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Updated: Nov 9, 2025
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Assembly of Nucleosomal Arrays from Recombinant Core Histones and Nucleosome Positioning DNA
Published on: September 10, 2013
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Nucleosome composition regulates the histone H3 tail conformational ensemble and accessibility
Emma A Morrison1,2, Lokesh Baweja3,4, Michael G Poirier5
1Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
Nucleic Acids Research
|April 15, 2021
Summary
Hexasomes and tetrasomes, key nucleosome intermediates, show H3 tail dynamics are regulated by their composition. Loss of the H2A/H2B dimer alters H3 tail conformation, increasing its dynamics and accessibility.
Area of Science:
- Chromatin biology
- Molecular genetics
- Biophysics
Background:
- Hexasomes and tetrasomes are crucial intermediates in nucleosome assembly and disassembly.
- Histone chaperones, ATP-dependent remodelers, and RNA polymerase II influence hexasome and tetrasome formation.
- Hexasomes are present in transcribed genes, suggesting a regulatory role in gene expression.
Purpose of the Study:
- To investigate the conformational dynamics of the H3 tail within hexasomes and tetrasomes.
- To understand how nucleosome composition influences H3 tail behavior.
- To explore the implications for chromatin structure and gene regulation.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy
- Molecular Dynamics (MD) simulations
- Trypsin proteolysis assays
Main Results:
- Nucleosome composition regulates the conformational ensemble of the H3 tail.
- H3 tails bind DNA robustly in hexasomes and tetrasomes.
- Loss of the H2A/H2B dimer alters the H3 tail's conformational ensemble, increasing its dynamics and accessibility, asymmetrically in hexasomes.
Conclusions:
- Nucleosome composition influences histone tail dynamics and accessibility.
- Altered H3 tail dynamics may play a role in chromatin signaling.
- These findings suggest a mechanism by which nucleosome composition shapes the chromatin landscape.
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