Format

Send to:

Choose Destination
See comment in PubMed Commons below
Biophys J. 1998 May;74(5):2531-44.

A topological approach to nucleosome structure and dynamics: the linking number paradox and other issues.

Author information

  • 1Institut Jacques Monod, Centre National de la Recherche Scientifique and Universit√© Paris 7, France. prunell@ccr.jussieu.fr

Abstract

The linking number paradox of DNA in chromatin (two negative crossings around the octamer, associated with a unit linking number reduction), which is 21 years old this year, has come of age. After stirring much debate in the past, the initially hypothetical explanation of the paradox by DNA overtwisting on the nucleosome surface is now presented as a hard fact in recent textbooks. The first part of this article presents a historical perspective of the problem and details the numerous attempts to measure DNA local periodicity, which in one remarkable example sowed the seeds for the discovery of DNA bending. The second part is devoted to the DNA minicircle system, which has been developed in the author's laboratory as an alternative to the local-periodicity-measurement approach. It offers a simple proposal: a unit linking number reduction associated with a single crossing. This conclusion is contrasted with the latest high-resolution crystallographic data of the nucleosome in the third part of the article, and the fourth part examines the available evidence supporting an extension of these results to nucleosomes in chromatin. The last part addresses another basic question pertaining to nucleosome dynamics, the conformational flexibility of the histone tetramer.

PMID:
9591679
[PubMed - indexed for MEDLINE]
PMCID:
PMC1299595
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science Icon for PubMed Central
    Loading ...
    Write to the Help Desk