title: Synthetic retinal analogues modify the spectral and kinetic characteristics of microbial rhodopsin optogenetic tools.
abstract: Optogenetic tools have become indispensable in neuroscience to stimulate or inhibit excitable cells by light. Channelrhodopsin-2 (ChR2) variants have been established by mutating the opsin backbone or by mining related algal genomes. As an alternative strategy, we surveyed synthetic retinal analogues combined with microbial rhodopsins for functional and spectral properties, capitalizing on assays in C. elegans, HEK cells and larval Drosophila. Compared with all-trans retinal (ATR), Dimethylamino-retinal (DMAR) shifts the action spectra maxima of ChR2 variants H134R and H134R/T159C from 480 to 520 nm. Moreover, DMAR decelerates the photocycle of ChR2(H134R) and (H134R/T159C), thereby reducing the light intensity required for persistent channel activation. In hyperpolarizing archaerhodopsin-3 and Mac, naphthyl-retinal and thiophene-retinal support activity alike ATR, yet at altered peak wavelengths. Our experiments enable applications of retinal analogues in colour tuning and altering photocycle characteristics of optogenetic tools, thereby increasing the operational light sensitivity of existing cell lines or transgenic animals.
authors.affiliation: 1] Buchmann Institute for Molecular Life Sciences (BMLS), Goethe-University, Max-von-Laue-Straße 15, 60438 Frankfurt, Germany [2] Institute of Biochemistry, Goethe-University, Max-von-Laue-Straße 9, 60438 Frankfurt, Germany.
authors.forename: N
authors.initials: N
authors.lastname: AzimiHashemi
authors.affiliation: 1] Buchmann Institute for Molecular Life Sciences (BMLS), Goethe-University, Max-von-Laue-Straße 15, 60438 Frankfurt, Germany [2] Institute of Biochemistry, Goethe-University, Max-von-Laue-Straße 9, 60438 Frankfurt, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Erbguth
authors.affiliation: Institute for Biology-Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115 Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Vogt
authors.affiliation: Department of Molecular Neurobiology of Behavior, Georg-August-Universität Göttingen, Julia-Lermontowa-Weg 3, 37077 Göttingen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Riemensperger
authors.affiliation: Endotherm, Science-Park II, 66123 Saarbrücken, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Rauch
authors.affiliation: Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstraße 5-13, 81377 München, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Woodmansee
authors.affiliation: 1] Buchmann Institute for Molecular Life Sciences (BMLS), Goethe-University, Max-von-Laue-Straße 15, 60438 Frankfurt, Germany [2] Institute of Biochemistry, Goethe-University, Max-von-Laue-Straße 9, 60438 Frankfurt, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Nagpal
authors.affiliation: Institute of Biochemistry, Goethe-University, Max-von-Laue-Straße 9, 60438 Frankfurt, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Brauner
authors.affiliation: Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: M
authors.initials: M
authors.lastname: Sheves
authors.affiliation: Department of Molecular Neurobiology of Behavior, Georg-August-Universität Göttingen, Julia-Lermontowa-Weg 3, 37077 Göttingen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Fiala
authors.affiliation: Endotherm, Science-Park II, 66123 Saarbrücken, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Kattner
authors.affiliation: Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstraße 5-13, 81377 München, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Trauner
authors.affiliation: Institute for Biology-Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115 Berlin, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Hegemann
authors.affiliation: 1] Buchmann Institute for Molecular Life Sciences (BMLS), Goethe-University, Max-von-Laue-Straße 15, 60438 Frankfurt, Germany [2] Institute of Biochemistry, Goethe-University, Max-von-Laue-Straße 9, 60438 Frankfurt, Germany [3] Cluster of Excellence Frankfurt Macromolecular Complexes (CEF-MC), Goethe University, Max-von-Laue Straße 15 60438, Frankfurt, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Gottschalk
authors.affiliation: 1] Buchmann Institute for Molecular Life Sciences (BMLS), Goethe-University, Max-von-Laue-Straße 15, 60438 Frankfurt, Germany [2] Institute of Biochemistry, Goethe-University, Max-von-Laue-Straße 9, 60438 Frankfurt, Germany.
authors.forename: J F
authors.initials: JF
authors.lastname: Liewald
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D030801:Animals, Genetically Modified; D001522:Behavior, Animal; D017173:Caenorhabditis elegans / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D029721:Drosophila Proteins / Q000737:chemistry*; D004331:Drosophila melanogaster / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D057809:HEK293 Cells; D015801:Helminth Proteins / Q000737:chemistry*; D006801:Humans; D007814:Larva / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D008027:Light; D062308:Optogenetics / Q000295:instrumentation; D018408:Patch-Clamp Techniques; D011994:Recombinant Proteins / Q000737:chemistry; D012172:Retinaldehyde / Q000737:chemistry* / Q000494:pharmacology; D012243:Rhodopsin / Q000737:chemistry*; D025604:Rhodopsins, Microbial / Q000737:chemistry*
chemical_list: D029721:Drosophila Proteins; D015801:Helminth Proteins; D011994:Recombinant Proteins; D025604:Rhodopsins, Microbial; D012243:Rhodopsin; D012172:Retinaldehyde