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10:03
Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
18.6K
Light-induced helix movements in channelrhodopsin-2
Maria Müller1, Christian Bamann2, Ernst Bamberg2
1Max Planck Institute of Biophysics Department of Structural Biology, Max von Laue Strasse 3, 60438 Frankfurt, Germany.
Journal of Molecular Biology
|December 3, 2014
Summary
This study reveals how Channelrhodopsin-2 (ChR2) changes shape when activated by light. Transmembrane helices TMH2, TMH6, and TMH7 reorient, with TMH2 playing a crucial role in channel gating.
Area of Science:
- Structural Biology
- Optogenetics
- Biophysics
Background:
- Channelrhodopsin-2 (ChR2) is a light-gated ion channel crucial for optogenetics.
- Understanding ChR2's conformational changes is key to its function.
Purpose of the Study:
- To elucidate the structural rearrangements of ChR2 during its photocycle.
- To identify the specific transmembrane helices involved in light-induced channel opening.
Main Methods:
- Two-dimensional crystallography of a ChR2 mutant (C128T).
- Cryo-trapping of the light-activated open state using 473 nm illumination.
- Analysis of projection difference maps at 6Å resolution.
Main Results:
- Light exposure induced conformational changes in ChR2.
- Transmembrane helices TMH2, TMH6, and TMH7 were identified as key players in the structural transition.
- TMH2 showed significant reorientation, suggesting a critical role in channel gating.
Conclusions:
- TMH2, TMH6, and TMH7 undergo reorientation during the ChR2 photocycle.
- TMH2 plays a pivotal role in the light-induced opening and closing mechanism of ChR2, distinct from other microbial rhodopsins.
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