1
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Byfield FJ, Eftekhari B, Kaymak-Loveless K, Mandal K, Li D, Wells RG, Chen W, Brujic J, Bergamaschi G, Wuite GJL, Patteson AE, Janmey PA. Metabolically intact nuclei are fluidized by the activity of the chromatin remodeling motor BRG1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.12.589275. [PMID: 38659735 PMCID: PMC11042217 DOI: 10.1101/2024.04.12.589275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The structure and dynamics of the cell nucleus regulate nearly every facet of the cell. Changes in nuclear shape limit cell motility and gene expression. Although the nucleus is generally seen as the stiffest organelle in the cell, cells can nevertheless deform the nucleus to large strains by small mechanical stresses. Here, we show that the mechanical response of the cell nucleus exhibits active fluidization that is driven by the BRG 1 motor of the SWI/SNF/BAF chromatin-remodeling complex. Atomic force microscopy measurements show that the nucleus alters stiffness in response to the cell substrate stiffness, which is retained after the nucleus is isolated and that the work of nuclear compression is mostly dissipated rather than elastically stored. Inhibiting BRG 1 stiffens the nucleus and eliminates dissipation and nuclear remodeling both in isolated nuclei and in intact cells. These findings demonstrate a novel link between nuclear motor activity and global nuclear mechanics.
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2
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Eustermann S, Patel AB, Hopfner KP, He Y, Korber P. Energy-driven genome regulation by ATP-dependent chromatin remodellers. Nat Rev Mol Cell Biol 2024; 25:309-332. [PMID: 38081975 DOI: 10.1038/s41580-023-00683-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2023] [Indexed: 03/28/2024]
Abstract
The packaging of DNA into chromatin in eukaryotes regulates gene transcription, DNA replication and DNA repair. ATP-dependent chromatin remodelling enzymes (re)arrange nucleosomes at the first level of chromatin organization. Their Snf2-type motor ATPases alter histone-DNA interactions through a common DNA translocation mechanism. Whether remodeller activities mainly catalyse nucleosome dynamics or accurately co-determine nucleosome organization remained unclear. In this Review, we discuss the emerging mechanisms of chromatin remodelling: dynamic remodeller architectures and their interactions, the inner workings of the ATPase cycle, allosteric regulation and pathological dysregulation. Recent mechanistic insights argue for a decisive role of remodellers in the energy-driven self-organization of chromatin, which enables both stability and plasticity of genome regulation - for example, during development and stress. Different remodellers, such as members of the SWI/SNF, ISWI, CHD and INO80 families, process (epi)genetic information through specific mechanisms into distinct functional outputs. Combinatorial assembly of remodellers and their interplay with histone modifications, histone variants, DNA sequence or DNA-bound transcription factors regulate nucleosome mobilization or eviction or histone exchange. Such input-output relationships determine specific nucleosome positions and compositions with distinct DNA accessibilities and mediate differential genome regulation. Finally, remodeller genes are often mutated in diseases characterized by genome dysregulation, notably in cancer, and we discuss their physiological relevance.
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Affiliation(s)
- Sebastian Eustermann
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Avinash B Patel
- Department of Molecular Biosciences, Robert H. Lurie Comprehensive Cancer Center, Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA
| | - Karl-Peter Hopfner
- Gene Center and Department of Biochemistry, Faculty of Chemistry and Pharmacy, LMU Munich, Munich, Germany
| | - Yuan He
- Department of Molecular Biosciences, Robert H. Lurie Comprehensive Cancer Center, Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA.
| | - Philipp Korber
- Biomedical Center (BMC), Molecular Biology, Faculty of Medicine, LMU Munich, Martinsried, Germany.
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3
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Ahmad K, Brahma S, Henikoff S. Epigenetic pioneering by SWI/SNF family remodelers. Mol Cell 2024; 84:194-201. [PMID: 38016477 PMCID: PMC10842064 DOI: 10.1016/j.molcel.2023.10.045] [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: 07/06/2023] [Revised: 09/20/2023] [Accepted: 10/31/2023] [Indexed: 11/30/2023]
Abstract
In eukaryotic genomes, transcriptional machinery and nucleosomes compete for binding to DNA sequences; thus, a crucial aspect of gene regulatory element function is to modulate chromatin accessibility for transcription factor (TF) and RNA polymerase binding. Recent structural studies have revealed multiple modes of TF engagement with nucleosomes, but how initial "pioneering" results in steady-state DNA accessibility for further TF binding and RNA polymerase II (RNAPII) engagement has been unclear. Even less well understood is how distant sites of open chromatin interact with one another, such as when developmental enhancers activate promoters to release RNAPII for productive elongation. Here, we review evidence for the centrality of the conserved SWI/SNF family of nucleosome remodeling complexes, both in pioneering and in mediating enhancer-promoter contacts. Consideration of the nucleosome unwrapping and ATP hydrolysis activities of SWI/SNF complexes, together with their architectural features, may reconcile steady-state TF occupancy with rapid TF dynamics observed by live imaging.
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Affiliation(s)
- Kami Ahmad
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Sandipan Brahma
- University of Nebraska Medical Center, Department of Genetics, Cell Biology & Anatomy, Omaha, NE, USA
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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4
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Fan H. Single‐molecule tethered particle motion to study
protein‐DNA
interaction. J CHIN CHEM SOC-TAIP 2023. [DOI: 10.1002/jccs.202300051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
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5
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Abstract
In anaphase, any unresolved DNA entanglements between the segregating sister chromatids can give rise to chromatin bridges. To prevent genome instability, chromatin bridges must be resolved prior to cytokinesis. The SNF2 protein PICH has been proposed to play a direct role in this process through the remodeling of nucleosomes. However, direct evidence of nucleosome remodeling by PICH has remained elusive. Here, we present an in vitro single-molecule assay that mimics chromatin under tension, as is found in anaphase chromatin bridges. Applying a combination of dual-trap optical tweezers and fluorescence imaging of PICH and histones bound to a nucleosome-array construct, we show that PICH is a tension- and ATP-dependent nucleosome remodeler that facilitates nucleosome unwrapping and then subsequently slides remaining histones along the DNA. This work elucidates the role of PICH in chromatin-bridge dissolution, and might provide molecular insights into the mechanisms of related SNF2 proteins.
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6
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Assignment of structural transitions during mechanical unwrapping of nucleosomes and their disassembly products. Proc Natl Acad Sci U S A 2022; 119:e2206513119. [PMID: 35939666 PMCID: PMC9388122 DOI: 10.1073/pnas.2206513119] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Nucleosomes, the fundamental structural unit of chromatin, consists of ∼147 DNA base pairs wrapped around a histone protein octamer. To characterize the strength of the nucleosomal barrier and its contribution as a mechanism of control of gene expression, it is essential to determine the forces required to unwrap the DNA from the core particle and the stepwise transitions involved. In this study, we performed combined optical tweezers and single-molecule fluorescence measurements to identify the specific DNA segments unwrapped during the force transitions observed in mechanical stretching of nucleosomes. Furthermore, we characterize the mechanical signatures of subnucleosomal hexasomes and tetrasomes. The characterization performed in this work is essential for the interpretation of ongoing studies of chromatin remodelers, polymerases, and histone chaperones. Nucleosome DNA unwrapping and its disassembly into hexasomes and tetrasomes is necessary for genomic access and plays an important role in transcription regulation. Previous single-molecule mechanical nucleosome unwrapping revealed a low- and a high-force transitions, and force-FRET pulling experiments showed that DNA unwrapping is asymmetric, occurring always first from one side before the other. However, the assignment of DNA segments involved in these transitions remains controversial. Here, using high-resolution optical tweezers with simultaneous single-molecule FRET detection, we show that the low-force transition corresponds to the undoing of the outer wrap of one side of the nucleosome (∼27 bp), a process that can occur either cooperatively or noncooperatively, whereas the high-force transition corresponds to the simultaneous unwrapping of ∼76 bp from both sides. This process may give rise stochastically to the disassembly of nucleosomes into hexasomes and tetrasomes whose unwrapping/rewrapping trajectories we establish. In contrast, nucleosome rewrapping does not exhibit asymmetry. To rationalize all previous nucleosome unwrapping experiments, it is necessary to invoke that mechanical unwrapping involves two nucleosome reorientations: one that contributes to the change in extension at the low-force transition and another that coincides but does not contribute to the high-force transition.
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7
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Bylino OV, Ibragimov AN, Digilio FA, Giordano E, Shidlovskii YV. Application of the 3C Method to Study the Developmental Genes in Drosophila Larvae. Front Genet 2022; 13:734208. [PMID: 35910225 PMCID: PMC9335292 DOI: 10.3389/fgene.2022.734208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 06/08/2022] [Indexed: 11/13/2022] Open
Abstract
A transition from one developmental stage to another is accompanied by activation of developmental programs and corresponding gene ensembles. Changes in the spatial conformation of the corresponding loci are associated with this activation and can be investigated with the help of the Chromosome Conformation Capture (3C) methodology. Application of 3C to specific developmental stages is a sophisticated task. Here, we describe the use of the 3C method to study the spatial organization of developmental loci in Drosophila larvae. We critically analyzed the existing protocols and offered our own solutions and the optimized protocol to overcome limitations. To demonstrate the efficiency of our procedure, we studied the spatial organization of the developmental locus Dad in 3rd instar Drosophila larvae. Differences in locus conformation were found between embryonic cells and living wild-type larvae. We also observed the establishment of novel regulatory interactions in the presence of an adjacent transgene upon activation of its expression in larvae. Our work fills the gap in the application of the 3C method to Drosophila larvae and provides a useful guide for establishing 3C on an animal model.
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Affiliation(s)
- Oleg V. Bylino
- Department of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Airat N. Ibragimov
- Department of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | | | - Ennio Giordano
- Department of Biology, Università di Napoli Federico II, Naples, Italy
| | - Yulii V. Shidlovskii
- Department of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Department of Biology and General Genetics, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
- *Correspondence: Yulii V. Shidlovskii,
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8
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Ryu JK, Rah SH, Janissen R, Kerssemakers JWJ, Bonato A, Michieletto D, Dekker C. Condensin extrudes DNA loops in steps up to hundreds of base pairs that are generated by ATP binding events. Nucleic Acids Res 2021; 50:820-832. [PMID: 34951453 PMCID: PMC8789078 DOI: 10.1093/nar/gkab1268] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 10/22/2021] [Accepted: 12/09/2021] [Indexed: 12/28/2022] Open
Abstract
The condensin SMC protein complex organizes chromosomal structure by extruding loops of DNA. Its ATP-dependent motor mechanism remains unclear but likely involves steps associated with large conformational changes within the ∼50 nm protein complex. Here, using high-resolution magnetic tweezers, we resolve single steps in the loop extrusion process by individual yeast condensins. The measured median step sizes range between 20–40 nm at forces of 1.0–0.2 pN, respectively, comparable with the holocomplex size. These large steps show that, strikingly, condensin typically reels in DNA in very sizeable amounts with ∼200 bp on average per single extrusion step at low force, and occasionally even much larger, exceeding 500 bp per step. Using Molecular Dynamics simulations, we demonstrate that this is due to the structural flexibility of the DNA polymer at these low forces. Using ATP-binding-impaired and ATP-hydrolysis-deficient mutants, we find that ATP binding is the primary step-generating stage underlying DNA loop extrusion. We discuss our findings in terms of a scrunching model where a stepwise DNA loop extrusion is generated by an ATP-binding-induced engagement of the hinge and the globular domain of the SMC complex.
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Affiliation(s)
- Je-Kyung Ryu
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Sang-Hyun Rah
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Richard Janissen
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Jacob W J Kerssemakers
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Andrea Bonato
- University of Edinburgh, SUPA, School of Physics and Astronomy, EH9 3FD, Edinburgh, UK
| | - Davide Michieletto
- University of Edinburgh, SUPA, School of Physics and Astronomy, EH9 3FD, Edinburgh, UK.,MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
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9
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Konrad SF, Vanderlinden W, Lipfert J. A High-throughput Pipeline to Determine DNA and Nucleosome Conformations by AFM Imaging. Bio Protoc 2021; 11:e4180. [PMID: 34722827 DOI: 10.21769/bioprotoc.4180] [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: 04/28/2021] [Revised: 06/30/2021] [Accepted: 07/28/2021] [Indexed: 11/02/2022] Open
Abstract
Atomic force microscopy (AFM) is a powerful tool to image macromolecular complexes with nanometer resolution and exquisite single-molecule sensitivity. While AFM imaging is well-established to investigate DNA and nucleoprotein complexes, AFM studies are often limited by small datasets and manual image analysis that is slow and prone to user bias. Recently, we have shown that a combination of large scale AFM imaging and automated image analysis of nucleosomes can overcome these previous limitations of AFM nucleoprotein studies. Using our high-throughput imaging and analysis pipeline, we have resolved nucleosome wrapping intermediates with five base pair resolution and revealed how distinct nucleosome variants and environmental conditions affect the unwrapping pathways of nucleosomal DNA. Here, we provide a detailed protocol of our workflow to analyze DNA and nucleosome conformations focusing on practical aspects and experimental parameters. We expect our protocol to drastically enhance AFM analyses of DNA and nucleosomes and to be readily adaptable to a wide variety of other protein and protein-nucleic acid complexes.
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Affiliation(s)
- Sebastian F Konrad
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany
| | - Willem Vanderlinden
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany
| | - Jan Lipfert
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany
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10
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Kim JM, Visanpattanasin P, Jou V, Liu S, Tang X, Zheng Q, Li KY, Snedeker J, Lavis LD, Lionnet T, Wu C. Single-molecule imaging of chromatin remodelers reveals role of ATPase in promoting fast kinetics of target search and dissociation from chromatin. eLife 2021; 10:e69387. [PMID: 34313223 PMCID: PMC8352589 DOI: 10.7554/elife.69387] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/26/2021] [Indexed: 12/14/2022] Open
Abstract
Conserved ATP-dependent chromatin remodelers establish and maintain genome-wide chromatin architectures of regulatory DNA during cellular lifespan, but the temporal interactions between remodelers and chromatin targets have been obscure. We performed live-cell single-molecule tracking for RSC, SWI/SNF, CHD1, ISW1, ISW2, and INO80 remodeling complexes in budding yeast and detected hyperkinetic behaviors for chromatin-bound molecules that frequently transition to the free state for all complexes. Chromatin-bound remodelers display notably higher diffusion than nucleosomal histones, and strikingly fast dissociation kinetics with 4-7 s mean residence times. These enhanced dynamics require ATP binding or hydrolysis by the catalytic ATPase, uncovering an additional function to its established role in nucleosome remodeling. Kinetic simulations show that multiple remodelers can repeatedly occupy the same promoter region on a timescale of minutes, implicating an unending 'tug-of-war' that controls a temporally shifting window of accessibility for the transcription initiation machinery.
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Affiliation(s)
- Jee Min Kim
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | | | - Vivian Jou
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Sheng Liu
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Xiaona Tang
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Qinsi Zheng
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Kai Yu Li
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Jonathan Snedeker
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Timothee Lionnet
- Institute of Systems Genetics, Langone Medical Center, New York UniversityNew YorkUnited 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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11
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Tilly BC, Chalkley GE, van der Knaap JA, Moshkin YM, Kan TW, Dekkers DH, Demmers JA, Verrijzer CP. In vivo analysis reveals that ATP-hydrolysis couples remodeling to SWI/SNF release from chromatin. eLife 2021; 10:69424. [PMID: 34313222 PMCID: PMC8352592 DOI: 10.7554/elife.69424] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 07/26/2021] [Indexed: 12/23/2022] Open
Abstract
ATP-dependent chromatin remodelers control the accessibility of genomic DNA through nucleosome mobilization. However, the dynamics of genome exploration by remodelers, and the role of ATP hydrolysis in this process remain unclear. We used live-cell imaging of Drosophila polytene nuclei to monitor Brahma (BRM) remodeler interactions with its chromosomal targets. In parallel, we measured local chromatin condensation and its effect on BRM association. Surprisingly, only a small portion of BRM is bound to chromatin at any given time. BRM binds decondensed chromatin but is excluded from condensed chromatin, limiting its genomic search space. BRM-chromatin interactions are highly dynamic, whereas histone-exchange is limited and much slower. Intriguingly, loss of ATP hydrolysis enhanced chromatin retention and clustering of BRM, which was associated with reduced histone turnover. Thus, ATP hydrolysis couples nucleosome remodeling to remodeler release, driving a continuous transient probing of the genome.
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Affiliation(s)
- Ben C Tilly
- Department of Biochemistry, Rotterdam, Netherlands
| | | | | | | | | | - Dick Hw Dekkers
- Department of Biochemistry, Rotterdam, Netherlands.,Proteomics Center, Erasmus University Medical Center, Rotterdam, Netherlands
| | - Jeroen Aa Demmers
- Department of Biochemistry, Rotterdam, Netherlands.,Proteomics Center, Erasmus University Medical Center, Rotterdam, Netherlands
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12
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Clapier CR. Sophisticated Conversations between Chromatin and Chromatin Remodelers, and Dissonances in Cancer. Int J Mol Sci 2021; 22:5578. [PMID: 34070411 PMCID: PMC8197500 DOI: 10.3390/ijms22115578] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/18/2021] [Accepted: 05/18/2021] [Indexed: 01/13/2023] Open
Abstract
The establishment and maintenance of genome packaging into chromatin contribute to define specific cellular identity and function. Dynamic regulation of chromatin organization and nucleosome positioning are critical to all DNA transactions-in particular, the regulation of gene expression-and involve the cooperative action of sequence-specific DNA-binding factors, histone modifying enzymes, and remodelers. Remodelers are molecular machines that generate various chromatin landscapes, adjust nucleosome positioning, and alter DNA accessibility by using ATP binding and hydrolysis to perform DNA translocation, which is highly regulated through sophisticated structural and functional conversations with nucleosomes. In this review, I first present the functional and structural diversity of remodelers, while emphasizing the basic mechanism of DNA translocation, the common regulatory aspects, and the hand-in-hand progressive increase in complexity of the regulatory conversations between remodelers and nucleosomes that accompanies the increase in challenges of remodeling processes. Next, I examine how, through nucleosome positioning, remodelers guide the regulation of gene expression. Finally, I explore various aspects of how alterations/mutations in remodelers introduce dissonance into the conversations between remodelers and nucleosomes, modify chromatin organization, and contribute to oncogenesis.
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Affiliation(s)
- Cedric R Clapier
- Department of Oncological Sciences & Howard Hughes Medical Institute, Huntsman Cancer Institute, University of Utah School of Medicine, 2000 Circle of Hope, Salt Lake City, UT 84112, USA
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13
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Song Y, Hyeon C. Thermodynamic uncertainty relation to assess biological processes. J Chem Phys 2021; 154:130901. [PMID: 33832251 DOI: 10.1063/5.0043671] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We review the trade-offs between speed, fluctuations, and thermodynamic cost involved with biological processes in nonequilibrium states and discuss how optimal these processes are in light of the universal bound set by the thermodynamic uncertainty relation (TUR). The values of the uncertainty product Q of TUR, which can be used as a measure of the precision of enzymatic processes realized for a given thermodynamic cost, are suboptimal when the substrate concentration is at the Michaelis constant, and some of the key biological processes are found to work around this condition. We illustrate the utility of Q in assessing how close the molecular motors and biomass producing machineries are to the TUR bound, and for the cases of biomass production (or biological copying processes), we discuss how their optimality quantified in terms of Q is balanced with the error rate in the information transfer process. We also touch upon the trade-offs in other error-minimizing processes in biology, such as gene regulation and chaperone-assisted protein folding. A spectrum of Q recapitulating the biological processes surveyed here provides glimpses into how biological systems are evolved to optimize and balance the conflicting functional requirements.
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Affiliation(s)
- Yonghyun Song
- Korea Institute for Advanced Study, Seoul 02455, South Korea
| | - Changbong Hyeon
- Korea Institute for Advanced Study, Seoul 02455, South Korea
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14
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Konrad SF, Vanderlinden W, Frederickx W, Brouns T, Menze BH, De Feyter S, Lipfert J. High-throughput AFM analysis reveals unwrapping pathways of H3 and CENP-A nucleosomes. NANOSCALE 2021; 13:5435-5447. [PMID: 33683227 DOI: 10.1039/d0nr08564b] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nucleosomes, the fundamental units of chromatin, regulate readout and expression of eukaryotic genomes. Single-molecule experiments have revealed force-induced nucleosome accessibility, but a high-resolution unwrapping landscape in the absence of external forces is currently lacking. Here, we introduce a high-throughput pipeline for the analysis of nucleosome conformations based on atomic force microscopy and automated, multi-parameter image analysis. Our data set of ∼10 000 nucleosomes reveals multiple unwrapping states corresponding to steps of 5 bp DNA. For canonical H3 nucleosomes, we observe that dissociation from one side impedes unwrapping from the other side, but in contrast to force-induced unwrapping, we find only a weak sequence-dependent asymmetry. Notably, centromeric CENP-A nucleosomes do not unwrap anti-cooperatively, in stark contrast to H3 nucleosomes. Finally, our results reconcile previous conflicting findings about the differences in height between H3 and CENP-A nucleosomes. We expect our approach to enable critical insights into epigenetic regulation of nucleosome structure and stability and to facilitate future high-throughput AFM studies that involve heterogeneous nucleoprotein complexes.
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Affiliation(s)
- Sebastian F Konrad
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany.
| | - Willem Vanderlinden
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany.
| | - Wout Frederickx
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Tine Brouns
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Björn H Menze
- Department of Informatics, Technical University of Munich, Boltzmannstr. 3, 85748 Garching, Germany
| | - Steven De Feyter
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Jan Lipfert
- Department of Physics and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany.
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15
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Abstract
As primary carriers of epigenetic information and gatekeepers of genomic DNA, nucleosomes are essential for proper growth and development of all eukaryotic cells. Although they are intrinsically dynamic, nucleosomes are actively reorganized by ATP-dependent chromatin remodelers. Chromatin remodelers contain helicase-like ATPase motor domains that can translocate along DNA, and a long-standing question in the field is how this activity is used to reposition or slide nucleosomes. In addition to ratcheting along DNA like their helicase ancestors, remodeler ATPases appear to dictate specific alternating geometries of the DNA duplex, providing an unexpected means for moving DNA past the histone core. Emerging evidence supports twist-based mechanisms for ATP-driven repositioning of nucleosomes along DNA. In this review, we discuss core experimental findings and ideas that have shaped the view of how nucleosome sliding may be achieved.
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Affiliation(s)
- Ilana M Nodelman
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, USA;
| | - Gregory D Bowman
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, USA;
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16
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Morgan A, LeGresley S, Fischer C. Remodeler Catalyzed Nucleosome Repositioning: Influence of Structure and Stability. Int J Mol Sci 2020; 22:ijms22010076. [PMID: 33374740 PMCID: PMC7793527 DOI: 10.3390/ijms22010076] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/04/2020] [Accepted: 12/16/2020] [Indexed: 02/06/2023] Open
Abstract
The packaging of the eukaryotic genome into chromatin regulates the storage of genetic information, including the access of the cell’s DNA metabolism machinery. Indeed, since the processes of DNA replication, translation, and repair require access to the underlying DNA, several mechanisms, both active and passive, have evolved by which chromatin structure can be regulated and modified. One mechanism relies upon the function of chromatin remodeling enzymes which couple the free energy obtained from the binding and hydrolysis of ATP to the mechanical work of repositioning and rearranging nucleosomes. Here, we review recent work on the nucleosome mobilization activity of this essential family of molecular machines.
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17
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Baker RW, Reimer JM, Carman PJ, Turegun B, Arakawa T, Dominguez R, Leschziner AE. Structural insights into assembly and function of the RSC chromatin remodeling complex. Nat Struct Mol Biol 2020; 28:71-80. [PMID: 33288924 PMCID: PMC7855068 DOI: 10.1038/s41594-020-00528-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 09/28/2020] [Indexed: 12/30/2022]
Abstract
SWI/SNF chromatin remodelers modify the position and spacing of nucleosomes and, in humans, are linked to cancer. To provide insights into the assembly and regulation of this protein family, we focused on a subcomplex of S. cerevisiae RSC comprising its ATPase (Sth1), the essential actin-related proteins (ARPs) Arp7 and Arp9, and the ARP-binding protein Rtt102. Cryo-EM and biochemical analysis of this subcomplex shows that ARP binding induces a helical conformation in the HSA domain of Sth1. Surprisingly, the ARP module is rotated 120° relative to full RSC, about a pivot point previously identified as a regulatory hub in Sth1, suggesting that large conformational changes are part of Sth1 regulation and RSC assembly. We also show that a conserved interaction between Sth1 and the nucleosome acidic patch enhances remodeling. As some cancer-associated mutations dysregulate rather than inactivate SWI/SNF remodelers, our insights into RSC complex regulation advance a mechanistic understanding of chromatin remodeling in disease states.
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Affiliation(s)
- Richard W Baker
- Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, CA, USA.,Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Janice M Reimer
- Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Peter J Carman
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Bengi Turegun
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Foghorn Therapeutics, Cambridge, MA, USA
| | - Tsutomu Arakawa
- Alliance Protein Laboratories, a Division of KBI BioPharma, San Diego, CA, USA
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Andres E Leschziner
- Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, CA, USA. .,Section of Molecular Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA.
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18
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Innis SM, Cabot B. GBAF, a small BAF sub-complex with big implications: a systematic review. Epigenetics Chromatin 2020; 13:48. [PMID: 33143733 PMCID: PMC7607862 DOI: 10.1186/s13072-020-00370-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 10/23/2020] [Indexed: 12/01/2022] Open
Abstract
ATP-dependent chromatin remodeling by histone-modifying enzymes and chromatin remodeling complexes is crucial for maintaining chromatin organization and facilitating gene transcription. In the SWI/SNF family of ATP-dependent chromatin remodelers, distinct complexes such as BAF, PBAF, GBAF, esBAF and npBAF/nBAF are of particular interest regarding their implications in cellular differentiation and development, as well as in various diseases. The recently identified BAF subcomplex GBAF is no exception to this, and information is emerging linking this complex and its components to crucial events in mammalian development. Furthermore, given the essential nature of many of its subunits in maintaining effective chromatin remodeling function, it comes as no surprise that aberrant expression of GBAF complex components is associated with disease development, including neurodevelopmental disorders and numerous malignancies. It becomes clear that building upon our knowledge of GBAF and BAF complex function will be essential for advancements in both mammalian reproductive applications and the development of more effective therapeutic interventions and strategies. Here, we review the roles of the SWI/SNF chromatin remodeling subcomplex GBAF and its subunits in mammalian development and disease.
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Affiliation(s)
- Sarah M Innis
- Department of Animal Sciences, Purdue University, West Lafayette, IN, USA
| | - Birgit Cabot
- Department of Animal Sciences, Purdue University, West Lafayette, IN, USA.
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19
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Blossey R, Schiessel H. Histone mark recognition controls nucleosome translocation via a kinetic proofreading mechanism: Confronting theory and high-throughput experiments. Phys Rev E 2019; 99:060401. [PMID: 31330635 DOI: 10.1103/physreve.99.060401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Indexed: 12/13/2022]
Abstract
Chromatin remodelers are multidomain enzymatic motor complexes that displace nucleosomes along DNA and hence "remodel chromatin structure," i.e., they dynamically reorganize nucleosome positions in both gene activation and gene repression. Recently, experimental insights from structural biology methods and remodeling assays have substantially advanced the understanding of these key chromatin components. Here we confront the kinetic proofreading scenario of chromatin remodeling, which proposes a mechanical link between histone residue modifications and the ATP-dependent action of remodelers, with recent experiments. We show that recent high-throughput data on nucleosome libraries assayed with remodelers from the Imitation Switch family are in accord with our earlier predictions of the kinetic proofreading scenario. We make suggestions for experimentally verifiable predictions of the kinetic proofreading scenarios for remodelers from other families.
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Affiliation(s)
- Ralf Blossey
- Université de Lille, CNRS, UMR8576 Unité de Glycobiologie Structurale et Fonctionnelle (UGSF), F-59000 Lille, France
| | - Helmut Schiessel
- Institute Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
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20
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Heiss G, Ploetz E, Voith von Voithenberg L, Viswanathan R, Glaser S, Schluesche P, Madhira S, Meisterernst M, Auble DT, Lamb DC. Conformational changes and catalytic inefficiency associated with Mot1-mediated TBP-DNA dissociation. Nucleic Acids Res 2019; 47:2793-2806. [PMID: 30649478 PMCID: PMC6451094 DOI: 10.1093/nar/gky1322] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 12/21/2018] [Accepted: 01/07/2019] [Indexed: 11/12/2022] Open
Abstract
The TATA-box Binding Protein (TBP) plays a central role in regulating gene expression and is the first step in the process of pre-initiation complex (PIC) formation on promoter DNA. The lifetime of TBP at the promoter site is controlled by several cofactors including the Modifier of transcription 1 (Mot1), an essential TBP-associated ATPase. Based on ensemble measurements, Mot1 can use adenosine triphosphate (ATP) hydrolysis to displace TBP from DNA and various models for how this activity is coupled to transcriptional regulation have been proposed. However, the underlying molecular mechanism of Mot1 action is not well understood. In this work, the interaction of Mot1 with the DNA/TBP complex was investigated by single-pair Förster resonance energy transfer (spFRET). Upon Mot1 binding to the DNA/TBP complex, a transition in the DNA/TBP conformation was observed. Hydrolysis of ATP by Mot1 led to a conformational change but was not sufficient to efficiently disrupt the complex. SpFRET measurements of dual-labeled DNA suggest that Mot1's ATPase activity primes incorrectly oriented TBP for dissociation from DNA and additional Mot1 in solution is necessary for TBP unbinding. These findings provide a framework for understanding how the efficiency of Mot1's catalytic activity is tuned to establish a dynamic pool of TBP without interfering with stable and functional TBP-containing complexes.
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Affiliation(s)
- Gregor Heiss
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Evelyn Ploetz
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Lena Voith von Voithenberg
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Ramya Viswanathan
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Samson Glaser
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Peter Schluesche
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Sushi Madhira
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Michael Meisterernst
- Institut für Molekulare Tumorbiologie, Westfälische Wilhelms-Universität, Münster 48149, Germany
| | - David T Auble
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Don C Lamb
- Department für Chemie, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-Universität, München 81377, Germany
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21
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Ye Y, Wu H, Chen K, Clapier CR, Verma N, Zhang W, Deng H, Cairns BR, Gao N, Chen Z. Structure of the RSC complex bound to the nucleosome. Science 2019; 366:838-843. [PMID: 31672915 DOI: 10.1126/science.aay0033] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Accepted: 10/20/2019] [Indexed: 12/12/2022]
Abstract
The RSC complex remodels chromatin structure and regulates gene transcription. We used cryo-electron microscopy to determine the structure of yeast RSC bound to the nucleosome. RSC is delineated into the adenosine triphosphatase motor, the actin-related protein module, and the substrate recruitment module (SRM). RSC binds the nucleosome mainly through the motor, with the auxiliary subunit Sfh1 engaging the H2A-H2B acidic patch to enable nucleosome ejection. SRM is organized into three substrate-binding lobes poised to bind their respective nucleosomal epitopes. The relative orientations of the SRM and the motor on the nucleosome explain the directionality of DNA translocation and promoter nucleosome repositioning by RSC. Our findings shed light on RSC assembly and functionality, and they provide a framework to understand the mammalian homologs BAF/PBAF and the Sfh1 ortholog INI1/BAF47, which are frequently mutated in cancers.
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Affiliation(s)
- Youpi Ye
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing 100084, P.R. China.,School of Life Science, Tsinghua University, Beijing 100084, P.R. China
| | - Hao Wu
- School of Life Science, Tsinghua University, Beijing 100084, P.R. China.,Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, Beijing 100084, China
| | - Kangjing Chen
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing 100084, P.R. China.,School of Life Science, Tsinghua University, Beijing 100084, P.R. China
| | - Cedric R Clapier
- Howard Hughes Medical Institute and Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Naveen Verma
- Howard Hughes Medical Institute and Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Wenhao Zhang
- School of Life Science, Tsinghua University, Beijing 100084, P.R. China
| | - Haiteng Deng
- School of Life Science, Tsinghua University, Beijing 100084, P.R. China
| | - Bradley R Cairns
- Howard Hughes Medical Institute and Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing 100871, China.
| | - Zhucheng Chen
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing 100084, P.R. China. .,School of Life Science, Tsinghua University, Beijing 100084, P.R. China.,Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing 100084, China
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22
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Mohapatra S, Lin CT, Feng XA, Basu A, Ha T. Single-Molecule Analysis and Engineering of DNA Motors. Chem Rev 2019; 120:36-78. [DOI: 10.1021/acs.chemrev.9b00361] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
| | | | | | | | - Taekjip Ha
- Howard Hughes Medical Institute, Baltimore, Maryland 21205, United States
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23
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Abstract
Protein complexes built of structural maintenance of chromosomes (SMC) and kleisin subunits, including cohesin, condensin and the Smc5/6 complex, are master organizers of genome architecture in all kingdoms of life. How these large ring-shaped molecular machines use the energy of ATP hydrolysis to change the topology of chromatin fibers has remained a central unresolved question of chromosome biology. A currently emerging concept suggests that the common principle that underlies the essential functions of SMC protein complexes in the control of gene expression, chromosome segregation or DNA damage repair is their ability to expand DNA into large loop structures. Here, we review the current knowledge about the biochemical and structural properties of SMC protein complexes that might enable them to extrude DNA loops and compare their action to other motor proteins and nucleic acid translocases. We evaluate the currently predominant models of active loop extrusion and propose a detailed version of a 'scrunching' model, which reconciles much of the available mechanistic data and provides an elegant explanation for how SMC protein complexes fulfill an array of seemingly diverse tasks during the organization of genomes.
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24
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Direct observation of coordinated DNA movements on the nucleosome during chromatin remodelling. Nat Commun 2019; 10:1720. [PMID: 30979890 PMCID: PMC6461674 DOI: 10.1038/s41467-019-09657-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 03/20/2019] [Indexed: 11/11/2022] Open
Abstract
ATP-dependent chromatin remodelling enzymes (remodellers) regulate DNA accessibility in eukaryotic genomes. Many remodellers reposition (slide) nucleosomes, however, how DNA is propagated around the histone octamer during this process is unclear. Here we examine the real-time coordination of remodeller-induced DNA movements on both sides of the nucleosome using three-colour single-molecule FRET. During sliding by Chd1 and SNF2h remodellers, DNA is shifted discontinuously, with movement of entry-side DNA preceding that of exit-side DNA. The temporal delay between these movements implies a single rate-limiting step dependent on ATP binding and transient absorption or buffering of at least one base pair. High-resolution cross-linking experiments show that sliding can be achieved by buffering as few as 3 bp between entry and exit sides of the nucleosome. We propose that DNA buffering ensures nucleosome stability during ATP-dependent remodelling, and provides a means for communication between remodellers acting on opposite sides of the nucleosome. Chromatin remodelling enzymes (remodellers) regulate DNA accessibility of eukaryotic genomes, which rely in large part on an ability to reposition nucleosomes. Here the authors use three-colour single-molecule FRET to simultaneously monitor remodeller-induced DNA movements on both sides of the nucleosome in real-time.
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25
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Ma L, Jiao J, Zhang Y. Single-Molecule Optical Tweezers Study of Regulated SNARE Assembly. Methods Mol Biol 2019; 1860:95-114. [PMID: 30317500 DOI: 10.1007/978-1-4939-8760-3_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Intracellular membrane fusion mediates material and information exchange among different cells or cellular compartments with high accuracy and spatiotemporal resolution. Fusion is driven by ordered folding and assembly of soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (SNAP) receptors (SNAREs) and regulated by many other proteins. Understanding regulated SNARE assembly is key to dissecting mechanisms and physiologies of various fusion processes and their associated diseases. Yet, it remains challenging to study regulated SNARE assembly using traditional ensemble-based experimental approaches. Here, we describe our new method to measure the energy and kinetics of neuronal SNARE assembly in the presence of α-SNAP, using a single-molecule manipulation approach based on high-resolution optical tweezers. Detailed experimental protocols and methods of data analysis are shown. This approach can be widely applied to elucidate the effects of regulatory proteins on SNARE assembly and membrane fusion.
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Affiliation(s)
- Lu Ma
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Junyi Jiao
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.,Integrated Graduate Program in Physical and Engineering Biology, New Haven, CT, USA
| | - Yongli Zhang
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
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26
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Hsu KW, Chow SY, Su BY, Lu YH, Chen CJ, Chen WL, Cheng MY, Fan HF. The synergy between RSC, Nap1 and adjacent nucleosome in nucleosome remodeling. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1862:129-140. [PMID: 30593928 DOI: 10.1016/j.bbagrm.2018.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/23/2018] [Accepted: 11/30/2018] [Indexed: 12/29/2022]
Abstract
Eukaryotes have evolved a specific strategy to package DNA. The nucleosome is a 147-base-pair DNA segment wrapped around histone core proteins that plays important roles regulating DNA-dependent biosynthesis and gene expression. Chromatin remodeling complexes (RSC, Remodel the Structure of Chromatin) hydrolyze ATP to perturb DNA-histone contacts, leading to nucleosome sliding and ejection. Here, we utilized tethered particle motion (TPM) experiments to investigate the mechanism of RSC-mediated nucleosome remodeling in detail. We observed ATP-dependent RSC-mediated DNA looping and nucleosome ejection along individual mononucleosomes and dinucleosomes. We found that nucleosome assembly protein 1 (Nap1) enhanced RSC-mediated nucleosome ejection in a two-step disassembly manner from dinucleosomes but not from mononucleosomes. Based on this work, we provide an entire reaction scheme for the RSC-mediated nucleosome remodeling process that includes DNA looping, nucleosome ejection, the influence of adjacent nucleosomes, and the coordinated action between Nap1 and RSC.
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Affiliation(s)
- Kuan-Wei Hsu
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taiwan
| | - Sih-Yao Chow
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taiwan
| | - Bo-Yu Su
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taiwan
| | - Yi-Han Lu
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taiwan
| | - Cyuan-Ji Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taiwan
| | - Wen-Ling Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taiwan
| | - Ming-Yuan Cheng
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taiwan
| | - Hsiu-Fang Fan
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taiwan.
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27
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Brandani GB, Takada S. Chromatin remodelers couple inchworm motion with twist-defect formation to slide nucleosomal DNA. PLoS Comput Biol 2018; 14:e1006512. [PMID: 30395604 PMCID: PMC6237416 DOI: 10.1371/journal.pcbi.1006512] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 11/15/2018] [Accepted: 09/13/2018] [Indexed: 01/25/2023] Open
Abstract
ATP-dependent chromatin remodelers are molecular machines that control genome organization by repositioning, ejecting, or editing nucleosomes, activities that confer them essential regulatory roles on gene expression and DNA replication. Here, we investigate the molecular mechanism of active nucleosome sliding by means of molecular dynamics simulations of the Snf2 remodeler translocase in complex with a nucleosome. During its inchworm motion driven by ATP consumption, the translocase overwrites the original nucleosome energy landscape via steric and electrostatic interactions to induce sliding of nucleosomal DNA unidirectionally. The sliding is initiated at the remodeler binding location via the generation of a pair of twist defects, which then spontaneously propagate to complete sliding throughout the entire nucleosome. We also reveal how remodeler mutations and DNA sequence control active nucleosome repositioning, explaining several past experimental observations. These results offer a detailed mechanistic picture of remodeling important for the complete understanding of these key biological processes. Nucleosomes are the protein-DNA complexes underlying Eukaryotic genome organization, and serve as regulators of gene expression by occluding DNA to other proteins. This regulation requires the precise positioning of nucleosomes along DNA. Chromatin remodelers are the molecular machines that consume ATP to slide nucleosome at their correct locations, but the mechanisms of remodeling are still unclear. Based on the static structural information of a remodeler bound on nucleosome, we performed molecular dynamics computer simulations revealing the details of how remodelers slide nucleosomal DNA: the inchworm-like motion of remodelers create small DNA deformations called twist defects, which then spontaneously propagate throughout the nucleosome to induce sliding. These simulations explain several past experimental findings and are important for our understanding of genome organization.
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Affiliation(s)
- Giovanni B. Brandani
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Shoji Takada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
- * E-mail:
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28
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Sundaramoorthy R, Hughes AL, El-Mkami H, Norman DG, Ferreira H, Owen-Hughes T. Structure of the chromatin remodelling enzyme Chd1 bound to a ubiquitinylated nucleosome. eLife 2018; 7:35720. [PMID: 30079888 PMCID: PMC6118821 DOI: 10.7554/elife.35720] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 07/24/2018] [Indexed: 12/23/2022] Open
Abstract
ATP-dependent chromatin remodelling proteins represent a diverse family of proteins that share ATPase domains that are adapted to regulate protein-DNA interactions. Here, we present structures of the Saccharomyces cerevisiae Chd1 protein engaged with nucleosomes in the presence of the transition state mimic ADP-beryllium fluoride. The path of DNA strands through the ATPase domains indicates the presence of contacts conserved with single strand translocases and additional contacts with both strands that are unique to Snf2 related proteins. The structure provides connectivity between rearrangement of ATPase lobes to a closed, nucleotide bound state and the sensing of linker DNA. Two turns of linker DNA are prised off the surface of the histone octamer as a result of Chd1 binding, and both the histone H3 tail and ubiquitin conjugated to lysine 120 are re-orientated towards the unravelled DNA. This indicates how changes to nucleosome structure can alter the way in which histone epitopes are presented.
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Affiliation(s)
| | - Amanda L Hughes
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Hassane El-Mkami
- School of Physics and Astronomy, University of St Andrews, St Andrews, United Kingdom
| | - David G Norman
- Nucleic Acids Structure Research Group, University of Dundee, Dundee, United Kingdom
| | - Helder Ferreira
- School of Biology, University of St Andrews, St Andrews, United Kingdom
| | - Tom Owen-Hughes
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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29
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Whitley KD, Comstock MJ, Chemla YR. Ultrashort Nucleic Acid Duplexes Exhibit Long Wormlike Chain Behavior with Force-Dependent Edge Effects. PHYSICAL REVIEW LETTERS 2018; 120:068102. [PMID: 29481284 DOI: 10.1103/physrevlett.120.068102] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/23/2017] [Indexed: 05/22/2023]
Abstract
Despite their importance in biology and use in nanotechnology, the elastic behavior of nucleic acids on "ultrashort" (<15 nt) length scales remains poorly understood. Here, we use optical tweezers combined with fluorescence imaging to observe directly the hybridization of oligonucleotides (7-12 nt) to a complementary strand under tension and to measure the difference in end-to-end extension between the single-stranded and duplex states. Data are consistent with long-polymer models at low forces (<8 pN) but smaller than predicted at higher forces (>8 pN), the result of the sequence-dependent duplex edge effects.
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Affiliation(s)
- Kevin D Whitley
- Center for Biophysics and Quantitative Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Matthew J Comstock
- Department of Physics, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
- Center for the Physics of Living Cells, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Yann R Chemla
- Center for Biophysics and Quantitative Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Physics, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
- Center for the Physics of Living Cells, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
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30
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Schwarz M, Schall K, Kallis E, Eustermann S, Guariento M, Moldt M, Hopfner KP, Michaelis J. Single-molecule nucleosome remodeling by INO80 and effects of histone tails. FEBS Lett 2018; 592:318-331. [PMID: 29331030 DOI: 10.1002/1873-3468.12973] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 12/22/2017] [Accepted: 12/29/2017] [Indexed: 01/30/2023]
Abstract
Genome maintenance and integrity requires continuous alterations of the compaction state of the chromatin structure. Chromatin remodelers, among others the INO80 complex, help organize chromatin by repositioning, reshaping, or evicting nucleosomes. We report on INO80 nucleosome remodeling, assayed by single-molecule Foerster resonance energy transfer on canonical nucleosomes as well as nucleosomes assembled from tailless histones. Nucleosome repositioning by INO80 is a processively catalyzed reaction. During the initiation of remodeling, probed by the INO80 bound state, the nucleosome reveals structurally heterogeneous states for tailless nucleosomes (in contrast to wild-type nucleosomes). We, therefore, propose an altered energy landscape for the INO80-mediated nucleosome sliding reaction in the absence of histone tails.
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Affiliation(s)
- Marianne Schwarz
- Faculty of Natural Sciences, Institute of Biophysics, Ulm University, Germany.,Gene Center and Department of Biochemistry, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Kevin Schall
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Eleni Kallis
- Faculty of Natural Sciences, Institute of Biophysics, Ulm University, Germany
| | - Sebastian Eustermann
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Mara Guariento
- Faculty of Natural Sciences, Institute of Biophysics, Ulm University, Germany
| | - Manuela Moldt
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Karl-Peter Hopfner
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Jens Michaelis
- Faculty of Natural Sciences, Institute of Biophysics, Ulm University, Germany
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31
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Clapier CR, Kasten MM, Parnell TJ, Viswanathan R, Szerlong H, Sirinakis G, Zhang Y, Cairns BR. Regulation of DNA Translocation Efficiency within the Chromatin Remodeler RSC/Sth1 Potentiates Nucleosome Sliding and Ejection. Mol Cell 2017; 62:453-461. [PMID: 27153540 DOI: 10.1016/j.molcel.2016.03.032] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 01/29/2016] [Accepted: 03/30/2016] [Indexed: 11/30/2022]
Abstract
The RSC chromatin remodeler slides and ejects nucleosomes, utilizing a catalytic subunit (Sth1) with DNA translocation activity, which can pump DNA around the nucleosome. A central question is whether and how DNA translocation is regulated to achieve sliding versus ejection. Here, we report the regulation of DNA translocation efficiency by two domains residing on Sth1 (Post-HSA and Protrusion 1) and by actin-related proteins (ARPs) that bind Sth1. ARPs facilitated sliding and ejection by improving "coupling"-the amount of DNA translocation by Sth1 relative to ATP hydrolysis. We also identified and characterized Protrusion 1 mutations that promote "coupling," and Post-HSA mutations that improve ATP hydrolysis; notably, the strongest mutations conferred efficient nucleosome ejection without ARPs. Taken together, sliding-to-ejection involves a continuum of DNA translocation efficiency, consistent with higher magnitudes of ATPase and coupling activities (involving ARPs and Sth1 domains), enabling the simultaneous rupture of multiple histone-DNA contacts facilitating ejection.
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Affiliation(s)
- Cedric R Clapier
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Margaret M Kasten
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Timothy J Parnell
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Ramya Viswanathan
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Heather Szerlong
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - George Sirinakis
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Yongli Zhang
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Bradley R Cairns
- Department of Oncological Sciences, Huntsman Cancer Institute and Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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32
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Polyvalent Proteins, a Pervasive Theme in the Intergenomic Biological Conflicts of Bacteriophages and Conjugative Elements. J Bacteriol 2017; 199:JB.00245-17. [PMID: 28559295 PMCID: PMC5512222 DOI: 10.1128/jb.00245-17] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 05/17/2017] [Indexed: 12/29/2022] Open
Abstract
Intense biological conflicts between prokaryotic genomes and their genomic parasites have resulted in an arms race in terms of the molecular “weaponry” deployed on both sides. Using a recursive computational approach, we uncovered a remarkable class of multidomain proteins with 2 to 15 domains in the same polypeptide deployed by viruses and plasmids in such conflicts. Domain architectures and genomic contexts indicate that they are part of a widespread conflict strategy involving proteins injected into the host cell along with parasite DNA during the earliest phase of infection. Their unique feature is the combination of domains with highly disparate biochemical activities in the same polypeptide; accordingly, we term them polyvalent proteins. Of the 131 domains in polyvalent proteins, a large fraction are enzymatic domains predicted to modify proteins, target nucleic acids, alter nucleotide signaling/metabolism, and attack peptidoglycan or cytoskeletal components. They further contain nucleic acid-binding domains, virion structural domains, and 40 novel uncharacterized domains. Analysis of their architectural network reveals both pervasive common themes and specialized strategies for conjugative elements and plasmids or (pro)phages. The themes include likely processing of multidomain polypeptides by zincin-like metallopeptidases and mechanisms to counter restriction or CRISPR/Cas systems and jump-start transcription or replication. DNA-binding domains acquired by eukaryotes from such systems have been reused in XPC/RAD4-dependent DNA repair and mitochondrial genome replication in kinetoplastids. Characterization of the novel domains discovered here, such as RNases and peptidases, are likely to aid in the development of new reagents and elucidation of the spread of antibiotic resistance. IMPORTANCE This is the first report of the widespread presence of large proteins, termed polyvalent proteins, predicted to be transmitted by genomic parasites such as conjugative elements, plasmids, and phages during the initial phase of infection along with their DNA. They are typified by the presence of multiple domains with disparate activities combined in the same protein. While some of these domains are predicted to assist the invasive element in replication, transcription, or protection of their DNA, several are likely to target various host defense systems or modify the host to favor the parasite's life cycle. Notably, DNA-binding domains from these systems have been transferred to eukaryotes, where they have been incorporated into DNA repair and mitochondrial genome replication systems.
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Zhang Y. Energetics, kinetics, and pathway of SNARE folding and assembly revealed by optical tweezers. Protein Sci 2017; 26:1252-1265. [PMID: 28097727 PMCID: PMC5477538 DOI: 10.1002/pro.3116] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/03/2017] [Indexed: 01/17/2023]
Abstract
Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are universal molecular engines that drive membrane fusion. Particularly, synaptic SNAREs mediate fast calcium-triggered fusion of neurotransmitter-containing vesicles with plasma membranes for synaptic transmission, the basis of all thought and action. During membrane fusion, complementary SNAREs located on two apposed membranes (often called t- and v-SNAREs) join together to assemble into a parallel four-helix bundle, releasing the energy to overcome the energy barrier for fusion. A long-standing hypothesis suggests that SNAREs act like a zipper to draw the two membranes into proximity and thereby force them to fuse. However, a quantitative test of this SNARE zippering hypothesis was hindered by difficulties to determine the energetics and kinetics of SNARE assembly and to identify the relevant folding intermediates. Here, we first review different approaches that have been applied to study SNARE assembly and then focus on high-resolution optical tweezers. We summarize the folding energies, kinetics, and pathways of both wild-type and mutant SNARE complexes derived from this new approach. These results show that synaptic SNAREs assemble in four distinct stages with different functions: slow N-terminal domain association initiates SNARE assembly; a middle domain suspends and controls SNARE assembly; and rapid sequential zippering of the C-terminal domain and the linker domain directly drive membrane fusion. In addition, the kinetics and pathway of the stagewise assembly are shared by other SNARE complexes. These measurements prove the SNARE zippering hypothesis and suggest new mechanisms for SNARE assembly regulated by other proteins.
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Affiliation(s)
- Yongli Zhang
- Department of Cell Biology, Yale School of MedicineYale UniversityNew HavenConnecticut06511
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Clapier CR, Iwasa J, Cairns BR, Peterson CL. Mechanisms of action and regulation of ATP-dependent chromatin-remodelling complexes. Nat Rev Mol Cell Biol 2017; 18:407-422. [PMID: 28512350 DOI: 10.1038/nrm.2017.26] [Citation(s) in RCA: 691] [Impact Index Per Article: 98.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cells utilize diverse ATP-dependent nucleosome-remodelling complexes to carry out histone sliding, ejection or the incorporation of histone variants, suggesting that different mechanisms of action are used by the various chromatin-remodelling complex subfamilies. However, all chromatin-remodelling complex subfamilies contain an ATPase-translocase 'motor' that translocates DNA from a common location within the nucleosome. In this Review, we discuss (and illustrate with animations) an alternative, unifying mechanism of chromatin remodelling, which is based on the regulation of DNA translocation. We propose the 'hourglass' model of remodeller function, in which each remodeller subfamily utilizes diverse specialized proteins and protein domains to assist in nucleosome targeting or to differentially detect nucleosome epitopes. These modules converge to regulate a common DNA translocation mechanism, to inform the conserved ATPase 'motor' on whether and how to apply DNA translocation, which together achieve the various outcomes of chromatin remodelling: nucleosome assembly, chromatin access and nucleosome editing.
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Affiliation(s)
- Cedric R Clapier
- Howard Hughes Medical Institute and Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Janet Iwasa
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Bradley R Cairns
- Howard Hughes Medical Institute and Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Craig L Peterson
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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Ordu O, Lusser A, Dekker NH. Recent insights from in vitro single-molecule studies into nucleosome structure and dynamics. Biophys Rev 2016; 8:33-49. [PMID: 28058066 PMCID: PMC5167136 DOI: 10.1007/s12551-016-0212-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/17/2016] [Indexed: 01/04/2023] Open
Abstract
Eukaryotic DNA is tightly packed into a hierarchically ordered structure called chromatin in order to fit into the micron-scaled nucleus. The basic unit of chromatin is the nucleosome, which consists of a short piece of DNA wrapped around a core of eight histone proteins. In addition to their role in packaging DNA, nucleosomes impact the regulation of essential nuclear processes such as replication, transcription, and repair by controlling the accessibility of DNA. Thus, knowledge of this fundamental DNA-protein complex is crucial for understanding the mechanisms of gene control. While structural and biochemical studies over the past few decades have provided key insights into both the molecular composition and functional aspects of nucleosomes, these approaches necessarily average over large populations and times. In contrast, single-molecule methods are capable of revealing features of subpopulations and dynamic changes in the structure or function of biomolecules, rendering them a powerful complementary tool for probing mechanistic aspects of DNA-protein interactions. In this review, we highlight how these single-molecule approaches have recently yielded new insights into nucleosomal and subnucleosomal structures and dynamics.
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Affiliation(s)
- Orkide Ordu
- Bionanoscience Department, Kavli Institute of Nanoscience,, Delft University of Technology, Van der Maasweg 9,, 2629 HZ Delft, The Netherlands
| | - Alexandra Lusser
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Nynke H. Dekker
- Bionanoscience Department, Kavli Institute of Nanoscience,, Delft University of Technology, Van der Maasweg 9,, 2629 HZ Delft, The Netherlands
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36
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Abstract
Chromatin remodeling motors play essential roles in all DNA-based processes. These motors catalyze diverse outcomes ranging from sliding the smallest units of chromatin, known as nucleosomes, to completely disassembling chromatin. The broad range of actions carried out by these motors on the complex template presented by chromatin raises many stimulating mechanistic questions. Other well-studied nucleic acid motors provide examples of the depth of mechanistic understanding that is achievable from detailed biophysical studies. We use these studies as a guiding framework to discuss the current state of knowledge of chromatin remodeling mechanisms and highlight exciting open questions that would continue to benefit from biophysical analyses.
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Affiliation(s)
- Coral Y Zhou
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, 94158; , , ,
| | - Stephanie L Johnson
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, 94158; , , ,
| | - Nathan I Gamarra
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, 94158; , , ,
| | - Geeta J Narlikar
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, 94158; , , ,
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37
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Harada BT, Hwang WL, Deindl S, Chatterjee N, Bartholomew B, Zhuang X. Stepwise nucleosome translocation by RSC remodeling complexes. eLife 2016; 5. [PMID: 26895087 PMCID: PMC4769157 DOI: 10.7554/elife.10051] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 12/29/2015] [Indexed: 12/30/2022] Open
Abstract
The SWI/SNF-family remodelers regulate chromatin structure by coupling the free energy from ATP hydrolysis to the repositioning and restructuring of nucleosomes, but how the ATPase activity of these enzymes drives the motion of DNA across the nucleosome remains unclear. Here, we used single-molecule FRET to monitor the remodeling of mononucleosomes by the yeast SWI/SNF remodeler, RSC. We observed that RSC primarily translocates DNA around the nucleosome without substantial displacement of the H2A-H2B dimer. At the sites where DNA enters and exits the nucleosome, the DNA moves largely along or near its canonical wrapping path. The translocation of DNA occurs in a stepwise manner, and at both sites where DNA enters and exits the nucleosome, the step size distributions exhibit a peak at approximately 1–2 bp. These results suggest that the movement of DNA across the nucleosome is likely coupled directly to DNA translocation by the ATPase at its binding site inside the nucleosome. DOI:http://dx.doi.org/10.7554/eLife.10051.001 Cells package their genetic information in a "complex” of proteins and DNA called chromatin. This complex is made of units called nucleosomes, each of which consist of a short stretch of DNA wrapped around proteins known as histones. These nucleosomes restrict access to the DNA wrapped around the histone proteins, and thus serve to regulate whether genes are activated and a variety of other cellular processes. Certain enzymes regulate the structure of chromatin by altering the position and structure of nucleosomes. However, it is not clear exactly how these “chromatin remodeling” enzymes alter the contacts between the DNA and histone proteins to move DNA around the nucleosome. RSC is a chromatin-remodeling enzyme that typically helps to activate genes. Harada et al. used a technique called single molecule fluorescence resonance energy transfer (or single molecule FRET for short) to observe the movement of DNA around the histone proteins. The technique involves placing a green fluorescent dye on the histone proteins and a red fluorescent dye on the DNA. If the red dye is close to the green dye, some of the energy can be transferred from the green dye to the red dye when the green dye is excited by a laser. By looking at the ratio of green and red light emitted, it is possible to tell how far apart they are, and how this changes over time. The experiments show that the RSC enzyme moves the DNA into and out of the nucleosome in small steps. These steps match the expected step size of DNA movements by a section of the enzyme called the ATPase domain. This suggests that the ATPase domain drives the motion of DNA across the entire nucleosome. A future challenge is to better understand how chromatin remodeling enzymes cooperate with other molecules in cells to remodel nucleosomes and chromatin. DOI:http://dx.doi.org/10.7554/eLife.10051.002
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Affiliation(s)
- Bryan T Harada
- Graduate Program in Biophysics, Harvard University, Cambridge, United States.,Howard Hughes Medical Institute, Harvard University, Cambridge, United States
| | - William L Hwang
- Graduate Program in Biophysics, Harvard University, Cambridge, United States.,Howard Hughes Medical Institute, Harvard University, Cambridge, United States.,Harvard/MIT MD-PhD Program, Harvard Medical School, Boston, United States
| | - Sebastian Deindl
- Howard Hughes Medical Institute, Harvard University, Cambridge, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Nilanjana Chatterjee
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Smithville, United States
| | - Blaine Bartholomew
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Smithville, United States
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Harvard University, Cambridge, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States.,Department of Physics, Harvard University, Cambridge, United States
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38
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Müller O, Kepper N, Schöpflin R, Ettig R, Rippe K, Wedemann G. Changing chromatin fiber conformation by nucleosome repositioning. Biophys J 2015; 107:2141-50. [PMID: 25418099 DOI: 10.1016/j.bpj.2014.09.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 09/11/2014] [Accepted: 09/12/2014] [Indexed: 10/24/2022] Open
Abstract
Chromatin conformation is dynamic and heterogeneous with respect to nucleosome positions, which can be changed by chromatin remodeling complexes in the cell. These molecular machines hydrolyze ATP to translocate or evict nucleosomes, and establish loci with regularly and more irregularly spaced nucleosomes as well as nucleosome-depleted regions. The impact of nucleosome repositioning on the three-dimensional chromatin structure is only poorly understood. Here, we address this issue by using a coarse-grained computer model of arrays of 101 nucleosomes considering several chromatin fiber models with and without linker histones, respectively. We investigated the folding of the chain in dependence of the position of the central nucleosome by changing the length of the adjacent linker DNA in basepair steps. We found in our simulations that these translocations had a strong effect on the shape and properties of chromatin fibers: i), Fiber curvature and flexibility at the center were largely increased and long-range contacts between distant nucleosomes on the chain were promoted. ii), The highest destabilization of the fiber conformation occurred for a nucleosome shifted by two basepairs from regular spacing, whereas effects of linker DNA changes of ?10 bp in phase with the helical twist of DNA were minimal. iii), A fiber conformation can stabilize a regular spacing of nucleosomes inasmuch as favorable stacking interactions between nucleosomes are facilitated. This can oppose nucleosome translocations and increase the energetic costs for chromatin remodeling. Our computational modeling framework makes it possible to describe the conformational heterogeneity of chromatin in terms of nucleosome positions, and thus advances theoretical models toward a better understanding of how genome compaction and access are regulated within the cell.
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Affiliation(s)
- Oliver Müller
- Institute for Applied Computer Science, University of Applied Sciences Stralsund, Stralsund, Germany
| | - Nick Kepper
- Deutsches Krebsforschungszentrum and BioQuant, Heidelberg, Germany
| | - Robert Schöpflin
- Institute for Applied Computer Science, University of Applied Sciences Stralsund, Stralsund, Germany
| | - Ramona Ettig
- Deutsches Krebsforschungszentrum and BioQuant, Heidelberg, Germany
| | - Karsten Rippe
- Deutsches Krebsforschungszentrum and BioQuant, Heidelberg, Germany
| | - Gero Wedemann
- Institute for Applied Computer Science, University of Applied Sciences Stralsund, Stralsund, Germany.
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39
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Briggs K, Fischer CJ. All motors have to decide is what to do with the DNA that is given them. Biomol Concepts 2015; 5:383-95. [PMID: 25367619 DOI: 10.1515/bmc-2014-0017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 09/09/2014] [Indexed: 11/15/2022] Open
Abstract
DNA translocases are a diverse group of molecular motors responsible for a wide variety of cellular functions. The goal of this review is to identify common aspects in the mechanisms for how these enzymes couple the binding and hydrolysis of ATP to their movement along DNA. Not surprisingly, the shared structural components contained within the catalytic domains of several of these motors appear to give rise to common aspects of DNA translocation. Perhaps more interesting, however, are the differences between the families of translocases and the potential associated implications both for the functions of the members of these families and for the evolution of these families. However, as there are few translocases for which complete characterizations of the mechanisms of DNA binding, DNA translocation, and DNA-stimulated ATPase have been completed, it is difficult to form many inferences. We therefore hope that this review motivates the necessary further experimentation required for broader comparisons and conclusions.
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40
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Chromatin Remodelers: From Function to Dysfunction. Genes (Basel) 2015; 6:299-324. [PMID: 26075616 PMCID: PMC4488666 DOI: 10.3390/genes6020299] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 06/01/2015] [Accepted: 06/03/2015] [Indexed: 12/20/2022] Open
Abstract
Chromatin remodelers are key players in the regulation of chromatin accessibility and nucleosome positioning on the eukaryotic DNA, thereby essential for all DNA dependent biological processes. Thus, it is not surprising that upon of deregulation of those molecular machines healthy cells can turn into cancerous cells. Even though the remodeling enzymes are very abundant and a multitude of different enzymes and chromatin remodeling complexes exist in the cell, the particular remodeling complex with its specific nucleosome positioning features must be at the right place at the right time in order to ensure the proper regulation of the DNA dependent processes. To achieve this, chromatin remodeling complexes harbor protein domains that specifically read chromatin targeting signals, such as histone modifications, DNA sequence/structure, non-coding RNAs, histone variants or DNA bound interacting proteins. Recent studies reveal the interaction between non-coding RNAs and chromatin remodeling complexes showing importance of RNA in remodeling enzyme targeting, scaffolding and regulation. In this review, we summarize current understanding of chromatin remodeling enzyme targeting to chromatin and their role in cancer development.
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41
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Li M, Hada A, Sen P, Olufemi L, Hall MA, Smith BY, Forth S, McKnight JN, Patel A, Bowman GD, Bartholomew B, Wang MD. Dynamic regulation of transcription factors by nucleosome remodeling. eLife 2015; 4. [PMID: 26047462 PMCID: PMC4456607 DOI: 10.7554/elife.06249] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/11/2015] [Indexed: 12/27/2022] Open
Abstract
The chromatin landscape and promoter architecture are dominated by the interplay of nucleosome and transcription factor (TF) binding to crucial DNA sequence elements. However, it remains unclear whether nucleosomes mobilized by chromatin remodelers can influence TFs that are already present on the DNA template. In this study, we investigated the interplay between nucleosome remodeling, by either yeast ISW1a or SWI/SNF, and a bound TF. We found that a TF serves as a major barrier to ISW1a remodeling, and acts as a boundary for nucleosome repositioning. In contrast, SWI/SNF was able to slide a nucleosome past a TF, with concurrent eviction of the TF from the DNA, and the TF did not significantly impact the nucleosome positioning. Our results provide direct evidence for a novel mechanism for both nucleosome positioning regulation by bound TFs and TF regulation via dynamic repositioning of nucleosomes. DOI:http://dx.doi.org/10.7554/eLife.06249.001 Cells contain thousands of genes that are encoded by molecules of DNA. In yeast and other eukaryotic organisms, this DNA is wrapped around proteins called histones to make structures called nucleosomes. This compacts the DNA and allows it to fit inside the tiny nucleus within the cell. The positioning of the nucleosomes influences how tightly packed the DNA is, which in turn influences the activity of genes. Less active genes tend to be found within regions of DNA that are tightly packed, while more active genes are found in less tightly packed regions. To activate a gene, proteins called transcription factors bind to a section of DNA within the gene called the promoter. Enzymes known as ‘chromatin remodelers’ can alter the locations of nucleosomes on DNA to allow the transcription factors access to the promoters of particular genes. In yeast, the SWI/SNF family of chromatin remodelers can disassemble nucleosomes to promote gene activity, while the ISW1 family organises nucleosomes into closely spaced groups to repress gene activity. However, it is not clear if, or how, chromatin remodelers can influence transcription factors that are already bound to DNA. Here, Li et al. studied the interactions between a transcription factor and the chromatin remodelers in yeast. The experiment used a piece of DNA that contained a bound transcription factor and a single nucleosome. Li et al. used a technique called ‘single molecule DNA unzipping’, which enabled them to precisely locate the position of the nucleosome and transcription factor before and after the nucleosome was remodeled. The experiments found that a chromatin remodeler called ISW1a moved the nucleosome away from the transcription factor, while a SWI/SNF chromatin remodeler moved the nucleosome towards it. Significantly, Li et al. also found that a transcription factor is a major barrier to ISW1a's remodeling activity, suggesting that ISW1a may use transcription factors as reference points to position nucleosomes. In contrast, SWI/SNF was able to slide a nucleosome past the transcription factor, which led to the transcription factor falling off the DNA. Therefore, SWI/SNF is able to move transcription factors out of the way to deactivate genes. Li et al. propose a new model for how chromatin remodelers can move nucleosomes and regulate transcription factors to alter gene activity. A future challenge will be to observe these types of activities in living cells. DOI:http://dx.doi.org/10.7554/eLife.06249.002
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Affiliation(s)
- Ming Li
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, United States
| | - Arjan Hada
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Payel Sen
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Lola Olufemi
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Michael A Hall
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
| | - Benjamin Y Smith
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
| | - Scott Forth
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
| | - Jeffrey N McKnight
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, United States
| | - Ashok Patel
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, United States
| | - Gregory D Bowman
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, United States
| | - Blaine Bartholomew
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Michelle D Wang
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
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42
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Jiao J, Rebane AA, Ma L, Gao Y, Zhang Y. Kinetically coupled folding of a single HIV-1 glycoprotein 41 complex in viral membrane fusion and inhibition. Proc Natl Acad Sci U S A 2015; 112:E2855-64. [PMID: 26038562 PMCID: PMC4460471 DOI: 10.1073/pnas.1424995112] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
HIV-1 glycoprotein 41 (gp41) mediates viral entry into host cells by coupling its folding energy to membrane fusion. Gp41 folding is blocked by fusion inhibitors, including the commercial drug T20, to treat HIV/AIDS. However, gp41 folding intermediates, energy, and kinetics are poorly understood. Here, we identified the folding intermediates of a single gp41 trimer-of-hairpins and measured their associated energy and kinetics using high-resolution optical tweezers. We found that folding of gp41 hairpins was energetically independent but kinetically coupled: Each hairpin contributed a folding energy of ∼-23 kBT, but folding of one hairpin successively accelerated the folding rate of the next one by ∼20-fold. Membrane-mimicking micelles slowed down gp41 folding and reduced the stability of the six-helix bundle. However, the stability was restored by cooperative folding of the membrane-proximal external region. Surprisingly, T20 strongly inhibited gp41 folding by actively displacing the C-terminal hairpin strand in a force-dependent manner. The inhibition was abolished by a T20-resistant gp41 mutation. The energetics and kinetics of gp41 folding established by us provides a basis to understand viral membrane fusion, infection, and therapeutic intervention.
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Affiliation(s)
- Junyi Jiao
- Department of Cell Biology, Yale University, School of Medicine, New Haven, CT 06511; Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, CT 06511
| | - Aleksander A Rebane
- Department of Cell Biology, Yale University, School of Medicine, New Haven, CT 06511; Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, CT 06511; Department of Physics, Yale University, New Haven, CT 06511
| | - Lu Ma
- Department of Cell Biology, Yale University, School of Medicine, New Haven, CT 06511
| | - Ying Gao
- Department of Cell Biology, Yale University, School of Medicine, New Haven, CT 06511; National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201210, China
| | - Yongli Zhang
- Department of Cell Biology, Yale University, School of Medicine, New Haven, CT 06511; Nanobiology Institute, Yale University, West Haven, CT 06477
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43
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Ngo TTM, Zhang Q, Zhou R, Yodh JG, Ha T. Asymmetric unwrapping of nucleosomes under tension directed by DNA local flexibility. Cell 2015; 160:1135-44. [PMID: 25768909 PMCID: PMC4409768 DOI: 10.1016/j.cell.2015.02.001] [Citation(s) in RCA: 212] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 10/07/2014] [Accepted: 01/17/2015] [Indexed: 02/06/2023]
Abstract
Dynamics of the nucleosome and exposure of nucleosomal DNA play key roles in many nuclear processes, but local dynamics of the nucleosome and its modulation by DNA sequence are poorly understood. Using single-molecule assays, we observed that the nucleosome can unwrap asymmetrically and directionally under force. The relative DNA flexibility of the inner quarters of nucleosomal DNA controls the unwrapping direction such that the nucleosome unwraps from the stiffer side. If the DNA flexibility is similar on two sides, it stochastically unwraps from either side. The two ends of the nucleosome are orchestrated such that the opening of one end helps to stabilize the other end, providing a mechanism to amplify even small differences in flexibility to a large asymmetry in nucleosome stability. Our discovery of DNA flexibility as a critical factor for nucleosome dynamics and mechanical stability suggests a novel mechanism of gene regulation by DNA sequence and modifications.
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Affiliation(s)
- Thuy T M Ngo
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801-2902, USA
| | - Qiucen Zhang
- Department of Physics, Center for Physics in Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801-2902, USA
| | - Ruobo Zhou
- Department of Physics, Center for Physics in Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801-2902, USA
| | - Jaya G Yodh
- Department of Physics, Center for Physics in Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801-2902, USA.
| | - Taekjip Ha
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801-2902, USA; Department of Physics, Center for Physics in Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801-2902, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801-2902, USA; Howard Hughes Medical Institute, University of Illinois, Urbana, IL 61801-2902, USA.
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44
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Zorman S, Rebane AA, Ma L, Yang G, Molski MA, Coleman J, Pincet F, Rothman JE, Zhang Y. Common intermediates and kinetics, but different energetics, in the assembly of SNARE proteins. eLife 2014; 3:e03348. [PMID: 25180101 PMCID: PMC4166003 DOI: 10.7554/elife.03348] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 08/29/2014] [Indexed: 01/10/2023] Open
Abstract
Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are evolutionarily conserved machines that couple their folding/assembly to membrane fusion. However, it is unclear how these processes are regulated and function. To determine these mechanisms, we characterized the folding energy and kinetics of four representative SNARE complexes at a single-molecule level using high-resolution optical tweezers. We found that all SNARE complexes assemble by the same step-wise zippering mechanism: slow N-terminal domain (NTD) association, a pause in a force-dependent half-zippered intermediate, and fast C-terminal domain (CTD) zippering. The energy release from CTD zippering differs for yeast (13 kBT) and neuronal SNARE complexes (27 kBT), and is concentrated at the C-terminal part of CTD zippering. Thus, SNARE complexes share a conserved zippering pathway and polarized energy release to efficiently drive membrane fusion, but generate different amounts of zippering energy to regulate fusion kinetics. DOI:http://dx.doi.org/10.7554/eLife.03348.001 Many processes in living things need molecules to be transported within, or between, cells. For example, damaged or waste molecules are transported within a cell to structures that can break the molecules down, while nerve impulses are transmitted from one neuron to the next via the release of signaling molecules. Cells—and the compartments within cells—are surrounded by membranes that act as barriers to certain molecules. Vesicles are small, membrane-enclosed packages that are used to transport molecules between different membranes; and in order to release its cargo, a vesicle must fuse with its target membrane. To fuse like this, the forces that act to push membranes away from one another need to be overcome. Proteins called SNARES, which are embedded in both membranes, are the molecular engines that power the fusion process. Once the SNARE proteins from the vesicle and the target membrane bind, they assemble into a more compact complex that pulls the two membranes close together and allows fusion to take place. The final shape of an assembled SNARE complex is essentially the same for all SNARE complexes; however, it is not known whether all of these complexes fold using the same method. Now Zorman et al. have used optical tweezers—an instrument that uses a highly focused laser beam to hold and manipulate microscopic objects—to observe the folding and unfolding of four different types of SNARE complex. All four SNARE complexes followed the same step-by-step process: the leading ends of the SNARE proteins slowly bound to each other; the process paused; then the rest of the proteins rapidly ‘zippered’ together. Zorman et al. revealed that, although the steps in the processes were the same, the energy released in the last step was different when different complexes assembled. This suggests that the energy released by the ‘zippering’ of different SNARE proteins is optimized to match the required speed of different membrane fusion events. Furthermore, Zorman et al. propose that the reason why the majority of energy is released in the later stages of complex assembly is because this is when the repulsion between the two membranes is strongest. The discoveries of Zorman et al. will now aid future efforts aimed at understanding better how the numerous other proteins that interact with SNARE proteins regulate the process of membrane fusion. DOI:http://dx.doi.org/10.7554/eLife.03348.002
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Affiliation(s)
- Sylvain Zorman
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
| | | | - Lu Ma
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
| | - Guangcan Yang
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
| | - Matthew A Molski
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
| | - Jeff Coleman
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
| | - Frederic Pincet
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
| | - James E Rothman
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
| | - Yongli Zhang
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
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Abstract
A large family of chromatin remodelers that noncovalently modify chromatin is crucial in cell development and differentiation. They are often the targets of cancer, neurological disorders, and other human diseases. These complexes alter nucleosome positioning, higher-order chromatin structure, and nuclear organization. They also assemble chromatin, exchange out histone variants, and disassemble chromatin at defined locations. We review aspects of the structural organization of these complexes, the functional properties of their protein domains, and variation between complexes. We also address the mechanistic details of these complexes in mobilizing nucleosomes and altering chromatin structure. A better understanding of these issues will be vital for further analyses of subunits of these chromatin remodelers, which are being identified as targets in human diseases by NGS (next-generation sequencing).
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Affiliation(s)
- Blaine Bartholomew
- University of Texas MD Anderson Cancer Center, Department of Molecular Carcinogenesis, Smithville, Texas 78957;
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Narlikar G, Sundaramoorthy R, Owen-Hughes T. Mechanisms and functions of ATP-dependent chromatin-remodeling enzymes. Cell 2013; 154:490-503. [PMID: 23911317 PMCID: PMC3781322 DOI: 10.1016/j.cell.2013.07.011] [Citation(s) in RCA: 447] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Indexed: 12/28/2022]
Abstract
Chromatin provides both a means to accommodate a large amount of genetic material in a small space and a means to package the same genetic material in different chromatin states. Transitions between chromatin states are enabled by chromatin-remodeling ATPases, which catalyze a diverse range of structural transformations. Biochemical evidence over the last two decades suggests that chromatin-remodeling activities may have emerged by adaptation of ancient DNA translocases to respond to specific features of chromatin. Here, we discuss such evidence and also relate mechanistic insights to our understanding of how chromatin-remodeling enzymes enable different in vivo processes.
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Affiliation(s)
- Geeta J. Narlikar
- Biochemistry and Biophysics, Genentech Hall 600, 16th Street, University of California, San Francisco, San Francisco, CA 94158, USA
- Corresponding author
| | | | - Tom Owen-Hughes
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Corresponding author
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Zhang X, Ma L, Zhang Y. High-resolution optical tweezers for single-molecule manipulation. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2013; 86:367-83. [PMID: 24058311 PMCID: PMC3767221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Forces hold everything together and determine its structure and dynamics. In particular, tiny forces of 1-100 piconewtons govern the structures and dynamics of biomacromolecules. These forces enable folding, assembly, conformational fluctuations, or directional movements of biomacromolecules over sub-nanometer to micron distances. Optical tweezers have become a revolutionary tool to probe the forces, structures, and dynamics associated with biomacromolecules at a single-molecule level with unprecedented resolution. In this review, we introduce the basic principles of optical tweezers and their latest applications in studies of protein folding and molecular motors. We describe the folding dynamics of two strong coiled coil proteins, the GCN4-derived protein pIL and the SNARE complex. Both complexes show multiple folding intermediates and pathways. ATP-dependent chromatin remodeling complexes translocate DNA to remodel chromatin structures. The detailed DNA translocation properties of such molecular motors have recently been characterized by optical tweezers, which are reviewed here. Finally, several future developments and applications of optical tweezers are discussed. These past and future applications demonstrate the unique advantages of high-resolution optical tweezers in quantitatively characterizing complex multi-scale dynamics of biomacromolecules.
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Affiliation(s)
- Xinming Zhang
- Department of Cell Biology, Yale School of Medicine, New Haven,
Connecticut
| | - Lu Ma
- Department of Cell Biology, Yale School of Medicine, New Haven,
Connecticut
| | - Yongli Zhang
- Department of Cell Biology, Yale School of Medicine, New Haven,
Connecticut
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48
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Mack AH, Schlingman DJ, Kamenetska M, Collins R, Regan L, Mochrie SGJ. The molecular yo-yo method: live jump detection improves throughput of single-molecule force spectroscopy for out-of-equilibrium transitions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:085119. [PMID: 24007119 DOI: 10.1063/1.4819026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
By monitoring multiple molecular transitions, force-clamp, and trap-position-clamp methods have led to precise determinations of the free energies and free energy landscapes for molecular states populated in equilibrium at the same or similar forces. Here, we present a powerful new elaboration of the force-clamp and force-jump methods, applicable to transitions far from equilibrium. Specifically, we have implemented a live jump detection and force-clamp algorithm that intelligently adjusts and maintains the force on a single molecule in response to the measured state of that molecule. We are able to collect hundreds of individual molecular transitions at different forces, many times faster than previously, permitting us to accurately determine force-dependent lifetime distributions and reaction rates. Application of our method to unwinding and rewinding the nucleosome inner turn, using optical tweezers reveals experimental lifetime distributions that comprise a statistically meaningful number of transitions, and that are accurately single exponential. These measurements significantly reduce the error in the previously measured rates, and demonstrate the existence of a single, dominant free energy barrier at each force studied. A key benefit of the molecular yo-yo method for nucleosomes is that it reduces as far as possible the time spent in the tangentially bound state, which minimizes the loss of nucleosomes by dissociation.
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Affiliation(s)
- A H Mack
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06511, USA
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49
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Vandecan Y, Blossey R. Fokker-Planck description of single nucleosome repositioning by dimeric chromatin remodelers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:012728. [PMID: 23944511 DOI: 10.1103/physreve.88.012728] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Indexed: 06/02/2023]
Abstract
Recent experiments have demonstrated that the ATP-utilizing chromatin assembly and remodeling factor (ACF) is a dimeric, processive motor complex which can move a nucleosome more efficiently towards longer flanking DNA than towards shorter flanking DNA strands, thereby centering an initially ill-positioned nucleosome on DNA substrates. We give a Fokker-Planck description for the repositioning process driven by transitions between internal chemical states of the remodelers. In the chemical states of ATP hydrolysis during which the repositioning takes place a power stroke is considered. The slope of the effective driving potential is directly related to ATP hydrolysis and leads to the unidirectional motion of the nucleosome-remodeler complex along the DNA strand. The Einstein force relation allows us to deduce the ATP-concentration dependence of the diffusion constant of the nucleosome-remodeler complex. We have employed our model to study the efficiency of positioning of nucleosomes as a function of the ATP sampling rate between the two motors which shows that the synchronization between the motors is crucial for the remodeling mechanism to work.
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Affiliation(s)
- Yves Vandecan
- Interdisciplinary Research Institute USR 3078 CNRS and Université de Sciences et de Technologies de Lille, Parc de la Haute Borne, 50 Avenue de Halley, 59658 Villeneuve d'Ascq, France
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50
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Deindl S, Hwang WL, Hota SK, Blosser TR, Prasad P, Bartholomew B, Zhuang X. ISWI remodelers slide nucleosomes with coordinated multi-base-pair entry steps and single-base-pair exit steps. Cell 2013; 152:442-52. [PMID: 23374341 DOI: 10.1016/j.cell.2012.12.040] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Revised: 10/16/2012] [Accepted: 12/17/2012] [Indexed: 12/27/2022]
Abstract
ISWI-family enzymes remodel chromatin by sliding nucleosomes along DNA, but the nucleosome translocation mechanism remains unclear. Here we use single-molecule FRET to probe nucleosome translocation by ISWI-family remodelers. Distinct ISWI-family members translocate nucleosomes with a similar stepping pattern maintained by the catalytic subunit of the enzyme. Nucleosome remodeling begins with a 7 bp step of DNA translocation followed by 3 bp subsequent steps toward the exit side of nucleosomes. These multi-bp, compound steps are comprised of 1 bp substeps. DNA movement on the entry side of the nucleosome occurs only after 7 bp of exit-side translocation, and each entry-side step draws in a 3 bp equivalent of DNA that allows three additional base pairs to be moved to the exit side. Our results suggest a remodeling mechanism with well-defined coordination at different nucleosomal sites featuring DNA translocation toward the exit side in 1 bp steps preceding multi-bp steps of DNA movement on the entry side.
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Affiliation(s)
- Sebastian Deindl
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
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