Berlin 2008 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 7: Posters I
BP 7.23: Poster
Montag, 25. Februar 2008, 17:00–19:30, Poster A
Microtubule dynamics depart from wormlike chain model — Katja M Taute1, •Francesco Pampaloni2, Erwin Frey3, and Ernst-Ludwig Florin1 — 1Center for Nonlinear Dynamics, University of Texas at Austin, 1 University Station C1610, Austin TX 78712, U.S.A. — 2Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany — 3Arnold Sommerfeld Center for Theoretical Physics and CeNS, Department of Physics, Ludwig-Maximilians-University at München, Theresienstraße 37, D-80333 München, Germany
We study the dynamics of the tip's thermal fluctuations of grafted microtubules in the length range of 2-30 um, by employing high precision particle tracking on attached fluorescent beads. First mode relaxation times were extracted from the mean square displacement in the transverse coordinate. For short microtubules, the relaxation times were found to follow an L^2 dependence instead of L^4 as expected from the standard wormlike chain model. As these time scales are determined by an interplay of filament stiffness and friction, persistence lengths and drag coefficients were examined. The persistence lengths show a complex dependence on overall filament length and indicate a plateau value of ~600 um for microtubules shorter than ~ 5 um. This behavior is consistent with the elastic properties of bundles of wormlike filaments and hence suggests modeling microtubules as bundles of their constituent protofilaments. Our results emphasize that microtubule mechanics can be understood as a consequence of their complex protofilament architecture.