TY  - JOUR
AU  - Govorunova, Elena G.
AU  - Sineshchekov, Oleg A.
AU  - Brown, Leonid S.
AU  - Bondar, Ana-Nicoleta
AU  - Spudich, John L.
TI  - Structural Foundations of Potassium Selectivity in Channelrhodopsins
JO  - mBio
VL  - 13
IS  - 6
SN  - 2161-2129
CY  - Washington, DC
PB  - American Society for Microbiology
M1  - FZJ-2023-00944
SP  - e03039-22
PY  - 2022
AB  - 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.
LB  - PUB:(DE-HGF)16
C6  - 36413022
UR  - <Go to ISI:>//WOS:000890586800001
DO  - DOI:10.1128/mbio.03039-22
UR  - https://juser.fz-juelich.de/record/943338
ER  -