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BP: Fachverband Biologische Physik

BP 7: Poster I

BP 7.14: Poster

Monday, March 23, 2009, 17:45–20:00, P3

Dependence of Eg5Kin force production on monastrol — •André Düselder, Stefan Lakämper, and Christoph Schmidt — 3. Physikalisches Institut, Fakultät für Physik, Georg-August-Universität, 37077 Göttingen

In the metaphase of mitosis, chromosomes are lined up in the midplane of the cell by the bipolar mitotic spindle. Tetrameric bipolar members of the Kinesin-5 family of motor proteins play an important role in the establishment of this spindle. We have previously characterized the motile characteristics of Eg5, the Kinesin-5 from Xenopus laevis, using single-molecule fluorescence and optical-trapping experiments. Surprisingly, we observed a novel slip-clutch force sensing mechanism. It remains unclear whether this mechanism is an intrinsic property of the motor domains themselves or if it is due to regulatory domains residing in the stalk or tail domains.

In order to investigate the motile properties of the force-generating units of Eg5 alone, we constructed a stably dimeric chimera, termed Eg5Kin, consisting of the Eg5 motor domain fused to the stalk of D. melanogaster Kinesin-1. In the presence of increasing monastrol concentrations, we observed a reduction in processive run length, but not speed, of single motors.

To date, there has been no data on how monastrol affects Eg5- or Eg5Kin-motility (speed, stallforce, detaching force) under load. Here, we present results from experiments using single-bead optical-trapping interferometry of single Eg5Kin-motors in the presence of increasing monastrol concentrations.