title: Archaerhodopsin variants with enhanced voltage-sensitive fluorescence in mammalian and Caenorhabditis elegans neurons.
abstract: Probing the neural circuit dynamics underlying behaviour would benefit greatly from improved genetically encoded voltage indicators. The proton pump Archaerhodopsin-3 (Arch), an optogenetic tool commonly used for neuronal inhibition, has been shown to emit voltage-sensitive fluorescence. Here we report two Arch variants with enhanced radiance (Archers) that in response to 655 nm light have 3-5 times increased fluorescence and 55-99 times reduced photocurrents compared with Arch WT. The most fluorescent variant, Archer1, has 25-40% fluorescence change in response to action potentials while using 9 times lower light intensity compared with other Arch-based voltage sensors. Archer1 is capable of wavelength-specific functionality as a voltage sensor under red light and as an inhibitory actuator under green light. As a proof-of-concept for the application of Arch-based sensors in vivo, we show fluorescence voltage sensing in behaving Caenorhabditis elegans. Archer1's characteristics contribute to the goal of all-optical detection and modulation of activity in neuronal networks in vivo.
authors.affiliation: 1] Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA [2].
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Flytzanis
authors.affiliation: 1] Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA [2].
authors.forename: Claire N
authors.initials: CN
authors.lastname: Bedbrook
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Chiu
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Martin K M
authors.initials: MK
authors.lastname: Engqvist
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Xiao
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Ken Y
authors.initials: KY
authors.lastname: Chan
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Sternberg
authors.affiliation: 1] Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA [2] Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Frances H
authors.initials: FH
authors.lastname: Arnold
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Viviana
authors.initials: V
authors.lastname: Gradinaru
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D017173:Caenorhabditis elegans / Q000737:chemistry / Q000378:metabolism; D015870:Gene Expression; D015801:Helminth Proteins / Q000737:chemistry* / Q000235:genetics; D006624:Hippocampus / Q000737:chemistry / Q000378:metabolism; D008027:Light; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics; D009474:Neurons / Q000737:chemistry* / Q000378:metabolism; D062308:Optogenetics / Q000379:methods; D018408:Patch-Clamp Techniques; D061251:Primary Cell Culture; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013050:Spectrometry, Fluorescence; D017494:Proton Pumps
chemical_list: D019843:Archaeal Proteins; D015801:Helminth Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D011994:Recombinant Proteins; C055476:archaerhodopsin protein, Archaea; D017494:Proton Pumps