In the wild, microbial rhodopsin proteins convert solar energy into a transmembrane voltage, which provides energy for their host. We engineered microbial rhodopsins to run backward: to convert membrane potential into a readily detectable optical signal. When expressed in a neuron or a cardiac myocyte, these voltage-indicating proteins convert electrical action potentials into visible flashes of fluorescence, allowing us to make movies of electrical activity in cells. Upon expression of the voltage indicator in E. coli, we discovered that bacteria generate electrical spikes too. These voltage-indicating proteins are a new class of environmentally sensitive fluorescent proteins that emit in the near infrared, are highly photostable, and have no homology to GFP or to any other fluorescent indicator.
J. Kralj, D. R. Hochbaum, A. D. Douglass, A. E. Cohen, “Electrical spiking in Escherichia coli probed with a fluorescent voltage-indicating protein,” Science, 333, 345-348 (2011)
J. Kralj*, A. D. Douglass*, D. R. Hochbaum*, D. Maclaurin, A. E.
Cohen, “Optical recording of action potentials in mammalian neurons using a microbial rhodopsin," Nature Methods, 9, 90-95 (2012)
Depts of Neurobiology & Physics of Complex Systems
Joint Seminar
