title: Confinement-Induced Glassy Dynamics in a Model for Chromosome Organization.
abstract: Recent experiments showing scaling of the intrachromosomal contact probability, P(s)∼s(-1) with the genomic distance s, are interpreted to mean a self-similar fractal-like chromosome organization. However, scaling of P(s) varies across organisms, requiring an explanation. We illustrate dynamical arrest in a highly confined space as a discriminating marker for genome organization, by modeling chromosomes inside a nucleus as a homopolymer confined to a sphere of varying sizes. Brownian dynamics simulations show that the chain dynamics slows down as the polymer volume fraction (ϕ) inside the confinement approaches a critical value ϕ(c). The universal value of ϕ(c)(∞)≈0.44 for a sufficiently long polymer (N≫1) allows us to discuss genome dynamics using ϕ as the sole parameter. Our study shows that the onset of glassy dynamics is the reason for the segregated chromosome organization in humans (N≈3×10(9), ϕ≳ϕ(c)(∞)), whereas chromosomes of budding yeast (N≈10(8), ϕ<ϕ(c)(∞)) are equilibrated with no clear signature of such organization.
authors.affiliation: Institute for Physical Sciences and Technology, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Hongsuk
authors.initials: H
authors.lastname: Kang
authors.affiliation: Department of Physics, Chung-Ang University, Seoul 156-756, Korea.
authors.forename: Young-Gui
authors.initials: YG
authors.lastname: Yoon
authors.affiliation: Institute for Physical Sciences and Technology, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: D
authors.initials: D
authors.lastname: Thirumalai
authors.affiliation: Korea Institute for Advanced Study, Seoul 130-722, Korea.
authors.forename: Changbong
authors.initials: C
authors.lastname: Hyeon
mesh_terms: D002875:Chromosomes / Q000737:chemistry* / Q000235:genetics*; D005898:Glass / Q000737:chemistry; D008956:Models, Chemical; D008957:Models, Genetic