ABSTRACT
The structure of rotation motors is similar to that of many electrical motors, in that they possess a nut and bolt framework. The structure of flagellar motors permits full clockwise and counterclockwise rotation. Unlike most biomotors, they are powered not by ATP, but by ions. FoF1 ATPase has two moving components, motors termed F1 and FO, which are located on opposite ends of a drive shaft that connects them. Movement of one motor can cause the other to rotate. These two motors are distinct both in structure and function and contain a number of subunits that serve specific roles.
There are two main parts of all rotation motors: the rotor, the portion that rotates, and stator, which is stationary. Many of these biomotors can resemble their electrical counterparts, as they share the same basic components. Also like electrical motors, they move through a nut and bolt mechanism around a central shaft. Most of these rotary ATPases are assembled into hexamers except for flagella and a few nucleic acid-tracking ATPases. For those hexameric rotation motors that track nucleic acids alone, they mostly rotate along one strand of the DNA/RNA and the other strand outside the motor channel. Most rotation dsDNA translocases operate distinctly from revolving dsDNA translocases. In this chapter, we use flagellar and FoF1 ATPase as examples to discuss the structural characteristics of the biomotors utilizing a rotary mechanism for translocation.
