Channelrhodopsin-1: A Light-Gated Proton Channel in Green Algae

Nagel, Georg; Ollig, Doris; Fuhrmann, Markus; Kateriya, Suneel; Musti, Anna Maria; Bamberg, Ernst; Hegemann, Peter

doi:10.1126/science.1072068

Cited by 1,046 publications

(891 citation statements)

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“…The 495-nm absorbance maximum of ChR1 (which does not express well in neurons) is indeed slightly red-shifted from that of ChR2 (ref. 9), but the combination of several substantial changes in VChR1 predicted a robust wavelength shift on a scale that would be useful for defining a new class of tool for neuroscience.…”

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confidence: 99%

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Red-shifted optogenetic excitation: a tool for fast neural control derived from Volvox carteri

et al. 2008

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The introduction of two microbial opsin-based tools, channelrhodopsin-2 (ChR2) and halorhodopsin (NpHR), to neuroscience has generated interest in fast, multimodal, cell type-specific neural circuit control. Here we describe a cation-conducting channelrhodopsin (VChR1) from Volvox carteri that can drive spiking at 589 nm, with excitation maximum red-shifted ~70 nm compared with ChR2. These results demonstrate fast photostimulation with yellow light, thereby defining a functionally distinct third category of microbial rhodopsin proteins.Microbial proteins that can be rapidly activated by light have been adapted for research in neuroscience, including ChR2 and NpHR, which permit millisecond-precision optical control of genetically defined cell types in intact neural tissue 1-6 . Because ChR2 is a blue light-gated cation channel and NpHR is a yellow light-driven chloride pump, the combination of these two proteins allows independent neural excitation and inhibition in the same preparation. However, there has been enormous interest in developing a hypothetical third major optogenetic tool, namely a second cation channel with an action spectrum that is substantially red-shifted relative to ChR2, to allow tests of the interaction of cell types in circuit computation or behavior.Although efforts to develop a distinct light-activated excitatory protein have been focused on molecular engineering of ChR2, another approach would be to identify previously unknown microbial channelrhodopsins using genomic tools. One ChR2-related sequence from the spheroidal alga Volvox carteri (Fig. 1a) has been described, but the absorption spectrum of the protein and the photocycle dynamics are virtually identical to those of ChR2 (refs. 7 ,8 ). Therefore, we searched the genome database from the US Department of Energy Joint Genome Institute, discovered a second Volvox ChR (VChR1) that is more related to ChR1 (ref. 9) from Chlamydomonas reinhardtii, explored its properties in heterologous expression systems and functionally tested the codon-optimized opsin gene in mammalian neurons.We expressed VChR1 in Xenopus oocytes and HEK293 cells and observed evoked photocurrents similar to those of ChR1 from Chlamydomonas 9,10 . The photocurrents were graded with light intensity and showed inactivation from a fast peak toward a reduced stationary plateau (Fig. 1b) (Fig. 1b) 9 , and currents showed an inwardly rectifying current-voltage relationship (Fig. 1c).Certain primary structural differences between VChR1 and the Chlamydomonas ChRs suggested that the properties of VChR1 would be distinct from those of the other ChRs (Fig. 1d). On the basis of electrostatic potential and quantum mechanical-molecular mechanical calculations for bacteriorhodopsin and relatives, the counterion complex of the all-trans retinal Schiff base (RSB; Fig. 1d) should be critical for color tuning 11,12 , but these residues are conserved in both ChR1 and VChR1 (blue sequence, Fig. 1d). On the other hand, calculations and mutational experiments 11,12 predict that fo...

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“…Therefore, we searched the genome database from the US Department of Energy Joint Genome Institute, discovered a second Volvox ChR (VChR1) that is more related to ChR1 (ref. 9) from Chlamydomonas reinhardtii, explored its properties in heterologous expression systems and functionally tested the codon-optimized opsin gene in mammalian neurons.…”

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Red-shifted optogenetic excitation: a tool for fast neural control derived from Volvox carteri

et al. 2008

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“…Optogenetics was born with the discovery of light-sensitive microbial membrane proteins [107,[109][110][111]. Channelrhodopsins, light-sensitive cation channels, rapidly open and depolarize neurons in response to blue light (460 nm) [110,111].…”

Section: Optogeneticsmentioning

confidence: 99%

Selective Manipulation of Neural Circuits

Park

Carmel

2016

Neurotherapeutics

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Unraveling the complex network of neural circuits that form the nervous system demands tools that can manipulate specific circuits. The recent evolution of genetic tools to target neural circuits allows an unprecedented precision in elucidating their function. Here we describe two general approaches for achieving circuit specificity. The first uses the genetic identity of a cell, such as a transcription factor unique to a circuit, to drive expression of a molecule that can manipulate cell function. The second uses the spatial connectivity of a circuit to achieve specificity: one genetic element is introduced at the origin of a circuit and the other at its termination. When the two genetic elements combine within a neuron, they can alter its function. These two general approaches can be combined to allow manipulation of neurons with a specific genetic identity by introducing a regulatory gene into the origin or termination of the circuit. We consider the advantages and disadvantages of both these general approaches with regard to specificity and efficacy of the manipulations. We also review the genetic techniques that allow gain-and loss-of-function within specific neural circuits. These approaches introduce light-sensitive channels (optogenetic) or drug sensitive channels (chemogenetic) into neurons that form specific circuits. We compare these tools with others developed for circuit-specific manipulation and describe the advantages of each. Finally, we discuss how these tools might be applied for identification of the neural circuits that mediate behavior and for repair of neural connections.

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“…9 The photo-reorientation of the organism away from light is modulated through increased levels of cyclic AMP produced by a blue-lightactivated adenylyl cyclase (PAC). 10,11 Similarly, whereas negative phototaxis in Chlamydomonasis is modulated by PAC, photoattraction occurs through the action of two sensory rhodopsins CSRA and CSRB discovered by Sineshchekov et al in 2002, 12 also called channelrhodopsins, ChR1 and ChR2 by Nagel's group, 13 and termed Acop1 by Susuki et al 14 The two photoreceptor proteins have different abosrption profiles with CSRA absorbing predominantly at blue-green wavelengths and promoting a photophobic response in response to strong illumination while CSRB absorbs at shorter wavelengths and leads to phototaxis at weaker light intensties. 15 There are around 9 × 10 4 molecules of CSRA and 1.5 × 10 4 molecules of CSRB in each cell.…”

Section: Euglena and Chlamydomonasmentioning

confidence: 99%

Light and the evolution of vision

Williams

2015

Eye

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It might seem a little ridiculous to cover the period over which vision evolved, perhaps 1.5 billion years, in only 3000 words. Yet, if we examine the photoreceptor molecules of the most basic eukaryote protists and even before that, in those of prokaryote bacteria and cyanobacteria, we see how similar they are to those of mammalian rod and cone photoreceptor opsins and the photoreceptive molecules of light sensitive ganglion cells. This shows us much with regard the development of vision once these proteins existed, but there is much more to discover about the evolution of even more primitive vision systems.

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Channelrhodopsin-1: A Light-Gated Proton Channel in Green Algae

Cited by 1,046 publications

References 18 publications

Red-shifted optogenetic excitation: a tool for fast neural control derived from Volvox carteri

Red-shifted optogenetic excitation: a tool for fast neural control derived from Volvox carteri

Selective Manipulation of Neural Circuits

Light and the evolution of vision

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