Séminaires MSC
"Matière et Systèmes Complexes"


Mercredi 9 mai 2007 à 11h30
Bâtiment Condorcet, 4ème étage, salle 454 A.

C. Lavelle
(IGR, Villejuif)

DNA metabolism in a chromatin context: some single molecules experiments

Genomic DNA is divided into chromosomes, each consisting in a single huge nucleosomal fiber hierarchically supercoiled, making chromatin the physiological template for DNA
metabolism in eukaryotic cells. Indeed, it is now well-acknowledge that the structure and dynamics of this macromolecular complex plays a critical role in all processes DNA
undergoes, including replication, transcription, recombination and repair. To understand how this works in vivo, one needs to integrate the many regulatory mechanisms at all
hierarchical levels.
Hence, from “free” linear DNA (sequence level) to compact protein-DNA complexes that form interphasic chromosome territories, numerous events occur that each depend on
various constraints (mechanical, topological, electrostatic) and interactions with numerous proteins in a multiscale interconnected control network.
The aim of this talk is to discuss some mechanistic aspects of transcription and recombination in a chromatin context. I will more particularly show recent data
we got using a "single molecules" approach, either to visualize (electronic and atomic force microscopy) or manipulate (magnetic tweezers) DNA/protein complexes.
Some preliminary results from current projects we are carrying on remodeling factor RSC and recombinase rad51 will also be presented.