title: Dynamic properties of independent chromatin domains measured by correlation spectroscopy in living cells.
abstract: BACKGROUND
  Genome organization into subchromosomal topologically associating domains (TADs) is linked to cell-type-specific gene expression programs. However, dynamic properties of such domains remain elusive, and it is unclear how domain plasticity modulates genomic accessibility for soluble factors.
  
  
  RESULTS
  Here, we combine and compare a high-resolution topology analysis of interacting chromatin loci with fluorescence correlation spectroscopy measurements of domain dynamics in single living cells. We identify topologically and dynamically independent chromatin domains of ~1 Mb in size that are best described by a loop-cluster polymer model. Hydrodynamic relaxation times and gyration radii of domains are larger for open (161 ± 15 ms, 297 ± 9 nm) than for dense chromatin (88 ± 7 ms, 243 ± 6 nm) and increase globally upon chromatin hyperacetylation or ATP depletion.
  
  
  CONCLUSIONS
  Based on the domain structure and dynamics measurements, we propose a loop-cluster model for chromatin domains. It suggests that the regulation of chromatin accessibility for soluble factors displays a significantly stronger dependence on factor concentration than search processes within a static network.
authors.affiliation: Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Malte
authors.initials: M
authors.lastname: Wachsmuth
authors.affiliation: Biophysical Genomics Group, Department of Cell Biology and Genetics, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands.
authors.forename: Tobias A
authors.initials: TA
authors.lastname: Knoch
authors.affiliation: Research Group Genome Organization and Function, Deutsches Krebsforschungszentrum (DKFZ) & BioQuant, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Rippe
keywords: Chromatin conformation capture carbon copy (5C); Chromatin structure; Fluorescence correlation spectroscopy (FCS); Polymer model; Quantitative microscopy; Targeted chromatin capture (T2C)