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Assembly of Nucleosomal Arrays from Recombinant Core Histones and Nucleosome Positioning DNA
Published on: September 10, 2013
Twist propagation in dinucleosome arrays
Irina V Dobrovolskaia1, Martin Kenward, Gaurav Arya
1Department of NanoEngineering, University of California at San Diego, La Jolla, CA, USA.
Biophysical Journal
|November 18, 2010
Summary
DNA twist distribution in nucleosome arrays can invert unexpectedly due to linker orientation. This "twist inversion" and "nucleosome flipping" reveal mechanisms of torsional stress in chromatin organization.
Area of Science:
- Structural biology
- Biophysics
- Computational biology
Background:
- Chromatin fibers are organized by nucleosomes and DNA linkers.
- Torsional stress influences chromatin structure and function.
- Understanding twist propagation in nucleosome arrays is crucial.
Purpose of the Study:
- To investigate how twist distributes and propagates through DNA linkers in a two-nucleosome array.
- To explore the phenomenon of
- twist inversion
- and
- nucleosome flipping
- under applied torsional stress.
Main Methods:
- Monte Carlo simulation of a mesoscopic model.
- Incorporation of nucleosome geometry and linker mechanics.
- Stepwise application of external twist to mimic quasistatic twisting.
Main Results:
- Twist distribution and propagation depend strongly on linker relative orientation.
- Observed
- twist inversion
- where induced twist opposes applied twist.
- Observed
- nucleosome flipping
- , leading to rapid linker bending and changes in twist and writhe.
Conclusions:
- Linker orientation is a key determinant of twist propagation in nucleosome arrays.
- Twist inversion and nucleosome flipping are significant phenomena impacting chromatin organization.
- Findings provide insight into the mechanisms of torsional stress effects on chromatin.
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