Berlin 2012 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 25: Posters: Molecular Motors
BP 25.1: Poster
Donnerstag, 29. März 2012, 17:30–19:30, Poster A
Cargo-regulated directionality switching of S. cerevisiae Kinesin-5 Cin8 — •Christina Thiede1, Alice Wiesbaum1, Adina Gerson-Gurwitz2, Natalia Movshovich2, Vladimir Fridman2, Maria Podolskaya2, Tsafi Danieli2, Stefan Lakämper1, Larisa Gheber2, Dieter R. Klopfenstein1, and Christoph F. Schmidt1 — 1Drittes Physikalisches Institut, Georg-August-Universität Göttingen, Germany — 2Department of Chemistry, Ben-Gurion University of the Negev, Israel
In mitotic spindle morphogenesis and dynamics kinesin-5 motors fulfil essential roles as slow, processive microtubule (MT) plus-end directed sliding motors. Eg5, the kinesin-5 from X. leavis, switches from a diffusive to a directional mode upon cross-linking a pair of microtubules. The mechanism may be related to kinesin-1 cargo regulation effected by a back-folding of the tail. Recently Cin8, a kinesin-5 from S. cerevisiae, was surprisingly found to be able to switch from processive plus-end to processive minus-end motility. Here we have studied the in vivo and in vitro properties and regulation of Cin8 using single-molecule fluorescence assays. In high salt, Cin8 moved rapidly and processively towards the MT minus-end. In low salt, Cin8 was 10x slower and moved towards the MT plus-end. Phosphorylation sites located in the unique 99 amino acids insert in Cin8’s loop 8 influence the switching. The most striking effect was, however, that Cin8 switched from minus- to plus-end directed motility as soon as it was located between two microtubules. This finding suggests that in Cin8 not only the mode of motility is regulated by cargo binding, but also its directionality.