Dresden 2014 – scientific programme
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BP: Fachverband Biologische Physik
BP 10: Posters: Molecular Motors
BP 10.9: Poster
Tuesday, April 1, 2014, 09:30–12:30, P1
Directionality of Single Kinesin-5 Cin8 Molecules is Mediated by the Tail Domains — •André Düselder1, Christina Thiede1, Alice Wiesbaum1, Vladimir Fridman2, Dieter Klopfenstein1, Larisa Gheber2, and Christoph F. Schmidt1 — 1Georg-August-Universität, Göttingen, Deutschland — 2Ben-Gurion University of the Negev, Beer-Sheva, Israel
Cin8, the tetrameric Kinesin-5 from budding yeast, shows the striking ability to move toward both the plus as well as the minus end of a microtubule. The molecular mechanism for this switch of directionality remains unknown. We have investigated this mechanism by examining the role of the C-terminal tail domains of Cin8 in the regulation of its directionality and motor function. To remove only the head-tail-interactions in the otherwise native tetramer, we built a Cin8 variant lacking the tail domains. In contrast to the wild type motor, this construct moves with a low velocity toward a randomly-chosen, but persistent direction. To look solely at the motility-generating subunits of Cin8, we fused the head domains and neck linker of Cin8 to the stalk of Kinesin-1 to construct a dimeric chimera. As a single molecule, this chimera is bidirectional with frequent changes in direction, indicating that the Cin8 head domains are inherently bidirectional. In optical trapping experiments, the probability of a switch of directionality increases with an increase of the force acting on the motor. We performed extensive power spectral analysis of the motor under various loads and different nucleotide conditions. Our findings suggest a force sensitive mechanism for a switch of directionality in Cin8.