Braun, Marcus

Diez, Stefan

Janson, Marcel E.

Lansky, Zdenek

ten Wolde, Pieter Rein

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The Open-Access Journal for the Basic Principles of Diffusion Theory, Experiment and ApplicationDiffusible crosslinkers generate directed forces in microtubule networksZdenek Lansky1,2∗, Marcus Braun1,2, Pieter Rein ten Wolde3, Marcel E. Janson4,Stefan Diez1,21B CUBE – Center for Molecular Bioengineering, Technische Universita¨t Dresden, Dresden, Germany2Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany3AMOLF, Amsterdam, The Netherlands4Laboratory of Cell Biology, Wageningen University, Wageningen, The Netherlands∗lansky@mpi-cbg.deRemodeling of cytoskeletal filament networks is essential to cell division and morphogenesis. The me-chanical forces driving the restructuring processes are attributed to the activity of molecular motorsand the dynamics of cytoskeletal filaments, which both consume chemical energy. Passive filamentcrosslinkers, on the other hand, are commonly regarded as mere friction-generating entities. Here,we report on the generation of directed forces by non-enzymatic, diffusible microtubule crosslinkersof the Ase1/PRC1/Map65 family. After experimentally confining Ase1 molecules between partiallyoverlapping microtubules, we observed overlap expansion through directed microtubule sliding. No-tably, the forces generated were sufficient to reverse the direction of motor-protein driven microtubulesliding. Force generation by Ase1 can be quantitatively explained by entropic expansion of confinedAse1 crosslinkers diffusing along microtubules in the overlap region. The thermal motion of confinedfilament crosslinkers is thus harnessed to generate mechanical work analogous to compressed gas pro-pelling a piston in a cylinder. We argue that this mechanism constitutes an active, force-producingelement of self-organizing filamentous networks inside cells.This work was supported by the DFG (FOR 877).

Diffusible crosslinkers generate directed forces in microtubule networks

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Diffusible crosslinkers generate directed forces in microtubule networks

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