Nucleosome positioning by excluding genomic energy barriers

Note: Note: Thursday at 11:45 AM;PRB 595; Pizza served at 11:30 AM
Speaker: Alain Arneodo, Laboratoire Joliot Curie et Laboratoire de Physique, Ecole Normale Supérieure de Lyon

When: May 26, 2011 (Thu), 11:45AM to 12:45PM (add to my calendar)
Location: PRB 595
Hosted by: Plamen Ivanov

This event is part of the Biophysics/Condensed Matter Seminar Series.

Abstract:
Chromatin is composed of regularly spaced nucleosomes in which about 146 base pairs of genomic DNA is wrapped around a complex of histone proteins. Whether or not a defined genomic region is occupied by a nucleosome is essential for the binding of this region to regulatory proteins. From the statistical analysis of recent nucleosome positioning in vivo data in yeast, we demonstrate that long-range correlations (LRC) in the genomic sequence strongly influence the organization of nucleosomes. We present a physical explanation of how LRC may significantly condition the overall formation and positioning of nucleosomes including the nucleosome-free regions observed at gene promoters. These results are corroborated by recent experimental AFM imaging of nucleosome positioning by excluding genomic energy barriers. We conclude by discussing the implications of such « positioning via excluding » mechanism on the structure and function of yeast genes.