Adam Cohen

Bringing Bioelectricity to Light

In the wild, microbial rhodopsin proteins convert sunlight into biochemical signals in their host organisms.  Some microbial rhodopsins convert sunlight into changes in membrane voltage.  We engineered a microbial rhodopsin to run in reverse: to convert changes in membrane voltage into optical signals that are readily detected in a microscope.  These proteins have very strong optical nonlinearities, enabling new approaches to optical control.  I will describe several types of molecular logic that can be implemented with engineered microbial rhodopsins: measurements of absolute membrane voltage; photochemical storage and readout of transient voltage changes; simultaneous optical perturbation and readout of membrane voltage.  I will also describe several applications: studies on transgenic zebrafish and mice, disease modeling in human induced pluripotent stem cell-derived neurons, and explorations of unconventional electrophysiology.