title: Temporal dynamics of microbial rhodopsin fluorescence reports absolute membrane voltage.
abstract: Plasma membrane voltage is a fundamentally important property of a living cell; its value is tightly coupled to membrane transport, the dynamics of transmembrane proteins, and to intercellular communication. Accurate measurement of the membrane voltage could elucidate subtle changes in cellular physiology, but existing genetically encoded fluorescent voltage reporters are better at reporting relative changes than absolute numbers. We developed an Archaerhodopsin-based fluorescent voltage sensor whose time-domain response to a stepwise change in illumination encodes the absolute membrane voltage. We validated this sensor in human embryonic kidney cells. Measurements were robust to variation in imaging parameters and in gene expression levels, and reported voltage with an absolute accuracy of 10 mV. With further improvements in membrane trafficking and signal amplitude, time-domain encoding of absolute voltage could be applied to investigate many important and previously intractable bioelectric phenomena.
authors: Department of Physics, Harvard University, Cambridge, Massachusetts.
authors: Jennifer H
authors: JH
authors: Hou
authors: Biophysics Program, Harvard University, Cambridge, Massachusetts.
authors: Veena
authors: V
authors: Venkatachalam
authors: Department of Physics, Harvard University, Cambridge, Massachusetts; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts. Electronic address: cohen@chemistry.harvard.edu.
authors: Adam E
authors: AE
authors: Cohen
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015374:Biosensing Techniques / Q000379:methods*; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology; D005453:Fluorescence; D057809:HEK293 Cells; D006801:Humans; D007700:Kinetics; D008564:Membrane Potentials; D062308:Optogenetics / Q000295:instrumentation / Q000379:methods*; D017434:Protein Structure, Tertiary; D017494:Proton Pumps
chemical_list: D019843:Archaeal Proteins; C055476:archaerhodopsin protein, Archaea; D017494:Proton Pumps