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Unique Dynamics in Asymmetric macroH2A-H2A Hybrid Nucleosomes Result in Increased Complex Stability
Samuel Bowerman1, Robert J Hickok1, Jeff Wereszczynski1
1Department of Physics and the Center for Molecular Study of Condensed Soft Matter, Illinois Institute of Technology , Chicago , Illinois 60616 , United States.
The Journal of Physical Chemistry. B
|December 18, 2018
Summary
Hybrid nucleosomes with both H2A and macroH2A histones are energetically favorable. These hybrid structures exhibit unique dynamics, enhancing stability and potentially hindering transcriptional activity in chromatin.
Area of Science:
- Molecular Biology
- Structural Biology
- Biophysics
Background:
- The nucleosome core particle, composed of histone octamers and DNA, is the fundamental unit of eukaryotic chromatin.
- Histone variants, like macroH2A, can modulate genetic accessibility by substituting canonical histones.
- Previous studies showed in vitro formation of hybrid nucleosomes containing both H2A and macroH2A dimers.
Purpose of the Study:
- To investigate the molecular dynamics and stability of hybrid macroH2A-H2A nucleosomes.
- To compare the dynamics of hybrid nucleosomes with homogeneous H2A- and macroH2A-containing nucleosomes.
- To assess the energetic favorability of hybrid nucleosome formation.
Main Methods:
- Molecular dynamics simulations of hybrid macroH2A-H2A nucleosomes.
- Comparison of simulation results with prior studies on homogeneous nucleosomes.
- Analysis of protein-DNA and protein-protein interactions within the nucleosome core.
Main Results:
- Hybrid nucleosomes exhibit unique dynamics, stabilizing protein-DNA and protein-protein interactions.
- Dimer-tetramer interactions are asymmetric, with the canonical H2A dimer showing increased stability.
- Hybrid nucleosome formation is energetically more favorable than homogeneous constructs.
Conclusions:
- Hybrid H2A-macroH2A nucleosomes are not only possible but energetically favored over homogeneous counterparts.
- Unique dynamics in hybrid nucleosomes contribute to increased stability.
- These findings suggest a role for hybrid nucleosomes in regulating transcriptional activity through higher-order chromatin structures.
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