Sunday, April 23, 2006, 11:15-12:15
Room 309
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Eran Segal
Weizmann Institute
Title: A Genomic Code for Nucleosome Positioning and Chromosome Function
Abstract:
To fit within the nucleus, DNA of eukaryotic genomes is
highly compacted
into protein-DNA complexes known as
nucleosomes. Nucleosomes
act as general
inhibitors, since DNA wrapped in nucleosomes is occluded from access to most
DNA binding proteins. Thus, understanding
the driving forces and mechanism
by which nucleosomes
are placed along the genome has important implications
for all aspects of gene regulation
and chromosome function. In this study,
we combined a statistical mechanics
based computational approach with
wet-lab experiments to discover and
decode a new kind of genetic
information, encoded in the genomes
of all eukaryotes, that specifies the
organization and positioning of nucleosomes. We show that this nucleosome
positioning code occurs abundantly
across the entire genome and is highly
conserved from yeast to human. We
show that this novel positioning code can,
on its own, successfully predict ~50%
of the entire in vivo nucleosome
organization. We also prove the correctness
of this code in in vitro
experiments. Our results establish
that genomes utilize this nucleosome
positioning code to direct
transcription factors to their appropriate
binding sites in the genome, and to
facilitate many other specific
chromosome functions, including
transcription initiation, and even
remodeling of the nucleosomes themselves.
The talk will assume no prior knowledge of Molecular Biology.