Laboratoire Matière et Systèmes Complexes

Traffic Jams of Kinesin Motors

Cécile Leduc, Institut Pasteur

ATTENTION LIEU EXCEPTIONNEL/UNUSUAL LOCATION : Amphiteatre Pierre Gilles de Gennes (Etage -1 Batiment Condorcet)

Abstract : Despite the crowdedness of the interior of cells, microtubule-based motor proteins are able to deliver cargoes rapidly and reliably throughout the cytoplasm. This active transport is crucial for cell organization and function. We hypothesize that motor proteins may be adapted to operate in crowded environments by having molecular properties that prevent them from forming traffic jams. In the first part of the talk, I will show how we tested this hypothesis using a in vitro reconstitution of high-density traffic of purified kinesin-8 protein, a highly processive motor with long end-residency time, along microtubules. Through comparison of our experimental results with theoretical models and stochastic simulations, we characterized in detail under which conditions kinesin traffic jams, characterized by an abrupt increase in the density of motors with an associated abrupt decrease in motor speed, form or do not form. In a second part of the talk, I will show how these results could be translated in live cells. Using a combination of PALM-single particle tracking experiments and numerical simulations, we showed that kinesin properties are specifically regulated by the presence of microtubule associated proteins inside the cell.