SynBERC:MIT/Calendar/2007-11-7

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Anyone in the synthetic biology community is welcome to attend.

Wednesday November 7, 2007 at 11:00am EST

32-D463, MIT

Topic of discussion

Kristin Verhey, U. of Michigan

Road signs for Kinesin motors

How molecular motors convert chemical energy into mechanical force has been the subject of intense investigation in vitro, yet little is known about how motors behave in vivo. In cells, motor activities are likely affected by factors such as viscosity and macromolecular crowding, the choice of microtubule tracks, and the presence of oncoming cargo complexes driven by motors that move in the opposite direction. Understanding how molecular motors function inside cells is likely to benefit engineering-based work on the creation of motor-driven nanoscale devices.

To investigate the motile properties of single Kinesin-1 motors in live cells, we utilized a three-tandem monomeric Citrine (3xmCit) tag and TIRF microscopy. We show that single Kinesin-1 molecules that cannot bind cargo move in vivo with similar motile properties as Kinesin-1 in vitro. These results suggest that the motility of single motors is neither hindered in cells nor upregulated by unknown cellular factors. Using two-color imaging of 3xmCit-Kinesin-1 and mCherry-microtubules, we show that Kinesin-1 motors move preferentially on a subset of microtubules in live cells. Retrospective immunofluorescence staining of the same cells demonstrates that Kinesin-1 moves preferentially on microtubules marked by specific post-translational modifications. Alterations in tubulin post-translational modifications can alter the trafficking of Kinesin-1 cargoes in vivo. Taken together, our results suggest that microtubule post-translational modifications facilitate Kinesin-1 transport. Thus, the marking of specific microtubule tracks by posttranslational modification may enable the creation of specialized tracks for differential transport in nanoscale devices.

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