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Structures of channelrhodopsin paralogs in peptidiscs explain their contrasting K(+) and Na(+) selectivities

Kalium channelrhodopsin 1 from Hyphochytrium catenoides (HcKCR1) is a light-gated channel used for optogenetic silencing of mammalian neurons. It selects K(+) over Na(+) in the absence of the canonical tetrameric K(+) selectivity filter found universally in voltage- and ligand-gated channels. The ge...

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Detalles Bibliográficos
Autores principales: Morizumi, Takefumi, Kim, Kyumhyuk, Li, Hai, Govorunova, Elena G., Sineshchekov, Oleg A., Wang, Yumei, Zheng, Lei, Bertalan, Éva, Bondar, Ana-Nicoleta, Askari, Azam, Brown, Leonid S., Spudich, John L., Ernst, Oliver P.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10359266/
https://www.ncbi.nlm.nih.gov/pubmed/37474513
http://dx.doi.org/10.1038/s41467-023-40041-2
Descripción
Sumario:Kalium channelrhodopsin 1 from Hyphochytrium catenoides (HcKCR1) is a light-gated channel used for optogenetic silencing of mammalian neurons. It selects K(+) over Na(+) in the absence of the canonical tetrameric K(+) selectivity filter found universally in voltage- and ligand-gated channels. The genome of H. catenoides also encodes a highly homologous cation channelrhodopsin (HcCCR), a Na(+) channel with >100-fold larger Na(+) to K(+) permeability ratio. Here, we use cryo-electron microscopy to determine atomic structures of these two channels embedded in peptidiscs to elucidate structural foundations of their dramatically different cation selectivity. Together with structure-guided mutagenesis, we show that K(+) versus Na(+) selectivity is determined at two distinct sites on the putative ion conduction pathway: in a patch of critical residues in the intracellular segment (Leu69/Phe69, Ile73/Ser73 and Asp116) and within a cluster of aromatic residues in the extracellular segment (primarily, Trp102 and Tyr222). The two filters are on the opposite sides of the photoactive site involved in channel gating.