Filming Dynamic Processes of Proteins by High-Speed Afm

Abstract

Directly observing individual protein molecules in action at high spatiotemporal resolution has long been the holy grail for biological science. High-speed atomic force microscopy (HS-AFM) which can perform this type of observations is now materialized. It opens up a new opportunity to directly observe the structure dynamics and dynamic processes of biological molecules in physiological solutions, at subsecond to sub-100 ms temporal resolution and ∼2 nm lateral and 0.1 nm vertical spatial resolution. Importantly, the tip-sample interaction does not disturb their function. In fact, functioning molecules, such as myosin V walking on an actin filament and bacteriorhodopsin in response to light, have been successfully visualized. In the quest for the functional mechanism of proteins, inferences no longer have to be made from static snapshots of their molecular structures and dynamic behavior of optical markers attached to proteins. High-resolution molecular movies reveal the details of dynamic behavior of molecules in action, which can be interpreted without intricate analyses and interpretations. In this talk, I will highlight recent imaging studies and then describe the fundamentals behind the achieved high imaging rate and low-invasiveness to the sample.