Active chromatin locus exhibits multimodal viscoelasticity

How different regions of the genome respond to mechanical stress and how this relates to their functions remain largely unknown. Here, we generalize a previously developed data-driven physical model to investigate the mechanical behavior of chromatin at the level of individual loci. We find that chromatin exhibits two distinct mechanical responses that correlate with its functions. Active genomic regions, enriched in active histone marks, display complex, multi-timescale mechanical responses and are more deformable under force. In contrast, inactive and heterochromatic regions show simpler, single-timescale behavior and are more rigid. These findings reveal a connection between the mechanical properties of chromatin and its functional state, opening new avenues for understanding how cells regulate their genetic programs.