Manipulation and observation of binding of molecules driven by motor proteins

We developed a system to visualize molecular bindings as colocalization of two Q-dots carried by motor proteins on a microtubule (MT) array with predefined polarities in nanotracks. The MT array was prepared utilizing gliding of MTs in micro/nano structures and a dissociation method of retrogressing MTs. Pairs of molecules for cargo transport was designed and evaluated experimentally. One of molecular systems, GSH-Q-dot525-dynein (GSH-Q525-D) and GST-Q-dot655-kinesin (GST-Q655-K), resulted in colocalizations by the GST-GSH binding. The other system, avidin-Q525-D (avi-Q525-D) and biotin-Q655-K (bio-Q655-K), also provided colocalization of Q-dots by specific bindings of avidin-biotin. Analysis of run length (RL) and velocity showed molecular transport without degrading motility of motor proteins. Quantitative analysis proved that colocalizations were achieved by the designed molecules carried by motors. The results show that a prototype of synthetic molecular transport driven by motor proteins was established. The reconstructed molecular system should be the basis of further miniaturization of on-chip analysis systems by directly manipulating countable number of molecules.