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BP: Fachverband Biologische Physik

BP 15: Single Molecules

BP 15.2: Talk

Wednesday, February 27, 2008, 14:15–14:30, C 243

Walking the line: kinesin motors observed with sub-molecular resolution by atomic force microscopy — •Iwan A.T. Schaap¹, Carolina Carrasco², Pedro J. de Pablo², and Christoph F. Schmidt³ — ¹National Institute for Medical Research, London, UK — ²Universidad Autónoma de Madrid, Madrid, Spain — ³Georg-August-Universität, Göttingen, Germany

Intracellular transport is largely driven by dyneins and kinesins moving on microtubules in complex, but highly coordinated patterns. How exactly a single motor proceeds on the 13 narrow "lanes" or protofilaments of a microtubule remains unknown because the required resolution lies beyond the reach of light microscopy. We have here succeeded to image kinesin-1 dimers immobilized on microtubules with single-head resolution and in addition in their motion along microtubules with nanometer resolution by atomic-force-microscopy. We show that both heads of one dimer are microtubule-bound for the major part of the chemical cycle. Furthermore, we could unambiguously resolve that both heads bind to the same protofilament, instead of straddling two, and remain on this track during processive movement.