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Dynein and Kinesin Intersecting Tau Interfaces on Microtubules

Ram Dixit, Jennifer L. Ross, Yale E. Goldman, Erika L. F. Holzbau

image 1

Direct observation of encounters between single molecules of kinesin or dynein-dynactin (green above) and Alexa-labeled tau (red patches). The kymographs (left) show dissociation of two kinesin molecules (A) or directional reversal of two dynein-dynactin molecules (B) upon encountering a tau cluster (dotted lines). (Right) Selected images from each experiment.

image 2

Model of the role of tau in the regulation of axonal transport (right). In a healthy neuron, tau is distributed in a proximal-distal gradient (gray) that allows kinesin-driven anterograde transport from the cell body (green arrow). At the synapse, a relatively high tau concentration facilitates kinesin dissociation (red arrow). Dynein is able to bind to distal microtubules because it is less sensitive to tau. In a degenerating neuron, tau accumulates at the soma and consequently inhibits kinesin-driven anterograde transport (red blocked arrow), leading to neuro-degeneration.

Dynein and kinesin motor proteins transport cellular cargoes toward opposite ends of microtubule tracks. In neurons, microtubules are abundantly decorated with microtubule-associated proteins (MAPs) such as tau. We conducted single-molecule studies of motor proteins moving along tau-decorated microtubules. Surprisingly, dynein tended to reverse direction, whereas kinesin tended to detach at patches of bound tau.

In Press Science 2008



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