Description:

Molecular shuttles powered by motor proteins permit nanoscale transport and piconewton force measurements.

Active transport is an essential part of technology, but difficult to realize on the nanoscale. Biomolecular motors, in particular motor proteins, provide us with highly efficient nanoscale engines. We engineered a hybrid nanoscale transport system (Molecular Shuttle), which integrate biological and synthetic components.

In our Molecular Shuttle, microtubules (extended protein filaments with an outer diameter of 30 nm) are actively transported across surfaces coated with the motor protein kinesin. If the microtubules are functionalized with biotin linkers, they can interact specifically with streptavidin-coated cargo. The speed is controlled by adjusting the supply of the "fuel" ATP.

The movie above shows in a sequence of optical microscopy images how a biotinylated microtubule gliding on a kinesin-coated surface picks up an aggregate of streptavidin-coated beads, transports it, and hands it off to a microtubule which is supported on only one end by another aggregate of beads. Based on the degree of bending of this second, cantilevered microtubule during the hand-off we can calculate the rupture force for the link between the two microtubules, which is several piconewtons.

Acknowledgements: The animated picture has been prepared by Sheila Luna.

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