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SUMMARY:Near-atomistic Modeling of Chromatin – Leveraging Computational 
  Advances to Uncover Mechanistic Insights - Xingcheng Lin\, Department of 
 Chemistry\, MIT
DTSTART:20220228T143000Z
DTEND:20220228T150000Z
UID:TALK167294@talks.cam.ac.uk
CONTACT:Dr Christoph Schran
DESCRIPTION:Three-dimensional chromatin organization lays the foundation f
 or biological processes involving\ngene expression and epigenetic regulati
 on. Nevertheless\, it is unclear how chromatin is structured\nat the funda
 mental level. There is a heated debate over the existence of chromatin fib
 ril structure\nand its response to environmental perturbations. Controvers
 y also remains on the solid or liquid properties of chromatin subject to d
 ifferent experimental conditions. Here\, building upon our recently implem
 ented near-atomistic chromatin model\, we leverage computational advances 
 to study structural details of large chromatin systems. Our study with a t
 etranucleosome\, the fundamental unit of chromatin\, captures multiple irr
 egular chromatin structures that emerge as intermediates of two chromatin 
 folding pathways. Our further study with a dodecameric nucleosomal array r
 epro-\nduces the force-extension curve measured by magnetic tweezers. The 
 simulation also reveals a more complicated folding landscape of chromatin 
 under tension than a two-state transition: Whereas the shearing motion of 
 compact chromatin under lower tension constitutes the “linear” respons
 e regime\,\na mixture of trinucleosome and tetranucleosome clutches appear
 s as tension increases\, leading to\nan extended nucleosomal array represe
 nted as the “plateau” regime on the force-extension curve.\nAdditional
  simulations with multiple chromatins reveal a stable interdigitated confi
 guration\, thereby suggesting a mechanism initiating the sol-gel transitio
 n of chromatin. Our integrated work demonstrates the usefulness of the nea
 r-atomistic model in reconciling the stability of different chromatin conf
 ormations under in vitro and in vivo environments and revealing mechanisti
 c insights underpin-\nning genome organization.
LOCATION:Zoom details: https://zoom.us/j/92447982065?pwd=RkhaYkM5VTZPZ3pYS
 HptUXlRSkppQT09
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