Manipulating single biomolecules

Omar Saleh

UCSB Materials

In the past fifteen years, a number of experimental techniques have emerged that allow the measurement of the physical properties and interactions of a single protein or DNA molecule. These techniques roughly split into two types: fluorescence, where the physical state of a biomolecule is visualized by labeling it with a light-emitting dye; and manipulation, in which a single biomolecule is held under tension and/or torque while its end-to-end distance is measured. This talk will focus on the latter: I will introduce the different types of manipulation experiments, how their basic parameters relate to the physical properties of biomolecules, and their rather powerful abilities in studying a class of enzymes known as motor proteins. I will describe in more detail one particular technique, the magnetic tweezer, and its ability to sense and control the twist of a DNA molecule; this will be illustrated through our results on the linear and rotational motion of the bacterial motor protein FtsK. Finally, I will describe why better spatial resolution is needed in the study of DNA-based motor proteins, and how we might attain it with the aid of nanofabrication.