Lecture Vincent Rossetto
|07 April 2008||FWN-Building 5113.0201, Nijenborgh 4, 9747 AG, Groningen|
|Affiliation:||Laboratoire de physique et modélisation de la matière condensée / CNRS Grenoble|
|Title:||Does the 30 nm chromatin fiber have a structure?|
|Date:||Mon Apr 7, 2008|
|Telephone:||+31 50 363 8039|
In eukaryotes, DNA is packed in the nucleus and forms a complex with proteins called chromatin. In the understanding of genetic machinery, it became more and more patent that the structure of chromatin takes part into several mechanisms. The details of this structure are nevertheless still subject to debate.
The basic reason of this controversy is that there is no satisfying method to observe in vivo a large amount of chromatin in detail. It is known that the elementary unit of chromatin, called nucleosome, is made of a protein octamer and this unit has been observed precisely in crystallography. On the other hand microscopic observations showed regular patterns, but the details of the DNA conformation remain invisible. Several models have been proposed to interprete the experiments, but none of them was able to conciliate all observations.
One way to investigate this puzzle is to study a geometrical and thermodynamical model which is broad enough to contain all existing models. Our model is based on the crystalized structure of a single nucleosome and the mechanics of DNA. The ensemble of structures is studied with thermodynamics.
I will present the classification of structures and compare their propertes, which will then confront the observations of actual chromatin fibers.
|Last modified:||22 October 2012 2.30 p.m.|