%0 Journal Article
%A Govorunova, Elena G.
%A Sineshchekov, Oleg A.
%A Brown, Leonid S.
%A Bondar, Ana-Nicoleta
%A Spudich, John L.
%T Structural Foundations of Potassium Selectivity in Channelrhodopsins
%J mBio
%V 13
%N 6
%@ 2161-2129
%C Washington, DC
%I American Society for Microbiology
%M FZJ-2023-00944
%P e03039-22
%D 2022
%X Potassium-selective channelrhodopsins (KCRs) are light-gated K+ channels recently found in the stramenopile protist Hyphochytrium catenoides. When expressed in neurons, KCRs enable high-precision optical inhibition of spiking (optogenetic silencing). KCRs are capable of discriminating K+ from Na+ without the conventional K+ selectivity filter found in classical K+ channels. The genome of H. catenoides also encodes a third paralog that is more permeable for Na+ than for K+. To identify structural motifs responsible for the unusual K+ selectivity of KCRs, we systematically analyzed a series of chimeras and mutants of this protein. We found that mutations of three critical residues in the paralog convert its Na+-selective channel into a K+-selective one. Our characterization of homologous proteins from other protists (Colponema vietnamica, Cafeteria burkhardae, and Chromera velia) and metagenomic samples confirmed the importance of these residues for K+ selectivity. We also show that Trp102 and Asp116, conserved in all three H. catenoides paralogs, are necessary, although not sufficient, for K+ selectivity. Our results provide the foundation for further engineering of KCRs for optogenetic needs.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ 36413022
%U <Go to ISI:>//WOS:000890586800001
%R 10.1128/mbio.03039-22
%U https://juser.fz-juelich.de/record/943338