title: Structural differences between the closed and open states of channelrhodopsin-2 as observed by EPR spectroscopy.
abstract: Channelrhodopsin is a cation channel with the unique property of being activated by light. To address structural changes of the open state of the channel, two variants, which contain either 1 or 2 wild-type cysteines, were derivatised with nitroxide spin label and subjected to electron paramagnetic resonance spectroscopy. Both variants contained the C128T mutation to trap the long-lived P3(520) state by illumination. Comparison of spin-spin distances in the dark state and after illumination reflect conformational changes in the conductive P3(520) state involving helices B and F. Spin distance measurements reveal that channelrhodopsin forms a dimer even in the absence of intermolecular N-terminal cysteines.
authors.affiliation: Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Krause
authors.forename: Christopher
authors.initials: C
authors.lastname: Engelhard
authors.forename: Joachim
authors.initials: J
authors.lastname: Heberle
authors.forename: Ramona
authors.initials: R
authors.lastname: Schlesinger
authors.forename: Robert
authors.initials: R
authors.lastname: Bittl
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012243:Rhodopsin / Q000737:chemistry*
chemical_list: D012243:Rhodopsin
keywords: (1-oxyl-2,2,5,5-tetramethylpyrroline-3-methyl)methanethiosulfonate spin label; 2-(N-morpholino)ethanesulfonic acid; BR; ChR2; DEER; DM; EPR; EPR spectroscopy; Light-activated cation channel; MES; MTSL; Membrane protein; Optogenetic; Photocycle; Rhodopsin; SRII; bacteriorhodopsin; channelrhodopsin 2; continuous wave electron paramagnetic resonance; cw-EPR; decyl-β-d-maltoside; double electron–electron resonance; electron paramagnetic resonance; pELDOR; pulsed electron–electron double resonance; sensory rhodopsin II