Title: DNA mechanics beyond the twistable wormlike chain
When: Thursday, September 11, 2025, 12:00
Place: Department of Theoretical Condensed Matter Physics, Faculty of Sciences, Module 5, Seminar Room (5th Floor)
Speaker: Enrico Carlon, KU Leuven
The twistable wormlike chain (TWLC) model is a natural generalization of the classic wormlike chain (WLC), in which the bending elasticity of a polymer backbone is complemented by an additional degree of freedom accounting for twist deformations. This model has proven especially powerful in the context of DNA mechanics, where it successfully captures a broad range of behaviors revealed in single-molecule experiments, including torsional responses and supercoiling phenomena. Despite its success, the TWLC is ultimately an idealized model, and recent studies—including those conducted by our group—have highlighted systematic deviations from its predictions. In this work, we focus on two such classes of deviations: (1) non-local coupling effects, where bending and twisting deformations interact over extended segments of the chain rather than locally, and (2) anharmonic couplings, which go beyond the harmonic elasticity assumed in the standard TWLC and introduce nonlinear responses at larger deformations. Using a combination of numerical simulations and analytical theory, we demonstrate how these deviations arise, quantify their impact on DNA mechanics, and provide a physical interpretation of their microscopic origin. Our results refine the theoretical foundation of polymer models for DNA and open the door to more accurate descriptions of biomolecular mechanics in regimes relevant to both cellular processes and nanotechnological applications.
