Conversion of channelrhodopsin into a light-gated chloride channel

Science. 2014 Apr 25;344(6182):409-12. doi: 10.1126/science.1249375. Epub 2014 Mar 27.


The field of optogenetics uses channelrhodopsins (ChRs) for light-induced neuronal activation. However, optimized tools for cellular inhibition at moderate light levels are lacking. We found that replacement of E90 in the central gate of ChR with positively charged residues produces chloride-conducting ChRs (ChloCs) with only negligible cation conductance. Molecular dynamics modeling unveiled that a high-affinity Cl(-)-binding site had been generated near the gate. Stabilizing the open state dramatically increased the operational light sensitivity of expressing cells (slow ChloC). In CA1 pyramidal cells, ChloCs completely inhibited action potentials triggered by depolarizing current injections or synaptic stimulation. Thus, by inverting the charge of the selectivity filter, we have created a class of directly light-gated anion channels that can be used to block neuronal output in a fully reversible fashion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials
  • Animals
  • Binding Sites
  • CA1 Region, Hippocampal / cytology
  • Chloride Channels / chemistry*
  • Chloride Channels / metabolism*
  • Chlorides / metabolism*
  • HEK293 Cells
  • Humans
  • Hydrogen Bonding
  • Ion Channel Gating
  • Light
  • Models, Molecular
  • Molecular Dynamics Simulation
  • Mutation
  • Patch-Clamp Techniques
  • Protein Conformation
  • Protein Engineering
  • Pyramidal Cells / metabolism
  • Rats
  • Recombinant Fusion Proteins / chemistry
  • Rhodopsin / chemistry*
  • Rhodopsin / genetics
  • Rhodopsin / metabolism*
  • Transfection


  • Chloride Channels
  • Chlorides
  • Recombinant Fusion Proteins
  • Rhodopsin