MULTI-LEGGED DNA-BASED MOLECULAR MOTORS

Natural molecular machines, made of proteins, play a major role in many important biological processes, often with impressive operational yields and speeds. Inspired by biological bipedal motors such as kinesin and with the assistance of single-molecule fluorescence and computer controlled microfluidic device we designed and operated a DNA-based bipedal motor that can stride on a DNA origami track with high operational yield. The reaction yield was 98% per step, which results in overall operational yield of 50% for 36 steps. To the best of our knowledge, this is the highest operational yield achieved by artificial molecular motors so far; however, it is not sufficient for repeatable operation of molecular machines for technological usage, for example, such as molecular assembly line and efficient maneuvering and manipulation of guest molecules.

This work focuses on the effort to understand the reasons for the 5-10% walker dissociation, and to increase walker processivity, operational yield and speed. To achieve a basic understanding of the motor`s limiting factors, kinetic measurements were made for the different reactions that make up a step, resulting with empiric reaction rates. We later built a kinetic numeric simulation to describe the correlation between each reaction rate and the final stepping yield. One possible solution for the walker dissociation is the multi-leg and multi-foothold approach, in which the walker consists of two pairs of legs and the track consist two rows of footholds. Preliminary results show an increase in yield per reaction of about two times, when operated 10uM fuel concentration. The walker, which consists of four legs, was prepared using “click” chemistry, and the motor, operated by microfluidics, was evaluated using single-molecule fluorescence