1
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Hengel SR, Oppenheimer KG, Smith CM, Schaich MA, Rein HL, Martino J, Darrah KE, Witham M, Ezekwenna OC, Burton KR, Van Houten B, Spies M, Bernstein KA. The human Shu complex promotes RAD51 activity by modulating RPA dynamics on ssDNA. Nat Commun 2024; 15:7197. [PMID: 39169038 PMCID: PMC11339404 DOI: 10.1038/s41467-024-51595-0] [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: 06/13/2023] [Accepted: 08/09/2024] [Indexed: 08/23/2024] Open
Abstract
Templated DNA repair that occurs during homologous recombination and replication stress relies on RAD51. RAD51 activity is positively regulated by BRCA2 and the RAD51 paralogs. The Shu complex is a RAD51 paralog-containing complex consisting of SWSAP1, SWS1, and SPIDR. We demonstrate that SWSAP1-SWS1 binds RAD51, maintains RAD51 filament stability, and enables strand exchange. Using single-molecule confocal fluorescence microscopy combined with optical tweezers, we show that SWSAP1-SWS1 decorates RAD51 filaments proficient for homologous recombination. We also find SWSAP1-SWS1 enhances RPA diffusion on ssDNA. Importantly, we show human sgSWSAP1 and sgSWS1 knockout cells are sensitive to pharmacological inhibition of PARP and APE1. Lastly, we identify cancer variants in SWSAP1 that alter Shu complex formation. Together, we show that SWSAP1-SWS1 stimulates RAD51-dependent high-fidelity repair and may be an important new cancer therapeutic target.
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Affiliation(s)
- Sarah R Hengel
- University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, UPMC-Hillman Cancer Center, Pittsburgh, PA, USA.
- Tufts University, Department of Biology, Medford, MA, USA.
| | - Katherine G Oppenheimer
- University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, UPMC-Hillman Cancer Center, Pittsburgh, PA, USA
| | - Chelsea M Smith
- University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, UPMC-Hillman Cancer Center, Pittsburgh, PA, USA
- University of North Carolina at Chapel Hill, Department of Pathology and Laboratory Medicine, Chapel Hill, NC, USA
| | - Matthew A Schaich
- University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, UPMC-Hillman Cancer Center, Pittsburgh, PA, USA
| | - Hayley L Rein
- University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, UPMC-Hillman Cancer Center, Pittsburgh, PA, USA
| | - Julieta Martino
- University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, UPMC-Hillman Cancer Center, Pittsburgh, PA, USA
- GeneDx, Gaithersburg, MD, USA
| | - Kristie E Darrah
- University of Pennsylvania School of Medicine, Penn Center for Genome Integrity, Department of Biochemistry and Biophysics, 421 Curie Boulevard, Philadelphia, PA, USA
| | - Maggie Witham
- Tufts University, Department of Biology, Medford, MA, USA
| | | | - Kyle R Burton
- Tufts University, Department of Biology, Medford, MA, USA
| | - Bennett Van Houten
- University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, UPMC-Hillman Cancer Center, Pittsburgh, PA, USA
| | - Maria Spies
- University of Iowa, Department of Biochemistry and Molecular Biology, Iowa City, IA, USA
| | - Kara A Bernstein
- University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, UPMC-Hillman Cancer Center, Pittsburgh, PA, USA.
- University of Pennsylvania School of Medicine, Penn Center for Genome Integrity, Department of Biochemistry and Biophysics, 421 Curie Boulevard, Philadelphia, PA, USA.
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2
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Rakowski JA, Schaich MA, Schnable BL, Van Houten B. Utilizing nuclear extracts to characterize protein: DNA interactions at the single molecule level. Methods Enzymol 2024; 705:397-426. [PMID: 39389671 DOI: 10.1016/bs.mie.2024.07.014] [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: 10/12/2024]
Abstract
Single molecule experiments are invaluable approaches to analyze the dynamics of protein-protein and protein-DNA interactions in real time. SMADNE, single molecule analysis of DNA binding proteins from nuclear extracts, is a new method that allows analysis of a fluorescently tagged overexpressed protein of interest near its native environment while still retaining the advantages of single molecule approaches. Having all the endogenous proteins found in the nucleus provides more biologically relevant information due to their interactions with the protein of interest. Examples of such include the ability for posttranslational modifications to occur, intrinsic stabilization factors, and high labeling efficacy of the protein of interest. Furthermore, having the capabilities to incorporate different DNA substrates and protein variants can elucidate information of the system in a more detailed manner. Finally, orthogonal labeling strategies allows determination of the order of assembly and disassembly of several proteins at sites of damage. This chapter will describe the methodologies, benefits, and applications of SMADNE.
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Affiliation(s)
- Jennifer A Rakowski
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Matthew A Schaich
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; UPMC-Hillman Cancer Center, Pittsburgh, PA, United States
| | - Brittani L Schnable
- UPMC-Hillman Cancer Center, Pittsburgh, PA, United States; Molecular Biophysics and Structural Biology Graduate Program, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Bennett Van Houten
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; UPMC-Hillman Cancer Center, Pittsburgh, PA, United States; Molecular Biophysics and Structural Biology Graduate Program, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
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3
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Irvin EM, Wang H. Single-molecule fluorescence imaging of DNA maintenance protein binding dynamics and activities on extended DNA. Curr Opin Struct Biol 2024; 87:102863. [PMID: 38879921 DOI: 10.1016/j.sbi.2024.102863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 05/23/2024] [Accepted: 05/24/2024] [Indexed: 06/18/2024]
Abstract
Defining the molecular mechanisms by which genome maintenance proteins dynamically associate with and process DNA is essential to understand the potential avenues by which these stabilizing mechanisms are disrupted. Single-molecule fluorescence imaging (SMFI) of protein dynamics on extended DNA has greatly expanded our ability to accomplish this, as it captures singular biomolecular interactions - in all their complexity and diversity - without relying on ensemble-averaging of bulk protein activity as most traditional biochemical techniques must do. In this review, we discuss how SMFI studies with extended DNA have substantially contributed to genome stability research over the past two years.
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Affiliation(s)
| | - Hong Wang
- Toxicology Program, North Carolina State University, Raleigh, NC, USA; Physics Department, North Carolina State University, Raleigh, NC, USA; Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA.
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4
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Schnable BL, Schaich MA, Roginskaya V, Leary LP, Weaver TM, Freudenthal BD, Drohat AC, Houten BV. Thymine DNA glycosylase combines sliding, hopping, and nucleosome interactions to efficiently search for 5-formylcytosine. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.04.560925. [PMID: 37873231 PMCID: PMC10592968 DOI: 10.1101/2023.10.04.560925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Base excision repair is the main pathway involved in active DNA demethylation. 5-formylctyosine and 5-carboxylcytosine, two oxidized moieties of methylated cytosine, are recognized and removed by thymine DNA glycosylase (TDG) to generate an abasic site. Using single molecule fluorescence experiments, we studied TDG in the presence and absence of 5-formylctyosine. TDG exhibits multiple modes of linear diffusion, including hopping and sliding, in search of a lesion. We probed TDG active site variants and truncated N-terminus revealing how these variants alter the lesion search and recognition mechanism of TDG. On DNA containing an undamaged nucleosome, TDG was found to either bypass, colocalize with, or encounter but not bypass the nucleosome. However, truncating the N-terminus reduced the number of interactions with the nucleosome. Our findings provide unprecedented mechanistic insights into how TDG searches for DNA lesions in chromatin.
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5
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Yao YM, Miodownik I, O'Hagan MP, Jbara M, Afek A. Deciphering the dynamic code: DNA recognition by transcription factors in the ever-changing genome. Transcription 2024:1-25. [PMID: 39033307 DOI: 10.1080/21541264.2024.2379161] [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: 03/15/2024] [Accepted: 07/03/2024] [Indexed: 07/23/2024] Open
Abstract
Transcription factors (TFs) intricately navigate the vast genomic landscape to locate and bind specific DNA sequences for the regulation of gene expression programs. These interactions occur within a dynamic cellular environment, where both DNA and TF proteins experience continual chemical and structural perturbations, including epigenetic modifications, DNA damage, mechanical stress, and post-translational modifications (PTMs). While many of these factors impact TF-DNA binding interactions, understanding their effects remains challenging and incomplete. This review explores the existing literature on these dynamic changes and their potential impact on TF-DNA interactions.
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Affiliation(s)
- Yumi Minyi Yao
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Irina Miodownik
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Michael P O'Hagan
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Muhammad Jbara
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ariel Afek
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
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6
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Chua GNL, Liu S. When Force Met Fluorescence: Single-Molecule Manipulation and Visualization of Protein-DNA Interactions. Annu Rev Biophys 2024; 53:169-191. [PMID: 38237015 DOI: 10.1146/annurev-biophys-030822-032904] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Myriad DNA-binding proteins undergo dynamic assembly, translocation, and conformational changes while on DNA or alter the physical configuration of the DNA substrate to control its metabolism. It is now possible to directly observe these activities-often central to the protein function-thanks to the advent of single-molecule fluorescence- and force-based techniques. In particular, the integration of fluorescence detection and force manipulation has unlocked multidimensional measurements of protein-DNA interactions and yielded unprecedented mechanistic insights into the biomolecular processes that orchestrate cellular life. In this review, we first introduce the different experimental geometries developed for single-molecule correlative force and fluorescence microscopy, with a focus on optical tweezers as the manipulation technique. We then describe the utility of these integrative platforms for imaging protein dynamics on DNA and chromatin, as well as their unique capabilities in generating complex DNA configurations and uncovering force-dependent protein behaviors. Finally, we give a perspective on the future directions of this emerging research field.
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Affiliation(s)
- Gabriella N L Chua
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, New York, USA;
- Tri-Institutional PhD Program in Chemical Biology, New York, New York, USA
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, New York, USA;
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7
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Rudnizky S, Murray PJ, Wolfe CH, Ha T. Single-Macromolecule Studies of Eukaryotic Genomic Maintenance. Annu Rev Phys Chem 2024; 75:209-230. [PMID: 38382570 DOI: 10.1146/annurev-physchem-090722-010601] [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: 02/23/2024]
Abstract
Genomes are self-organized and self-maintained as long, complex macromolecules of chromatin. The inherent heterogeneity, stochasticity, phase separation, and chromatin dynamics of genome operation make it challenging to study genomes using ensemble methods. Various single-molecule force-, fluorescent-, and sequencing-based techniques rooted in different disciplines have been developed to fill critical gaps in the capabilities of bulk measurements, each providing unique, otherwise inaccessible, insights into the structure and maintenance of the genome. Capable of capturing molecular-level details about the organization, conformational changes, and packaging of genetic material, as well as processive and stochastic movements of maintenance factors, a single-molecule toolbox provides an excellent opportunity for collaborative research to understand how genetic material functions in health and malfunctions in disease. In this review, we discuss novel insights brought to genomic sciences by single-molecule techniques and their potential to continue to revolutionize the field-one molecule at a time.
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Affiliation(s)
- Sergei Rudnizky
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Peter J Murray
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA;
| | - Clara H Wolfe
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA;
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts, USA
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8
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Liu Z, van Veen E, Sánchez H, Solano B, Palmero Moya FJ, McCluskey KA, Ramírez Montero D, van Laar T, Dekker NH. A Biophysics Toolbox for Reliable Data Acquisition and Processing in Integrated Force-Confocal Fluorescence Microscopy. ACS PHOTONICS 2024; 11:1592-1603. [PMID: 38645993 PMCID: PMC11027178 DOI: 10.1021/acsphotonics.3c01739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 03/01/2024] [Accepted: 03/01/2024] [Indexed: 04/23/2024]
Abstract
Integrated single-molecule force-fluorescence spectroscopy setups allow for simultaneous fluorescence imaging and mechanical force manipulation and measurements on individual molecules, providing comprehensive dynamic and spatiotemporal information. Dual-beam optical tweezers (OT) combined with a confocal scanning microscope form a force-fluorescence spectroscopy apparatus broadly used to investigate various biological processes, in particular, protein:DNA interactions. Such experiments typically involve imaging of fluorescently labeled proteins bound to DNA and force spectroscopy measurements of trapped individual DNA molecules. Here, we present a versatile state-of-the-art toolbox including the preparation of protein:DNA complex samples, design of a microfluidic flow cell incorporated with OT, automation of OT-confocal scanning measurements, and the development and implementation of a streamlined data analysis package for force and fluorescence spectroscopy data processing. Its components can be adapted to any commercialized or home-built dual-beam OT setup equipped with a confocal scanning microscope, which will facilitate single-molecule force-fluorescence spectroscopy studies on a large variety of biological systems.
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Affiliation(s)
- Zhaowei Liu
- Department
of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Edo van Veen
- Department
of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Humberto Sánchez
- Department
of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Belén Solano
- Department
of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Francisco J. Palmero Moya
- Department
of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Kaley A. McCluskey
- Department
of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Daniel Ramírez Montero
- Department
of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Theo van Laar
- Department
of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Nynke H. Dekker
- Department
of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
- Clarendon
Laboratory, Department of Physics, University
of Oxford, Oxford OX1 3PU, U.K.
- Kavli
Institute of Nanoscience Discovery, University
of Oxford, Dorothy Crowfoot
Hodgkin Building, Oxford OX1 3QU, U.K.
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9
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Chatterjee S, Chaubet L, van den Berg A, Mukhortava A, Gulkis M, Çağlayan M. Uncovering nick DNA binding by LIG1 at the single-molecule level. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.28.587287. [PMID: 38586032 PMCID: PMC10996606 DOI: 10.1101/2024.03.28.587287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
DNA ligases repair the strand breaks are made continually and naturally throughout the genome, if left unrepaired and allowed to persist, they can lead to genome instability in the forms of lethal double-strand (ds) breaks, deletions, and duplications. DNA ligase 1 (LIG1) joins Okazaki fragments during the replication machinery and seals nicks at the end of most DNA repair pathways. Yet, how LIG1 recognizes its target substrate is entirely missing. Here, we uncover the dynamics of nick DNA binding by LIG1 at the single-molecule level. Our findings reveal that LIG1 binds to dsDNA both specifically and non-specifically and exhibits diffusive behavior to form a stable complex at the nick. Furthermore, by comparing with the LIG1 C-terminal protein, we demonstrate that the N-terminal non-catalytic region promotes binding enriched at nick sites and facilitates an efficient nick search process by promoting 1D diffusion along the DNA. Our findings provide a novel single-molecule insight into the nick binding by LIG1, which is critical to repair broken phosphodiester bonds in the DNA backbone to maintain genome integrity.
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10
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Halma MTJ, Xu L. Life under tension: the relevance of force on biological polymers. BIOPHYSICS REPORTS 2024; 10:48-56. [PMID: 38737478 PMCID: PMC11079598 DOI: 10.52601/bpr.2023.230019] [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: 10/11/2023] [Accepted: 12/06/2023] [Indexed: 05/14/2024] Open
Abstract
Optical tweezers have elucidated numerous biological processes, particularly by enabling the precise manipulation and measurement of tension. One question concerns the biological relevance of these experiments and the generalizability of these experiments to wider biological systems. Here, we categorize the applicability of the information garnered from optical tweezers in two distinct categories: the direct relevance of tension in biological systems, and what experiments under tension can tell us about biological systems, while these systems do not reach the same tension as the experiment, still, these artificial experimental systems reveal insights into the operations of biological machines and life processes.
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Affiliation(s)
- Matthew T. J. Halma
- Department of Physics and Astronomy and LaserLab, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands
- LUMICKS B. V., 1081 HV, Amsterdam, the Netherlands
| | - Longfu Xu
- Department of Physics and Astronomy and LaserLab, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands
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11
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Hengel SR, Oppenheimer K, Smith C, Schaich MA, Rein HL, Martino J, Darrah K, Ezekwenna O, Burton K, Van Houten B, Spies M, Bernstein KA. The human Shu complex promotes RAD51 activity by modulating RPA dynamics on ssDNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580393. [PMID: 38405734 PMCID: PMC10888808 DOI: 10.1101/2024.02.14.580393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Templated DNA repair that occurs during homologous recombination and replication stress relies on RAD51. RAD51 activity is positively regulated by BRCA2 and the RAD51 paralogs. The Shu complex is a RAD51 paralog-containing complex consisting of SWSAP1 and SWS1. We demonstrate that SWSAP1-SWS1 binds RAD51, maintains RAD51 filament stability, and enables strand exchange. Using single molecule confocal fluorescence microscopy combined with optical tweezers, we show that SWSAP1-SWS1 decorates RAD51 filaments proficient for homologous recombination. We also find SWSAP1-SWS1 enhances RPA diffusion on ssDNA. Importantly, we show human sgSWSAP1 and sgSWS1 knockout cells are sensitive to pharmacological inhibition of PARP and APE1. Lastly, we identify cancer variants in SWSAP1 that alter SWS1 complex formation. Together, we show that SWSAP1-SWS1 stimulates RAD51-dependent high-fidelity repair and may be an important new cancer therapeutic target.
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12
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Schaich MA, Weaver TM, Roginskaya V, Freudenthal BD, Van Houten B. Single-molecule analysis of purified proteins and nuclear extracts: Insights from 8-oxoguanine glycosylase 1. DNA Repair (Amst) 2024; 134:103625. [PMID: 38237481 PMCID: PMC11287474 DOI: 10.1016/j.dnarep.2024.103625] [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: 10/13/2023] [Revised: 12/15/2023] [Accepted: 01/02/2024] [Indexed: 01/30/2024]
Abstract
By observing one molecule at a time, single-molecule studies can offer detailed insights about biomolecular processes including on rates, off rates, and diffusivity of molecules on strands of DNA. A recent technological advance (Single-molecule Analysis of DNA-binding proteins from Nuclear Extracts, SMADNE) has lowered the barrier to entry for single-molecule studies, and single-molecule dynamics can now be determined directly out of nuclear extracts, providing information in an intermediate environment between purified proteins in isolation and the heterogeneity of a nucleus. To compare and contrast the single-molecule DNA binding dynamics in nuclear extracts versus purified proteins, combined optical tweezers and fluorescence microscopy experiments were performed with purified GFP-tagged 8-oxoguanine glycosylase 1 (OGG1), purified GFP-OGG1 spiked into nuclear extracts, and nuclear extracts from human cells overexpressing GFP-OGG1. We observed differences in undamaged DNA binding during DNA damage search in each of the three conditions. Purified GFP-OGG1 engaged undamaged DNA for a weighted average lifetime of 5.7 s and 21% of these events underwent DNA diffusion after binding. However, unlike other glycosylases studied by SMADNE, OGG1 does not bind non-damaged DNA efficiently in nuclear extracts. In contrast, GFP-OGG1 binding dynamics on DNA substrates containing oxidative damage were relatively similar in all three conditions, with the weighted average binding lifetimes varying from 2.2 s in nuclear extracts to 7.8 s with purified GFP-OGG1 in isolation. Finally, we compared the purified protein and nuclear extract approaches for a catalytically dead OGG1 variant (GFP-OGG1-K249Q). This variant greatly increased the binding lifetime for oxidative DNA damage, with the weighted average lifetime for GFP-OGG1-249Q in nuclear extracts at 15.4 s vs 10.7 s for the purified protein. SMADNE will provide a new window of observation into the behavior of nucleic acid binding proteins only accessible by biophysicists trained in protein purification and protein labeling.
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Affiliation(s)
- Matthew A Schaich
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; UPMC-Hillman Cancer Center, USA
| | - Tyler M Weaver
- Department of Biochemistry and Molecular Biology, Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | | | - Bret D Freudenthal
- Department of Biochemistry and Molecular Biology, Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA; University of Kansas Cancer Center, Kansas City, KS 66160, USA
| | - Bennett Van Houten
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; UPMC-Hillman Cancer Center, USA.
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13
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Robeska E, Lalanne K, Vianna F, Sutcu HH, Khobta A, Busso D, Radicella JP, Campalans A, Baldeyron C. Targeted nuclear irradiation with a proton microbeam induces oxidative DNA base damage and triggers the recruitment of DNA glycosylases OGG1 and NTH1. DNA Repair (Amst) 2024; 133:103610. [PMID: 38101146 DOI: 10.1016/j.dnarep.2023.103610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 11/10/2023] [Accepted: 11/30/2023] [Indexed: 12/17/2023]
Abstract
DNA is the major target of radiation therapy of malignant tumors. Ionizing radiation (IR) induces a variety of DNA lesions, including chemically modified bases and strand breaks. The use of proton beam therapy for cancer treatment is ramping up, as it is expected to reduce normal tissue damage. Thus, it is important to understand the molecular mechanisms of recognition, signaling, and repair of DNA damage induced by protons in the perspective of assessing not only the risk associated with human exposure to IR but also the possibility to improve the efficacy of therapy. Here, we used targeted irradiation of nuclear regions of living cells with controlled number of protons at a high spatio-temporal resolution to detect the induced base lesions and characterize the recruitment kinetics of the specific DNA glycosylases to DNA damage sites. We show that localized irradiation with 4 MeV protons induces, in addition to DNA double strand breaks (DSBs), the oxidized bases 7,8-dihydro-8-oxoguanine (8-oxoG) and thymine glycol (TG) at the site of irradiation. Consistently, the DNA glycosylases OGG1 and NTH1, capable of excising 8-oxoG and TG, respectively, and initiating the base excision repair (BER) pathway, are recruited to the site of damage. To our knowledge, this is the first direct evidence indicating that proton microbeams induce oxidative base damage, and thus implicating BER in the repair of DNA lesions induced by protons.
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Affiliation(s)
- Elena Robeska
- Université Paris-Saclay, iRCM/IBFJ, CEA, Genetic Stability, Stem Cells and Radiation, F-92260 Fontenay-aux-Roses, France; Université Paris Cité, iRCM/IBFJ, CEA, Genetic Stability, Stem Cells and Radiation, F-92260 Fontenay-aux-Roses, France
| | - Kévin Lalanne
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-SANTE/SDOS/LMDN, Cadarache, F-13115 Saint-Paul-Lez-Durance, France
| | - François Vianna
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-SANTE/SDOS/LMDN, Cadarache, F-13115 Saint-Paul-Lez-Durance, France
| | - Haser Hasan Sutcu
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-SANTE/SERAMED/LRAcc, F-92262 Fontenay aux Roses, France
| | - Andriy Khobta
- Institute of Nutritional Sciences, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Didier Busso
- Université Paris Cité et Université Paris-Saclay, INSERM, CEA, iRCM/IBFJ, Genetic Stability, Stem Cells and Radiation, F-92260 Fontenay-aux-Roses, France
| | - J Pablo Radicella
- Université Paris-Saclay, iRCM/IBFJ, CEA, Genetic Stability, Stem Cells and Radiation, F-92260 Fontenay-aux-Roses, France; Université Paris Cité, iRCM/IBFJ, CEA, Genetic Stability, Stem Cells and Radiation, F-92260 Fontenay-aux-Roses, France
| | - Anna Campalans
- Université Paris-Saclay, iRCM/IBFJ, CEA, Genetic Stability, Stem Cells and Radiation, F-92260 Fontenay-aux-Roses, France; Université Paris Cité, iRCM/IBFJ, CEA, Genetic Stability, Stem Cells and Radiation, F-92260 Fontenay-aux-Roses, France.
| | - Céline Baldeyron
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-SANTE/SERAMED/LRAcc, F-92262 Fontenay aux Roses, France.
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Schaich MA, Weaver TM, Roginskaya V, Freudenthal BD, Van Houten B. Single-molecule analysis of purified proteins and nuclear extracts: insights from 8-oxoguanine glycosylase 1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.01.565178. [PMID: 37961208 PMCID: PMC10635064 DOI: 10.1101/2023.11.01.565178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
By observing one molecule at a time, single-molecule studies can offer detailed insights about biomolecular processes including on rates, off rates, and diffusivity of molecules on strands of DNA. A recent technological advance (Single-molecule Analysis of DNA-binding proteins from Nuclear Extracts, SMADNE) has lowered the barrier to entry for single-molecule studies, and single-molecule dynamics can now be determined directly out of nuclear extracts, providing information in an intermediate environment between purified proteins in isolation and the heterogeneity of a nucleus. To compare and contrast the single-molecule DNA binding dynamics in nuclear extracts versus purified proteins, combined optical tweezers and fluorescence microscopy experiments were performed with purified GFP-tagged 8-oxoguanine glycosylase 1 (OGG1), purified GFP-OGG1 spiked into nuclear extracts, and nuclear extracts from human cells overexpressing GFP-OGG1. We observed differences in undamaged DNA binding during DNA damage search in each of the three conditions. Purified GFP-OGG1 engaged undamaged DNA for a weighted average lifetime of 5.7 s and 21% of these events underwent DNA diffusion after binding. However, unlike other glycosylases studied by SMADNE, OGG1 does not bind non-damaged DNA efficiently in nuclear extracts. In contrast, GFP-OGG1 binding dynamics on DNA substrates containing oxidative damage were relatively similar in all three conditions, with the weighted average binding lifetimes varying from 2.2 s in nuclear extracts to 7.8 s with purified GFP-OGG1 in isolation. Finally, we compared the purified protein and nuclear extract approaches for a catalytically dead OGG1 variant (GFP-OGG1-K249Q). This variant greatly increased the binding lifetime for oxidative DNA damage, with the weighted average lifetime for GFP-OGG1-249Q in nuclear extracts at 15.4 s vs 10.7 s for the purified protein. SMADNE will provide a new window of observation into the behavior of nucleic acid binding proteins only accessible by biophysicists trained in protein purification and protein labeling.
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Cintori L, Di Guilmi AM, Canitrot Y, Huet S, Campalans A. Spatio-temporal dynamics of the DNA glycosylase OGG1 in finding and processing 8-oxoguanine. DNA Repair (Amst) 2023; 129:103550. [PMID: 37542751 DOI: 10.1016/j.dnarep.2023.103550] [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: 05/30/2023] [Revised: 07/26/2023] [Accepted: 07/29/2023] [Indexed: 08/07/2023]
Abstract
OGG1 is the DNA glycosylase responsible for the removal of the oxidative lesion 8-oxoguanine (8-oxoG) from DNA. The recognition of this lesion by OGG1 is a complex process that involves scanning the DNA for the presence of 8-oxoG, followed by recognition and lesion removal. Structural data have shown that OGG1 evolves through different stages of conformation onto the DNA, corresponding to elementary steps of the 8-oxoG recognition and extrusion from the double helix. Single-molecule studies of OGG1 on naked DNA have shown that OGG1 slides in persistent contact with the DNA, displaying different binding states probably corresponding to the different conformation stages. However, in cells, the DNA is not naked and OGG1 has to navigate into a complex and highly crowded environment within the nucleus. To ensure rapid detection of 8-oxoG, OGG1 alternates between 3D diffusion and sliding along the DNA. This process is regulated by the local chromatin state but also by protein co-factors that could facilitate the detection of oxidized lesions. We will review here the different methods that have been used over the last years to better understand how OGG1 detects and process 8-oxoG lesions.
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Affiliation(s)
- Luana Cintori
- Molecular, Cellular and Developmental Biology unit, Centre de Biologie Integrative, University of Toulouse, CNRS, F-31062 Toulouse, France
| | - Anne-Marie Di Guilmi
- Université de Paris-Cite, CEA /IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France; Université Paris-Saclay, CEA /IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
| | - Yvan Canitrot
- Molecular, Cellular and Developmental Biology unit, Centre de Biologie Integrative, University of Toulouse, CNRS, F-31062 Toulouse, France
| | - Sebastien Huet
- Université Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, ´ Sante, Innovation Technologique de Rennes) - UMS 3480, US 018, F-35000 Rennes, France; Institut Universitaire de France, Paris, France
| | - Anna Campalans
- Université de Paris-Cite, CEA /IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France; Université Paris-Saclay, CEA /IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France.
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Tessmer I. The roles of non-productive complexes of DNA repair proteins with DNA lesions. DNA Repair (Amst) 2023; 129:103542. [PMID: 37453245 DOI: 10.1016/j.dnarep.2023.103542] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 06/30/2023] [Accepted: 07/07/2023] [Indexed: 07/18/2023]
Abstract
A multitude of different types of lesions is continuously introduced into the DNA inside our cells, and their rapid and efficient repair is fundamentally important for the maintenance of genomic stability and cellular viability. This is achieved by a number of DNA repair systems that each involve different protein factors and employ versatile strategies to target different types of DNA lesions. Intriguingly, specialized DNA repair proteins have also evolved to form non-functional complexes with their target lesions. These proteins allow the marking of innocuous lesions to render them visible for DNA repair systems and can serve to directly recruit DNA repair cascades. Moreover, they also provide links between different DNA repair mechanisms or even between DNA lesions and transcription regulation. I will focus here in particular on recent findings from single molecule analyses on the alkyltransferase-like protein ATL, which is believed to initiate nucleotide excision repair (NER) of non-native NER target lesions, and the base excision repair (BER) enzyme hOGG1, which recruits the oncogene transcription factor Myc to gene promoters under oxidative stress.
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Affiliation(s)
- Ingrid Tessmer
- Rudolf Virchow Center, University of Würzburg, Josef Schneider Str. 2, 97080 Würzburg, Germany
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17
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Diao L, Liu M. Rethinking Antigen Source: Cancer Vaccines Based on Whole Tumor Cell/tissue Lysate or Whole Tumor Cell. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2300121. [PMID: 37254712 PMCID: PMC10401146 DOI: 10.1002/advs.202300121] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/29/2023] [Indexed: 06/01/2023]
Abstract
Cancer immunotherapies have improved human health, and one among the important technologies for cancer immunotherapy is cancer vaccine. Antigens are the most important components in cancer vaccines. Generally, antigens in cancer vaccines can be divided into two categories: pre-defined antigens and unidentified antigens. Although, cancer vaccines loaded with predefined antigens are commonly used, cancer vaccine loaded with mixed unidentified antigens, especially whole cancer cells or cancer cell lysates, is a very promising approach, and such vaccine can obviate some limitations in cancer vaccines. Their advantages include, but are not limited to, the inclusion of pan-spectra (all or most kinds of) antigens, inducing pan-clones specific T cells, and overcoming the heterogeneity of cancer cells. In this review, the recent advances in cancer vaccines based on whole-tumor antigens, either based on whole cancer cells or whole cancer cell lysates, are summarized. In terms of whole cancer cell lysates, the focus is on applying whole water-soluble cell lysates as antigens. Recently, utilizing the whole cancer cell lysates as antigens in cancer vaccines has become feasible. Considering that pre-determined antigen-based cancer vaccines (mainly peptide-based or mRNA-based) have various limitations, developing cancer vaccines based on whole-tumor antigens is a promising alternative.
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Affiliation(s)
- Lu Diao
- Department of PharmaceuticsCollege of Pharmaceutical Sciences, Soochow University199 of Ren ai RoadSuzhouJiangsu215123P. R. China
- Kunshan Hospital of Traditional Chinese MedicineKunshanJiangsu215300P. R. China
- Suzhou Ersheng Biopharmaceutical Co., Ltd.Suzhou215123P. R. China
| | - Mi Liu
- Department of PharmaceuticsCollege of Pharmaceutical Sciences, Soochow University199 of Ren ai RoadSuzhouJiangsu215123P. R. China
- Kunshan Hospital of Traditional Chinese MedicineKunshanJiangsu215300P. R. China
- Suzhou Ersheng Biopharmaceutical Co., Ltd.Suzhou215123P. R. China
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18
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Irvin EM, Wang H. Single-molecule imaging of genome maintenance proteins encountering specific DNA sequences and structures. DNA Repair (Amst) 2023; 128:103528. [PMID: 37392578 PMCID: PMC10989508 DOI: 10.1016/j.dnarep.2023.103528] [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: 04/08/2023] [Revised: 06/08/2023] [Accepted: 06/21/2023] [Indexed: 07/03/2023]
Abstract
DNA repair pathways are tightly regulated processes that recognize specific hallmarks of DNA damage and coordinate lesion repair through discrete mechanisms, all within the context of a three-dimensional chromatin landscape. Dysregulation or malfunction of any one of the protein constituents in these pathways can contribute to aging and a variety of diseases. While the collective action of these many proteins is what drives DNA repair on the organismal scale, it is the interactions between individual proteins and DNA that facilitate each step of these pathways. In much the same way that ensemble biochemical techniques have characterized the various steps of DNA repair pathways, single-molecule imaging (SMI) approaches zoom in further, characterizing the individual protein-DNA interactions that compose each pathway step. SMI techniques offer the high resolving power needed to characterize the molecular structure and functional dynamics of individual biological interactions on the nanoscale. In this review, we highlight how our lab has used SMI techniques - traditional atomic force microscopy (AFM) imaging in air, high-speed AFM (HS-AFM) in liquids, and the DNA tightrope assay - over the past decade to study protein-nucleic acid interactions involved in DNA repair, mitochondrial DNA replication, and telomere maintenance. We discuss how DNA substrates containing specific DNA sequences or structures that emulate DNA repair intermediates or telomeres were generated and validated. For each highlighted project, we discuss novel findings made possible by the spatial and temporal resolution offered by these SMI techniques and unique DNA substrates.
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Affiliation(s)
| | - Hong Wang
- Toxicology Program, North Carolina State University, Raleigh, NC, USA; Physics Department, North Carolina State University, Raleigh, NC, USA; Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA.
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Wan L, Toland S, Robinson-McCarthy LR, Lee N, Schaich MA, Hengel SR, Li X, Bernstein KA, Van Houten B, Chang Y, Moore PS. Unlicensed origin DNA melting by MCV and SV40 polyomavirus LT proteins is independent of ATP-dependent helicase activity. Proc Natl Acad Sci U S A 2023; 120:e2308010120. [PMID: 37459531 PMCID: PMC10372695 DOI: 10.1073/pnas.2308010120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 06/21/2023] [Indexed: 07/20/2023] Open
Abstract
Cellular eukaryotic replication initiation helicases are first loaded as head-to-head double hexamers on double-stranded (ds) DNA origins and then initiate S-phase DNA melting during licensed (once per cell cycle) replication. Merkel cell polyomavirus (MCV) large T (LT) helicase oncoprotein similarly binds and melts its own 98-bp origin but replicates multiple times in a single cell cycle. To examine the actions of this unlicensed viral helicase, we quantitated multimerization of MCV LT molecules as they assembled on MCV DNA origins using real-time single-molecule microscopy. MCV LT formed highly stable double hexamers having 17-fold longer mean lifetime (τ, >1,500 s) on DNA than single hexamers. Unexpectedly, partial MCV LT assembly without double-hexamer formation was sufficient to melt origin dsDNA as measured by RAD51, RPA70, or S1 nuclease cobinding. DNA melting also occurred with truncated MCV LT proteins lacking the helicase domain, but was lost from a protein without the multimerization domain that could bind only as a monomer to DNA. SV40 polyomavirus LT also multimerized to the MCV origin without forming a functional hexamer but still melted origin DNA. MCV origin melting did not require ATP hydrolysis and occurred for both MCV and SV40 LT proteins using the nonhydrolyzable ATP analog, adenylyl-imidodiphosphate (AMP-PNP). LT double hexamers formed in AMP-PNP, and melted DNA, consistent with direct LT hexamer assembly around single-stranded (ss) DNA without the energy-dependent dsDNA-to-ssDNA melting and remodeling steps used by cellular helicases. These results indicate that LT multimerization rather than helicase activity is required for origin DNA melting during unlicensed virus replication.
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Affiliation(s)
- Li Wan
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
| | - Sabrina Toland
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
| | | | - Nara Lee
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA15219
| | - Matthew A. Schaich
- Genome Stability Program, Hillman Cancer Center, Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA15232
| | - Sarah R. Hengel
- Department of Pharmacology, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15232
| | - Xiaochen Li
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
- School of Medicine, Tsinghua University, Beijing100084, China
| | - Kara A. Bernstein
- Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA19104
| | - Bennett Van Houten
- Genome Stability Program, Hillman Cancer Center, Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA15232
| | - Yuan Chang
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
| | - Patrick S. Moore
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
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Raja SJ, Van Houten B. UV-DDB as a General Sensor of DNA Damage in Chromatin: Multifaceted Approaches to Assess Its Direct Role in Base Excision Repair. Int J Mol Sci 2023; 24:10168. [PMID: 37373320 PMCID: PMC10298998 DOI: 10.3390/ijms241210168] [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: 05/26/2023] [Revised: 06/12/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023] Open
Abstract
Base excision repair (BER) is a cellular process that removes damaged bases arising from exogenous and endogenous sources including reactive oxygen species, alkylation agents, and ionizing radiation. BER is mediated by the actions of multiple proteins which work in a highly concerted manner to resolve DNA damage efficiently to prevent toxic repair intermediates. During the initiation of BER, the damaged base is removed by one of 11 mammalian DNA glycosylases, resulting in abasic sites. Many DNA glycosylases are product-inhibited by binding to the abasic site more avidly than the damaged base. Traditionally, apurinic/apyrimidinic endonuclease 1, APE1, was believed to help turn over the glycosylases to undergo multiple rounds of damaged base removal. However, in a series of papers from our laboratory, we have demonstrated that UV-damaged DNA binding protein (UV-DDB) stimulates the glycosylase activities of human 8-oxoguanine glycosylase (OGG1), MUTY DNA glycosylase (MUTYH), alkyladenine glycosylase/N-methylpurine DNA glycosylase (AAG/MPG), and single-strand selective monofunctional glycosylase (SMUG1), between three- and five-fold. Moreover, we have shown that UV-DDB can assist chromatin decompaction, facilitating access of OGG1 to 8-oxoguanine damage in telomeres. This review summarizes the biochemistry, single-molecule, and cell biology approaches that our group used to directly demonstrate the essential role of UV-DDB in BER.
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Affiliation(s)
- Sripriya J. Raja
- Molecular Pharmacology Graduate Program, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA;
- UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Bennett Van Houten
- Molecular Pharmacology Graduate Program, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA;
- UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
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