Issue
EPL
Volume 82, Number 2, April 2008
Article Number 28001
Number of page(s) 6
Section Interdisciplinary Physics and Related Areas of Science and Technology
DOI http://dx.doi.org/10.1209/0295-5075/82/28001
Published online 20 March 2008
EPL, 82 (2008) 28001
DOI: 10.1209/0295-5075/82/28001

Discrete elastic model for stretching-induced flagellar polymorphs

H. 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

hwada@yukawa.kyoto-u.ac.jp

received 5 February 2008; accepted in final form 19 February 2008; published April 2008
published online 20 March 2008

Abstract
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.

PACS
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