Related Experiment Video

Updated: Sep 12, 2025

Whole-cell Patch-clamp Recordings for Electrophysiological Determination of Ion Selectivity in Channelrhodopsins
08:39

Whole-cell Patch-clamp Recordings for Electrophysiological Determination of Ion Selectivity in Channelrhodopsins

Published on: May 22, 2017

17.4K

A second photoactivatable state of the anion-conducting channelrhodopsin GtACR1 empowers persistent activity

Kristin Labudda1,2, Mohamad Javad Norahan1,2, Lisa-Marie Hübner1,2

  • 1Center for Protein Diagnostics (PRODI), Biospectroscopy, Ruhr University Bochum, Bochum, Germany.

Communications Biology
|August 8, 2025
PubMed

Insights

Researchers discovered a photoactivable O intermediate in GtACR1, a channelrhodopsin, enabling fast channel reopening. This finding advances optogenetic tools for neuroscience and disease therapy.

Area of Science:

  • Optogenetics
  • Neuroscience
  • Biophysics

Background:

  • Optogenetics utilizes light to control cellular functions, with applications in neuroscience and disease therapeutics.
  • Channelrhodopsins like ChR2 enable neuronal depolarization but have limited ion currents due to photocycle pathways.
  • Anion-conducting channelrhodopsins, such as GtACR1, exhibit significantly higher photocurrents.

Purpose of the Study:

  • To elucidate the mechanistic basis for the high photocurrents observed in Guillardia theta anion channelrhodopsin 1 (GtACR1).
  • To investigate the photocycle dynamics and gating mechanisms of GtACR1 using advanced spectroscopic techniques.

Main Methods:

  • Fourier-transform infrared (FTIR) spectroscopy was employed to analyze GtACR1's photocycle.
  • Vibrational spectra were used to study the conformational and protonation state changes during the photoactivation process.

Main Results:

  • FTIR spectroscopy revealed that the O intermediate of GtACR1 is photoactivable, facilitating rapid channel reopening.
  • Excitation of the O intermediate initiated a photocyclic reaction sequence comparable to the ground state, albeit with subtle alterations in channel conformation and protonation.
  • These findings provide mechanistic insights into the efficient gating of GtACR1.

Conclusions:

  • The photoactivable O intermediate is a key factor contributing to GtACR1's high photocurrents.
  • Understanding this mechanism offers a pathway for developing enhanced optogenetic tools with improved efficiency.
  • This research deepens our comprehension of channelrhodopsin gating mechanisms.

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