Evaluation of extensional and torsional stiffness of single actin filaments by molecular dynamics analysis

JOURNAL OF BIOMECHANICS

卷:43

Article

Matsushita, Shinji^2,3  Adachi, Taiji^1,2,3  Inoue, Yasuhiro^2,3  Hojo, Masaki²  Sokabe, Masahiro^4,5 

[1] Kyoto Univ, Inst Frontier Med Sci, Res Ctr Nano Med Engn, Dept Biomech,Sakyo Ku, Kyoto 6068507, Japan

[2] Kyoto Univ, Grad Sch Engn, Dept Mech Engn & Sci, Sakyo Ku, Kyoto 6068501, Japan

[3] RIKEN, VCAD Syst Res Program, Computat Cell Biomech Team, Wako, Saitama 3510198, Japan

[4] Nagoya Univ, Grad Sch Med, Dept Physiol, Nagoya, Aichi 4668550, Japan

[5] Japan Sci & Technol Agcy, ICORP SORST, Nagoya, Aichi 4668550, Japan

关键词: Actin filament;    Extensional and torsional stiffness;    Thermal fluctuation;    Molecular dynamics simulation;    Computational biomechanics;    Cell mechanics;   

DOI  :  10.1016/j.jbiomech.2010.07.022

来源: Elsevier

【 摘 要 】

It is essential to investigate the mechanical behaviour of cytoskeletal actin filaments in order to understand their critical role as mechanical components in various cellular functional activities. These actin filaments consisting of monomeric molecules function in the thermal fluctuations. Hence, it is important to understand their mechanical behaviour on the microscopic scale by comparing the stiffness based on thermal fluctuations with the one experimentally measured on the macroscopic scale. In this study, we perform a large-scale molecular dynamics (MD) simulation for a half-turn structure of an actin filament. We analyse its longitudinal and twisting Brownian motions in equilibrium and evaluated its apparent extensional and torsional stiffness on the nanosecond scale. Upon increasing the sampling-window durations for analysis, the apparent stiffness gradually decreases and exhibits a trend to converge to a value that is close to the experimental value. This suggests that by extrapolating the data obtained in the MD analysis, we can estimate the experimentally determined stiffness on the microsecond to millisecond scales. For shorter temporal scales, the apparent stiffness is larger than experimental values, indicating that fast, local motions of the molecular structure are dominant. To quantify the local structural changes within the filament on the nanosecond scale and investigate the molecular mechanisms, such as the binding of the actin-regulatory proteins to the filaments, it is preferable to analyse the mechanical behaviour on the nanometre and nanosecond scales using MD simulation. (C) 2010 Elsevier Ltd. All rights reserved.

【 授权许可】

Free