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Zhou Z, Pan Q, Lv X, Yuan J, Zhang Y, Zhang MX, Ke M, Mo XM, Xie YL, Liu Y, Chen T, Liang M, Yin F, Liu L, Zhou Y, Qiao K, Liu R, Li Z, Wong NK. Structural insights into the inhibition of bacterial RecA by naphthalene polysulfonated compounds. iScience 2021; 24:101952. [PMID: 33458611 PMCID: PMC7797525 DOI: 10.1016/j.isci.2020.101952] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 10/23/2020] [Accepted: 12/14/2020] [Indexed: 02/05/2023] Open
Abstract
As a promising target for alternative antimicrobials, bacterial recombinase A (RecA) protein has attracted much attention for its roles in antibiotic-driven SOS response and mutagenesis. Naphthalene polysulfonated compounds (NPS) such as suramin have previously been explored as antibiotic adjuvants targeting RecA, although the underlying structural bases for RecA-ligand interactions remain obscure. Based on our in silico predictions and documented activity of NPS in vitro, we conclude that the analyzed NPS likely interact with Tyr103 (Y103) and other key residues in the ATPase activity center (pocket A). For validation, we generated recombinant RecA proteins (wild-type versus Y103 mutant) to determine the binding affinities for RecA protein interactions with suramin and underexamined NPS in isothermal titration calorimetry. The corresponding dissociation constants (K d) ranged from 11.5 to 18.8 μM, and Y103 was experimentally shown to be critical to RecA-NPS interactions.
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Affiliation(s)
- Ziyuan Zhou
- Department of Pharmacology, Shantou University Medical College, Shantou 515041, China
- National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China
| | - Qing Pan
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Xinchen Lv
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
- National Key Laboratory of Plant Molecular Genetics & Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Jing Yuan
- National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China
| | - Yang Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China
| | - Ming-Xia Zhang
- National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China
| | - Ming Ke
- BGI-Shenzhen, Shenzhen 518083, China
| | - Xiao-Mei Mo
- National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China
| | - Yong-Li Xie
- National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China
| | - Yingxia Liu
- National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China
| | - Ting Chen
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China
| | - Mingchan Liang
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, Shenzhen 518055, China
| | - Feng Yin
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, Shenzhen 518055, China
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Shenzhen Graduate School of Peking University, Shenzhen 518055, China
| | - Lei Liu
- National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China
| | - Yiqing Zhou
- School of Biotechnology and Food Engineering, Changshu Institute of Technology, Changshu, Jiangsu 215500, China
| | - Kun Qiao
- National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China
| | - Rui Liu
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
- National Key Laboratory of Plant Molecular Genetics & Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Zigang Li
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, Shenzhen 518055, China
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Shenzhen Graduate School of Peking University, Shenzhen 518055, China
| | - Nai-Kei Wong
- Department of Pharmacology, Shantou University Medical College, Shantou 515041, China
- National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China
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Sun Y, McCorvie TJ, Yates LA, Zhang X. Structural basis of homologous recombination. Cell Mol Life Sci 2020; 77:3-18. [PMID: 31748913 PMCID: PMC6957567 DOI: 10.1007/s00018-019-03365-1] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 10/10/2019] [Accepted: 10/31/2019] [Indexed: 12/12/2022]
Abstract
Homologous recombination (HR) is a pathway to faithfully repair DNA double-strand breaks (DSBs). At the core of this pathway is a DNA recombinase, which, as a nucleoprotein filament on ssDNA, pairs with homologous DNA as a template to repair the damaged site. In eukaryotes Rad51 is the recombinase capable of carrying out essential steps including strand invasion, homology search on the sister chromatid and strand exchange. Importantly, a tightly regulated process involving many protein factors has evolved to ensure proper localisation of this DNA repair machinery and its correct timing within the cell cycle. Dysregulation of any of the proteins involved can result in unchecked DNA damage, leading to uncontrolled cell division and cancer. Indeed, many are tumour suppressors and are key targets in the development of new cancer therapies. Over the past 40 years, our structural and mechanistic understanding of homologous recombination has steadily increased with notable recent advancements due to the advances in single particle cryo electron microscopy. These have resulted in higher resolution structural models of the signalling proteins ATM (ataxia telangiectasia mutated), and ATR (ataxia telangiectasia and Rad3-related protein), along with various structures of Rad51. However, structural information of the other major players involved, such as BRCA1 (breast cancer type 1 susceptibility protein) and BRCA2 (breast cancer type 2 susceptibility protein), has been limited to crystal structures of isolated domains and low-resolution electron microscopy reconstructions of the full-length proteins. Here we summarise the current structural understanding of homologous recombination, focusing on key proteins in recruitment and signalling events as well as the mediators for the Rad51 recombinase.
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Affiliation(s)
- Yueru Sun
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK
| | - Thomas J McCorvie
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK
| | - Luke A Yates
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Infectious Diseases, Imperial College, London, SW7 2AZ, UK.
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3
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Abstract
Human RAD51 promotes accurate DNA repair by homologous recombination and is involved in protection and repair of damaged DNA replication forks. The active species of RAD51 and related recombinases in all organisms is a nucleoprotein filament assembled on single-stranded DNA (ssDNA). The formation of a nucleoprotein filament competent for the recombination reaction, or for DNA replication support, is a delicate and strictly regulated process, which occurs through filament nucleation followed by filament extension. The rates of these two phases of filament formation define the capacity of RAD51 to compete with the ssDNA-binding protein RPA, as well as the lengths of the resulting filament segments. Single-molecule approaches can provide a wealth of quantitative information on the kinetics of RAD51 nucleoprotein filament assembly, internal dynamics, and disassembly. In this chapter, we describe how to set up a single-molecule total internal reflection fluorescence microscopy experiment to monitor the initial steps of RAD51 nucleoprotein filament formation in real-time and at single-monomer resolution. This approach is based on the unique, stretched-ssDNA conformation within the recombinase nucleoprotein filament and follows the efficiency of Förster resonance energy transfer (EFRET) between two DNA-conjugated fluorophores. We will discuss the practical aspects of the experimental setup, extraction of the FRET trajectories, and how to analyze and interpret the data to obtain information on RAD51 nucleation kinetics, the mechanism of nucleation, and the oligomeric species involved in filament formation.
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Tyrosine phosphorylation stimulates activity of human RAD51 recombinase through altered nucleoprotein filament dynamics. Proc Natl Acad Sci U S A 2016; 113:E6045-E6054. [PMID: 27671650 DOI: 10.1073/pnas.1604807113] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The DNA strand exchange protein RAD51 facilitates the central step in homologous recombination, a process fundamentally important for accurate repair of damaged chromosomes, restart of collapsed replication forks, and telomere maintenance. The active form of RAD51 is a nucleoprotein filament that assembles on single-stranded DNA (ssDNA) at the sites of DNA damage. The c-Abl tyrosine kinase and its oncogenic counterpart BCR-ABL fusion kinase phosphorylate human RAD51 on tyrosine residues 54 and 315. We combined biochemical reconstitutions of the DNA strand exchange reactions with total internal reflection fluorescence microscopy to determine how the two phosphorylation events affect the biochemical activities of human RAD51 and properties of the RAD51 nucleoprotein filament. By mimicking RAD51 tyrosine phosphorylation with a nonnatural amino acid, p-carboxymethyl-l-phenylalanine (pCMF), we demonstrated that Y54 phosphorylation enhances the RAD51 recombinase activity by at least two different mechanisms, modifies the RAD51 nucleoprotein filament formation, and allows RAD51 to compete efficiently with ssDNA binding protein RPA. In contrast, Y315 phosphorylation has little effect on the RAD51 activities. Based on our work and previous cellular studies, we propose a mechanism underlying RAD51 activation by c-Abl/BCR-ABL kinases.
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Fornander LH, Frykholm K, Fritzsche J, Araya J, Nevin P, Werner E, Çakır A, Persson F, Garcin EB, Beuning PJ, Mehlig B, Modesti M, Westerlund F. Visualizing the Nonhomogeneous Structure of RAD51 Filaments Using Nanofluidic Channels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8403-8412. [PMID: 27479732 DOI: 10.1021/acs.langmuir.6b01877] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
RAD51 is the key component of the homologous recombination pathway in eukaryotic cells and performs its task by forming filaments on DNA. In this study we investigate the physical properties of RAD51 filaments formed on DNA using nanofluidic channels and fluorescence microscopy. Contrary to the bacterial ortholog RecA, RAD51 forms inhomogeneous filaments on long DNA in vitro, consisting of several protein patches. We demonstrate that a permanent "kink" in the filament is formed where two patches meet if the stretch of naked DNA between the patches is short. The kinks are readily seen in the present microscopy approach but would be hard to identify using conventional single DNA molecule techniques where the DNA is more stretched. We also demonstrate that protein patches separated by longer stretches of bare DNA roll up on each other and this is visualized as transiently overlapping filaments. RAD51 filaments can be formed at several different conditions, varying the cation (Mg(2+) or Ca(2+)), the DNA substrate (single-stranded or double-stranded), and the RAD51 concentration during filament nucleation, and we compare the properties of the different filaments formed. The results provide important information regarding the physical properties of RAD51 filaments but also demonstrate that nanofluidic channels are perfectly suited to study protein-DNA complexes.
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Affiliation(s)
| | | | | | - Joshua Araya
- Department of Chemistry and Chemical Biology, Northeastern University , Boston, Massachusetts 02115, United States
| | - Philip Nevin
- Department of Chemistry and Chemical Biology, Northeastern University , Boston, Massachusetts 02115, United States
| | - Erik Werner
- Department of Physics, University of Gothenburg , 412 96 Gothenburg, Sweden
| | - Ali Çakır
- Department of Physics, University of Gothenburg , 412 96 Gothenburg, Sweden
| | - Fredrik Persson
- Department for Cell and Molecular Biology, Science for Life Laboratory, Uppsala University , 751 24 Uppsala, Sweden
| | - Edwige B Garcin
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université , 13273 Marseille, France
| | - Penny J Beuning
- Department of Chemistry and Chemical Biology, Northeastern University , Boston, Massachusetts 02115, United States
| | - Bernhard Mehlig
- Department of Physics, University of Gothenburg , 412 96 Gothenburg, Sweden
| | - Mauro Modesti
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université , 13273 Marseille, France
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Abstract
The repair of DNA by homologous recombination is an essential, efficient, and high-fidelity process that mends DNA lesions formed during cellular metabolism; these lesions include double-stranded DNA breaks, daughter-strand gaps, and DNA cross-links. Genetic defects in the homologous recombination pathway undermine genomic integrity and cause the accumulation of gross chromosomal abnormalities-including rearrangements, deletions, and aneuploidy-that contribute to cancer formation. Recombination proceeds through the formation of joint DNA molecules-homologously paired but metastable DNA intermediates that are processed by several alternative subpathways-making recombination a versatile and robust mechanism to repair damaged chromosomes. Modern biophysical methods make it possible to visualize, probe, and manipulate the individual molecules participating in the intermediate steps of recombination, revealing new details about the mechanics of genetic recombination. We review and discuss the individual stages of homologous recombination, focusing on common pathways in bacteria, yeast, and humans, and place particular emphasis on the molecular mechanisms illuminated by single-molecule methods.
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Affiliation(s)
- Jason C Bell
- Department of Microbiology and Molecular Genetics, and Department of Molecular and Cellular Biology, University of California, Davis, California 95616;
| | - Stephen C Kowalczykowski
- Department of Microbiology and Molecular Genetics, and Department of Molecular and Cellular Biology, University of California, Davis, California 95616;
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Chang HY, Liao CY, Su GC, Lin SW, Wang HW, Chi P. Functional Relationship of ATP Hydrolysis, Presynaptic Filament Stability, and Homologous DNA Pairing Activity of the Human Meiotic Recombinase DMC1. J Biol Chem 2015; 290:19863-73. [PMID: 26088134 DOI: 10.1074/jbc.m115.666289] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Indexed: 11/06/2022] Open
Abstract
DMC1 and RAD51 are conserved recombinases that catalyze homologous recombination. DMC1 and RAD51 share similar properties in DNA binding, DNA-stimulated ATP hydrolysis, and catalysis of homologous DNA strand exchange. A large body of evidence indicates that attenuation of ATP hydrolysis leads to stabilization of the RAD51-ssDNA presynaptic filament and enhancement of DNA strand exchange. However, the functional relationship of ATPase activity, presynaptic filament stability, and DMC1-mediated homologous DNA strand exchange has remained largely unexplored. To address this important question, we have constructed several mutant variants of human DMC1 and characterized them biochemically to gain mechanistic insights. Two mutations, K132R and D223N, that change key residues in the Walker A and B nucleotide-binding motifs ablate ATP binding and render DMC1 inactive. On the other hand, the nucleotide-binding cap D317K mutant binds ATP normally but shows significantly attenuated ATPase activity and, accordingly, forms a highly stable presynaptic filament. Surprisingly, unlike RAD51, presynaptic filament stabilization achieved via ATP hydrolysis attenuation does not lead to any enhancement of DMC1-catalyzed homologous DNA pairing and strand exchange. This conclusion is further supported by examining wild-type DMC1 with non-hydrolyzable ATP analogues. Thus, our results reveal an important mechanistic difference between RAD51 and DMC1.
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Affiliation(s)
- Hao-Yen Chang
- From the Institute of Biochemical Sciences, National Taiwan University, Number 1, Section 4, Roosevelt Road, Taipei 10617 Taiwan
| | - Chia-Yu Liao
- From the Institute of Biochemical Sciences, National Taiwan University, Number 1, Section 4, Roosevelt Road, Taipei 10617 Taiwan
| | - Guan-Chin Su
- From the Institute of Biochemical Sciences, National Taiwan University, Number 1, Section 4, Roosevelt Road, Taipei 10617 Taiwan
| | - Sheng-Wei Lin
- the Institute of Biological Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan, and
| | - Hong-Wei Wang
- the Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Peter Chi
- From the Institute of Biochemical Sciences, National Taiwan University, Number 1, Section 4, Roosevelt Road, Taipei 10617 Taiwan, the Institute of Biological Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan, and
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Esnault C, Renodon-Cornière A, Takahashi M, Casse N, Delorme N, Louarn G, Fleury F, Pilard JF, Chénais B. Assessment of DNA binding to human Rad51 protein by using quartz crystal microbalance and atomic force microscopy: effects of ADP and BRC4-28 peptide inhibitor. Chemphyschem 2014; 15:3753-60. [PMID: 25208912 DOI: 10.1002/cphc.201402451] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Indexed: 11/06/2022]
Abstract
The interaction of human Rad51 protein (HsRad51) with single-stranded deoxyribonucleic acid (ssDNA) was investigated by using quartz crystal microbalance (QCM) monitoring and atomic force microscopy (AFM) visualization. Gold surfaces for QCM and AFM were modified by electrografting of the in situ generated aryldiazonium salt from the sulfanilic acid to obtain the organic layer Au-ArSO3 H. The Au-ArSO3 H layer was activated by using a solution of PCl5 in CH2 Cl2 to give a Au-ArSO2 Cl layer. The modified surface was then used to immobilize long ssDNA molecules. The results obtained showed that the presence of adenosine diphosphate promotes the protein autoassociation rather than nucleation around DNA. In addition, when the BRC4-28 peptide inhibitor was used, both QCM and AFM confirmed the inhibitory effect of BRC4-28 toward HsRad51 autoassociation. Altogether these results show the suitability of this modified surface to investigate the kinetics and structure of DNA-protein interactions and for the screening of inhibitors.
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Affiliation(s)
- Charles Esnault
- Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, Université du Maine, Av. Olivier Messiaen, 72085 Le Mans Cedex 9 (France)
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9
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van Mameren J, Modesti M, Kanaar R, Wyman C, Peterman EJG, Wuite GJL. Counting RAD51 proteins disassembling from nucleoprotein filaments under tension. Nature 2008; 457:745-8. [PMID: 19060884 PMCID: PMC3871861 DOI: 10.1038/nature07581] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Accepted: 10/24/2008] [Indexed: 11/09/2022]
Abstract
The central catalyst in eukaryotic ATP-dependent homologous recombination consists of RAD51 proteins, polymerized around single-stranded DNA. This nucleoprotein filament recognizes a homologous duplex DNA segment and invades it1,2. After strand exchange, the nucleoprotein filament should disassemble in order for the recombination process to complete3. The molecular mechanism of RAD51 filament disassembly is poorly understood. Here, we have combined optical tweezers with single-molecule fluorescence microscopy and microfluidics4,5 to reveal that disassembly results from the interplay between ATP hydrolysis and release of the tension stored in the nucleoprotein filament. Applying external tension to the DNA, we found that disassembly slows down and can even be stalled. We quantified the fluorescence of RAD51 patches and found that disassembly occurs in bursts interspersed by long pauses. Upon relaxation of a stalled complex, pauses were suppressed resulting in a large burst. These results imply that tension-dependent disassembly takes place only from filament ends, after tension-independent ATP hydrolysis. This integrative single-molecule approach allowed us to dissect the mechanism of this key homologous recombination reaction step, which in turn clarifies how disassembly can be influenced by accessory proteins.
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Affiliation(s)
- Joost van Mameren
- Laser Centre and Department of Physics and Astronomy, VU University, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
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van der Heijden T, Seidel R, Modesti M, Kanaar R, Wyman C, Dekker C. Real-time assembly and disassembly of human RAD51 filaments on individual DNA molecules. Nucleic Acids Res 2007; 35:5646-57. [PMID: 17709342 PMCID: PMC2034483 DOI: 10.1093/nar/gkm629] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The human DNA repair protein RAD51 is the crucial component of helical nucleoprotein filaments that drive homologous recombination. The molecular mechanistic details of how this structure facilitates the requisite DNA strand rearrangements are not known but must involve dynamic interactions between RAD51 and DNA. Here, we report the real-time kinetics of human RAD51 filament assembly and disassembly on individual molecules of both single- and double-stranded DNA, as measured using magnetic tweezers. The relative rates of nucleation and filament extension are such that the observed filament formation consists of multiple nucleation events that are in competition with each other. For varying concentration of RAD51, a Hill coefficient of 4.3 ± 0.5 is obtained for both nucleation and filament extension, indicating binding to dsDNA with a binding unit consisting of multiple (≥4) RAD51 monomers. We report Monte Carlo simulations that fit the (dis)assembly data very well. The results show that, surprisingly, human RAD51 does not form long continuous filaments on DNA. Instead each nucleoprotein filament consists of a string of many small filament patches that are only a few tens of monomers long. The high flexibility and dynamic nature of this arrangement is likely to facilitate strand exchange.
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Affiliation(s)
- Thijn van der Heijden
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Department of Cell Biology and Genetics and Department of Radiation Oncology, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Ralf Seidel
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Department of Cell Biology and Genetics and Department of Radiation Oncology, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Mauro Modesti
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Department of Cell Biology and Genetics and Department of Radiation Oncology, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Roland Kanaar
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Department of Cell Biology and Genetics and Department of Radiation Oncology, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Claire Wyman
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Department of Cell Biology and Genetics and Department of Radiation Oncology, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands
- *To whom correspondence should be addressed. +31 15 2786094, Fax: +31 15 2781202, ,
| | - Cees Dekker
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Department of Cell Biology and Genetics and Department of Radiation Oncology, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands
- *To whom correspondence should be addressed. +31 15 2786094, Fax: +31 15 2781202, ,
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Li X, Zhang XP, Solinger JA, Kiianitsa K, Yu X, Egelman EH, Heyer WD. Rad51 and Rad54 ATPase activities are both required to modulate Rad51-dsDNA filament dynamics. Nucleic Acids Res 2007; 35:4124-40. [PMID: 17567608 PMCID: PMC1919488 DOI: 10.1093/nar/gkm412] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Rad51 and Rad54 are key proteins that collaborate during homologous recombination. Rad51 forms a presynaptic filament with ATP and ssDNA active in homology search and DNA strand exchange, but the precise role of its ATPase activity is poorly understood. Rad54 is an ATP-dependent dsDNA motor protein that can dissociate Rad51 from dsDNA, the product complex of DNA strand exchange. Kinetic analysis of the budding yeast proteins revealed that the catalytic efficiency of the Rad54 ATPase was stimulated by partial filaments of wild-type and Rad51-K191R mutant protein on dsDNA, unambiguously demonstrating that the Rad54 ATPase activity is stimulated under these conditions. Experiments with Rad51-K191R as well as with wild-type Rad51-dsDNA filaments formed in the presence of ATP, ADP or ATP-γ-S showed that efficient Rad51 turnover from dsDNA requires both the Rad51 ATPase and the Rad54 ATPase activities. The results with Rad51-K191R mutant protein also revealed an unexpected defect in binding to DNA. Once formed, Rad51-K191R-DNA filaments appeared normal upon electron microscopic inspection, but displayed significantly increased stability. These biochemical defects in the Rad51-K191R protein could lead to deficiencies in presynapsis (filament formation) and postsynapsis (filament disassembly) in vivo.
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Affiliation(s)
- Xuan Li
- Section of Microbiology, University of California, Davis, CA 95616-8665, Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908 and Section of Molecular and Cellular Biology, University of California, Davis, CA 95616-8665, USA
| | - Xiao-Ping Zhang
- Section of Microbiology, University of California, Davis, CA 95616-8665, Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908 and Section of Molecular and Cellular Biology, University of California, Davis, CA 95616-8665, USA
| | - Jachen A. Solinger
- Section of Microbiology, University of California, Davis, CA 95616-8665, Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908 and Section of Molecular and Cellular Biology, University of California, Davis, CA 95616-8665, USA
| | - Konstantin Kiianitsa
- Section of Microbiology, University of California, Davis, CA 95616-8665, Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908 and Section of Molecular and Cellular Biology, University of California, Davis, CA 95616-8665, USA
| | - Xiong Yu
- Section of Microbiology, University of California, Davis, CA 95616-8665, Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908 and Section of Molecular and Cellular Biology, University of California, Davis, CA 95616-8665, USA
| | - Edward H. Egelman
- Section of Microbiology, University of California, Davis, CA 95616-8665, Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908 and Section of Molecular and Cellular Biology, University of California, Davis, CA 95616-8665, USA
| | - Wolf-Dietrich Heyer
- Section of Microbiology, University of California, Davis, CA 95616-8665, Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908 and Section of Molecular and Cellular Biology, University of California, Davis, CA 95616-8665, USA
- *To whom correspondence should be addressed. Tel.: 530 752 3001; Fax: 530 752 3011
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Qian X, He Y, Luo Y. Binding of a Second Magnesium Is Required for ATPase Activity of RadA from Methanococcus voltae. Biochemistry 2007; 46:5855-63. [PMID: 17455906 DOI: 10.1021/bi6024098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
RecA-like strand exchange proteins, which include closely related archaeal Rad51/RadA and eukaryal Rad51 and DMC1, play a key role in DNA repair by forming helical nucleoprotein filaments which promote a hallmark strand exchange reaction between homologous DNA substrates. Our recent crystallographic studies on a RadA recombinase from Methanococcus voltae (MvRadA) have unexpectedly revealed a secondary magnesium at the subunit interface approximately 11 A from the primary one coordinated by ATP and the canonical P-loop. The DNA-dependent ATPase activity of MvRadA appears to be dependent on the concentration of free Mg2+, while the strand exchange activity does not. We also made site-directed mutagenesis at the Mg2+-liganding residue Asp-246. The mutant proteins exhibited approximately 20-fold reduced ATPase activity but normal strand exchange activity. Structurally, the main chain carbonyl of the conserved catalytic residue Glu-151 is hydrogen bonded with one of the magnesium-liganding water molecules. Changes in the secondary magnesium site may therefore induce conformational changes around this catalytic glutamate and affect the ATPase activity without significantly altering the stability of the extended recombinase filament. Asp-246 is somewhat conserved among archaeal and eukaryal homologues, implying some homologues may share this allosteric site for ATPase function.
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Affiliation(s)
- Xinguo Qian
- Department of Biochemistry, University of Saskatchewan, A3 Health Sciences Building, 107 Wiggins Road, Saskatoon, Saskatchewan, Canada S7N 5E5
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Forget AL, Kudron MM, McGrew DA, Calmann MA, Schiffer C, Knight KL. RecA dimers serve as a functional unit for assembly of active nucleoprotein filaments. Biochemistry 2007; 45:13537-42. [PMID: 17087507 PMCID: PMC2522307 DOI: 10.1021/bi060938q] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
All RecA-like recombinase enzymes catalyze DNA strand exchange as elongated filaments on DNA. Despite numerous biochemical and structural studies of RecA and the related Rad51 and RadA proteins, the unit oligomer(s) responsible for nucleoprotein filament assembly and coordinated filament activity remains undefined. We have created a RecA fused dimer protein and show that it maintains in vivo DNA repair and LexA co-protease activities, as well as in vitro ATPase and DNA strand exchange activities. Our results support the idea that dimeric RecA is an important functional unit both for assembly of nucleoprotein filaments and for their coordinated activity during the catalysis of homologous recombination.
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Shim KS, Schmutte C, Yoder K, Fishel R. Defining the salt effect on human RAD51 activities. DNA Repair (Amst) 2006; 5:718-30. [PMID: 16644292 DOI: 10.1016/j.dnarep.2006.03.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 03/09/2006] [Accepted: 03/10/2006] [Indexed: 10/24/2022]
Abstract
Previous work by Sung and colleagues identified unusual salt requirements for hRAD51 strand exchange compared to RecA [S. Sigurdsson, K. Trujillo, B. Song, S. Stratton, P. Sung, Basis for avid homologous DNA strand exchange by human Rad51 and RPA, J. Biol. Chem. 276 (2001) 8798-8806]. Later studies showed that this salt [(NH4)2SO4] appeared to enhance the ability of hRAD51 to distinguish ssDNA from dsDNA [Y. Liu, A.Z. Stasiak, J.Y. Masson, M.J. McIlwraith, A. Stasiak, S.C. West, Conformational changes modulate the activity of human RAD51 protein, J. Mol. Biol. 337 (2004) 817-827]. The mechanism of this salt effect remains enigmatic. Here, we detail the properties of several neutral salts on hRAD51 activities. We found that the cation identity correlated with the stimulatory effect of these neutral salts on hRAD51 ATPase and strand exchange activities. The salt effect appears to be related to the size of the cation, which may be largely mimicked with the cesium ion. These results are consistent with the hypothesis that stimulating cations induce an important conformation and/or transition state in hRAD51. In the presence of an optimal ammonium-based salt (NaNH4HPO4), hRAD51 mediated strand exchange was successfully performed using a simplified protocol. We confirmed and extend the observation that efficient strand exchange correlated with preferential binding of ssDNA over dsDNA. In addition we observed an induced stability of the hRAD51-DNA complex in the presence of ATP that becomes unstable following ATP hydrolysis (the ADP form or nucleotide free form). These salt-induced characteristics of hRAD51 increasingly resemble RecA-mediated recombinase activities, which should help in dissecting the mechanism of these proteins in homologous recombination.
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Affiliation(s)
- Kang-Sup Shim
- Department of Molecular Virology, Immunology, and Medical Genetics, Human Cancer Genetics, The Ohio State University College of Medicine and Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43102, USA.
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Shim KS, Tombline G, Heinen CD, Charbonneau N, Schmutte C, Fishel R. Magnesium influences the discrimination and release of ADP by human RAD51. DNA Repair (Amst) 2006; 5:704-17. [PMID: 16624636 DOI: 10.1016/j.dnarep.2006.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 03/09/2006] [Accepted: 03/10/2006] [Indexed: 10/24/2022]
Abstract
hRAD51 lacks cooperative DNA-dependent ATPase activity and appears to function with 5-10-fold less Mg2+ compared to RecA. We have further explored the effect of Mg2+ on adenosine nucleotide binding, ATPase, and DNA strand exchange activities. hRAD51 was saturated with the poorly hydrolyzable analog of ATP, ATPgammaS, at approximately 0.08 mM Mg2+. In contrast, > 0.5 mM Mg2+ was required to saturate hRAD51 with ADP. We found ADP to be a significantly less effective competitive inhibitor of the hRAD51 ATPase at low Mg2+ concentrations (0.08 mM). Mg2+ did not appear to affect the ability of ATPgammaS to competitively inhibit the hRAD51 ATPase. Low Mg2+ (0.08-0.12 mM) enhanced the steady-state ATPase of hRAD51 while higher Mg2+ concentration (> 0.3 mM) was inhibitory. At low Mg2+, hRAD51 appeared capable of nearly complete hydrolysis of available ATP, suggesting a lack of ADP product inhibition. There was a strong correlation between the amount of Mg2+ required for stable ADP binding and the inhibition of hRad51 strand exchange activity. Simultaneous inclusion of exogenous ATP and chelation of Mg2+ with EDTA significantly enhanced ADP-->ATP exchange by hRAD51. These studies are consistent with the hypothesis that Mg2+ influences the discrimination and release of ADP, which may sequentially impose an important regulatory step in the hRAD51 ATPase cycle.
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Affiliation(s)
- Kang-Sup Shim
- Department of Molecular Virology, Immunology, and Medical Genetics, Human Cancer, Genetics, The Ohio State University College of Medicine, The Ohio State University, Comprehensive Cancer Center, Columbus, OH 43102, USA.
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Qian X, Wu Y, He Y, Luo Y. Crystal structure of Methanococcus voltae RadA in complex with ADP: hydrolysis-induced conformational change. Biochemistry 2006; 44:13753-61. [PMID: 16229465 DOI: 10.1021/bi051222i] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Members of a superfamily of RecA-like recombinases facilitate a central strand exchange reaction in the DNA repair process. Archaeal RadA and Rad51 and eukaryal Rad51 and meiosis-specific DMC1 form a closely related group of recombinases distinct from bacterial RecA. Nevertheless, all such recombinases share a conserved core domain which carries the ATPase site and putative DNA-binding sites. Here we present the crystal structure of an archaeal RadA from Methanococcus voltae (MvRadA) in complex with ADP and Mg2+ at 2.1 A resolution. The crystallized RadA-ADP filament has an extended helical pitch similar to those of previously determined structures in the presence of nonhydrolyzable ATP analogue AMP-PNP. Structural comparison reveals two recurrent conformations with an extensive allosteric effect spanning the ATPase site and the putative DNA-binding L2 region. Varied conformations of the L2 region also imply a dynamic nature of recombinase-bound DNA.
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Affiliation(s)
- Xinguo Qian
- Department of Biochemistry, University of Saskatchewan, A3 Health Sciences Building, 107 Wiggins Road, Saskatoon, Saskatchewan, Canada S7N 5E5
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Reiss K, Khalili K, Giordano A, Trojanek J. JC virus large T-antigen and IGF-I signaling system merge to affect DNA repair and genomic integrity. J Cell Physiol 2005; 206:295-300. [PMID: 15991250 DOI: 10.1002/jcp.20455] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The progression of cancer is often associated with genomic instability, which may develop as a result of compromised defense mechanisms responsible for the maintenance of chromosomal integrity. These include defects in telomere preservation, chromosomal segregation, and DNA repair. In this review, we discuss molecular interactions between viral and cellular signaling components, which interfere with DNA repair mechanisms, and possibly contribute to the development of a mutagenic phenotype. Our studies indicate that large T-antigen from the human polyomavirus JC (JCV T-antigen) inhibits homologous recombination directed DNA repair (HRR)-causing accumulation of mutations in the affected cells (JCP 2005, in press). Surprisingly, T-antigen does not operate directly, but utilizes insulin receptor substrate 1 (IRS-1), which is the major signaling molecule for insulin-like growth factor I receptor (IGF-IR). Following T-antigen-mediated nuclear translocation, IRS-1 binds Rad51 at the site of damaged DNA. This T-antigen-mediated inhibition of HRR does not function in cells lacking IRS-1, and can be reproduced in the absence of T-antigen by IRS-1 with an artificial nuclear localization signal. The interplay described between the IGF-IR signaling system and JCV T-antigen in the process of DNA repair could be relevant, since nearly 90% of the human population is seropositive for JC virus, JCV T-antigen transforms cells in vitro, is tumorigenic in experimental animals, and the presence of JC virus has been shown in an increasing number of biopsies of human cancer.
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Affiliation(s)
- Krzysztof Reiss
- Center for Neurovirology and Cancer Biology, Temple University, 1900 North 12th Street, Biology Life Science Building, Philadelphia, Pennsylvania 19122, USA.
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Wang JY, Ho T, Trojanek J, Chintapalli J, Grabacka M, Stoklosa T, Garcia FU, Skorski T, Reiss K. Impaired homologous recombination DNA repair and enhanced sensitivity to DNA damage in prostate cancer cells exposed to anchorage-independence. Oncogene 2005; 24:3748-58. [PMID: 15782124 DOI: 10.1038/sj.onc.1208537] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During metastases, cancer cells are temporarily exposed to the condition in which interactions with extracellular environment can be restricted (anchorage-independence). We demonstrate that the sensitivity of prostate cancer cell lines, DU145 and PC-3, to genotoxic treatment (cisplatin and gamma-irradiation) increased several folds when cells were forced to grow in anchorage-independence. This enhanced drug sensitivity was associated with a severe impairment of homologous recombination-directed DNA repair (HRR). The mechanism involves Rad51, which is the major enzymatic component of HRR. The protein level of Rad51 and its recruitment to DNA double-strand breaks (DSBs) were both attenuated. Rad51 deficiency in anchorage-independence was not associated with Rad51 promoter activity, and was not compensated by a constitutive overexpression of Rad51 cDNA. Instead, Rad51 protein level and its ability to colocalize with DSBs were restored in the presence of proteosome inhibitors, or when cells from the suspension cultures were allowed reattachment. Presented results indicate that anchorage-independence sensitizes prostate cancer cells to genotoxic agents; however, it also attenuates faithful component of DNA repair by targeting stability of Rad51. This temporal attenuation of HRR may contribute to the accumulation mutations after DNA damage, and possibly the selection of new adaptations in cells, which survived genotoxic treatment.
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Affiliation(s)
- Jin Ying Wang
- 1Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, 1900 North 12th Street, Biology Life Science Building, Philadelphia, PA 19122, USA
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Bugreev DV, Mazin AV. Ca2+ activates human homologous recombination protein Rad51 by modulating its ATPase activity. Proc Natl Acad Sci U S A 2004; 101:9988-93. [PMID: 15226506 PMCID: PMC454202 DOI: 10.1073/pnas.0402105101] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human Rad51 (hRad51) protein plays a key role in homologous recombination and DNA repair. hRad51 protein forms a helical filament on single-stranded DNA (ssDNA), which performs the basic steps of homologous recombination: a search for homologous double-stranded DNA (dsDNA) and DNA strand exchange. hRad51 protein possesses DNA-dependent ATPase activity; however, the role of this activity has not been understood. Our current results show that Ca(2+) greatly stimulates DNA strand exchange activity of hRad51 protein. We found that Ca(2+) exerts its stimulatory effect by modulating the ATPase activity of hRad51 protein. Our data demonstrate that, in the presence of Mg(2+), the hRad51-ATP-ssDNA filament is quickly converted to an inactive hRad51-ADP-ssDNA form, due to relatively rapid ATP hydrolysis and slow dissociation of ADP. Ca(2+) maintains the active hRad51-ATP-ssDNA filament by reducing the ATP hydrolysis rate. These findings demonstrate a crucial role of the ATPase activity in regulation of DNA strand exchange activity of hRad51 protein. This mechanism of Rad51 protein regulation by modulating its ATPase activity is evolutionarily recent; we found no such mechanism for yeast Rad51 (yRad51) protein.
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Affiliation(s)
- Dmitry V Bugreev
- Department of Biochemistry, Drexel University College of Medicine, Philadelphia, PA 19102-1192, USA
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Shim KS, Schmutte C, Tombline G, Heinen CD, Fishel R. hXRCC2 enhances ADP/ATP processing and strand exchange by hRAD51. J Biol Chem 2004; 279:30385-94. [PMID: 15123651 DOI: 10.1074/jbc.m306066200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The assembly of bacterial RecA, and its human homolog hRAD51, into an operational ADP/ATP-regulated DNA-protein (nucleoprotein) filament is essential for homologous recombination repair (HRR). Yet hRAD51 lacks the coordinated ADP/ATP processing exhibited by RecA and is less efficient in HRR reactions in vitro. In this study, we demonstrate that hXRCC2, one of five other poorly understood non-redundant human mitotic RecA homologs (hRAD51B, hRAD51C, hRAD51D, hXRCC2, and hXRCC3), stimulates hRAD51 ATP processing. hXRCC2 also increases hRAD51-mediated DNA unwinding and strand exchange activities that are integral for HRR. Although there does not seem to be a long-lived interaction between hXRCC2 and hRAD51, we detail a strong adenosine nucleotide-regulated interaction between the hXRCC2-hRAD51D heterodimer and hRAD51. These observations begin to elucidate the separate and specialized functions of the human mitotic RecA homologs that enable an efficient nucleoprotein filament required for HRR.
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Affiliation(s)
- Kang Sup Shim
- Genetics and Molecular Biology Program, Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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Trojanek J, Ho T, Del Valle L, Nowicki M, Wang JY, Lassak A, Peruzzi F, Khalili K, Skorski T, Reiss K. Role of the insulin-like growth factor I/insulin receptor substrate 1 axis in Rad51 trafficking and DNA repair by homologous recombination. Mol Cell Biol 2003; 23:7510-24. [PMID: 14559999 PMCID: PMC207618 DOI: 10.1128/mcb.23.21.7510-7524.2003] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The receptor for insulin-like growth factor I (IGF-IR) controls normal and pathological growth of cells. DNA repair pathways represent an unexplored target through which the IGF-IR signaling system might support pathological growth leading to cellular transformation. However, this study demonstrates that IGF-I stimulation supports homologous recombination-directed DNA repair (HRR). This effect involves an interaction between Rad51 and the major IGF-IR signaling molecule, insulin receptor substrate 1 (IRS-1). The binding occurs within the cytoplasm, engages the N-terminal domain of IRS-1, and is attenuated by IGF-I-mediated IRS-1 tyrosine phosphorylation. In the absence of IGF-I stimulation, or if mutated IGF-IR fails to phosphorylate IRS-1, localization of Rad51 to the sites of damaged DNA is diminished. These results point to a direct role of IRS-1 in HRR and suggest a novel role for the IGF-IR/IRS-1 axis in supporting the stability of the genome.
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Affiliation(s)
- Joanna Trojanek
- Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, USA
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Tombline G, Heinen CD, Shim KS, Fishel R. Biochemical characterization of the human RAD51 protein. III. Modulation of DNA binding by adenosine nucleotides. J Biol Chem 2002; 277:14434-42. [PMID: 11839741 DOI: 10.1074/jbc.m109917200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Adenosine nucleotides affect the ability of RecA small middle dotsingle-stranded DNA (ssDNA) nucleoprotein filaments to cooperatively assume and maintain an extended structure that facilitates DNA pairing during recombination. Here we have determined that ADP and ATP/ATPgammaS affect the DNA binding and aggregation properties of the human RecA homolog human RAD51 protein (hRAD51). These studies have revealed significant differences between hRAD51 and RecA. In the presence of ATPgammaS, RecA forms a stable complex with ssDNA, while the hRAD51 ssDNA complex is destabilized. Conversely, in the presence of ADP and ATP, the RecA ssDNA complex is unstable, while the hRAD51 ssDNA complex is stabilized. We identified two hRAD51 small middle dotssDNA binding forms by gel shift analysis, which were distinct from a well defined RecA small middle dotssDNA binding form. The available evidence suggests that a low molecular weight hRAD51 small middle dotssDNA binding form (hRAD51 small middle dotssDNA(low)) correlates with active ADP and ATP processing. A high molecular weight hRAD51 small middle dotssDNA aggregate (hRAD51 small middle dotssDNA(high)) appears to correlate with a form that fails to process ADP and ATP. Our data are consistent with the notion that hRAD51 is unable to appropriately coordinate ssDNA binding with adenosine nucleotide processing. These observations suggest that other factors may assist hRAD51 in order to mirror RecA recombinational function.
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Affiliation(s)
- Gregory Tombline
- Genetics and Molecular Biology Program, Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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Tombline G, Fishel R. Biochemical characterization of the human RAD51 protein. I. ATP hydrolysis. J Biol Chem 2002; 277:14417-25. [PMID: 11839739 DOI: 10.1074/jbc.m109915200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The prototypical bacterial RecA protein promotes recombination/repair by catalyzing strand exchange between homologous DNAs. While the mechanism of strand exchange remains enigmatic, ATP-induced cooperativity between RecA protomers is critical for its function. A human RecA homolog, human RAD51 protein (hRAD51), facilitates eukaryotic recombination/repair, although its ability to hydrolyze ATP and/or promote strand exchange appears distinct from the bacterial RecA. We have quantitatively examined the hRAD51 ATPase. The catalytic efficiency (k(cat)/K(m)) of the hRAD51 ATPase was approximately 50-fold lower than the RecA ATPase. Altering the ratio of DNA/hRAD51 and including salts that stimulate DNA strand exchange (ammonium sulfate and spermidine) were found to affect the catalytic efficiency of hRAD51. The average site size of hRAD51 was determined to be approximately 3 nt (bp) for both single-stranded and double-stranded DNA. Importantly, hRAD51 lacks the magnitude of ATP-induced cooperativity that is a hallmark of RecA. Together, these results suggest that hRAD51 may be unable to coordinate ATP hydrolysis between neighboring protomers.
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Affiliation(s)
- Gregory Tombline
- Genetics and Molecular Biology Program, Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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