mycobacteria contain a homo-dimeric Ku protein, homologous to the eukaryotic Ku70/Ku80 dimer, that plays roles in double-stranded break repair via non-homologous end-joining. Kuhas been shown to stimulate the helicase activity of UvrD1, but the molecular mechanism, as well as which redox form of UvrD1 is activated, is unknown. We show here that Ku specifically stimulates multi-round unwinding by UvrD1 monomers which are able to slowly unwind DNA, but at rates 100-fold slower than the dimer. We also demonstrate that the UvrD1 C-terminal Tudor domain is required for the formation of a Ku-UvrD1 protein complex and activation. We show that Mtb Ku dimers bind with high nearest neighbor cooperativity to duplex DNA and that UvrD1 activation is observed when the DNA substrate is bound with two or three Ku dimers. Our observations reveal aspects of the interactions between DNA, Mtb Ku, and UvrD1 and highlight the potential role of UvrD1 in multiple DNA repair pathways through different mechanisms of activation.
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Affiliation(s)
- Ankita Chadda
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Alexander G Kozlov
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Binh Nguyen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Timothy M Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Eric A Galburt
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Meir A, Raina VB, Rivera CE, Marie L, Symington LS, Greene EC. The separation pin distinguishes the pro- and anti-recombinogenic functions of Saccharomyces cerevisiae Srs2. Nat Commun 2023; 14:8144. [PMID: 38065943 PMCID: PMC10709652 DOI: 10.1038/s41467-023-43918-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 11/23/2023] [Indexed: 12/18/2023] Open
Abstract
Srs2 is an Sf1a helicase that helps maintain genome stability in Saccharomyces cerevisiae through its ability to regulate homologous recombination. Srs2 downregulates HR by stripping Rad51 from single-stranded DNA, and Srs2 is also thought to promote synthesis-dependent strand annealing by unwinding D-loops. However, it has not been possible to evaluate the relative contributions of these two distinct activities to any aspect of recombination. Here, we used a structure-based approach to design an Srs2 separation-of-function mutant that can dismantle Rad51-ssDNA filaments but is incapable of disrupting D-loops, allowing us to assess the relative contributions of these pro- and anti-recombinogenic functions. We show that this separation-of-function mutant phenocopies wild-type SRS2 in vivo, suggesting that the ability of Srs2 to remove Rad51 from ssDNA is its primary role during HR.
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Affiliation(s)
- Aviv Meir
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Vivek B Raina
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Carly E Rivera
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Léa Marie
- Department of Microbiology & Immunology, Columbia University, New York, NY, 10032, USA
- Institute of Pharmacology and Structural Biology (IPBS), French National Centre for Scientific Research (CNRS), Université Toulouse III, Toulouse, France
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University, New York, NY, 10032, USA
- Department of Genetics & Development, Columbia University, New York, NY, 10032, USA
| | - Eric C Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, 10032, USA.
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10
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Ploetz E, Ambrose B, Barth A, Börner R, Erichson F, Kapanidis AN, Kim HD, Levitus M, Lohman TM, Mazumder A, Rueda DS, Steffen FD, Cordes T, Magennis SW, Lerner E. A new twist on PIFE: photoisomerisation-related fluorescence enhancement. Methods Appl Fluoresc 2023; 12:012001. [PMID: 37726007 PMCID: PMC10570931 DOI: 10.1088/2050-6120/acfb58] [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: 02/27/2023] [Revised: 07/24/2023] [Accepted: 09/19/2023] [Indexed: 09/21/2023]
Abstract
PIFE was first used as an acronym for protein-induced fluorescence enhancement, which refers to the increase in fluorescence observed upon the interaction of a fluorophore, such as a cyanine, with a protein. This fluorescence enhancement is due to changes in the rate ofcis/transphotoisomerisation. It is clear now that this mechanism is generally applicable to interactions with any biomolecule. In this review, we propose that PIFE is thereby renamed according to its fundamental working principle as photoisomerisation-related fluorescence enhancement, keeping the PIFE acronym intact. We discuss the photochemistry of cyanine fluorophores, the mechanism of PIFE, its advantages and limitations, and recent approaches to turning PIFE into a quantitative assay. We provide an overview of its current applications to different biomolecules and discuss potential future uses, including the study of protein-protein interactions, protein-ligand interactions and conformational changes in biomolecules.
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Affiliation(s)
- Evelyn Ploetz
- Department of Chemistry and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - Benjamin Ambrose
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, W12 0HS, United Kingdom
- Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, W12 0HS, United Kingdom
| | - Anders Barth
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2629 HZ, The Netherlands
| | - Richard Börner
- Laserinstitut Hochschule Mittweida, Mittweida University of Applied Sciences, Mittweida, Germany
| | - Felix Erichson
- Laserinstitut Hochschule Mittweida, Mittweida University of Applied Sciences, Mittweida, Germany
| | - Achillefs N Kapanidis
- Biological Physics Research Group, Department of Physics, University of Oxford, Oxford, United Kingdom
- Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin Building, University of Oxford, Oxford, United Kingdom
| | - Harold D Kim
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332, United States of America
| | - Marcia Levitus
- School of Molecular Sciences, Arizona State University, 551 E. University Drive, Tempe, AZ,85287, United States of America
| | - Timothy M Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, United States of America
| | - Abhishek Mazumder
- CSIR-Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata-700032, West Bengal, India
| | - David S Rueda
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, W12 0HS, United Kingdom
- Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, W12 0HS, United Kingdom
| | - Fabio D Steffen
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Großhadernerstr. 2-4, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
| | - Steven W Magennis
- School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow, G12 8QQ, United Kingdom
| | - Eitan Lerner
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, Edmond J. Safra Campus, Hebrew University of Jerusalem; Jerusalem 9190401, Israel
- Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem; Jerusalem 9190401, Israel
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11
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Deveryshetty J, Chadda R, Mattice JR, Karunakaran S, Rau MJ, Basore K, Pokhrel N, Englander N, Fitzpatrick JAJ, Bothner B, Antony E. Yeast Rad52 is a homodecamer and possesses BRCA2-like bipartite Rad51 binding modes. Nat Commun 2023; 14:6215. [PMID: 37798272 PMCID: PMC10556141 DOI: 10.1038/s41467-023-41993-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 09/25/2023] [Indexed: 10/07/2023] Open
Abstract
Homologous recombination (HR) is an essential double-stranded DNA break repair pathway. In HR, Rad52 facilitates the formation of Rad51 nucleoprotein filaments on RPA-coated ssDNA. Here, we decipher how Rad52 functions using single-particle cryo-electron microscopy and biophysical approaches. We report that Rad52 is a homodecameric ring and each subunit possesses an ordered N-terminal and disordered C-terminal half. An intrinsic structural asymmetry is observed where a few of the C-terminal halves interact with the ordered ring. We describe two conserved charged patches in the C-terminal half that harbor Rad51 and RPA interacting motifs. Interactions between these patches regulate ssDNA binding. Surprisingly, Rad51 interacts with Rad52 at two different bindings sites: one within the positive patch in the disordered C-terminus and the other in the ordered ring. We propose that these features drive Rad51 nucleation onto a single position on the DNA to promote formation of uniform pre-synaptic Rad51 filaments in HR.
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Affiliation(s)
- Jaigeeth Deveryshetty
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Rahul Chadda
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Jenna R Mattice
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA
| | - Simrithaa Karunakaran
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Michael J Rau
- Center for Cellular Imaging, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Katherine Basore
- Center for Cellular Imaging, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Nilisha Pokhrel
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA
- Aera Therapeutics, Boston, MA, USA
| | - Noah Englander
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - James A J Fitzpatrick
- Center for Cellular Imaging, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA
| | - Edwin Antony
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, USA.
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12
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Adolph MB, Garje AS, Balakrishnan S, Morati F, Modesti M, Chazin WJ, Cortez D. CRISPR-dependent Base Editing Screens Identify Separation of Function Mutants of RADX with Altered RAD51 Regulatory Activity. J Mol Biol 2023; 435:168236. [PMID: 37572935 PMCID: PMC10530557 DOI: 10.1016/j.jmb.2023.168236] [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: 06/19/2023] [Revised: 08/01/2023] [Accepted: 08/04/2023] [Indexed: 08/14/2023]
Abstract
RAD51 forms nucleoprotein filaments to promote homologous recombination, replication fork reversal, and fork protection. Numerous factors regulate the stability of these filaments and improper regulation leads to genomic instability and ultimately disease including cancer. RADX is a single stranded DNA binding protein that modulates RAD51 filament stability. Here, we utilize a CRISPR-dependent base editing screen to tile mutations across RADX to delineate motifs required for RADX function. We identified separation of function mutants of RADX that bind DNA and RAD51 but have a reduced ability to stimulate its ATP hydrolysis activity. Cells expressing these RADX mutants accumulate RAD51 on chromatin, exhibit replication defects, have reduced growth, accumulate DNA damage, and are hypersensitive to DNA damage and replication stress. These results indicate that RADX must promote RAD51 ATP turnover to regulate RAD51 and genome stability during DNA replication.
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Affiliation(s)
- Madison B Adolph
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Atharv S Garje
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Swati Balakrishnan
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Florian Morati
- Cancer Research Center of Marseille, Department of Genome Integrity, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix Marseille Univ, Marseille, France
| | - Mauro Modesti
- Cancer Research Center of Marseille, Department of Genome Integrity, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix Marseille Univ, Marseille, France
| | - Walter J Chazin
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
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13
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Lever R, Simmons E, Gamble-Milner R, Buckley R, Harrison C, Parkes A, Mitchell L, Gausden J, Škulj S, Bertoša B, Bolt E, Allers T. Archaeal Hel308 suppresses recombination through a catalytic switch that controls DNA annealing. Nucleic Acids Res 2023; 51:8563-8574. [PMID: 37409572 PMCID: PMC10484726 DOI: 10.1093/nar/gkad572] [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: 03/25/2023] [Revised: 06/14/2023] [Accepted: 06/23/2023] [Indexed: 07/07/2023] Open
Abstract
Hel308 helicases promote genome stability in archaea and are conserved in metazoans, where they are known as HELQ. Their helicase mechanism is well characterised, but it is unclear how they specifically contribute to genome stability in archaea. We show here that a highly conserved motif of Hel308/HELQ helicases (motif IVa, F/YHHAGL) modulates both DNA unwinding and a newly identified strand annealing function of archaeal Hel308. A single amino acid substitution in motif IVa results in hyper-active DNA helicase and annealase activities of purified Hel308 in vitro. All-atom molecular dynamics simulations using Hel308 crystal structures provided a molecular basis for these differences between mutant and wild type Hel308. In archaeal cells, the same mutation results in 160000-fold increased recombination, exclusively as gene conversion (non-crossover) events. However, crossover recombination is unaffected by the motif IVa mutation, as is cell viability or DNA damage sensitivity. By contrast, cells lacking Hel308 show impaired growth, increased sensitivity to DNA cross-linking agents, and only moderately increased recombination. Our data reveal that archaeal Hel308 suppresses recombination and promotes DNA repair, and that motif IVa in the RecA2 domain acts as a catalytic switch to modulate the separable recombination and repair activities of Hel308.
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Affiliation(s)
- Rebecca J Lever
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Emily Simmons
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | | | - Ryan J Buckley
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Catherine Harrison
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Ashley J Parkes
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Laura Mitchell
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Jacob A Gausden
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Sanja Škulj
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
| | - Branimir Bertoša
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
| | - Edward L Bolt
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
| | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
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14
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Sugaya N, Tanaka S, Keyamura K, Noda S, Akanuma G, Hishida T. N-terminal acetyltransferase NatB regulates Rad51-dependent repair of double-strand breaks in Saccharomyces cerevisiae. Genes Genet Syst 2023; 98:61-72. [PMID: 37331807 DOI: 10.1266/ggs.23-00013] [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: 06/20/2023] Open
Abstract
Homologous recombination (HR) is a highly accurate mechanism for repairing DNA double-strand breaks (DSBs) that arise from various genotoxic insults and blocked replication forks. Defects in HR and unscheduled HR can interfere with other cellular processes such as DNA replication and chromosome segregation, leading to genome instability and cell death. Therefore, the HR process has to be tightly controlled. Protein N-terminal acetylation is one of the most common modifications in eukaryotic organisms. Studies in budding yeast implicate a role for NatB acetyltransferase in HR repair, but precisely how this modification regulates HR repair and genome integrity is unknown. In this study, we show that cells lacking NatB, a dimeric complex composed of Nat3 and Mdm2, are sensitive to the DNA alkylating agent methyl methanesulfonate (MMS), and that overexpression of Rad51 suppresses the MMS sensitivity of nat3Δ cells. Nat3-deficient cells have increased levels of Rad52-yellow fluorescent protein foci and fail to repair DSBs after release from MMS exposure. We also found that Nat3 is required for HR-dependent gene conversion and gene targeting. Importantly, we observed that nat3Δ mutation partially suppressed MMS sensitivity in srs2Δ cells and the synthetic sickness of srs2Δ sgs1Δ cells. Altogether, our results indicate that NatB functions upstream of Srs2 to activate the Rad51-dependent HR pathway for DSB repair.
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Affiliation(s)
- Natsuki Sugaya
- Department of Molecular Biology, Graduate School of Science, Gakushuin University
| | - Shion Tanaka
- Department of Molecular Biology, Graduate School of Science, Gakushuin University
| | - Kenji Keyamura
- Department of Molecular Biology, Graduate School of Science, Gakushuin University
| | - Shunsuke Noda
- Department of Molecular Biology, Graduate School of Science, Gakushuin University
| | - Genki Akanuma
- Department of Molecular Biology, Graduate School of Science, Gakushuin University
| | - Takashi Hishida
- Department of Molecular Biology, Graduate School of Science, Gakushuin University
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15
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Luo SC, Yeh MC, Lien YH, Yeh HY, Siao HL, Tu IP, Chi P, Ho MC. A RAD51-ADP double filament structure unveils the mechanism of filament dynamics in homologous recombination. Nat Commun 2023; 14:4993. [PMID: 37591853 PMCID: PMC10435448 DOI: 10.1038/s41467-023-40672-5] [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: 12/28/2022] [Accepted: 08/04/2023] [Indexed: 08/19/2023] Open
Abstract
ATP-dependent RAD51 recombinases play an essential role in eukaryotic homologous recombination by catalyzing a four-step process: 1) formation of a RAD51 single-filament assembly on ssDNA in the presence of ATP, 2) complementary DNA strand-exchange, 3) ATP hydrolysis transforming the RAD51 filament into an ADP-bound disassembly-competent state, and 4) RAD51 disassembly to provide access for DNA repairing enzymes. Of these steps, filament dynamics between the ATP- and ADP-bound states, and the RAD51 disassembly mechanism, are poorly understood due to the lack of near-atomic-resolution information of the ADP-bound RAD51-DNA filament structure. We report the cryo-EM structure of ADP-bound RAD51-DNA filaments at 3.1 Å resolution, revealing a unique RAD51 double-filament that wraps around ssDNA. Structural analysis, supported by ATP-chase and time-resolved cryo-EM experiments, reveals a collapsing mechanism involving two four-protomer movements along ssDNA for mechanical transition between RAD51 single- and double-filament without RAD51 dissociation. This mechanism enables elastic change of RAD51 filament length during structural transitions between ATP- and ADP-states.
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Affiliation(s)
- Shih-Chi Luo
- Institute of Biological Chemistry, Academia Sinica, 11529, Taipei, Taiwan
| | - Min-Chi Yeh
- Institute of Biological Chemistry, Academia Sinica, 11529, Taipei, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, 10617, Taipei, Taiwan
| | - Yu-Hsiang Lien
- Institute of Statistical Science, Academia Sinica, 11529, Taipei, Taiwan
| | - Hsin-Yi Yeh
- Institute of Biochemical Sciences, National Taiwan University, 10617, Taipei, Taiwan
| | - Huei-Lun Siao
- Institute of Statistical Science, Academia Sinica, 11529, Taipei, Taiwan
| | - I-Ping Tu
- Institute of Statistical Science, Academia Sinica, 11529, Taipei, Taiwan
| | - Peter Chi
- Institute of Biological Chemistry, Academia Sinica, 11529, Taipei, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, 10617, Taipei, Taiwan
| | - Meng-Chiao Ho
- Institute of Biological Chemistry, Academia Sinica, 11529, Taipei, Taiwan.
- Institute of Biochemical Sciences, National Taiwan University, 10617, Taipei, Taiwan.
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16
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Venkadakrishnan J, Lahane G, Dhar A, Xiao W, Bhat KM, Pandita TK, Bhat A. Implications of Translesion DNA Synthesis Polymerases on Genomic Stability and Human Health. Mol Cell Biol 2023; 43:401-425. [PMID: 37439479 PMCID: PMC10448981 DOI: 10.1080/10985549.2023.2224199] [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: 01/31/2023] [Revised: 05/03/2023] [Accepted: 06/01/2023] [Indexed: 07/14/2023] Open
Abstract
Replication fork arrest-induced DNA double strand breaks (DSBs) caused by lesions are effectively suppressed in cells due to the presence of a specialized mechanism, commonly referred to as DNA damage tolerance (DDT). In eukaryotic cells, DDT is facilitated through translesion DNA synthesis (TLS) carried out by a set of DNA polymerases known as TLS polymerases. Another parallel mechanism, referred to as homology-directed DDT, is error-free and involves either template switching or fork reversal. The significance of the DDT pathway is well established. Several diseases have been attributed to defects in the TLS pathway, caused either by mutations in the TLS polymerase genes or dysregulation. In the event of a replication fork encountering a DNA lesion, cells switch from high-fidelity replicative polymerases to low-fidelity TLS polymerases, which are associated with genomic instability linked with several human diseases including, cancer. The role of TLS polymerases in chemoresistance has been recognized in recent years. In addition to their roles in the DDT pathway, understanding noncanonical functions of TLS polymerases is also a key to unraveling their importance in maintaining genomic stability. Here we summarize the current understanding of TLS pathway in DDT and its implication for human health.
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Affiliation(s)
| | - Ganesh Lahane
- Department of Pharmacy, Birla Institute of Technology and Sciences Pilani, Hyderabad Campus, Hyderabad, India
| | - Arti Dhar
- Department of Pharmacy, Birla Institute of Technology and Sciences Pilani, Hyderabad Campus, Hyderabad, India
| | - Wei Xiao
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Canada
| | - Krishna Moorthi Bhat
- Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA
| | - Tej K. Pandita
- Center for Genomics and Precision Medicine, Texas A&M College of Medicine, Houston, Texas, USA
| | - Audesh Bhat
- Center for Molecular Biology, Central University of Jammu, UT Jammu and Kashmir, India
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17
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Ploetz E, Ambrose B, Barth A, Börner R, Erichson F, Kapanidis AN, Kim HD, Levitus M, Lohman TM, Mazumder A, Rueda DS, Steffen FD, Cordes T, Magennis SW, Lerner E. A new twist on PIFE: photoisomerisation-related fluorescence enhancement. ARXIV 2023:arXiv:2302.12455v2. [PMID: 36866225 PMCID: PMC9980184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
PIFE was first used as an acronym for protein-induced fluorescence enhancement, which refers to the increase in fluorescence observed upon the interaction of a fluorophore, such as a cyanine, with a protein. This fluorescence enhancement is due to changes in the rate of cis/trans photoisomerisation. It is clear now that this mechanism is generally applicable to interactions with any biomolecule and, in this review, we propose that PIFE is thereby renamed according to its fundamental working principle as photoisomerisation-related fluorescence enhancement, keeping the PIFE acronym intact. We discuss the photochemistry of cyanine fluorophores, the mechanism of PIFE, its advantages and limitations, and recent approaches to turn PIFE into a quantitative assay. We provide an overview of its current applications to different biomolecules and discuss potential future uses, including the study of protein-protein interactions, protein-ligand interactions and conformational changes in biomolecules.
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Affiliation(s)
- Evelyn Ploetz
- Department of Chemistry and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - Benjamin Ambrose
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, W12 0HS, UK, Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, W12 0HS, UK
| | - Anders Barth
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2629 HZ, The Netherlands
| | - Richard Börner
- Laserinstitut Hochschule Mittweida, Mittweida University of Applied Sciences, Mittweida, Germany
| | - Felix Erichson
- Laserinstitut Hochschule Mittweida, Mittweida University of Applied Sciences, Mittweida, Germany
| | - Achillefs N. Kapanidis
- Kavli Institute for Nanoscience Discovery, Department of Biological Physics, The University of Oxford, UK
| | - Harold D. Kim
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332, USA
| | - Marcia Levitus
- School of Molecular Sciences, Arizona State University, 551 E. University Drive, Tempe, AZ, 85287, USA
| | - Timothy M. Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
| | - Abhishek Mazumder
- Kavli Institute for Nanoscience Discovery, Department of Biological Physics, The University of Oxford, UK
| | - David S. Rueda
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, W12 0HS, UK, Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, W12 0HS, UK
| | - Fabio D. Steffen
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Großhadernerstr, 2-4, 82152 Planegg-Martinsried, Germany
| | - Steven W. Magennis
- School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow, G12 8QQ, UK
| | - Eitan Lerner
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, Edmond J. Safra Campus, Hebrew University of Jerusalem; Jerusalem 9190401, Israel, Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem; Jerusalem 9190401, Israel
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18
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Stok C, Tsaridou S, van den Tempel N, Everts M, Wierenga E, Bakker FJ, Kok Y, Alves IT, Jae LT, Raas MWD, Huis In 't Veld PJ, de Boer HR, Bhattacharya A, Karanika E, Warner H, Chen M, van de Kooij B, Dessapt J, Ter Morsche L, Perepelkina P, Fradet-Turcotte A, Guryev V, Tromer EC, Chan KL, Fehrmann RSN, van Vugt MATM. FIRRM/C1orf112 is synthetic lethal with PICH and mediates RAD51 dynamics. Cell Rep 2023; 42:112668. [PMID: 37347663 DOI: 10.1016/j.celrep.2023.112668] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 04/21/2023] [Accepted: 06/05/2023] [Indexed: 06/24/2023] Open
Abstract
Joint DNA molecules are natural byproducts of DNA replication and repair. Persistent joint molecules give rise to ultrafine DNA bridges (UFBs) in mitosis, compromising sister chromatid separation. The DNA translocase PICH (ERCC6L) has a central role in UFB resolution. A genome-wide loss-of-function screen is performed to identify the genetic context of PICH dependency. In addition to genes involved in DNA condensation, centromere stability, and DNA-damage repair, we identify FIGNL1-interacting regulator of recombination and mitosis (FIRRM), formerly known as C1orf112. We find that FIRRM interacts with and stabilizes the AAA+ ATPase FIGNL1. Inactivation of either FIRRM or FIGNL1 results in UFB formation, prolonged accumulation of RAD51 at nuclear foci, and impaired replication fork dynamics and consequently impairs genome maintenance. Combined, our data suggest that inactivation of FIRRM and FIGNL1 dysregulates RAD51 dynamics at replication forks, resulting in persistent DNA lesions and a dependency on PICH to preserve cell viability.
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Affiliation(s)
- Colin Stok
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Stavroula Tsaridou
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Nathalie van den Tempel
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Marieke Everts
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Elles Wierenga
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Femke J Bakker
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Yannick Kok
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Inês Teles Alves
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Lucas T Jae
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany
| | - Maximilian W D Raas
- Oncode Institute, Hubrecht Institute, Royal Academy of Arts and Sciences, Uppsalalaan 8, 3584CT Utrecht, the Netherlands; Theoretical Biology and Bioinformatics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Pim J Huis In 't Veld
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - H Rudolf de Boer
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Arkajyoti Bhattacharya
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Eleftheria Karanika
- Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, UK
| | - Harry Warner
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Mengting Chen
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Bert van de Kooij
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Julien Dessapt
- CHU de Québec Research Center-Université Laval (L'Hôtel-Dieu de Québec), Cancer Research Center, Université Laval, Québec, QC GIR 3S3, Canada
| | - Lars Ter Morsche
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Polina Perepelkina
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Amelie Fradet-Turcotte
- CHU de Québec Research Center-Université Laval (L'Hôtel-Dieu de Québec), Cancer Research Center, Université Laval, Québec, QC GIR 3S3, Canada
| | - Victor Guryev
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Eelco C Tromer
- Cell Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, Faculty of Science and Engineering, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Kok-Lung Chan
- Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, UK
| | - Rudolf S N Fehrmann
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands
| | - Marcel A T M van Vugt
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, the Netherlands.
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19
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Deveryshetty J, Chadda R, Mattice J, Karunakaran S, Rau MJ, Basore K, Pokhrel N, Englander N, Fitzpatrick JA, Bothner B, Antony E. Homodecameric Rad52 promotes single-position Rad51 nucleation in homologous recombination. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.05.527205. [PMID: 36778491 PMCID: PMC9915710 DOI: 10.1101/2023.02.05.527205] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Homologous recombination (HR) is a pathway for the accurate repair of double-stranded DNA breaks. These breaks are resected to yield single-stranded DNA (ssDNA) that are coated by Replication Protein A (RPA). Saccharomyces cerevisiae Rad52 is a mediator protein that promotes HR by facilitating formation of Rad51 nucleoprotein filaments on RPA-coated ssDNA. Canonically, Rad52 has been described to function by displacing RPA to promote Rad51 binding. However, in vitro, Rad51 readily forms a filament by displacing RPA in the absence of Rad52. Yet, in vivo, Rad52 is essential for HR. Here, we resolve how Rad52 functions as a mediator using single-particle cryo-electron microscopy and biophysical approaches. We show that Rad52 functions as a homodecamer and catalyzes single-position nucleation of Rad51. The N-terminal half of Rad52 is a well-ordered ring, while the C-terminal half is disordered. An intrinsic asymmetry within Rad52 is observed, where one or a few of the C-terminal halves interact with the ordered N-terminal ring. Within the C-terminal half, we identify two conserved charged patches that harbor the Rad51 and RPA interacting motifs. Interactions between these two charged patches regulate a ssDNA binding. These features drive Rad51 binding to a single position on the Rad52 decameric ring. We propose a Rad52 catalyzed single-position nucleation model for the formation of pre-synaptic Rad51 filaments in HR.
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Affiliation(s)
- Jaigeeth Deveryshetty
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO
| | - Rahul Chadda
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO
| | - Jenna Mattice
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT
| | - Simrithaa Karunakaran
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO
| | - Michael J. Rau
- Center for Cellular Imaging, Washington University in St. Louis School of Medicine, St. Louis, MO
| | - Katherine Basore
- Center for Cellular Imaging, Washington University in St. Louis School of Medicine, St. Louis, MO
| | - Nilisha Pokhrel
- Department of Biological Sciences, Marquette University, Milwaukee, WI (Present address: Aera Therapeutics, Boston, MA, USA)
| | - Noah Englander
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO
| | - James A.J. Fitzpatrick
- Center for Cellular Imaging, Washington University in St. Louis School of Medicine, St. Louis, MO
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT
| | - Edwin Antony
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO
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20
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Andriuskevicius T, Dubenko A, Makovets S. The Inability to Disassemble Rad51 Nucleoprotein Filaments Leads to Aberrant Mitosis and Cell Death. Biomedicines 2023; 11:biomedicines11051450. [PMID: 37239121 DOI: 10.3390/biomedicines11051450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 04/30/2023] [Accepted: 05/09/2023] [Indexed: 05/28/2023] Open
Abstract
The proper maintenance of genetic material is essential for the survival of living organisms. One of the main safeguards of genome stability is homologous recombination involved in the faithful repair of DNA double-strand breaks, the restoration of collapsed replication forks, and the bypass of replication barriers. Homologous recombination relies on the formation of Rad51 nucleoprotein filaments which are responsible for the homology-based interactions between DNA strands. Here, we demonstrate that without the regulation of these filaments by Srs2 and Rad54, which are known to remove Rad51 from single-stranded and double-stranded DNA, respectively, the filaments strongly inhibit damage-associated DNA synthesis during DNA repair. Furthermore, this regulation is essential for cell survival under normal growth conditions, as in the srs2Δ rad54Δ mutants, unregulated Rad51 nucleoprotein filaments cause activation of the DNA damage checkpoint, formation of mitotic bridges, and loss of genetic material. These genome instability features may stem from the problems at stalled replication forks as the lack of Srs2 and Rad54 in the presence of Rad51 nucleoprotein filaments impedes cell recovery from replication stress. This study demonstrates that the timely and efficient disassembly of recombination machinery is essential for genome maintenance and cell survival.
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Affiliation(s)
- Tadas Andriuskevicius
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Alexander Crum Brown Road, Edinburgh EH9 3FF, UK
| | - Anton Dubenko
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Alexander Crum Brown Road, Edinburgh EH9 3FF, UK
| | - Svetlana Makovets
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Alexander Crum Brown Road, Edinburgh EH9 3FF, UK
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21
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Kang Y, An S, Min D, Lee JY. Single-molecule fluorescence imaging techniques reveal molecular mechanisms underlying deoxyribonucleic acid damage repair. Front Bioeng Biotechnol 2022; 10:973314. [PMID: 36185427 PMCID: PMC9520083 DOI: 10.3389/fbioe.2022.973314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/25/2022] [Indexed: 11/13/2022] Open
Abstract
Advances in single-molecule techniques have uncovered numerous biological secrets that cannot be disclosed by traditional methods. Among a variety of single-molecule methods, single-molecule fluorescence imaging techniques enable real-time visualization of biomolecular interactions and have allowed the accumulation of convincing evidence. These techniques have been broadly utilized for studying DNA metabolic events such as replication, transcription, and DNA repair, which are fundamental biological reactions. In particular, DNA repair has received much attention because it maintains genomic integrity and is associated with diverse human diseases. In this review, we introduce representative single-molecule fluorescence imaging techniques and survey how each technique has been employed for investigating the detailed mechanisms underlying DNA repair pathways. In addition, we briefly show how live-cell imaging at the single-molecule level contributes to understanding DNA repair processes inside cells.
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Affiliation(s)
- Yujin Kang
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Soyeong An
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Duyoung Min
- Department of Chemistry, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Ja Yil Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
- Center for Genomic Integrity, Institute of Basic Sciences, Ulsan, South Korea
- *Correspondence: Ja Yil Lee,
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22
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Firlej M, Weir JR. Unwinding during stressful times: Mechanisms of helicases in meiotic recombination. Curr Top Dev Biol 2022; 151:191-215. [PMID: 36681470 DOI: 10.1016/bs.ctdb.2022.06.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Successful meiosis I requires that homologous chromosomes be correctly linked before they are segregated. In most organisms this physical linkage is achieved through the generation of crossovers between the homologs. Meiotic recombination co-opts and modifies the canonical homologous recombination pathway to successfully generate crossovers One of the central components of this pathway are a number of conserved DNA helicases. Helicases couple nucleic acid binding to nucleotide hydrolysis and use this activity to modify DNA or protein-DNA substrates. During meiosis I it is necessary for the cell to modulate the canonical DNA repair pathways in order to facilitate the generation of interhomolog crossovers. Many of these meiotic modulations take place in pathways involving DNA helicases, or with a meiosis specific helicase. This short review explores what is currently understood about these helicases, their interaction partners, and the role of regulatory modifications during meiosis I. We focus in particular on the molecular structure and mechanisms of these helicases.
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Affiliation(s)
- Magdalena Firlej
- Structural Biochemistry of Meiosis Group, Friedrich Miescher Laboratory of the Max Planck Society, Tuebingen, Germany
| | - John R Weir
- Structural Biochemistry of Meiosis Group, Friedrich Miescher Laboratory of the Max Planck Society, Tuebingen, Germany.
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23
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Carrasco B, Moreno-del Álamo M, Torres R, Alonso JC. PcrA Dissociates RecA Filaments and the SsbA and RecO Mediators Counterbalance Such Activity. Front Mol Biosci 2022; 9:836211. [PMID: 35223992 PMCID: PMC8865920 DOI: 10.3389/fmolb.2022.836211] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 01/05/2022] [Indexed: 11/24/2022] Open
Abstract
PcrA depletion is lethal in wild-type Bacillus subtilis cells. The PcrA DNA helicase contributes to unwinding RNA from the template strand, backtracking the RNA polymerase, rescuing replication-transcription conflicts, and disassembling RecA from single-stranded DNA (ssDNA) by poorly understood mechanisms. We show that, in the presence of RecA, circa one PcrA/plasmid-size circular ssDNA (cssDNA) molecule hydrolyzes ATP at a rate similar to that on the isolated cssDNA. PcrA K37A, which poorly hydrolyses ATP, fails to displace RecA from cssDNA. SsbA inhibits and blocks the ATPase activities of PcrA and RecA, respectively. RecO partially antagonizes and counteracts the negative effect of SsbA on PcrA- and RecA-mediated ATP hydrolysis, respectively. Conversely, multiple PcrA molecules are required to inhibit RecA·ATP-mediated DNA strand exchange (DSE). RecO and SsbA poorly antagonize the PcrA inhibitory effect on RecA·ATP-mediated DSE. We propose that two separable PcrA functions exist: an iterative translocating PcrA monomer strips RecA from cssDNA to prevent unnecessary recombination with the mediators SsbA and RecO balancing such activity; and a PcrA cluster that disrupts DNA transactions, as RecA-mediated DSE.
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24
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Ler AAL, Carty MP. DNA Damage Tolerance Pathways in Human Cells: A Potential Therapeutic Target. Front Oncol 2022; 11:822500. [PMID: 35198436 PMCID: PMC8859465 DOI: 10.3389/fonc.2021.822500] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 12/30/2021] [Indexed: 12/26/2022] Open
Abstract
DNA lesions arising from both exogenous and endogenous sources occur frequently in DNA. During DNA replication, the presence of unrepaired DNA damage in the template can arrest replication fork progression, leading to fork collapse, double-strand break formation, and to genome instability. To facilitate completion of replication and prevent the generation of strand breaks, DNA damage tolerance (DDT) pathways play a key role in allowing replication to proceed in the presence of lesions in the template. The two main DDT pathways are translesion synthesis (TLS), which involves the recruitment of specialized TLS polymerases to the site of replication arrest to bypass lesions, and homology-directed damage tolerance, which includes the template switching and fork reversal pathways. With some exceptions, lesion bypass by TLS polymerases is a source of mutagenesis, potentially contributing to the development of cancer. The capacity of TLS polymerases to bypass replication-blocking lesions induced by anti-cancer drugs such as cisplatin can also contribute to tumor chemoresistance. On the other hand, during homology-directed DDT the nascent sister strand is transiently utilised as a template for replication, allowing for error-free lesion bypass. Given the role of DNA damage tolerance pathways in replication, mutagenesis and chemoresistance, a more complete understanding of these pathways can provide avenues for therapeutic exploitation. A number of small molecule inhibitors of TLS polymerase activity have been identified that show synergy with conventional chemotherapeutic agents in killing cancer cells. In this review, we will summarize the major DDT pathways, explore the relationship between damage tolerance and carcinogenesis, and discuss the potential of targeting TLS polymerases as a therapeutic approach.
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Affiliation(s)
- Ashlynn Ai Li Ler
- Biochemistry, School of Biological and Chemical Sciences, The National University of Ireland (NUI) Galway, Galway, Ireland
| | - Michael P. Carty
- Biochemistry, School of Biological and Chemical Sciences, The National University of Ireland (NUI) Galway, Galway, Ireland
- DNA Damage Response Laboratory, Centre for Chromosome Biology, NUI Galway, Galway, Ireland
- *Correspondence: Michael P. Carty,
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25
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Rad54 and Rdh54 prevent Srs2-mediated disruption of Rad51 presynaptic filaments. Proc Natl Acad Sci U S A 2022; 119:2113871119. [PMID: 35042797 PMCID: PMC8795549 DOI: 10.1073/pnas.2113871119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2021] [Indexed: 11/18/2022] Open
Abstract
Homologous DNA recombination is an essential pathway necessary for the repair of double-stranded DNA breaks. Defects in this pathway are associated with hereditary breast cancer, ovarian cancer, and cancer-prone syndromes. Although essential, too much recombination is also bad and can lead to genetic mutations. Thus, cells have evolved “antirecombinase” enzymes that can actively dismantle recombination intermediates to prevent excessive recombination. However, our current understanding of how antirecombinases are themselves regulated remains very limited. Here, we study the antirecombinase Srs2 and its regulation by the recombination accessory factors Rad54 and Rdh54. Our data suggest that Rad54 and Rdh54 act synergistically to function as key regulators of Srs2, thus serving as “licensing factors” that enable timely progression of DNA repair. Srs2 is a superfamily 1 (SF1) helicase that participates in several pathways necessary for the repair of damaged DNA. Srs2 regulates formation of early homologous recombination (HR) intermediates by actively removing the recombinase Rad51 from single-stranded DNA (ssDNA). It is not known whether and how Srs2 itself is down-regulated to allow for timely HR progression. Rad54 and Rdh54 are two closely related superfamily 2 (SF2) motor proteins that promote the formation of Rad51-dependent recombination intermediates. Rad54 and Rdh54 bind tightly to Rad51-ssDNA and act downstream of Srs2, suggesting that they may affect the ability of Srs2 to dismantle Rad51 filaments. Here, we used DNA curtains to determine whether Rad54 and Rdh54 alter the ability of Srs2 to disrupt Rad51 filaments. We show that Rad54 and Rdh54 act synergistically to greatly restrict the antirecombinase activity of Srs2. Our findings suggest that Srs2 may be accorded only a limited time window to act and that Rad54 and Rdh54 fulfill a role of prorecombinogenic licensing factors.
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26
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Kong M, Greene EC. Mechanistic Insights From Single-Molecule Studies of Repair of Double Strand Breaks. Front Cell Dev Biol 2021; 9:745311. [PMID: 34869333 PMCID: PMC8636147 DOI: 10.3389/fcell.2021.745311] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/28/2021] [Indexed: 01/01/2023] Open
Abstract
DNA double strand breaks (DSBs) are among some of the most deleterious forms of DNA damage. Left unrepaired, they are detrimental to genome stability, leading to high risk of cancer. Two major mechanisms are responsible for the repair of DSBs, homologous recombination (HR) and nonhomologous end joining (NHEJ). The complex nature of both pathways, involving a myriad of protein factors functioning in a highly coordinated manner at distinct stages of repair, lend themselves to detailed mechanistic studies using the latest single-molecule techniques. In avoiding ensemble averaging effects inherent to traditional biochemical or genetic methods, single-molecule studies have painted an increasingly detailed picture for every step of the DSB repair processes.
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Affiliation(s)
| | - Eric C. Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, United States
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27
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Single-molecule studies of helicases and translocases in prokaryotic genome-maintenance pathways. DNA Repair (Amst) 2021; 108:103229. [PMID: 34601381 DOI: 10.1016/j.dnarep.2021.103229] [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: 05/03/2021] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 11/22/2022]
Abstract
Helicases involved in genomic maintenance are a class of nucleic-acid dependent ATPases that convert the energy of ATP hydrolysis into physical work to execute irreversible steps in DNA replication, repair, and recombination. Prokaryotic helicases provide simple models to understand broadly conserved molecular mechanisms involved in manipulating nucleic acids during genome maintenance. Our understanding of the catalytic properties, mechanisms of regulation, and roles of prokaryotic helicases in DNA metabolism has been assembled through a combination of genetic, biochemical, and structural methods, further refined by single-molecule approaches. Together, these investigations have constructed a framework for understanding the mechanisms that maintain genomic integrity in cells. This review discusses recent single-molecule insights into molecular mechanisms of prokaryotic helicases and translocases.
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28
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Špírek M, Taylor MRG, Belan O, Boulton SJ, Krejci L. Nucleotide proofreading functions by nematode RAD51 paralogs facilitate optimal RAD51 filament function. Nat Commun 2021; 12:5545. [PMID: 34545070 PMCID: PMC8452638 DOI: 10.1038/s41467-021-25830-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 09/02/2021] [Indexed: 12/30/2022] Open
Abstract
The RAD51 recombinase assembles as helical nucleoprotein filaments on single-stranded DNA (ssDNA) and mediates invasion and strand exchange with homologous duplex DNA (dsDNA) during homologous recombination (HR), as well as protection and restart of stalled replication forks. Strand invasion by RAD51-ssDNA complexes depends on ATP binding. However, RAD51 can bind ssDNA in non-productive ADP-bound or nucleotide-free states, and ATP-RAD51-ssDNA complexes hydrolyse ATP over time. Here, we define unappreciated mechanisms by which the RAD51 paralog complex RFS-1/RIP-1 limits the accumulation of RAD-51-ssDNA complexes with unfavorable nucleotide content. We find RAD51 paralogs promote the turnover of ADP-bound RAD-51 from ssDNA, in striking contrast to their ability to stabilize productive ATP-bound RAD-51 nucleoprotein filaments. In addition, RFS-1/RIP-1 inhibits binding of nucleotide-free RAD-51 to ssDNA. We propose that ‘nucleotide proofreading’ activities of RAD51 paralogs co-operate to ensure the enrichment of active, ATP-bound RAD-51 filaments on ssDNA to promote HR. A RAD51 paralog complex, RFS-1/RIP-1, is shown to control ssDNA binding and dissociation by RAD-51 differentially in the presence and absence of nucleotide cofactors. These nucleotide proofreading activities drive a preferential accumulation of RAD-51-ssDNA complexes with optimal nucleotide content.
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Affiliation(s)
- Mário Špírek
- International Clinical Research Center, St. Anne's University Hospital in Brno, 62500, Brno, Czech Republic.,Department of Biology Masaryk University, 62500, Brno, Czech Republic
| | | | - Ondrej Belan
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.,National Centre for Biomolecular Research, Masaryk University, 62500, Brno, Czech Republic
| | - Simon J Boulton
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Lumir Krejci
- International Clinical Research Center, St. Anne's University Hospital in Brno, 62500, Brno, Czech Republic. .,Department of Biology Masaryk University, 62500, Brno, Czech Republic. .,National Centre for Biomolecular Research, Masaryk University, 62500, Brno, Czech Republic.
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29
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The Role of the Rad55-Rad57 Complex in DNA Repair. Genes (Basel) 2021; 12:genes12091390. [PMID: 34573372 PMCID: PMC8472222 DOI: 10.3390/genes12091390] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 08/30/2021] [Accepted: 09/03/2021] [Indexed: 11/29/2022] Open
Abstract
Homologous recombination (HR) is a mechanism conserved from bacteria to humans essential for the accurate repair of DNA double-stranded breaks, and maintenance of genome integrity. In eukaryotes, the key DNA transactions in HR are catalyzed by the Rad51 recombinase, assisted by a host of regulatory factors including mediators such as Rad52 and Rad51 paralogs. Rad51 paralogs play a crucial role in regulating proper levels of HR, and mutations in the human counterparts have been associated with diseases such as cancer and Fanconi Anemia. In this review, we focus on the Saccharomyces cerevisiae Rad51 paralog complex Rad55–Rad57, which has served as a model for understanding the conserved role of Rad51 paralogs in higher eukaryotes. Here, we discuss the results from early genetic studies, biochemical assays, and new single-molecule observations that have together contributed to our current understanding of the molecular role of Rad55–Rad57 in HR.
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30
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Meir A, Greene EC. Srs2 and Pif1 as Model Systems for Understanding Sf1a and Sf1b Helicase Structure and Function. Genes (Basel) 2021; 12:1319. [PMID: 34573298 PMCID: PMC8469786 DOI: 10.3390/genes12091319] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 01/19/2023] Open
Abstract
Helicases are enzymes that convert the chemical energy stored in ATP into mechanical work, allowing them to move along and manipulate nucleic acids. The helicase superfamily 1 (Sf1) is one of the largest subgroups of helicases and they are required for a range of cellular activities across all domains of life. Sf1 helicases can be further subdivided into two classes called the Sf1a and Sf1b helicases, which move in opposite directions on nucleic acids. The results of this movement can range from the separation of strands within duplex nucleic acids to the physical remodeling or removal of nucleoprotein complexes. Here, we describe the characteristics of the Sf1a helicase Srs2 and the Sf1b helicase Pif1, both from the model organism Saccharomyces cerevisiae, focusing on the roles that they play in homologous recombination, a DNA repair pathway that is necessary for maintaining genome integrity.
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Affiliation(s)
| | - Eric C. Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA;
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31
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Carver A, Zhang X. Rad51 filament dynamics and its antagonistic modulators. Semin Cell Dev Biol 2021; 113:3-13. [PMID: 32631783 DOI: 10.1016/j.semcdb.2020.06.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/10/2020] [Accepted: 06/20/2020] [Indexed: 02/07/2023]
Abstract
Rad51 recombinase is the central player in homologous recombination, the faithful repair pathway for double-strand breaks and key event during meiosis. Rad51 forms nucleoprotein filaments on single-stranded DNA, exposed by a double-strand break. These filaments are responsible for homology search and strand invasion, which lead to homology-directed repair. Due to its central roles in DNA repair and genome stability, Rad51 is modulated by multiple factors and post-translational modifications. In this review, we summarize our current understanding of the dynamics of Rad51 filaments, the roles of other factors and their modes of action in modulating key stages of Rad51 filaments: formation, stability and disassembly.
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Affiliation(s)
- Alexander Carver
- Section of Structural Biology, Department of Infectious Diseases, Sir Alexander Fleming Building, Imperial College London, SW7 2AZ, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Infectious Diseases, Sir Alexander Fleming Building, Imperial College London, SW7 2AZ, UK.
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32
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Roy U, Kwon Y, Marie L, Symington L, Sung P, Lisby M, Greene EC. The Rad51 paralog complex Rad55-Rad57 acts as a molecular chaperone during homologous recombination. Mol Cell 2021; 81:1043-1057.e8. [PMID: 33421364 PMCID: PMC8262405 DOI: 10.1016/j.molcel.2020.12.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/02/2020] [Accepted: 12/10/2020] [Indexed: 12/29/2022]
Abstract
Homologous recombination (HR) is essential for maintenance of genome integrity. Rad51 paralogs fulfill a conserved but undefined role in HR, and their mutations are associated with increased cancer risk in humans. Here, we use single-molecule imaging to reveal that the Saccharomyces cerevisiae Rad51 paralog complex Rad55-Rad57 promotes assembly of Rad51 recombinase filament through transient interactions, providing evidence that it acts like a classical molecular chaperone. Srs2 is an ATP-dependent anti-recombinase that downregulates HR by actively dismantling Rad51 filaments. Contrary to the current model, we find that Rad55-Rad57 does not physically block the movement of Srs2. Instead, Rad55-Rad57 promotes rapid re-assembly of Rad51 filaments after their disruption by Srs2. Our findings support a model in which Rad51 is in flux between free and single-stranded DNA (ssDNA)-bound states, the rate of which is controlled dynamically though the opposing actions of Rad55-Rad57 and Srs2.
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Affiliation(s)
- Upasana Roy
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Youngho Kwon
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Lea Marie
- Department of Microbiology and Immunology, Columbia University, New York, NY 10032, USA
| | - Lorraine Symington
- Department of Microbiology and Immunology, Columbia University, New York, NY 10032, USA
| | - Patrick Sung
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Michael Lisby
- Department of Biology, University of Copenhagen, 2200 Copenhagen N, Denmark; Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
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33
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Adolph MB, Mohamed TM, Balakrishnan S, Xue C, Morati F, Modesti M, Greene EC, Chazin WJ, Cortez D. RADX controls RAD51 filament dynamics to regulate replication fork stability. Mol Cell 2021; 81:1074-1083.e5. [PMID: 33453169 PMCID: PMC7935748 DOI: 10.1016/j.molcel.2020.12.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 11/02/2020] [Accepted: 12/21/2020] [Indexed: 01/10/2023]
Abstract
The RAD51 recombinase forms nucleoprotein filaments to promote double-strand break repair, replication fork reversal, and fork stabilization. The stability of these filaments is highly regulated, as both too little and too much RAD51 activity can cause genome instability. RADX is a single-strand DNA (ssDNA) binding protein that regulates DNA replication. Here, we define its mechanism of action. We find that RADX inhibits RAD51 strand exchange and D-loop formation activities. RADX directly and selectively interacts with ATP-bound RAD51, stimulates ATP hydrolysis, and destabilizes RAD51 nucleofilaments. The RADX interaction with RAD51, in addition to its ssDNA binding capability, is required to maintain replication fork elongation rates and fork stability. Furthermore, BRCA2 can overcome the RADX-dependent RAD51 inhibition. Thus, RADX functions in opposition to BRCA2 in regulating RAD51 nucleofilament stability to ensure the right level of RAD51 function during DNA replication.
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Affiliation(s)
- Madison B Adolph
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Taha M Mohamed
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Swati Balakrishnan
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Chaoyou Xue
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY USA
| | - Florian Morati
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université U105, Marseille, France
| | - Mauro Modesti
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université U105, Marseille, France
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY USA
| | - Walter J Chazin
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN, USA.
| | - David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
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34
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The Srs2 helicase dampens DNA damage checkpoint by recycling RPA from chromatin. Proc Natl Acad Sci U S A 2021; 118:2020185118. [PMID: 33602817 DOI: 10.1073/pnas.2020185118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The DNA damage checkpoint induces many cellular changes to cope with genotoxic stress. However, persistent checkpoint signaling can be detrimental to growth partly due to blockage of cell cycle resumption. Checkpoint dampening is essential to counter such harmful effects, but its mechanisms remain to be understood. Here, we show that the DNA helicase Srs2 removes a key checkpoint sensor complex, RPA, from chromatin to down-regulate checkpoint signaling in budding yeast. The Srs2 and RPA antagonism is supported by their numerous suppressive genetic interactions. Importantly, moderate reduction of RPA binding to single-strand DNA (ssDNA) rescues hypercheckpoint signaling caused by the loss of Srs2 or its helicase activity. This rescue correlates with a reduction in the accumulated RPA and the associated checkpoint kinase on chromatin in srs2 mutants. Moreover, our data suggest that Srs2 regulation of RPA is separable from its roles in recombinational repair and critically contributes to genotoxin resistance. We conclude that dampening checkpoint by Srs2-mediated RPA recycling from chromatin aids cellular survival of genotoxic stress and has potential implications in other types of DNA transactions.
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35
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Xue C, Molnarova L, Steinfeld JB, Zhao W, Ma C, Spirek M, Kaniecki K, Kwon Y, Beláň O, Krejci K, Boulton S, Sung P, Greene EC, Krejci L. Single-molecule visualization of human RECQ5 interactions with single-stranded DNA recombination intermediates. Nucleic Acids Res 2021; 49:285-305. [PMID: 33332547 PMCID: PMC7797033 DOI: 10.1093/nar/gkaa1184] [Citation(s) in RCA: 10] [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: 05/22/2020] [Revised: 11/03/2020] [Accepted: 12/11/2020] [Indexed: 12/12/2022] Open
Abstract
RECQ5 is one of five RecQ helicases found in humans and is thought to participate in homologous DNA recombination by acting as a negative regulator of the recombinase protein RAD51. Here, we use kinetic and single molecule imaging methods to monitor RECQ5 behavior on various nucleoprotein complexes. Our data demonstrate that RECQ5 can act as an ATP-dependent single-stranded DNA (ssDNA) motor protein and can translocate on ssDNA that is bound by replication protein A (RPA). RECQ5 can also translocate on RAD51-coated ssDNA and readily dismantles RAD51-ssDNA filaments. RECQ5 interacts with RAD51 through protein-protein contacts, and disruption of this interface through a RECQ5-F666A mutation reduces translocation velocity by ∼50%. However, RECQ5 readily removes the ATP hydrolysis-deficient mutant RAD51-K133R from ssDNA, suggesting that filament disruption is not coupled to the RAD51 ATP hydrolysis cycle. RECQ5 also readily removes RAD51-I287T, a RAD51 mutant with enhanced ssDNA-binding activity, from ssDNA. Surprisingly, RECQ5 can bind to double-stranded DNA (dsDNA), but it is unable to translocate. Similarly, RECQ5 cannot dismantle RAD51-bound heteroduplex joint molecules. Our results suggest that the roles of RECQ5 in genome maintenance may be regulated in part at the level of substrate specificity.
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Affiliation(s)
- Chaoyou Xue
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Lucia Molnarova
- Department of Biology, Masaryk University, Brno 62500, Czech Republic
| | - Justin B Steinfeld
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Weixing Zhao
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Chujian Ma
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Mario Spirek
- Department of Biology, Masaryk University, Brno 62500, Czech Republic
| | - Kyle Kaniecki
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Youngho Kwon
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Ondrej Beláň
- DSB Repair Metabolism Lab, The Francis Crick Institute, Midland Road, London NW1 1AT, UK
| | - Katerina Krejci
- Department of Biology, Masaryk University, Brno 62500, Czech Republic
- International Clinical Research Center, St. Anne's University Hospital Brno, Brno 65691, Czech Republic
| | - Simon J Boulton
- DSB Repair Metabolism Lab, The Francis Crick Institute, Midland Road, London NW1 1AT, UK
| | - Patrick Sung
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Eric C Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Lumir Krejci
- Department of Biology, Masaryk University, Brno 62500, Czech Republic
- International Clinical Research Center, St. Anne's University Hospital Brno, Brno 65691, Czech Republic
- National Centre for Biomolecular Research, Masaryk, Brno 62500, Czech Republic
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Moreno-Del Alamo M, Torres R, Manfredi C, Ruiz-Masó JA, Del Solar G, Alonso JC. Bacillus subtilis PcrA Couples DNA Replication, Transcription, Recombination and Segregation. Front Mol Biosci 2020; 7:140. [PMID: 32793628 PMCID: PMC7385302 DOI: 10.3389/fmolb.2020.00140] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/10/2020] [Indexed: 01/08/2023] Open
Abstract
Bacillus subtilis PcrA abrogates replication-transcription conflicts in vivo and disrupts RecA nucleoprotein filaments in vitro. Inactivation of pcrA is lethal. We show that PcrA depletion lethality is suppressed by recJ (involved in end resection), recA (the recombinase), or mfd (transcription-coupled repair) inactivation, but not by inactivating end resection (addAB or recQ), positive and negative RecA modulators (rarA or recX and recU), or genes involved in the reactivation of a stalled RNA polymerase (recD2, helD, hepA, and ywqA). We also report that B. subtilis mutations previously designated as recL16 actually map to the recO locus, and confirm that PcrA depletion lethality is suppressed by recO inactivation. The pcrA gene is epistatic to recA or mfd, but it is not epistatic to addAB, recJ, recQ, recO16, rarA, recX, recU, recD2, helD, hepA, or ywqA in response to DNA damage. PcrA depletion led to the accumulation of unsegregated chromosomes, and this defect is increased by recQ, rarA, or recU inactivation. We propose that PcrA, which is crucial to maintain cell viability, is involved in different DNA transactions.
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Affiliation(s)
- María Moreno-Del Alamo
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Madrid, Spain
| | - Rubén Torres
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Madrid, Spain
| | - Candela Manfredi
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Madrid, Spain
| | - José A Ruiz-Masó
- Centro de Investigaciones Biológicas Margarita Salas, CIB-CSIC, Madrid, Spain
| | - Gloria Del Solar
- Centro de Investigaciones Biológicas Margarita Salas, CIB-CSIC, Madrid, Spain
| | - Juan Carlos Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, Madrid, Spain
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Gupta SV, Schmidt KH. Maintenance of Yeast Genome Integrity by RecQ Family DNA Helicases. Genes (Basel) 2020; 11:E205. [PMID: 32085395 PMCID: PMC7074392 DOI: 10.3390/genes11020205] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/11/2020] [Accepted: 02/14/2020] [Indexed: 12/28/2022] Open
Abstract
With roles in DNA repair, recombination, replication and transcription, members of the RecQ DNA helicase family maintain genome integrity from bacteria to mammals. Mutations in human RecQ helicases BLM, WRN and RecQL4 cause incurable disorders characterized by genome instability, increased cancer predisposition and premature adult-onset aging. Yeast cells lacking the RecQ helicase Sgs1 share many of the cellular defects of human cells lacking BLM, including hypersensitivity to DNA damaging agents and replication stress, shortened lifespan, genome instability and mitotic hyper-recombination, making them invaluable model systems for elucidating eukaryotic RecQ helicase function. Yeast and human RecQ helicases have common DNA substrates and domain structures and share similar physical interaction partners. Here, we review the major cellular functions of the yeast RecQ helicases Sgs1 of Saccharomyces cerevisiae and Rqh1 of Schizosaccharomyces pombe and provide an outlook on some of the outstanding questions in the field.
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Affiliation(s)
- Sonia Vidushi Gupta
- Department of Cell Biology, Microbiology and Molecular Biology, University of South, Florida, Tampa, FL 33620, USA;
| | - Kristina Hildegard Schmidt
- Department of Cell Biology, Microbiology and Molecular Biology, University of South, Florida, Tampa, FL 33620, USA;
- Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research, Institute, Tampa, FL 33612, USA
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38
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Resolvases, Dissolvases, and Helicases in Homologous Recombination: Clearing the Road for Chromosome Segregation. Genes (Basel) 2020; 11:genes11010071. [PMID: 31936378 PMCID: PMC7017083 DOI: 10.3390/genes11010071] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/29/2019] [Accepted: 01/01/2020] [Indexed: 12/13/2022] Open
Abstract
The execution of recombinational pathways during the repair of certain DNA lesions or in the meiotic program is associated to the formation of joint molecules that physically hold chromosomes together. These structures must be disengaged prior to the onset of chromosome segregation. Failure in the resolution of these linkages can lead to chromosome breakage and nondisjunction events that can alter the normal distribution of the genomic material to the progeny. To avoid this situation, cells have developed an arsenal of molecular complexes involving helicases, resolvases, and dissolvases that recognize and eliminate chromosome links. The correct orchestration of these enzymes promotes the timely removal of chromosomal connections ensuring the efficient segregation of the genome during cell division. In this review, we focus on the role of different DNA processing enzymes that collaborate in removing the linkages generated during the activation of the homologous recombination machinery as a consequence of the appearance of DNA breaks during the mitotic and meiotic programs. We will also discuss about the temporal regulation of these factors along the cell cycle, the consequences of their loss of function, and their specific role in the removal of chromosomal links to ensure the accurate segregation of the genomic material during cell division.
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Xue C, Daley JM, Xue X, Steinfeld J, Kwon Y, Sung P, Greene EC. Single-molecule visualization of human BLM helicase as it acts upon double- and single-stranded DNA substrates. Nucleic Acids Res 2019; 47:11225-11237. [PMID: 31544923 PMCID: PMC6868385 DOI: 10.1093/nar/gkz810] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 09/06/2019] [Accepted: 09/17/2019] [Indexed: 11/12/2022] Open
Abstract
Bloom helicase (BLM) and its orthologs are essential for the maintenance of genome integrity. BLM defects represent the underlying cause of Bloom Syndrome, a rare genetic disorder that is marked by strong cancer predisposition. BLM deficient cells accumulate extensive chromosomal aberrations stemming from dysfunctions in homologous recombination (HR). BLM participates in several HR stages and helps dismantle potentially harmful HR intermediates. However, much remains to be learned about the molecular mechanisms of these BLM-mediated regulatory effects. Here, we use DNA curtains to directly visualize the activity of BLM helicase on single molecules of DNA. Our data show that BLM is a robust helicase capable of rapidly (∼70-80 base pairs per second) unwinding extensive tracts (∼8-10 kilobases) of double-stranded DNA (dsDNA). Importantly, we find no evidence for BLM activity on single-stranded DNA (ssDNA) that is bound by replication protein A (RPA). Likewise, our results show that BLM can neither associate with nor translocate on ssDNA that is bound by the recombinase protein RAD51. Moreover, our data reveal that the presence of RAD51 also blocks BLM translocation on dsDNA substrates. We discuss our findings within the context of potential regulator roles for BLM helicase during DNA replication and repair.
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Affiliation(s)
- Chaoyou Xue
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - James M Daley
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Xiaoyu Xue
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
| | - Justin Steinfeld
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Youngho Kwon
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Patrick Sung
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Eric C Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
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Špírek M, Mlcoušková J, Belán O, Gyimesi M, Harami GM, Molnár E, Novacek J, Kovács M, Krejci L. Human RAD51 rapidly forms intrinsically dynamic nucleoprotein filaments modulated by nucleotide binding state. Nucleic Acids Res 2019; 46:3967-3980. [PMID: 29481689 PMCID: PMC5934667 DOI: 10.1093/nar/gky111] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 02/08/2018] [Indexed: 12/31/2022] Open
Abstract
Formation of RAD51 filaments on single-stranded DNA is an essential event during homologous recombination, which is required for homology search, strand exchange and protection of replication forks. Formation of nucleoprotein filaments (NF) is required for development and genomic stability, and its failure is associated with developmental abnormalities and tumorigenesis. Here we describe the structure of the human RAD51 NFs and of its Walker box mutants using electron microscopy. Wild-type RAD51 filaments adopt an ‘open’ conformation when compared to a ‘closed’ structure formed by mutants, reflecting alterations in helical pitch. The kinetics of formation/disassembly of RAD51 filaments show rapid and high ssDNA coverage via low cooperativity binding of RAD51 units along the DNA. Subsequently, a series of isomerization or dissociation events mediated by nucleotide binding state creates intrinsically dynamic RAD51 NFs. Our findings highlight important a mechanistic divergence among recombinases from different organisms, in line with the diversity of biological mechanisms of HR initiation and quality control. These data reveal unexpected intrinsic dynamic properties of the RAD51 filament during assembly/disassembly, which may be important for the proper control of homologous recombination.
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Affiliation(s)
- Mário Špírek
- Department of Biology, Masaryk University, Brno 62500, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno, Brno 65691, Czech Republic
| | - Jarmila Mlcoušková
- Department of Biology, Masaryk University, Brno 62500, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno, Brno 65691, Czech Republic
| | - Ondrej Belán
- Department of Biology, Masaryk University, Brno 62500, Czech Republic
| | - Máté Gyimesi
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Gábor M Harami
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Eszter Molnár
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Jiri Novacek
- CEITEC, Masaryk University, Brno, Czech Republic
| | - Mihály Kovács
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Lumir Krejci
- Department of Biology, Masaryk University, Brno 62500, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital Brno, Brno 65691, Czech Republic.,National Centre for Biomolecular Research, Masaryk University, Brno 62500, Czech Republic
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41
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Jenkins SS, Gore S, Guo X, Liu J, Ede C, Veaute X, Jinks-Robertson S, Kowalczykowski SC, Heyer WD. Role of the Srs2-Rad51 Interaction Domain in Crossover Control in Saccharomyces cerevisiae. Genetics 2019; 212:1133-1145. [PMID: 31142613 PMCID: PMC6707447 DOI: 10.1534/genetics.119.302337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 05/22/2019] [Indexed: 02/05/2023] Open
Abstract
Saccharomyces cerevisiae Srs2, in addition to its well-documented antirecombination activity, has been proposed to play a role in promoting synthesis-dependent strand annealing (SDSA). Here we report the identification and characterization of an SRS2 mutant with a single amino acid substitution (srs2-F891A) that specifically affects the Srs2 pro-SDSA function. This residue is located within the Srs2-Rad51 interaction domain and embedded within a protein sequence resembling a BRC repeat motif. The srs2-F891A mutation leads to a complete loss of interaction with Rad51 as measured through yeast two-hybrid analysis and a partial loss of interaction as determined through protein pull-down assays with purified Srs2, Srs2-F891A, and Rad51 proteins. Even though previous work has shown that internal deletions of the Srs2-Rad51 interaction domain block Srs2 antirecombination activity in vitro, the Srs2-F891A mutant protein, despite its weakened interaction with Rad51, exhibits no measurable defect in antirecombination activity in vitro or in vivo Surprisingly, srs2-F891A shows a robust shift from noncrossover to crossover repair products in a plasmid-based gap repair assay, but not in an ectopic physical recombination assay. Our findings suggest that the Srs2 C-terminal Rad51 interaction domain is more complex than previously thought, containing multiple interaction sites with unique effects on Srs2 activity.
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Affiliation(s)
- Shirin S Jenkins
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616
| | - Steven Gore
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616
| | - Xiaoge Guo
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina 27710
| | - Jie Liu
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616
| | - Christopher Ede
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616
| | - Xavier Veaute
- CEA, CIGEx, F-92265 Fontenay-aux-Roses Cedex, France
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina 27710
| | - Stephen C Kowalczykowski
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616
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42
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Protein Environment and DNA Orientation Affect Protein-Induced Cy3 Fluorescence Enhancement. Biophys J 2019; 117:66-73. [PMID: 31235181 DOI: 10.1016/j.bpj.2019.05.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/23/2019] [Accepted: 05/29/2019] [Indexed: 11/20/2022] Open
Abstract
The cyanine dye Cy3 is a popular fluorophore used to probe the binding of proteins to nucleic acids as well as their conformational transitions. Nucleic acids labeled only with Cy3 can often be used to monitor interactions with unlabeled proteins because of an enhancement of Cy3 fluorescence intensity that results when the protein contacts Cy3, a property sometimes referred to as protein-induced fluorescence enhancement (PIFE). Although Cy3 fluorescence is enhanced upon contacting most proteins, we show here in studies of human replication protein A and Escherichia coli single-stranded DNA binding protein that the magnitude of the Cy3 enhancement is dependent on both the protein as well as the orientation of the protein with respect to the Cy3 label on the DNA. This difference in PIFE is due entirely to differences in the final protein-DNA complex. We also show that the origin of PIFE is the longer fluorescence lifetime induced by the local protein environment. These results indicate that PIFE is not a through space distance-dependent phenomenon but requires a direct interaction of Cy3 with the protein, and the magnitude of the effect is influenced by the region of the protein contacting Cy3. Hence, use of the Cy3 PIFE effect for quantitative studies may require careful calibration.
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43
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Crickard J, Xue C, Wang W, Kwon Y, Sung P, Greene E. The RecQ helicase Sgs1 drives ATP-dependent disruption of Rad51 filaments. Nucleic Acids Res 2019; 47:4694-4706. [PMID: 30916344 PMCID: PMC6511845 DOI: 10.1093/nar/gkz186] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/06/2019] [Accepted: 03/20/2019] [Indexed: 12/21/2022] Open
Abstract
DNA helicases of the RecQ family are conserved among the three domains of life and play essential roles in genome maintenance. Mutations in several human RecQ helicases lead to diseases that are marked by cancer predisposition. The Saccharomyces cerevisiae RecQ helicase Sgs1 is orthologous to human BLM, defects in which cause the cancer-prone Bloom's Syndrome. Here, we use single-molecule imaging to provide a quantitative mechanistic understanding of Sgs1 activities on single stranded DNA (ssDNA), which is a central intermediate in all aspects of DNA metabolism. We show that Sgs1 acts upon ssDNA bound by either replication protein A (RPA) or the recombinase Rad51. Surprisingly, we find that Sgs1 utilizes a novel motor mechanism for disrupting ssDNA intermediates bound by the recombinase protein Rad51. The ability of Sgs1 to disrupt Rad51-ssDNA filaments may explain some of the defects engendered by RECQ helicase deficiencies in human cells.
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Affiliation(s)
- J Brooks Crickard
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Chaoyou Xue
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Weibin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Youngho Kwon
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Eric C Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
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44
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Crickard JB, Greene EC. Helicase Mechanisms During Homologous Recombination in Saccharomyces cerevisiae. Annu Rev Biophys 2019; 48:255-273. [PMID: 30857400 DOI: 10.1146/annurev-biophys-052118-115418] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Helicases are enzymes that move, manage, and manipulate nucleic acids. They can be subdivided into six super families and are required for all aspects of nucleic acid metabolism. In general, all helicases function by converting the chemical energy stored in the bond between the gamma and beta phosphates of adenosine triphosphate into mechanical work, which results in the unidirectional movement of the helicase protein along one strand of a nucleic acid. The results of this translocation activity can range from separation of strands within duplex nucleic acids to the physical remodeling or removal of nucleoprotein complexes. In this review, we focus on describing key helicases from the model organism Saccharomyces cerevisiae that contribute to the regulation of homologous recombination, which is an essential DNA repair pathway for fixing damaged chromosomes.
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Affiliation(s)
- J Brooks Crickard
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; ,
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; ,
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45
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Abstract
Meiosis is the basis for sexual reproduction and is marked by the sequential reduction of chromosome number during successive cell cycles, resulting in four haploid gametes. A central component of the meiotic program is the formation and repair of programmed double strand breaks. Recombination-driven repair of these meiotic breaks differs from recombination during mitosis in that meiotic breaks are preferentially repaired using the homologous chromosomes in a process known as homolog bias. Homolog bias allows for physical interactions between homologous chromosomes that are required for proper chromosome segregation, and the formation of crossover products ensuring genetic diversity in progeny. An important aspect of meiosis in the differential regulation of the two eukaryotic RecA homologs, Rad51 and Dmc1. In this review we will discuss the relationship between biological programs designed to regulate recombinase function.
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Affiliation(s)
- J Brooks Crickard
- a Department of Biochemistry & Molecular Biophysics , Columbia University , New York , NY , USA
| | - Eric C Greene
- a Department of Biochemistry & Molecular Biophysics , Columbia University , New York , NY , USA
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46
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Meiosis-specific recombinase Dmc1 is a potent inhibitor of the Srs2 antirecombinase. Proc Natl Acad Sci U S A 2018; 115:E10041-E10048. [PMID: 30301803 DOI: 10.1073/pnas.1810457115] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cross-over recombination products are a hallmark of meiosis because they are necessary for accurate chromosome segregation and they also allow for increased genetic diversity during sexual reproduction. However, cross-overs can also cause gross chromosomal rearrangements and are therefore normally down-regulated during mitotic growth. The mechanisms that enhance cross-over product formation upon entry into meiosis remain poorly understood. In Saccharomyces cerevisiae, the Superfamily 1 (Sf1) helicase Srs2, which is an ATP hydrolysis-dependent motor protein that actively dismantles recombination intermediates, promotes synthesis-dependent strand annealing, the result of which is a reduction in cross-over recombination products. Here, we show that the meiosis-specific recombinase Dmc1 is a potent inhibitor of Srs2. Biochemical and single-molecule assays demonstrate that Dmc1 acts by inhibiting Srs2 ATP hydrolysis activity, which prevents the motor protein from undergoing ATP hydrolysis-dependent translocation on Dmc1-bound recombination intermediates. We propose a model in which Dmc1 helps contribute to cross-over formation during meiosis by antagonizing the antirecombinase activity of Srs2.
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47
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Swi5-Sfr1 stimulates Rad51 recombinase filament assembly by modulating Rad51 dissociation. Proc Natl Acad Sci U S A 2018; 115:E10059-E10068. [PMID: 30297419 DOI: 10.1073/pnas.1812753115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic Rad51 protein is essential for homologous-recombination repair of DNA double-strand breaks. Rad51 recombinases first assemble onto single-stranded DNA to form a nucleoprotein filament, required for function in homology pairing and strand exchange. This filament assembly is the first regulation step in homologous recombination. Rad51 nucleation is kinetically slow, and several accessory factors have been identified to regulate this step. Swi5-Sfr1 (S5S1) stimulates Rad51-mediated homologous recombination by stabilizing Rad51 nucleoprotein filaments, but the mechanism of stabilization is unclear. We used single-molecule tethered particle motion experiments to show that mouse S5S1 (mS5S1) efficiently stimulates mouse RAD51 (mRAD51) nucleus formation and inhibits mRAD51 dissociation from filaments. We also used single-molecule fluorescence resonance energy transfer experiments to show that mS5S1 promotes stable nucleus formation by specifically preventing mRAD51 dissociation. This leads to a reduction of nucleation size from three mRAD51 to two mRAD51 molecules in the presence of mS5S1. Compared with mRAD51, fission yeast Rad51 (SpRad51) exhibits fast nucleation but quickly dissociates from the filament. SpS5S1 specifically reduces SpRad51 disassembly to maintain a stable filament. These results clearly demonstrate the conserved function of S5S1 by primarily stabilizing Rad51 on DNA, allowing both the formation of the stable nucleus and the maintenance of filament length.
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48
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Abstract
Homologous recombination (HR) is a universally conserved mechanism used to maintain genomic integrity. In eukaryotes, HR is used to repair the spontaneous double strand breaks (DSBs) that arise during mitotic growth, and the programmed DSBs that form during meiosis. The mechanisms that govern mitotic and meiotic HR share many similarities, however, there are also several key differences, which reflect the unique attributes of each process. For instance, even though many of the proteins involved in mitotic and meiotic HR are the same, DNA target specificity is not: mitotic DSBs are repaired primarily using the sister chromatid as a template, whereas meiotic DBSs are repaired primarily through targeting of the homologous chromosome. These changes in template specificity are induced by expression of meiosis-specific HR proteins, down-regulation of mitotic HR proteins, and the formation of meiosis-specific chromosomal structures. Here, we compare and contrast the biochemical properties of key recombination intermediates formed during the pre-synapsis phase of mitotic and meiotic HR. Throughout, we try to highlight unanswered questions that will shape our understanding of how homologous recombination contributes to human cancer biology and sexual reproduction.
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The Main Role of Srs2 in DNA Repair Depends on Its Helicase Activity, Rather than on Its Interactions with PCNA or Rad51. mBio 2018; 9:mBio.01192-18. [PMID: 30018112 PMCID: PMC6050964 DOI: 10.1128/mbio.01192-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Homologous recombination (HR) is a mechanism that repairs a variety of DNA lesions. Under certain circumstances, however, HR can generate intermediates that can interfere with other cellular processes such as DNA transcription or replication. Cells have therefore developed pathways that abolish undesirable HR intermediates. The Saccharomyces cerevisiae yeast Srs2 helicase has a major role in one of these pathways. Srs2 also works during DNA replication and interacts with the clamp PCNA. The relative importance of Srs2’s helicase activity, Rad51 removal function, and PCNA interaction in genome stability remains unclear. We created a new SRS2 allele [srs2(1-850)] that lacks the whole C terminus, containing the interaction site for Rad51 and PCNA and interactions with many other proteins. Thus, the new allele encodes an Srs2 protein bearing only the activity of the DNA helicase. We find that the interactions of Srs2 with Rad51 and PCNA are dispensable for the main role of Srs2 in the repair of DNA damage in vegetative cells and for proper completion of meiosis. On the other hand, it has been shown that in cells impaired for the DNA damage tolerance (DDT) pathways, Srs2 generates toxic intermediates that lead to DNA damage sensitivity; we show that this negative Srs2 activity requires the C terminus of Srs2. Dissection of the genetic interactions of the srs2(1-850) allele suggest a role for Srs2’s helicase activity in sister chromatid cohesion. Our results also indicate that Srs2’s function becomes more central in diploid cells. Homologous recombination (HR) is a key mechanism that repairs damaged DNA. However, this process has to be tightly regulated; failure to regulate it can lead to genome instability. The Srs2 helicase is considered a regulator of HR; it was shown to be able to evict the recombinase Rad51 from DNA. Cells lacking Srs2 exhibit sensitivity to DNA-damaging agents, and in some cases, they display defects in DNA replication. The relative roles of the helicase and Rad51 removal activities of Srs2 in genome stability remain unclear. To address this question, we created a new Srs2 mutant which has only the DNA helicase domain. Our study shows that only the DNA helicase domain is needed to deal with DNA damage and assist in DNA replication during vegetative growth and in meiosis. Thus, our findings shift the view on the role of Srs2 in the maintenance of genome integrity.
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Serrano E, Carrasco B, Gilmore JL, Takeyasu K, Alonso JC. RecA Regulation by RecU and DprA During Bacillus subtilis Natural Plasmid Transformation. Front Microbiol 2018; 9:1514. [PMID: 30050509 PMCID: PMC6050356 DOI: 10.3389/fmicb.2018.01514] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 06/18/2018] [Indexed: 01/19/2023] Open
Abstract
Natural plasmid transformation plays an important role in the dissemination of antibiotic resistance genes in bacteria. During this process, Bacillus subtilis RecA physically interacts with RecU, RecX, and DprA. These three proteins are required for plasmid transformation, but RecA is not. In vitro, DprA recruits RecA onto SsbA-coated single-stranded (ss) DNA, whereas RecX inhibits RecA filament formation, leading to net filament disassembly. We show that a null recA (ΔrecA) mutation suppresses the plasmid transformation defect of competent ΔrecU cells, and that RecU is essential for both chromosomal and plasmid transformation in the ΔrecX context. RecU inhibits RecA filament growth and facilitates RecA disassembly from preformed filaments. Increasing SsbA concentrations additively contributes to RecU-mediated inhibition of RecA filament extension. DprA is necessary and sufficient to counteract the negative effect of both RecU and SsbA on RecA filament growth onto ssDNA. DprA-SsbA activates RecA to catalyze DNA strand exchange in the presence of RecU, but this effect was not observed if RecU was added prior to RecA. We propose that DprA contributes to RecA filament growth onto any internalized SsbA-coated ssDNA. When the ssDNA is homologous to the recipient, DprA antagonizes the inhibitory effect of RecU on RecA filament growth and helps RecA to catalyze chromosomal transformation. On the contrary, RecU promotes RecA filament disassembly from a heterologous (plasmid) ssDNA, overcoming an unsuccessful homology search and favoring plasmid transformation. The DprA–DprA interaction may promote strand annealing upon binding to the complementary plasmid strands and facilitating thereby plasmid transformation rather than through a mediation of RecA filament growth.
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Affiliation(s)
- Ester Serrano
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología - Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Begoña Carrasco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología - Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Jamie L Gilmore
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Kunio Takeyasu
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología - Consejo Superior de Investigaciones Científicas, Madrid, Spain
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