Small steps and giant leaps

Abstract

A study of kinesin-1 has shed new light on how motor proteins are able to move along microtubules inside cells.

Keywords: E. coli; biophysics; human; molecular motor; optical trap; single molecule; structural biology.

Figure 1.. Kinesin-1 cycles through three gates to step along a microtubule.

Kinesin-1 moves along a microtubule in a similar way to how a person would walk successfully along a tightrope. (A) When the tightrope walker (moving from left to right) has his/her front foot (red) in contact with the rope, the ‘stepping gate’ holds the red foot on the rope and keeps the rear foot (blue) away from the rope. (B) The blue foot moves in front of the red foot and the ‘binding gate’ allows the blue foot to contact the rope while preventing the red foot from coming away. (C) Now that the blue foot is in contact with the rope, the ‘unbinding gate’ allows the red (rear) foot to leave the rope while holding the blue foot in place. Cycling through these gates will ensure that at least one of the feet is tightly connected to the rope at all times, which allows the tightrope walker to cross the canyon safely. However, if any of these gates should fail, both feet may lose contact with the rope, resulting in a disastrous fall. This figure is based on the general gating framework for kinesin-1 by Andreasson et al. (2015).