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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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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