Dresden 2014 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 1: Molecular Motors
BP 1.3: Vortrag
Montag, 31. März 2014, 10:15–10:30, HÜL 386
The kinesin-8, Kip3, frequently switches microtubule protofilaments in a biased random walk — •Michael Bugiel1, Elisa Böhl1, and Erik Schäffer2 — 1Nanomechanics Group, Biotechnology Center, TU Dresden, Tatzberg 47/49, 01307 Dresden, Germany — 2Zentrum für Molekularbiologie der Pflanzen (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076 Tübingen, Germany
The budding yeast Kinesin-8 Kip3 is a highly processive motor protein that walks to the end of cytoskeletal microtubules and shortens them in a collective manner. Microtubules usually consist of 12 to 15 circularly-arranged tubulin polymer chains, called protofilaments. Left-handed rotations of microtubules in Kip3 gliding assays indicate sideward motion of Kip3 perpendicular to the microtubule axis, i.e. a switching between single protofilaments. Here, we used high-resolution optical tweezers in a force feedback mode to track the path of single Kip3 motors by applying alternating sideward loads. Our studies show that Kip3 steps sideward in both directions, but follows the load on average with a preference towards the left. Based on statistical data analysis and comparison with simulations, we propose a diffusive sideward motion of Kip3 on the microtubule lattice. This diffusive switching mechanism may enable Kip3 to bypass obstacles and reach the microtubule end for length regulation.