title: Light-induced helix movements in channelrhodopsin-2.
abstract: Channelrhodopsin-2 (ChR2) is a cation-selective light-gated channel from Chlamydomonas reinhardtii (Nagel G, Szellas T, Huhn W, Kateriya S, Adeishvili N, Berthold P, et al. Channelrhodopsin-2, a directly light-gated cation-selective membrane channel. Proc Natl Acad Sci USA 2003;100:13940-5), which has become a powerful tool in optogenetics. Two-dimensional crystals of the slow photocycling C128T ChR2 mutant were exposed to 473 nm light and rapidly frozen to trap the open state. Projection difference maps at 6Å resolution show the location, extent and direction of light-induced conformational changes in ChR2 during the transition from the closed state to the ion-conducting open state. Difference peaks indicate that transmembrane helices (TMHs) TMH2, TMH6 and TMH7 reorient or rearrange during the photocycle. No major differences were found near TMH3 and TMH4 at the dimer interface. While conformational changes in TMH6 and TMH7 are known from other microbial-type rhodopsins, our results indicate that TMH2 has a key role in light-induced channel opening and closing in ChR2.
authors.affiliation: Max Planck Institute of Biophysics Department of Structural Biology, Max von Laue Strasse 3, 60438 Frankfurt, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Müller
authors.affiliation: Max Planck Institute of Biophysics Department of Biophysical Chemistry, Max von Laue Strasse 3, 60438 Frankfurt, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Bamann
authors.affiliation: Max Planck Institute of Biophysics Department of Biophysical Chemistry, Max von Laue Strasse 3, 60438 Frankfurt, Germany.
authors.forename: Ernst
authors.initials: E
authors.lastname: Bamberg
authors.affiliation: Max Planck Institute of Biophysics Department of Structural Biology, Max von Laue Strasse 3, 60438 Frankfurt, Germany. Electronic address: werner.kuehlbrandt@biophys.mpg.de.
authors.forename: Werner
authors.initials: W
authors.lastname: Kühlbrandt
mesh_terms: D015220:Calcium Channels / Q000737:chemistry* / Q000235:genetics; D016825:Chlamydomonas reinhardtii / Q000737:chemistry* / Q000235:genetics; D003001:Cloning, Molecular; D008027:Light; D008854:Microscopy, Electron; D010843:Pichia / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics; D017433:Protein Structure, Secondary; D012243:Rhodopsin / Q000737:chemistry* / Q000235:genetics
chemical_list: D015220:Calcium Channels; D010940:Plant Proteins; D012243:Rhodopsin
keywords: channelrhodopsin; conformational changes; electron cryo-microscopy; light-gated ion channel; microbial rhodopsin