Berlin 2012 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 16: Molecular Motors

BP 16.1: Hauptvortrag

Mittwoch, 28. März 2012, 15:00–15:30, H 1028

Molecular Crowding Creates Traffic Jams of Kinesin Motors On Microtubules — •Cecile Leduc^1,2, Kathrin Padberg-Gehle³, Vladimír Varga², Dirk Helbing⁴, Stefan Diez^2,5, and Jonathon Howard² — ¹LP2N-CNRS-U-Bordeaux 1 — ²MPI-CBG, Dresden — ³TU-Dresden — ⁴ETH Zürich — ⁵Technische Universität Dresden, B CUBE

Despite the crowdedness of the interior of cells, microtubule-based motor proteins are able to deliver cargoes rapidly and reliably throughout the cytoplasm. We hypothesize that motor proteins may be adapted to operate in crowded environments by having molecular properties that prevent them from forming traffic jams. To test this hypothesis, we reconstitute high-density traffic of purified kinesin-8 motor proteins along microtubules in a total-internal-reflection microscopy assay. We find that traffic jams, characterized by an abrupt increase in the density of motors with an associated abrupt decrease in motor speed, can even form in the absence of other obstructing proteins. To determine the molecular properties that lead to jamming, we altered the concentration of motors, their processivity and their rate of dissociation from microtubule ends. We find that traffic jams form when the motor density exceeds a critical value (density-induced jams) or when motor-dissociation from the microtubule ends is so slow that it results in a pile-up (bottleneck-induced jams). Through comparison of our experimental results with theoretical models and stochastic simulations, we characterize in detail under which conditions density- and bottleneck-induced traffic jams form or do not form.