Dresden 2014 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 1: Molecular Motors
BP 1.6: Vortrag
Montag, 31. März 2014, 11:00–11:15, HÜL 386
Direct measurement of the pressure generated by a 1D protein gas confined within microtubule overlaps — •Annemarie Lüdecke1,2, Marcus Braun1,2, Zdenek Lansky1,2, Michael Schlierf1, Pieter Rein ten Wolde3, Marcel E. Janson4, and Stefan Diez1,2 — 1B CUBE, TU Dresden, Dresden, Germany — 2Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany — 3AMOLF, Amsterdam, Netherlands — 4Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
The integrity of the mitotic spindle during anaphase is facilitated by antiparallel microtubule-microtubule overlaps in the spindle midzone. Within these overlaps, motor proteins (e.g. kinesin-5, kinesin-14) as well as passive, non-enzymatic microtubule crosslinkers (e.g. from the MAP65 family) localize and influence the mechanical stability of the overlaps. Here, we show in vitro that the diffusible microtubule crosslinker Ase1, a member of the MAP65 family, can slow down and halt the shortening of microtubule-microtubule overlaps driven by the kinesin-14 Ncd. Using mathematical modeling we show that Ase1 confined in a microtubule overlap behaves like a 1D gas upon compression, i.e. producing an entropic force opposing the compression. Direct measurement of the entropic force by optical tweezers yielded values in the pN-range, comparable to the forces produced by motor proteins present in the spindle midzone. We hypothesize that entropic pressure may be a general mechanism of force production in biological systems.