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BP: Fachverband Biologische Physik
BP 42: Cytoskeletal filaments (joint BP/CPP)
BP 42.3: Vortrag
Donnerstag, 19. März 2015, 10:15–10:30, H 1028
Diffusible crosslinkers generate directed forces in microtubule networks — Zdenek Lansky1,2,5, •Marcus Braun1,2,5, Annemarie Lüdecke1,2, Michael Schlierf1, Pieter Rein ten Wode3, Marcel Janson4, and Stefan Diez1,2 — 1B CUBE, TU Dresden, Germany — 2MPI-DBG, Dresden, Germany — 3AMOLF, Amsterdam, The Netherlands — 4Laboratory of Cell Biology, Wageningen University, The Netherlands — 5equal contribution
Remodeling of cytoskeletal filament networks is essential to cell division and morphogenesis. The mechanical forces driving the restructuring are attributed to the action of molecular motors and filament dynamics, which both consume chemical energy. By contrast, non-enzymatic filament crosslinkers are regarded as mere friction-generating entities. Here, we experimentally demonstrate that non-enzymatic, diffusible microtubule crosslinkers of the Ase1/PRC1/Map65 family generate directed microtubule sliding when confined between partially-overlapping microtubules. The Ase1-generated forces, directly measured by optical tweezers to be in the piconewton-range, were sufficient to antagonize motor-protein driven microtubule sliding. Force generation can be quantitatively explained by the entropic expansion of confined Ase1 molecules diffusing within the microtubule overlaps. The thermal motion of confined crosslinkers is thus harnessed to generate mechanical work analogous to compressed gas propelling a piston in a cylinder. As confinement of diffusible crosslinkers is ubiquitous in cells, the associated entropic forces are likely to be of importance for cellular mechanics beyond cytoskeletal networks.