Studying the Bacterial Flagellar Motor using an Optical Torque Wrench

Abstract

At the biomolecular level, the physical quantity torque manifests itself in a number of ways e.g. in the conformational changes of biopolymers such as DNA and in actions of both linear and rotary molecular motors. The optical torque wrench, an optical tweezers setup with the capability of applying and measuring both force and torque, has been developed as a versatile setup in tackling biologically relevant issues at high spatial and temporal resolution. Torque control in this optical tweezers setup relies on the manipulation and readout of the polarization state of light used to trap nano-fabricated birefringent cylinders.