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CATEGORIES:Lennard-Jones Centre
SUMMARY:Near-atomistic Modeling of Chromatin – Leveraging 
 Computational  Advances to Uncover Mechanistic Ins
 ights - Xingcheng Lin\, Department of Chemistry\, 
 MIT
DTSTART;TZID=Europe/London:20220228T143000
DTEND;TZID=Europe/London:20220228T150000
UID:TALK167294AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/167294
DESCRIPTION:Three-dimensional chromatin organization lays the 
 foundation for biological processes involving\ngen
 e expression and epigenetic regulation. Neverthele
 ss\, it is unclear how chromatin is structured\nat
  the fundamental level. There is a heated debate o
 ver the existence of chromatin fibril structure\na
 nd its response to environmental perturbations. Co
 ntroversy also remains on the solid or liquid prop
 erties of chromatin subject to different experimen
 tal conditions. Here\, building upon our recently 
 implemented near-atomistic chromatin model\, we le
 verage computational advances to study structural 
 details of large chromatin systems. Our study with
  a tetranucleosome\, the fundamental unit of chrom
 atin\, captures multiple irregular chromatin struc
 tures that emerge as intermediates of two chromati
 n folding pathways. Our further study with a dodec
 americ nucleosomal array repro-\nduces the force-e
 xtension curve measured by magnetic tweezers. The 
 simulation also reveals a more complicated folding
  landscape of chromatin under tension than a two-s
 tate transition: Whereas the shearing motion of co
 mpact chromatin under lower tension constitutes th
 e “linear” response regime\,\na mixture of trinucl
 eosome and tetranucleosome clutches appears as ten
 sion increases\, leading to\nan extended nucleosom
 al array represented as the “plateau” regime on th
 e force-extension curve.\nAdditional simulations w
 ith multiple chromatins reveal a stable interdigit
 ated configuration\, thereby suggesting a mechanis
 m initiating the sol-gel transition of chromatin. 
 Our integrated work demonstrates the usefulness of
  the near-atomistic model in reconciling the stabi
 lity of different chromatin conformations under in
  vitro and in vivo environments and revealing mech
 anistic insights underpin-\nning genome organizati
 on.
LOCATION:Zoom details: https://zoom.us/j/92447982065?pwd=Rk
 haYkM5VTZPZ3pYSHptUXlRSkppQT09
CONTACT:Dr Christoph Schran
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