PIP2 inhibits pore opening of the cyclic nucleotide-gated channel SthK.

TitlePIP2 inhibits pore opening of the cyclic nucleotide-gated channel SthK.
Publication TypeJournal Article
Year of Publication2024
AuthorsThon O, Wang Z, Schmidpeter PAM, Nimigean CM
JournalNat Commun
Volume15
Issue1
Pagination8230
Date Published2024 Sep 19
ISSN2041-1723
KeywordsArginine, Bacterial Proteins, Binding Sites, Cryoelectron Microscopy, Cyclic Nucleotide-Gated Cation Channels, Ion Channel Gating, Models, Molecular, Mutation, Phosphatidylinositol 4,5-Diphosphate, Spirochaeta
Abstract

The signaling lipid phosphatidylinositol-4,5-bisphosphate (PIP2) regulates many ion channels. It inhibits eukaryotic cyclic nucleotide-gated (CNG) channels while activating their relatives, the hyperpolarization-activated and cyclic nucleotide-modulated (HCN) channels. The prokaryotic SthK channel from Spirochaeta thermophila shares features with CNG and HCN channels and is an established model for this channel family. Here, we show SthK activity is inhibited by PIP2. A cryo-EM structure of SthK in nanodiscs reveals a PIP2-fitting density coordinated by arginine and lysine residues from the S4 helix and the C-linker, located between voltage-sensing and pore domains of adjacent subunits. Mutation of two arginine residues weakens PIP2 inhibition with the double mutant displaying insensitivity to PIP2. We propose that PIP2 inhibits SthK by gluing S4 and S6 together, stabilizing a resting channel conformation. The PIP2 binding site is partially conserved in CNG channels suggesting the possibility of a similar inhibition mechanism in the eukaryotic homologs.

DOI10.1038/s41467-024-52469-1
Alternate JournalNat Commun
PubMed ID39300080
PubMed Central IDPMC11413322
Grant ListR01 GM124451 / GM / NIGMS NIH HHS / United States
GM124451 / / U.S. Department of Health & Human Services | NIH | National Institute of General Medical Sciences (NIGMS) /
N/A / / Deutscher Akademischer Austauschdienst (German Academic Exchange Service) /