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bioRxiv · 10.1101/2025.09.16.676638

Loop extrusion provides mechanical robustness to chromatin

Jost, D.·salari, h.
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Abstract

Chromosomes are complex biopolymers folded into dynamic loops via a loop extrusion process and may experience various mechanical forces in vivo. We develop a force-dependent model of chromatin loop extrusion and investigate its mechanical consequences on chromosome organization using simulations and analytical theory. We show that loop extrusion alters the force-extension behavior of DNA in a non-monotonic manner: extrusion stiffens the chain at low forces but softens it at intermediate and high forces. Our model predicts hysteresis in pulling-recoiling cycles and out-of-equilibrium responses, consistent with recent single-chromosome stretching experiments. We further find that loop extrusion provides mechanical robustness to chromatin by promoting compaction while enabling rapid structural recovery after stress. These results establish loop extrusion as a key regulator of chromatin mechanics.

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Jost, D., salari, h.. 2025-09-18. Loop extrusion provides mechanical robustness to chromatin. https://doi.org/10.1101/2025.09.16.676638

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