Electrical spiking in Escherichia coli probed with a fluorescent voltage-indicating protein

Science. 2011 Jul 15;333(6040):345-8. doi: 10.1126/science.1204763.


Bacteria have many voltage- and ligand-gated ion channels, and population-level measurements indicate that membrane potential is important for bacterial survival. However, it has not been possible to probe voltage dynamics in an intact bacterium. Here we developed a method to reveal electrical spiking in Escherichia coli. To probe bacterial membrane potential, we engineered a voltage-sensitive fluorescent protein based on green-absorbing proteorhodopsin. Expression of the proteorhodopsin optical proton sensor (PROPS) in E. coli revealed electrical spiking at up to 1 hertz. Spiking was sensitive to chemical and physical perturbations and coincided with rapid efflux of a small-molecule fluorophore, suggesting that bacterial efflux machinery may be electrically regulated.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Action Potentials
  • Escherichia coli / genetics
  • Escherichia coli / physiology*
  • Fluorescence
  • Fluorescent Dyes
  • Hydrogen-Ion Concentration
  • Ion Channels / metabolism
  • Ion Transport
  • Light
  • Membrane Potentials*
  • Protons
  • Rhodamines / metabolism
  • Rhodopsin / chemistry
  • Rhodopsin / genetics
  • Rhodopsin / metabolism*
  • Rhodopsins, Microbial
  • Spectrometry, Fluorescence
  • Stress, Physiological


  • Fluorescent Dyes
  • Ion Channels
  • Protons
  • Rhodamines
  • Rhodopsins, Microbial
  • proteorhodopsin
  • tetramethylrhodamine methyl ester
  • Rhodopsin