Synergistic interactions between DNA and actin trigger emergent viscoelastic behavior

Abstract

Composites of flexible and rigid polymers are ubiquitous in biology and industry alike, yet the physical principles determining their mechanical properties are far from understood. Here, we couple force spectroscopy with large-scale Brownian Dynamics simulations to elucidate the unique viscoelastic properties of custom-engineered blends of entangled flexible DNA molecules and semiflexible actin filaments. We show that composites exhibit enhanced stress-stiffening and prolonged mechano-memory compared to systems of actin or DNA alone, and that these nonlinear features display a surprising non-monotonic dependence on the fraction of actin in the composite. Simulations reveal that these counterintuitive results arise from synergistic microscale interactions between the two biopolymers. Namely, DNA entropically drives actin filaments to form bundles that stiffen the network but reduce the entanglement density, while a percolating actin network is required to reinforce the DNA network against yielding and flow. The competition between bundling and percolation triggers an unexpected stress response that leads equal mass actin-DNA composites to exhibit the most pronounced stress-stiffening and the most long-lived entanglements.

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Cited by in corpus (8)

• Unexpected entanglement dynamics in semidilute blends of supercoiled and ring DNA
• Optical tweezers microrheology maps the dynamics of strain-induced local inhomogeneities in entangled polymers
• Viscoelastic properties of ring-linear DNA blends exhibit non-monotonic dependence on blend composition
• OpTiDDM (Optical Tweezers integrating Differential Dynamic Microscopy) maps the spatiotemporal propagation of nonlinear stresses in polymer blends and composites
• Recoil experiments determine the eigenmodes of viscoelastic fluids
• Persistence Homology Of Entangled Rings
• Rheology and Viscoelasticity of Proteins and Nucleic Acids Condensates
• Polymer threadings and rigidity dictate the viscoelasticity and nonlinear relaxation dynamics of entangled ring-linear blends and their composites with rigid rod microtubules