1
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Schwab S, Dame RT. Identification, characterization and classification of prokaryotic nucleoid-associated proteins. Mol Microbiol 2024. [PMID: 39039769 DOI: 10.1111/mmi.15298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 07/02/2024] [Accepted: 07/06/2024] [Indexed: 07/24/2024]
Abstract
Common throughout life is the need to compact and organize the genome. Possible mechanisms involved in this process include supercoiling, phase separation, charge neutralization, macromolecular crowding, and nucleoid-associated proteins (NAPs). NAPs are special in that they can organize the genome at multiple length scales, and thus are often considered as the architects of the genome. NAPs shape the genome by either bending DNA, wrapping DNA, bridging DNA, or forming nucleoprotein filaments on the DNA. In this mini-review, we discuss recent advancements of unique NAPs with differing architectural properties across the tree of life, including NAPs from bacteria, archaea, and viruses. To help the characterization of NAPs from the ever-increasing number of metagenomes, we recommend a set of cheap and simple in vitro biochemical assays that give unambiguous insights into the architectural properties of NAPs. Finally, we highlight and showcase the usefulness of AlphaFold in the characterization of novel NAPs.
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Affiliation(s)
- Samuel Schwab
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
- Centre for Interdisciplinary Genome Research, Leiden University, Leiden, The Netherlands
| | - Remus T Dame
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
- Centre for Interdisciplinary Genome Research, Leiden University, Leiden, The Netherlands
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2
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Lin SN, Qin L, Taris KKH, Wuite GJL, Dame RT. Unravelling the Biophysical Properties of Chromatin Proteins and DNA Using Acoustic Force Spectroscopy. Methods Mol Biol 2024; 2819:519-534. [PMID: 39028522 DOI: 10.1007/978-1-0716-3930-6_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Acoustic force spectroscopy (AFS) is a single-molecule micromanipulation technique that uses sound waves to exert force on surface-tethered DNA molecules in a microfluidic chamber. As large numbers of individual protein-DNA complexes are tracked in parallel, AFS provides insight into the individual properties of such complexes as well as their population averages. In this chapter, we describe in detail how to perform AFS experiments specifically on bare DNA, protein-DNA complexes, and how to extract their (effective) persistence length and contour length from force-extension relations.
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Affiliation(s)
- Szu-Ning Lin
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
- Department of Physics and Astronomy, VU University Amsterdam, Amsterdam, The Netherlands
| | - Liang Qin
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Kees-Karel H Taris
- Department of Physics and Astronomy, VU University Amsterdam, Amsterdam, The Netherlands
| | - Gijs J L Wuite
- Department of Physics and Astronomy, VU University Amsterdam, Amsterdam, The Netherlands
| | - Remus T Dame
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands.
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands.
- Centre for Interdisciplinary Genome Research, Leiden University, Leiden, The Netherlands.
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3
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Ofer S, Blombach F, Erkelens AM, Barker D, Soloviev Z, Schwab S, Smollett K, Matelska D, Fouqueau T, van der Vis N, Kent NA, Thalassinos K, Dame RT, Werner F. DNA-bridging by an archaeal histone variant via a unique tetramerisation interface. Commun Biol 2023; 6:968. [PMID: 37740023 PMCID: PMC10516927 DOI: 10.1038/s42003-023-05348-2] [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: 12/21/2022] [Accepted: 09/12/2023] [Indexed: 09/24/2023] Open
Abstract
In eukaryotes, histone paralogues form obligate heterodimers such as H3/H4 and H2A/H2B that assemble into octameric nucleosome particles. Archaeal histones are dimeric and assemble on DNA into 'hypernucleosome' particles of varying sizes with each dimer wrapping 30 bp of DNA. These are composed of canonical and variant histone paralogues, but the function of these variants is poorly understood. Here, we characterise the structure and function of the histone paralogue MJ1647 from Methanocaldococcus jannaschii that has a unique C-terminal extension enabling homotetramerisation. The 1.9 Å X-ray structure of a dimeric MJ1647 species, structural modelling of the tetramer, and site-directed mutagenesis reveal that the C-terminal tetramerization module consists of two alpha helices in a handshake arrangement. Unlike canonical histones, MJ1647 tetramers can bridge two DNA molecules in vitro. Using single-molecule tethered particle motion and DNA binding assays, we show that MJ1647 tetramers bind ~60 bp DNA and compact DNA in a highly cooperative manner. We furthermore show that MJ1647 effectively competes with the transcription machinery to block access to the promoter in vitro. To the best of our knowledge, MJ1647 is the first histone shown to have DNA bridging properties, which has important implications for genome structure and gene expression in archaea.
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Affiliation(s)
- Sapir Ofer
- Institute for Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Fabian Blombach
- Institute for Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Amanda M Erkelens
- Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands
| | - Declan Barker
- Institute for Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Zoja Soloviev
- Institute for Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Samuel Schwab
- Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands
| | - Katherine Smollett
- Institute for Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Dorota Matelska
- Institute for Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
- Centre for Genomics Research, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Thomas Fouqueau
- Institute for Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Nico van der Vis
- Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands
| | - Nicholas A Kent
- School of Biosciences, Cardiff University, Museum Avenue, Cardiff, CF10 3AX, UK
| | - Konstantinos Thalassinos
- Institute for Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Remus T Dame
- Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands.
| | - Finn Werner
- Institute for Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK.
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4
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Erkelens AM, Henneman B, van der Valk RA, Kirolos NCS, Dame RT. Specific DNA binding of archaeal histones HMfA and HMfB. Front Microbiol 2023; 14:1166608. [PMID: 37143534 PMCID: PMC10151503 DOI: 10.3389/fmicb.2023.1166608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 03/27/2023] [Indexed: 05/06/2023] Open
Abstract
In archaea, histones play a role in genome compaction and are involved in transcription regulation. Whereas archaeal histones bind DNA without sequence specificity, they bind preferentially to DNA containing repeats of alternating A/T and G/C motifs. These motifs are also present on the artificial sequence "Clone20," a high-affinity model sequence for binding of the histones from Methanothermus fervidus. Here, we investigate the binding of HMfA and HMfB to Clone20 DNA. We show that specific binding at low protein concentrations (<30 nM) yields a modest level of DNA compaction, attributed to tetrameric nucleosome formation, whereas nonspecific binding strongly compacts DNA. We also demonstrate that histones impaired in hypernucleosome formation are still able to recognize the Clone20 sequence. Histone tetramers indeed exhibit a higher binding affinity for Clone20 than nonspecific DNA. Our results indicate that a high-affinity DNA sequence does not act as a nucleation site, but is bound by a tetramer which we propose is geometrically different from the hypernucleosome. Such a mode of histone binding might permit sequence-driven modulation of hypernucleosome size. These findings might be extrapolated to histone variants that do not form hypernucleosomes. Versatile binding modes of histones could provide a platform for functional interplay between genome compaction and transcription.
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Affiliation(s)
| | - Bram Henneman
- Leiden Institute of Chemistry, Leiden University, Leiden, Netherlands
| | | | | | - Remus T. Dame
- Leiden Institute of Chemistry, Leiden University, Leiden, Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, Netherlands
- *Correspondence: Remus T. Dame,
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5
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System-Wide Analysis of the GATC-Binding Nucleoid-Associated Protein Gbn and Its Impact on
Streptomyces
Development. mSystems 2022; 7:e0006122. [PMID: 35575488 PMCID: PMC9239103 DOI: 10.1128/msystems.00061-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A large part of the chemical space of bioactive natural products is derived from
Actinobacteria
. Many of the biosynthetic gene clusters for these compounds are cryptic; in others words, they are expressed in nature but not in the laboratory.
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6
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Henneman B, Brouwer TB, Erkelens AM, Kuijntjes GJ, van Emmerik C, van der Valk RA, Timmer M, Kirolos NCS, van Ingen H, van Noort J, Dame RT. Mechanical and structural properties of archaeal hypernucleosomes. Nucleic Acids Res 2021; 49:4338-4349. [PMID: 33341892 PMCID: PMC8096283 DOI: 10.1093/nar/gkaa1196] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 11/13/2020] [Accepted: 11/23/2020] [Indexed: 11/21/2022] Open
Abstract
Many archaea express histones, which organize the genome and play a key role in gene regulation. The structure and function of archaeal histone–DNA complexes remain however largely unclear. Recent studies show formation of hypernucleosomes consisting of DNA wrapped around an ‘endless’ histone-protein core. However, if and how such a hypernucleosome structure assembles on a long DNA substrate and which interactions provide for its stability, remains unclear. Here, we describe micromanipulation studies of complexes of the histones HMfA and HMfB with DNA. Our experiments show hypernucleosome assembly which results from cooperative binding of histones to DNA, facilitated by weak stacking interactions between neighboring histone dimers. Furthermore, rotational force spectroscopy demonstrates that the HMfB–DNA complex has a left-handed chirality, but that torque can drive it in a right-handed conformation. The structure of the hypernucleosome thus depends on stacking interactions, torque, and force. In vivo, such modulation of the archaeal hypernucleosome structure may play an important role in transcription regulation in response to environmental changes.
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Affiliation(s)
- Bram Henneman
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands
| | - Thomas B Brouwer
- Biological and Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
| | - Amanda M Erkelens
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands
| | - Gert-Jan Kuijntjes
- Biological and Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
| | - Clara van Emmerik
- Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584CH Utrecht, The Netherlands
| | - Ramon A van der Valk
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands
| | - Monika Timmer
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands
| | - Nancy C S Kirolos
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands
| | - Hugo van Ingen
- Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584CH Utrecht, The Netherlands
| | - John van Noort
- Biological and Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
| | - Remus T Dame
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands.,Centre for Microbial Cell Biology, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands
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7
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Lin SN, Wuite GJ, Dame RT. Effect of Different Crowding Agents on the Architectural Properties of the Bacterial Nucleoid-Associated Protein HU. Int J Mol Sci 2020; 21:ijms21249553. [PMID: 33334011 PMCID: PMC7765392 DOI: 10.3390/ijms21249553] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/09/2020] [Accepted: 12/09/2020] [Indexed: 12/31/2022] Open
Abstract
HU is a nucleoid-associated protein expressed in most eubacteria at a high amount of copies (tens of thousands). The protein is believed to bind across the genome to organize and compact the DNA. Most of the studies on HU have been carried out in a simple in vitro system, and to what extent these observations can be extrapolated to a living cell is unclear. In this study, we investigate the DNA binding properties of HU under conditions approximating physiological ones. We report that these properties are influenced by both macromolecular crowding and salt conditions. We use three different crowding agents (blotting grade blocker (BGB), bovine serum albumin (BSA), and polyethylene glycol 8000 (PEG8000)) as well as two different MgCl2 conditions to mimic the intracellular environment. Using tethered particle motion (TPM), we show that the transition between two binding regimes, compaction and extension of the HU protein, is strongly affected by crowding agents. Our observations suggest that magnesium ions enhance the compaction of HU–DNA and suppress filamentation, while BGB and BSA increase the local concentration of the HU protein by more than 4-fold. Moreover, BGB and BSA seem to suppress filament formation. On the other hand, PEG8000 is not a good crowding agent for concentrations above 9% (w/v), because it might interact with DNA, the protein, and/or surfaces. Together, these results reveal a complex interplay between the HU protein and the various crowding agents that should be taken into consideration when using crowding agents to mimic an in vivo system.
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Affiliation(s)
- Szu-Ning Lin
- Leiden Institute of Chemistry, Leiden University, 2333 CC Leiden, The Netherlands;
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Gijs J.L. Wuite
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
- LaserLaB Amsterdam, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
- Correspondence: (G.J.L.W.); (R.T.D.)
| | - Remus T. Dame
- Leiden Institute of Chemistry, Leiden University, 2333 CC Leiden, The Netherlands;
- Centre for Microbial Cell Biology, Leiden University, 2333 CC Leiden, The Netherlands
- Correspondence: (G.J.L.W.); (R.T.D.)
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8
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Qin L, Bdira FB, Sterckx YGJ, Volkov AN, Vreede J, Giachin G, van Schaik P, Ubbink M, Dame R. Structural basis for osmotic regulation of the DNA binding properties of H-NS proteins. Nucleic Acids Res 2020; 48:2156-2172. [PMID: 31925429 PMCID: PMC7039000 DOI: 10.1093/nar/gkz1226] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/29/2019] [Accepted: 12/19/2019] [Indexed: 01/07/2023] Open
Abstract
H-NS proteins act as osmotic sensors translating changes in osmolarity into altered DNA binding properties, thus, regulating enterobacterial genome organization and genes transcription. The molecular mechanism underlying the switching process and its conservation among H-NS family members remains elusive. Here, we focus on the H-NS family protein MvaT from Pseudomonas aeruginosa and demonstrate experimentally that its protomer exists in two different conformations, corresponding to two different functional states. In the half-opened state (dominant at low salt) the protein forms filaments along DNA, in the fully opened state (dominant at high salt) the protein bridges DNA. This switching is a direct effect of ionic strength on electrostatic interactions between the oppositely charged DNA binding and N-terminal domains of MvaT. The asymmetric charge distribution and intramolecular interactions are conserved among the H-NS family of proteins. Therefore, our study establishes a general paradigm for the molecular mechanistic basis of the osmosensitivity of H-NS proteins.
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Affiliation(s)
- Liang Qin
- Department of Macromolecular Biochemistry, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, the Netherlands
- Centre for Microbial Cell Biology, Leiden University, Einsteinweg 55, 2333CC Leiden, the Netherlands
| | - Fredj Ben Bdira
- Department of Macromolecular Biochemistry, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, the Netherlands
- Centre for Microbial Cell Biology, Leiden University, Einsteinweg 55, 2333CC Leiden, the Netherlands
| | - Yann G J Sterckx
- Laboratory of Medical Biochemistry, University of Antwerp, Campus Drie Eiken, University Square 1, 2610 Wilrijk, Belgium
| | - Alexander N Volkov
- VIB-VUB Structural Biology Research Center, Pleinlaan 2, 1050 Brussels, Belgium
- Jean Jeener NMR Centre, VUB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Jocelyne Vreede
- Department of Computational Chemistry, Van’t Hoff Institute for Molecular Sciences, University of Amsterdam Science Park 904, 1098 XH Amsterdam, the Netherlands
| | - Gabriele Giachin
- Structural Biology Group, European Synchrotron Radiation Facility (ESRF), Grenoble, France
| | - Peter van Schaik
- Department of Macromolecular Biochemistry, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, the Netherlands
- Centre for Microbial Cell Biology, Leiden University, Einsteinweg 55, 2333CC Leiden, the Netherlands
| | - Marcellus Ubbink
- Department of Macromolecular Biochemistry, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, the Netherlands
| | - Remus T Dame
- Department of Macromolecular Biochemistry, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, the Netherlands
- Centre for Microbial Cell Biology, Leiden University, Einsteinweg 55, 2333CC Leiden, the Netherlands
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9
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Abstract
The genomes of all organisms throughout the tree of life are compacted and organized in chromatin by association of chromatin proteins. Eukaryotic genomes encode histones, which are assembled on the genome into octamers, yielding nucleosomes. Post-translational modifications of the histones, which occur mostly on their N-terminal tails, define the functional state of chromatin. Like eukaryotes, most archaeal genomes encode histones, which are believed to be involved in the compaction and organization of their genomes. Instead of discrete multimers, in vivo data suggest assembly of “nucleosomes” of variable size, consisting of multiples of dimers, which are able to induce repression of transcription. Based on these data and a model derived from X-ray crystallography, it was recently proposed that archaeal histones assemble on DNA into “endless” hypernucleosomes. In this review, we discuss the amino acid determinants of hypernucleosome formation and highlight differences with the canonical eukaryotic octamer. We identify archaeal histones differing from the consensus, which are expected to be unable to assemble into hypernucleosomes. Finally, we identify atypical archaeal histones with short N- or C-terminal extensions and C-terminal tails similar to the tails of eukaryotic histones, which are subject to post-translational modification. Based on the expected characteristics of these archaeal histones, we discuss possibilities of involvement of histones in archaeal transcription regulation. Both Archaea and eukaryotes express histones, but whereas the tertiary structure of histones is conserved, the quaternary structure of histone–DNA complexes is very different. In a recent study, the crystal structure of the archaeal hypernucleosome was revealed to be an “endless” core of interacting histones that wraps the DNA around it in a left-handed manner. The ability to form a hypernucleosome is likely determined by dimer–dimer interactions as well as stacking interactions between individual layers of the hypernucleosome. We analyzed a wide variety of archaeal histones and found that most but not all histones possess residues able to facilitate hypernucleosome formation. Among these are histones with truncated termini or extended histone tails. Based on our analysis, we propose several possibilities of archaeal histone involvement in transcription regulation.
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Affiliation(s)
- Bram Henneman
- Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands
| | - Clara van Emmerik
- Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands
| | - Hugo van Ingen
- Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands
| | - Remus T. Dame
- Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, the Netherlands
- * E-mail:
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10
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Lin SN, Qin L, Wuite GJL, Dame RT. Unraveling the Biophysical Properties of Chromatin Proteins and DNA Using Acoustic Force Spectroscopy. Methods Mol Biol 2018; 1837:301-316. [PMID: 30109617 DOI: 10.1007/978-1-4939-8675-0_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Acoustic Force Spectroscopy (AFS) is a single-molecule micromanipulation technique that uses sound waves to exert force on surface-tethered DNA molecules in a microfluidic chamber. As large numbers of individual protein-DNA complexes are tracked in parallel, AFS provides insight into the individual properties of such complexes as well as their population averages. In this chapter, we describe in detail how to perform AFS experiments specifically on bare DNA, protein-DNA complexes, and how to extract their (effective) persistence length and contour length from force-extension relations.
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Affiliation(s)
- Szu-Ning Lin
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands.,Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Liang Qin
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Gijs J L Wuite
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
| | - Remus T Dame
- Leiden Institute of Chemistry and Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands.
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11
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Fan HF, Ma CH, Jayaram M. Single-Molecule Tethered Particle Motion: Stepwise Analyses of Site-Specific DNA Recombination. MICROMACHINES 2018; 9:E216. [PMID: 30424148 PMCID: PMC6187709 DOI: 10.3390/mi9050216] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 04/25/2018] [Accepted: 04/28/2018] [Indexed: 12/17/2022]
Abstract
Tethered particle motion/microscopy (TPM) is a biophysical tool used to analyze changes in the effective length of a polymer, tethered at one end, under changing conditions. The tether length is measured indirectly by recording the Brownian motion amplitude of a bead attached to the other end. In the biological realm, DNA, whose interactions with proteins are often accompanied by apparent or real changes in length, has almost exclusively been the subject of TPM studies. TPM has been employed to study DNA bending, looping and wrapping, DNA compaction, high-order DNA⁻protein assembly, and protein translocation along DNA. Our TPM analyses have focused on tyrosine and serine site-specific recombinases. Their pre-chemical interactions with DNA cause reversible changes in DNA length, detectable by TPM. The chemical steps of recombination, depending on the substrate and the type of recombinase, may result in a permanent length change. Single molecule TPM time traces provide thermodynamic and kinetic information on each step of the recombination pathway. They reveal how mechanistically related recombinases may differ in their early commitment to recombination, reversibility of individual steps, and in the rate-limiting step of the reaction. They shed light on the pre-chemical roles of catalytic residues, and on the mechanisms by which accessory proteins regulate recombination directionality.
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Affiliation(s)
- Hsiu-Fang Fan
- Biophotonics and Molecular Imaging Center, Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei 112, Taiwan.
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan.
| | - Chien-Hui Ma
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
| | - Makkuni Jayaram
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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12
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van der Valk RA, Vreede J, Qin L, Moolenaar GF, Hofmann A, Goosen N, Dame RT. Mechanism of environmentally driven conformational changes that modulate H-NS DNA-bridging activity. eLife 2017; 6:e27369. [PMID: 28949292 PMCID: PMC5647153 DOI: 10.7554/elife.27369] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 09/25/2017] [Indexed: 11/13/2022] Open
Abstract
Bacteria frequently need to adapt to altered environmental conditions. Adaptation requires changes in gene expression, often mediated by global regulators of transcription. The nucleoid-associated protein H-NS is a key global regulator in Gram-negative bacteria and is believed to be a crucial player in bacterial chromatin organization via its DNA-bridging activity. H-NS activity in vivo is modulated by physico-chemical factors (osmolarity, pH, temperature) and interaction partners. Mechanistically, it is unclear how functional modulation of H-NS by such factors is achieved. Here, we show that a diverse spectrum of H-NS modulators alter the DNA-bridging activity of H-NS. Changes in monovalent and divalent ion concentrations drive an abrupt switch between a bridging and non-bridging DNA-binding mode. Similarly, synergistic and antagonistic co-regulators modulate the DNA-bridging efficiency. Structural studies suggest a conserved mechanism: H-NS switches between a 'closed' and an 'open', bridging competent, conformation driven by environmental cues and interaction partners.
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Affiliation(s)
| | - Jocelyne Vreede
- Computational ChemistryVan ‘t Hoff Institute for Molecular Sciences, University of AmsterdamAmsterdamNetherlands
| | - Liang Qin
- Leiden Institute of ChemistryLeiden UniversityLeidenNetherlands
| | | | - Andreas Hofmann
- Institute for Theoretical PhysicsUniversity of HeidelbergHeidelbergGermany
| | - Nora Goosen
- Leiden Institute of ChemistryLeiden UniversityLeidenNetherlands
| | - Remus T Dame
- Leiden Institute of ChemistryLeiden UniversityLeidenNetherlands
- Centre for Microbial Cell BiologyLeiden UniversityLeidenNetherlands
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