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Huber J, Tanasie NL, Zernia S, Stigler J. Single-molecule imaging reveals a direct role of CTCF's zinc fingers in SA interaction and cluster-dependent RNA recruitment. Nucleic Acids Res 2024; 52:6490-6506. [PMID: 38742641 PMCID: PMC11194110 DOI: 10.1093/nar/gkae391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/21/2024] [Accepted: 05/01/2024] [Indexed: 05/16/2024] Open
Abstract
CTCF is a zinc finger protein associated with transcription regulation that also acts as a barrier factor for topologically associated domains (TADs) generated by cohesin via loop extrusion. These processes require different properties of CTCF-DNA interaction, and it is still unclear how CTCF's structural features may modulate its diverse roles. Here, we employ single-molecule imaging to study both full-length CTCF and truncation mutants. We show that CTCF enriches at CTCF binding sites (CBSs), displaying a longer lifetime than observed previously. We demonstrate that the zinc finger domains mediate CTCF clustering and that clustering enables RNA recruitment, possibly creating a scaffold for interaction with RNA-binding proteins like cohesin's subunit SA. We further reveal a direct recruitment and an increase of SA residence time by CTCF bound at CBSs, suggesting that CTCF-SA interactions are crucial for cohesin stability on chromatin at TAD borders. Furthermore, we establish a single-molecule T7 transcription assay and show that although a transcribing polymerase can remove CTCF from CBSs, transcription is impaired. Our study shows that context-dependent nucleic acid binding determines the multifaceted CTCF roles in genome organization and transcription regulation.
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Affiliation(s)
- Jonas Huber
- Gene Center Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Sarah Zernia
- Gene Center Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Johannes Stigler
- Gene Center Munich, Ludwig-Maximilians-Universität München, Munich, Germany
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2
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Wulfridge P, Yan Q, Rell N, Doherty J, Jacobson S, Offley S, Deliard S, Feng K, Phillips-Cremins JE, Gardini A, Sarma K. G-quadruplexes associated with R-loops promote CTCF binding. Mol Cell 2023; 83:3064-3079.e5. [PMID: 37552993 PMCID: PMC10529333 DOI: 10.1016/j.molcel.2023.07.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 03/24/2023] [Accepted: 07/07/2023] [Indexed: 08/10/2023]
Abstract
CTCF is a critical regulator of genome architecture and gene expression that binds thousands of sites on chromatin. CTCF genomic localization is controlled by the recognition of a DNA sequence motif and regulated by DNA modifications. However, CTCF does not bind to all its potential sites in all cell types, raising the question of whether the underlying chromatin structure can regulate CTCF occupancy. Here, we report that R-loops facilitate CTCF binding through the formation of associated G-quadruplex (G4) structures. R-loops and G4s co-localize with CTCF at many genomic regions in mouse embryonic stem cells and promote CTCF binding to its cognate DNA motif in vitro. R-loop attenuation reduces CTCF binding in vivo. Deletion of a specific G4-forming motif in a gene reduces CTCF binding and alters gene expression. Conversely, chemical stabilization of G4s results in CTCF gains and accompanying alterations in chromatin organization, suggesting a pivotal role for G4 structures in reinforcing long-range genome interactions through CTCF.
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Affiliation(s)
- Phillip Wulfridge
- Gene expression and Regulation program, The Wistar Institute, Philadelphia, PA 19104, USA; Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Qingqing Yan
- Gene expression and Regulation program, The Wistar Institute, Philadelphia, PA 19104, USA; Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nathaniel Rell
- Gene expression and Regulation program, The Wistar Institute, Philadelphia, PA 19104, USA; Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - John Doherty
- Gene expression and Regulation program, The Wistar Institute, Philadelphia, PA 19104, USA; Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Skye Jacobson
- Gene expression and Regulation program, The Wistar Institute, Philadelphia, PA 19104, USA; Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sarah Offley
- Gene expression and Regulation program, The Wistar Institute, Philadelphia, PA 19104, USA; Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sandra Deliard
- Gene expression and Regulation program, The Wistar Institute, Philadelphia, PA 19104, USA
| | - Kelly Feng
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jennifer E Phillips-Cremins
- Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Alessandro Gardini
- Gene expression and Regulation program, The Wistar Institute, Philadelphia, PA 19104, USA
| | - Kavitha Sarma
- Gene expression and Regulation program, The Wistar Institute, Philadelphia, PA 19104, USA; Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA.
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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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Dubrovin EV, Dadinova LA, Petoukhov MV, Soshinskaya EY, Mozhaev AA, Klinov DV, Schäffer TE, Shtykova EV, Batishchev OV. Spatial organization of Dps and DNA-Dps complexes. J Mol Biol 2021; 433:166930. [PMID: 33713674 DOI: 10.1016/j.jmb.2021.166930] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 02/24/2021] [Accepted: 03/05/2021] [Indexed: 02/04/2023]
Abstract
DNA co-crystallization with Dps family proteins is a fundamental mechanism, which preserves DNA in bacteria from harsh conditions. Though many aspects of this phenomenon are well characterized, the spatial organization of DNA in DNA-Dps co-crystals is not completely understood, and existing models need further clarification. To advance in this problem we have utilized atomic force microscopy (AFM) as the main structural tool, and small-angle X-scattering (SAXS) to characterize Dps as a key component of the DNA-protein complex. SAXS analysis in the presence of EDTA indicates a significantly larger radius of gyration for Dps than would be expected for the core of the dodecamer, consistent with the N-terminal regions extending out into solution and being accessible for interaction with DNA. In AFM experiments, both Dps protein molecules and DNA-Dps complexes adsorbed on mica or highly oriented pyrolytic graphite (HOPG) surfaces form densely packed hexagonal structures with a characteristic size of about 9 nm. To shed light on the peculiarities of DNA interaction with Dps molecules, we have characterized individual DNA-Dps complexes. Contour length evaluation has confirmed the non-specific character of Dps binding with DNA and revealed that DNA does not wrap Dps molecules in DNA-Dps complexes. Angle analysis has demonstrated that in DNA-Dps complexes a Dps molecule contacts with a DNA segment of ~6 nm in length. Consideration of DNA condensation upon complex formation with small Dps quasi-crystals indicates that DNA may be arranged along the rows of ordered protein molecules on a Dps sheet.
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Affiliation(s)
- Evgeniy V Dubrovin
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy prospekt, Moscow 119071, Russia; Lomonosov Moscow State University, Faculty of Physics, Leninskie Gory 1 bld 2, 119991 Moscow, Russia.
| | - Liubov A Dadinova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics," Russian Academy of Sciences, 119333 Moscow, Russia
| | - Maxim V Petoukhov
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics," Russian Academy of Sciences, 119333 Moscow, Russia
| | - Ekaterina Yu Soshinskaya
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics," Russian Academy of Sciences, 119333 Moscow, Russia
| | - Andrey A Mozhaev
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics," Russian Academy of Sciences, 119333 Moscow, Russia; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Dmitry V Klinov
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Malaya Pirogovskaya 1a, 119435 Moscow, Russia
| | - Tilman E Schäffer
- University of Tübingen, Institute of Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Eleonora V Shtykova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics," Russian Academy of Sciences, 119333 Moscow, Russia
| | - Oleg V Batishchev
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy prospekt, Moscow 119071, Russia
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Ramani V, Qiu R, Shendure J. High Sensitivity Profiling of Chromatin Structure by MNase-SSP. Cell Rep 2020; 26:2465-2476.e4. [PMID: 30811994 PMCID: PMC6582983 DOI: 10.1016/j.celrep.2019.02.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 11/07/2018] [Accepted: 02/01/2019] [Indexed: 12/11/2022] Open
Abstract
A complete view of eukaryotic gene regulation requires that we accurately delineate how transcription factors (TFs) and nucleosomes are arranged along linear DNA in a sensitive, unbiased manner. Here we introduce MNase-SSP, a single-stranded sequencing library preparation method for nuclease-digested chromatin that enables simultaneous mapping of TF and nucleosome positions. As a proof of concept, we apply MNase-SSP toward the genome-wide, high-resolution mapping of nucleosome and TF occupancy in murine embryonic stem cells (mESCs). Compared with existing MNase-seq protocols, MNase-SSP markedly enriches for short DNA fragments, enabling detection of binding by subnucleosomal particles and TFs, in addition to nucleosomes. From these same data, we identify multiple, sequence-dependent binding modes of the architectural TF Ctcf and extend this analysis to the TF Nrsf/ Rest. Looking forward, we anticipate that single stranded protocol (SSP) adaptations of any protein-DNA interaction mapping technique (e.g., ChIP-exo and CUT&RUN) will enhance the information content of the resulting data. Ramani et al. describe MNase-SSP, a single-stranded DNA sequencing library preparation method for profiling chromatin structure. MNase-SSP libraries harbor diminished sequence bias and capture shorter DNA fragments compared to traditional MNase-seq libraries. Applying MNase-SSP to murine embryonic stem cells enables simultaneous analysis of nucleosomal, subnucleosomal, and transcription factor-DNA interactions genome-wide.
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Affiliation(s)
- Vijay Ramani
- Department of Genome Sciences, University of Washington, Seattle, WA, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA.
| | - Ruolan Qiu
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA; Brotman-Baty Institute for Precision Medicine, Seattle, WA, USA; Howard Hughes Medical Institute, Seattle, WA, USA.
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Wang DC, Wang W, Zhang L, Wang X. A tour of 3D genome with a focus on CTCF. Semin Cell Dev Biol 2019; 90:4-11. [PMID: 30031214 DOI: 10.1016/j.semcdb.2018.07.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 07/17/2018] [Indexed: 12/19/2022]
Abstract
The complex three-dimensional (3D) structure of the genome plays critical roles in the maintenance of genome stability, organization, and dynamics and in regulation of gene expression for understanding molecular mechanisms and diseases. Chromatin maintains biological functions and transcriptional activities through long distance interaction and interactions between loops and enhancers-promoters. We firstly overview the architecture and biology of chromatin and loops, topologically associated domains (TADs) and interactions, and compartments and functions. We specifically focus on CCCTC-binding factor (CTCF) in 3D genome organization and function to furthermore understand the significance of CTCF biology, transcriptional regulations, interactions with cohesin, roles in DNA binding, influences of CTCF degradation, and communication with wings-apart like (Wapl) protein. We also summarize the advanced single cell approaches to further monitor dynamics of CTCF functions and structures in the maintenance of 3D genome organization and function at single cell level.
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Affiliation(s)
- Diane C Wang
- Zhongshan Hospital Institute of Clinical Science, Zhongshan Hospital, Fudan University Medical School, Shanghai Institute of Clinical Bioinformatics Shanghai, China
| | - William Wang
- Zhongshan Hospital Institute of Clinical Science, Zhongshan Hospital, Fudan University Medical School, Shanghai Institute of Clinical Bioinformatics Shanghai, China
| | - Linlin Zhang
- Zhongshan Hospital Institute of Clinical Science, Zhongshan Hospital, Fudan University Medical School, Shanghai Institute of Clinical Bioinformatics Shanghai, China
| | - Xiangdong Wang
- Zhongshan Hospital Institute of Clinical Science, Zhongshan Hospital, Fudan University Medical School, Shanghai Institute of Clinical Bioinformatics Shanghai, China.
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Abstract
Studies of 3D chromatin organization have suggested that chromosomes are hierarchically organized into large compartments composed of smaller domains called topologically associating domains (TADs). Recent evidence suggests that compartments are smaller than previously thought and that the transcriptional or chromatin state is responsible for interactions leading to the formation of small compartmental domains in all organisms. In vertebrates, CTCF forms loop domains, probably via an extrusion process involving cohesin. CTCF loops cooperate with compartmental domains to establish the 3D organization of the genome. The continuous extrusion of the chromatin fibre by cohesin may also be responsible for the establishment of enhancer-promoter interactions and stochastic aspects of the transcription process. These observations suggest that the 3D organization of the genome is an emergent property of chromatin and its components, and thus may not be only a determinant but also a consequence of its function.
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Luo Z, Wang Y, Li S, Yang G. DNA Phase Transition in Charge Neutralization and Comformation Induced by Trivalent-Hydrolysed Metal Ions. Polymers (Basel) 2018; 10:E394. [PMID: 30966429 PMCID: PMC6415217 DOI: 10.3390/polym10040394] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/10/2018] [Accepted: 03/29/2018] [Indexed: 01/26/2023] Open
Abstract
It is well known that common trivalent counter ions can induce DNA compaction or condensation but are unable to invert DNA surface charge in a normal aqueous solution. In the present study, we found that trivalent-hydrolysed metal ions (Fe3+, Al3+) are not only capable of inducing DNA condensation, but they also invert the electrophoretic mobility of DNA by electrophoretic light scattering and single molecular techniques. In comparison with neutral trivalent cations, hydrolysed metal ions such as Fe3+ can induce DNA condensation at a much lower concentration of cations, and its corresponding morphology of condensed DNA was directly observed by atomic force microscopy (AFM). The condensing and unravelling forces of DNA condensates were measured by tethering DNA by magnetic tweezers (MT) measurements at various concentration of Fe3+ and Al3+. We found that a coil⁻globule transition of DNA by hydrolysed metal ions not only was observed in DNA-complex sizes, but also in the curve of electrophoretic mobility of DNA in solution. In contrast, the transition was not observed in the case of neutral trivalent cations such as La3+ and Co3+. We attribute the transition and charge inversion to the ion-specific interaction between hydrolysed metal ions and phosphates of DNA backbone.
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Affiliation(s)
- Zhaoxu Luo
- College of Mathematical, Physics and Electronic Information Engineering, Wenzhou University, Wenzhou 325035, China.
| | - Yanwei Wang
- College of Mathematical, Physics and Electronic Information Engineering, Wenzhou University, Wenzhou 325035, China.
| | - Shuhang Li
- College of Mathematical, Physics and Electronic Information Engineering, Wenzhou University, Wenzhou 325035, China.
| | - Guangcan Yang
- College of Mathematical, Physics and Electronic Information Engineering, Wenzhou University, Wenzhou 325035, China.
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