8GI9

Cation channelrhodopsin from Hyphochytrium catenoides (HcCCR) embedded in peptidisc

Summary for 8GI9

• Entry DOI: 10.2210/pdb8gi9/pdb
• EMDB information: 40062 40063
• Descriptor: Cation Channelrhodopsin, RETINAL, SODIUM ION, ... (6 entities in total)
• Functional Keywords: retinal protein, channelrhodopsin, cation channel, peptidisc, optogenetics, transport protein
• Biological source: Hyphochytrium catenoides
• Total number of polymer chains: 1
• Total formula weight: 34772.26

Authors

Morizumi, T.,Kim, K.,Li, H.,Spudich, J.L.,Ernst, O.P. (deposition date: 2023-03-13, release date: 2023-07-26, Last modification date: 2024-05-01)

Primary citation

Morizumi, T.,Kim, K.,Li, H.,Govorunova, E.G.,Sineshchekov, O.A.,Wang, Y.,Zheng, L.,Bertalan, E.,Bondar, A.N.,Askari, A.,Brown, L.S.,Spudich, J.L.,Ernst, O.P.
Structures of channelrhodopsin paralogs in peptidiscs explain their contrasting K + and Na + selectivities.
Nat Commun, 14:4365-4365, 2023

PubMed Abstract: 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.

PubMed: 37474513
DOI: 10.1038/s41467-023-40041-2

Experimental method

ELECTRON MICROSCOPY (2.84 Å)