Regensburg 2013 – scientific programme
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BP: Fachverband Biologische Physik
BP 25: Posters: Cytoskeleton
BP 25.8: Poster
Wednesday, March 13, 2013, 17:30–19:30, Poster C
Single-molecule motility of kinesin-5 motors between cross-linked microtubules — •Alice Wiesbaum1, Christina Thiede1, Olga Zaitsava2, Vladimir Fridman3, Marcel Janson2, Larisa Gheber3, and Christoph Schmidt1 — 1Georg-August Universität, Göttingen, DE — 2Wageningen University, Wageningen, NL — 3Ben-Gurion University of Negev, Beer-Sheva, IL
During mitosis, a group of several proteins organizes the dynamics of the mitotic spindle midzone. Two essential functions that need to be fulfilled in the midzone are crosslinking and active sliding of antiparallel microtubules (MTs). In S. cerevisiae, crosslinking is done by the protein Ase1, and sliding is powered by the tetrameric kinesin-5 motors Cin8 and Kip1. It is known that kinesin-5 motors are regulated by binding conditions to MTs. X. laevis Eg5 only moves processively when it is bound between two MTs. Cin8 was found to change its directionality when binding between two MTs. On a single MT, Cin8 is minus-end directed and moves processively. When bound between two MTs, Cin8 drives slow, plus-end directed relative sliding. To test if this property is a cooperative phenomenon of multiple motors or a single-motor property, we performed in vitro TIRF single-molecule experiments. In order to ensure bundling even at low motor concentrations, we employed the crosslinking protein Ase1. We found that single Cin8 motors are capable of switching direction when between MTs. In addition, we analyzed the behavior of a Cin8 mutant, Cin8*tail, which lacks the C-terminal tail domain. This mutant still supports sliding of MTs, but lacks a clear directionality switch.