Dresden 2006 – scientific programme
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AKB: Biologische Physik
AKB 7: Biopolymers I
AKB 7.5: Talk
Tuesday, March 28, 2006, 11:00–11:15, ZEU 255
The flexural rigidity of microtubules relates to a limited compliance of inter-protofilaments bonds — •Francesco Pampaloni1, Gianluca Lattanzi2, and Davide Marenduzzo3 — 1EMBL Heidelberg - Cell Biology and Biophysics Programme - Heidelberg (Germany) — 2University of Bari - Faculty of Medicine (Italy) — 3Mathematics Institute - University of Warwick (UK)
The structure of microtubules (MT) is highly optimized to a maximum of mechanical performance: the hollow tube shape allows high strength and stiffness combined with a minimum of structural elements (tubulin dimers). Moreover, MTs are anisotropic in their elastic properties: they are softer on basal plane than along the axial direction. Such unusual properties of MTs - light, flexible, stiff - make them very similar to composite materials designed by engineers. Remarkably, tiny structural variations in the MT lattice, like protofilaments torsion and shifting, are not confined locally, but propagate in a concerted way along the whole MT length. It is likely that the energy required by this deformation is very low, of the order of the thermal fluctuations. Sub-nanometer deformations of the lateral bonds produce a slight relative shift between protofilaments, that introduces a significant shear component to MTs deflection. Consequently, for MTs the shear modulus is small enough to produce a length dependence of the bending stiffness. We present a multi-scale approach to investigate the elastic properties of MTs based on Monte Carlo simulation and conformational analysis of tubulin dimers in typical MTs architecture and we provide an useful framework for the interpretation of experimental data.