How the chromatin fiber deals with topological constraints

Maria Barbi, Julien Mozziconacci, and Jean-Marc Victor
Phys. Rev. E 71, 031910 – Published 23 March 2005

Abstract

In the nuclei of eukaryotic cells, DNA is packaged through several levels of compaction in an orderly retrievable way that enables the correct regulation of gene expression. The functional dynamics of this assembly involves the unwinding of the so-called 30nm chromatin fiber and accordingly imposes strong topological constraints. We present a general method for computing both the twist and the writhe of any winding pattern. An explicit derivation is implemented for the chromatin fiber which provides the linking number of DNA in eukaryotic chromosomes. We show that there exists one and only one unwinding path which satisfies both topological and mechanical constraints that DNA has to deal with during condensation/decondensation processes.

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  • Received 13 April 2004

DOI:https://doi.org/10.1103/PhysRevE.71.031910

©2005 American Physical Society

Authors & Affiliations

Maria Barbi, Julien Mozziconacci, and Jean-Marc Victor*

  • Laboratoire de Physique Theorique des Liquides, CNRS UMR 7600, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France

  • *Author to whom all correspondence should be addressed. Email address: victor@lptl.jussieu.fr

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Issue

Vol. 71, Iss. 3 — March 2005

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