Discrete elastic model for stretching-induced flagellar polymorphsH. Wada1, 2 and R. R. Netz1
1 Physics Department, Technical University Munich - 85748 Garching, Germany, EU
2 Yukawa Institute for Theoretical Physics, Kyoto Universiy - Kyoto, 606-8502, Japan
received 5 February 2008; accepted in final form 19 February 2008; published April 2008
published online 20 March 2008
Force-induced reversible transformations between coiled and normal polymorphs of bacterial flagella have been observed in recent optical-tweezer experiment. We introduce a discrete elastic rod model with two competing helical states governed by a fluctuating spin-like variable that represents the underlying conformational states of flagellin monomers. Using hybrid Brownian dynamics Monte Carlo simulations, we show that a helix undergoes shape transitions dominated by domain wall nucleation and motion in response to externally applied uniaxial tension. A scaling argument for the critical force is presented in good agreement with experimental and simulation results. Stretching-rate-dependent elasticity including a buckling instability are found, also consistent with the experiment.
87.16.Ka - Filaments, microtubules, their networks, and supermolecular assemblies.
87.15.-v - Biomolecules: structure and physical properties.
64.70.Nd - Structural transitions in nanoscale materials.
© EPLA 2008