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Updated: Mar 8, 2026

Author Spotlight: Investigating the Motion Dynamics of the Eukaryotic Replisome Components at the Single-Molecule Level
Published on: July 26, 2024
Visualization of Chromatin Decompaction and Break Site Extrusion as Predicted by Statistical Polymer Modeling of
Assaf Amitai1, Andrew Seeber2, Susan M Gasser2
1Institut de Biologie de l'École Normale Supérieure, Ecole Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France; Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Abstract:
Chromatin moves with subdiffusive and spatially constrained dynamics within the cell nucleus. Here, we use single-locus tracking by time-lapse fluorescence microscopy to uncover information regarding the forces that influence chromatin movement following the induction of a persistent DNA double-strand break (DSB). Using improved time-lapse imaging regimens, we monitor trajectories of tagged DNA loci at a high temporal resolution, which allows us to extract biophysical parameters through robust statistical analysis. Polymer modeling based on these parameters predicts chromatin domain expansion near a DSB and damage extrusion from the domain. Both phenomena are confirmed by live imaging in budding yeast. Calculation of the anomalous exponent of locus movement allows us to differentiate forces imposed on the nucleus through the actin cytoskeleton from those that arise from INO80 remodeler-dependent changes in nucleosome organization. Our analytical approach can be applied to high-density single-locus trajectories obtained in any cell type.
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