Berlin 2015 – wissenschaftliches Programm

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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 Lansky^1,2,5, •Marcus Braun^1,2,5, Annemarie Lüdecke^1,2, Michael Schlierf¹, Pieter Rein ten Wode³, Marcel Janson⁴, and Stefan Diez^1,2 — 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.