title: Resonance Raman and FTIR spectroscopic characterization of the closed and open states of channelrhodopsin-1.
abstract: Channelrhodopsin-1 from Chlamydomonas augustae (CaChR1) is a light-activated cation channel, which is a promising optogenetic tool. We show by resonance Raman spectroscopy and retinal extraction followed by high pressure liquid chromatography (HPLC) that the isomeric ratio of all-trans to 13-cis of solubilized channelrhodopsin-1 is with 70:30 identical to channelrhodopsin-2 from Chlamydomonas reinhardtii (CrChR2). Critical frequency shifts in the retinal vibrations are identified in the Raman spectrum upon transition to the open (conductive P2(380)) state. Fourier transform infrared spectroscopy (FTIR) spectra indicate different structures of the open states in the two channelrhodopsins as reflected by the amide I bands and the protonation pattern of acidic amino acids.
authors.affiliation: Genetic Biophysics, Freie Universität Berlin, 14195 Berlin, Germany.
authors.forename: Vera
authors.initials: V
authors.lastname: Muders
authors.affiliation: Experimental Molecular Biophysics, Freie Universität Berlin, 14195 Berlin, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Kerruth
authors.affiliation: Experimental Molecular Biophysics, Freie Universität Berlin, 14195 Berlin, Germany.
authors.forename: Víctor A
authors.initials: VA
authors.lastname: Lórenz-Fonfría
authors.affiliation: Max-Planck-Institute of Biophysics, Department of Biophysical Chemistry, 60438 Frankfurt/Main, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Bamann
authors.affiliation: Experimental Molecular Biophysics, Freie Universität Berlin, 14195 Berlin, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Heberle
authors.affiliation: Genetic Biophysics, Freie Universität Berlin, 14195 Berlin, Germany. Electronic address: r.schlesinger@fu-berlin.de.
authors.forename: Ramona
authors.initials: R
authors.lastname: Schlesinger
mesh_terms: D002696:Chlamydomonas / Q000737:chemistry*; D015640:Ion Channel Gating; D008027:Light; D010940:Plant Proteins / Q000737:chemistry*; D011487:Protein Conformation / Q000528:radiation effects; D012172:Retinaldehyde / Q000737:chemistry; D012243:Rhodopsin / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D010940:Plant Proteins; D012243:Rhodopsin; D012172:Retinaldehyde
keywords: CaChR1; Channelrhodopsin; Optogenetics; Photoreceptor; Resonance Raman spectroscopy; Retinal