University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Thursday, November 17th 2016
11:15 am:
Biophysics Seminar in 120 PAN
Speaker: Razvan Chereji, National Institute of Child Health and Human Development
Subject: The Universality of Nucleosome Organization: From Yeast to Human

It is estimated that a human body contains about 100 trillion meters of DNA, enough to circle the Earth's Equator 2.5 million times. DNA is remarkably tightly packed inside the cell nucleus; nevertheless, transcription factors must quickly find and access the regulatory regions along the genome, should the need arise. Nucleosomes -- 147 basepairs of DNA wrapped around a histone octamer in about 2 turns -- are the basic units of DNA packaging. The precise positions of nucleosomes along the genome play an essential role in gene regulation, dictating which genes can be regulated by transcription factors. I study the nucleosome positions in various organisms (yeast, fly, mouse and human) and I build biophysical models that explain their organization. I will show that nucleosomes have a universal organization at the gene promoters, which is shared by multiple organisms, and that statistical mechanics can predict this common organization. I will show that DNA sequence alone has a limited effect in organizing the chromatin, and I will discuss the other mechanisms that have a major role in nucleosome positioning.

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