1
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Chua GNL, Watters JW, Olinares PDB, Begum M, Vostal LE, Luo JA, Chait BT, Liu S. Differential dynamics specify MeCP2 function at nucleosomes and methylated DNA. Nat Struct Mol Biol 2024:10.1038/s41594-024-01373-9. [PMID: 39164525 DOI: 10.1038/s41594-024-01373-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 07/16/2024] [Indexed: 08/22/2024]
Abstract
Methyl-CpG-binding protein 2 (MeCP2) is an essential chromatin-binding protein whose mutations cause Rett syndrome (RTT), a severe neurological disorder that primarily affects young females. The canonical view of MeCP2 as a DNA methylation-dependent transcriptional repressor has proven insufficient to describe its dynamic interaction with chromatin and multifaceted roles in genome organization and gene expression. Here we used single-molecule correlative force and fluorescence microscopy to directly visualize the dynamics of wild-type and RTT-causing mutant MeCP2 on DNA. We discovered that MeCP2 exhibits distinct one-dimensional diffusion kinetics when bound to unmethylated versus CpG methylated DNA, enabling methylation-specific activities such as co-repressor recruitment. We further found that, on chromatinized DNA, MeCP2 preferentially localizes to nucleosomes and stabilizes them from mechanical perturbation. Our results reveal the multimodal behavior of MeCP2 on chromatin that underlies its DNA methylation- and nucleosome-dependent functions and provide a biophysical framework for dissecting the molecular pathology of RTT mutations.
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Affiliation(s)
- Gabriella N L Chua
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY, USA
- Tri-Institutional PhD Program in Chemical Biology, New York, NY, USA
| | - John W Watters
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY, USA
| | - Paul Dominic B Olinares
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY, USA
| | - Masuda Begum
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY, USA
| | - Lauren E Vostal
- Tri-Institutional PhD Program in Chemical Biology, New York, NY, USA
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Joshua A Luo
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY, USA
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY, USA
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY, USA.
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2
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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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3
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Park G, Patel AB, Wu C, Louder RK. Structures of H2A.Z-associated human chromatin remodelers SRCAP and TIP60 reveal divergent mechanisms of chromatin engagement. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.30.605802. [PMID: 39131301 PMCID: PMC11312561 DOI: 10.1101/2024.07.30.605802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
H2A.Z is a conserved histone variant that is localized to specific genomic regions where it plays important roles in transcription, DNA repair, and replication. Central to the biochemistry of human H2A.Z are the SRCAP and TIP60 chromatin remodelers, homologs of yeast SWR1 which catalyzes ATP-dependent H2A.Z exchange. Here, we use cryo-electron microscopy to resolve six structural states of the native SRCAP complex, uncovering conformational intermediates interpreted as a stepwise path to full nucleosome engagement. We also resolve the structure of the native TIP60 complex which consists of a structured core from which flexibly tethered chromatin binding domains emerge. Despite the shared subunit composition, the core of TIP60 displays divergent architectures from SRCAP that structurally disfavor nucleosome engagement, suggesting a distinct biochemical function.
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Affiliation(s)
- Giho Park
- Biochemistry, Cellular and Molecular Graduate Program, Johns Hopkins School of Medicine; Baltimore, MD 21205, USA
- Department of Molecular Biology and Genetics, Johns Hopkins School of Medicine; Baltimore, MD 21205, USA
| | - Avinash B. Patel
- Department of Biophysics, Johns Hopkins University; Baltimore, MD 21218, USA
| | - Carl Wu
- Department of Molecular Biology and Genetics, Johns Hopkins School of Medicine; Baltimore, MD 21205, USA
- Department of Biology, Johns Hopkins University; Baltimore, MD 21218, USA
| | - Robert K. Louder
- Department of Molecular Biology and Genetics, Johns Hopkins School of Medicine; Baltimore, MD 21205, USA
- Department of Biology, Johns Hopkins University; Baltimore, MD 21218, USA
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4
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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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5
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Feng XA, Yamadi M, Fu Y, Ness KM, Liu C, Ahmed I, Bowman GD, Johnson ME, Ha T, Wu C. GAGA zinc finger transcription factor searches chromatin by 1D-3D facilitated diffusion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.14.549009. [PMID: 37502885 PMCID: PMC10369947 DOI: 10.1101/2023.07.14.549009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
To elucidate how eukaryotic sequence-specific transcription factors (TFs) search for gene targets on chromatin, we used multi-color smFRET and single-particle imaging to track the diffusion of purified GAGA-Associated Factor (GAF) on DNA and nucleosomes. Monomeric GAF DNA-binding domain (DBD) bearing one zinc finger finds its cognate site by 1D or 3D diffusion on bare DNA and rapidly slides back-and-forth between naturally clustered motifs for seconds before escape. Multimeric, full-length GAF also finds clustered motifs on DNA by 1D-3D diffusion, but remains locked on target for longer periods. Nucleosome architecture effectively blocks GAF-DBD 1D-sliding into the histone core but favors retention of GAF-DBD when targeting solvent-exposed sites by 3D-diffusion. Despite the occlusive power of nucleosomes, 1D-3D facilitated diffusion enables GAF to effectively search for clustered cognate motifs in chromatin, providing a mechanism for navigation to nucleosome and nucleosome-free sites by a member of the largest TF family.
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Affiliation(s)
- Xinyu A Feng
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Maryam Yamadi
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Yiben Fu
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Kaitlin M Ness
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Celina Liu
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Ishtiyaq Ahmed
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Gregory D Bowman
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Margaret E Johnson
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Taekjip Ha
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
- 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, United States
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Boston, Massachusetts, USA
| | - Carl Wu
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
- Department of Molecular Biology and Genetics, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
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6
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Kim JM, Carcamo CC, Jazani S, Xie Z, Feng XA, Yamadi M, Poyton M, Holland KL, Grimm JB, Lavis LD, Ha T, Wu C. Dynamic 1D search and processive nucleosome translocations by RSC and ISW2 chromatin remodelers. eLife 2024; 12:RP91433. [PMID: 38497611 PMCID: PMC10948146 DOI: 10.7554/elife.91433] [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] [Indexed: 03/19/2024] Open
Abstract
Eukaryotic gene expression is linked to chromatin structure and nucleosome positioning by ATP-dependent chromatin remodelers that establish and maintain nucleosome-depleted regions (NDRs) near transcription start sites. Conserved yeast RSC and ISW2 remodelers exert antagonistic effects on nucleosomes flanking NDRs, but the temporal dynamics of remodeler search, engagement, and directional nucleosome mobilization for promoter accessibility are unknown. Using optical tweezers and two-color single-particle imaging, we investigated the Brownian diffusion of RSC and ISW2 on free DNA and sparse nucleosome arrays. RSC and ISW2 rapidly scan DNA by one-dimensional hopping and sliding, respectively, with dynamic collisions between remodelers followed by recoil or apparent co-diffusion. Static nucleosomes block remodeler diffusion resulting in remodeler recoil or sequestration. Remarkably, both RSC and ISW2 use ATP hydrolysis to translocate mono-nucleosomes processively at ~30 bp/s on extended linear DNA under tension. Processivity and opposing push-pull directionalities of nucleosome translocation shown by RSC and ISW2 shape the distinctive landscape of promoter chromatin.
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Affiliation(s)
- Jee Min Kim
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Claudia C Carcamo
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Sina Jazani
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Zepei Xie
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Xinyu A Feng
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Maryam Yamadi
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Matthew Poyton
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Katie L Holland
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Jonathan B Grimm
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of MedicineBaltimoreUnited States
- Howard Hughes Medical InstituteBostonUnited States
| | - Carl Wu
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
- Department of Molecular Biology and Genetics, Johns Hopkins School of MedicineBaltimoreUnited States
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7
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Yu J, Sui F, Gu F, Li W, Yu Z, Wang Q, He S, Wang L, Xu Y. Structural insights into histone exchange by human SRCAP complex. Cell Discov 2024; 10:15. [PMID: 38331872 PMCID: PMC10853557 DOI: 10.1038/s41421-023-00640-1] [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: 09/13/2023] [Accepted: 12/18/2023] [Indexed: 02/10/2024] Open
Abstract
Histone variant H2A.Z is found at promoters and regulates transcription. The ATP-dependent chromatin remodeler SRCAP complex (SRCAP-C) promotes the replacement of canonical histone H2A-H2B dimer with H2A.Z-H2B dimer. Here, we determined structures of human SRCAP-C bound to H2A-containing nucleosome at near-atomic resolution. The SRCAP subunit integrates a 6-subunit actin-related protein (ARP) module and an ATPase-containing motor module. The ATPase-associated ARP module encircles half of the nucleosome along the DNA and may restrain net DNA translocation, a unique feature of SRCAP-C. The motor module adopts distinct nucleosome binding modes in the apo (nucleotide-free), ADP-bound, and ADP-BeFx-bound states, suggesting that ATPase-driven movement destabilizes H2A-H2B by unwrapping the entry DNA and pulls H2A-H2B out of nucleosome through the ZNHIT1 subunit. Structure-guided chromatin immunoprecipitation sequencing analysis confirmed the requirement of H2A-contacting ZNHIT1 in maintaining H2A.Z occupancy on the genome. Our study provides structural insights into the mechanism of H2A-H2A.Z exchange mediated by SRCAP-C.
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Affiliation(s)
- Jiali Yu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, China
- The International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology of China, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Fengrui Sui
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, China
| | - Feng Gu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, China
| | - Wanjun Li
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, China
| | - Zishuo Yu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, China
| | - Qianmin Wang
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, China
| | - Shuang He
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, China
| | - Li Wang
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, China.
- Greater Bay Area Institute of Precision Medicine, Fudan University, Nansha District, Guangzhou, Guangdong, China.
| | - Yanhui Xu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, China.
- The International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology of China, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China.
- Greater Bay Area Institute of Precision Medicine, Fudan University, Nansha District, Guangzhou, Guangdong, China.
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8
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Kim JM, Carcamo CC, Jazani S, Xie Z, Feng XA, Yamadi M, Poyton M, Holland KL, Grimm JB, Lavis LD, Ha T, Wu C. Dynamic 1D Search and Processive Nucleosome Translocations by RSC and ISW2 Chromatin Remodelers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.13.544671. [PMID: 38293098 PMCID: PMC10827135 DOI: 10.1101/2023.06.13.544671] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Eukaryotic gene expression is linked to chromatin structure and nucleosome positioning by ATP-dependent chromatin remodelers that establish and maintain nucleosome-depleted regions (NDRs) near transcription start-sites. Conserved yeast RSC and ISW2 remodelers exert antagonistic effects on nucleosomes flanking NDRs, but the temporal dynamics of remodeler search, engagement and directional nucleosome mobilization for promoter accessibility are unknown. Using optical tweezers and 2-color single-particle imaging, we investigated the Brownian diffusion of RSC and ISW2 on free DNA and sparse nucleosome arrays. RSC and ISW2 rapidly scan DNA by one-dimensional hopping and sliding respectively, with dynamic collisions between remodelers followed by recoil or apparent co-diffusion. Static nucleosomes block remodeler diffusion resulting in remodeler recoil or sequestration. Remarkably, both RSC and ISW2 use ATP hydrolysis to translocate mono-nucleosomes processively at ~30 bp/sec on extended linear DNA under tension. Processivity and opposing push-pull directionalities of nucleosome translocation shown by RSC and ISW2 shape the distinctive landscape of promoter chromatin.
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Affiliation(s)
- Jee Min Kim
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Claudia C. Carcamo
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sina Jazani
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Zepei Xie
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Xinyu A. Feng
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Maryam Yamadi
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Matthew Poyton
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Katie L. Holland
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Jonathan B. Grimm
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Luke D. Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Howard Hughes Medical Institute, Boston, Massachusetts, USA
| | - Carl Wu
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Molecular Biology and Genetics, Johns Hopkins School of Medicine, Baltimore, MD 21287, USA
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9
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Converso C, Pierrakeas L, Chan L, Chowdhury S, Kuznetsov VI, Denu JM, Luk E. Nucleic acid sequence contributes to remodeler-mediated targeting of histone H2A.Z. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.06.570360. [PMID: 38106078 PMCID: PMC10723385 DOI: 10.1101/2023.12.06.570360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
The variant histone H2A.Z is inserted into nucleosomes immediately downstream of promoters and is important for transcription. The site-specific deposition of H2A.Z is catalyzed by SWR, a conserved chromatin remodeler with affinity for promoter-proximal nucleosome depleted regions (NDRs) and histone acetylation. By comparing the genomic distribution of H2A.Z in wild-type and SWR-deficient cells, we found that SWR is also responsible for depositing H2A.Z at thousands of non-canonical sites not directly linked to NDRs or histone acetylation. To understand the targeting mechanism of H2A.Z, we presented SWR with a library of nucleosomes isolated from yeast and characterized those preferred by SWR. We found that SWR prefers nucleosomes associated with intergenic over coding regions, especially when polyadenine tracks are present. Insertion of polyadenine sequences into recombinant nucleosomes near the H2A-H2B binding site stimulated the H2A.Z insertion activity of SWR. Therefore, the genome is encoded with information contributing to remodeler-mediated targeting of H2A.Z.
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10
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Biswas A, Basu A. The impact of the sequence-dependent physical properties of DNA on chromatin dynamics. Curr Opin Struct Biol 2023; 83:102698. [PMID: 37696706 DOI: 10.1016/j.sbi.2023.102698] [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: 04/17/2023] [Revised: 07/07/2023] [Accepted: 08/14/2023] [Indexed: 09/13/2023]
Abstract
The local mechanical properties of DNA depend on local sequence. Here we review recent genomic, structural, and computational efforts at deciphering the "mechanical code", i.e., the mapping between sequence and mechanics. We then discuss works that suggest how evolution has exploited the mechanical code to control the energetics of DNA-deforming biological processes such as nucleosome organization, transcription factor binding, DNA supercoiling, gene regulation, and 3D chromatin organization. As a whole, these recent works suggest that DNA sequence in diverse organisms can encode regulatory information governing diverse processes via the mechanical code.
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Affiliation(s)
- Aditi Biswas
- Department of Biosciences, Durham University, Durham, UK
| | - Aakash Basu
- Department of Biosciences, Durham University, Durham, UK.
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11
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Belan O, Greenhough L, Kuhlen L, Anand R, Kaczmarczyk A, Gruszka DT, Yardimci H, Zhang X, Rueda DS, West SC, Boulton SJ. Visualization of direct and diffusion-assisted RAD51 nucleation by full-length human BRCA2 protein. Mol Cell 2023; 83:2925-2940.e8. [PMID: 37499663 PMCID: PMC7615647 DOI: 10.1016/j.molcel.2023.06.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 06/09/2023] [Accepted: 06/26/2023] [Indexed: 07/29/2023]
Abstract
Homologous recombination (HR) is essential for error-free repair of DNA double-strand breaks, perturbed replication forks (RFs), and post-replicative single-stranded DNA (ssDNA) gaps. To initiate HR, the recombination mediator and tumor suppressor protein BRCA2 facilitates nucleation of RAD51 on ssDNA prior to stimulation of RAD51 filament growth by RAD51 paralogs. Although ssDNA binding by BRCA2 has been implicated in RAD51 nucleation, the function of double-stranded DNA (dsDNA) binding by BRCA2 remains unclear. Here, we exploit single-molecule (SM) imaging to visualize BRCA2-mediated RAD51 nucleation in real time using purified proteins. We report that BRCA2 nucleates and stabilizes RAD51 on ssDNA either directly or through an unappreciated diffusion-assisted delivery mechanism involving binding to and sliding along dsDNA, which requires the cooperative action of multiple dsDNA-binding modules in BRCA2. Collectively, our work reveals two distinct mechanisms of BRCA2-dependent RAD51 loading onto ssDNA, which we propose are critical for its diverse functions in maintaining genome stability and cancer suppression.
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Affiliation(s)
- Ondrej Belan
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Luke Greenhough
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Lucas Kuhlen
- Section of Structural Biology, Faculty of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London SW7 2AZ, UK
| | - Roopesh Anand
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Artur Kaczmarczyk
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London W12 0NN, UK; Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London W12 0NN, UK
| | - Dominika T Gruszka
- Single Molecule Imaging of Genome Duplication and Maintenance Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Hasan Yardimci
- Single Molecule Imaging of Genome Duplication and Maintenance Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Faculty of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London SW7 2AZ, UK
| | - David S Rueda
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London W12 0NN, UK; Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London W12 0NN, UK
| | - Stephen C West
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Simon J Boulton
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
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12
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Ball DA, Jalloh B, Karpova TS. Impact of Saccharomyces cerevisiae on the Field of Single-Molecule Biophysics. Int J Mol Sci 2022; 23:ijms232415895. [PMID: 36555532 PMCID: PMC9781480 DOI: 10.3390/ijms232415895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/10/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022] Open
Abstract
Cellular functions depend on the dynamic assembly of protein regulator complexes at specific cellular locations. Single Molecule Tracking (SMT) is a method of choice for the biochemical characterization of protein dynamics in vitro and in vivo. SMT follows individual molecules in live cells and provides direct information about their behavior. SMT was successfully applied to mammalian models. However, mammalian cells provide a complex environment where protein mobility depends on numerous factors that are difficult to control experimentally. Therefore, yeast cells, which are unicellular and well-studied with a small and completely sequenced genome, provide an attractive alternative for SMT. The simplicity of organization, ease of genetic manipulation, and tolerance to gene fusions all make yeast a great model for quantifying the kinetics of major enzymes, membrane proteins, and nuclear and cellular bodies. However, very few researchers apply SMT techniques to yeast. Our goal is to promote SMT in yeast to a wider research community. Our review serves a dual purpose. We explain how SMT is conducted in yeast cells, and we discuss the latest insights from yeast SMT while putting them in perspective with SMT of higher eukaryotes.
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