+Search query
-Structure paper
Title | Prolyl isomerization controls activation kinetics of a cyclic nucleotide-gated ion channel. |
---|---|
Journal, issue, pages | Nat Commun, Vol. 11, Issue 1, Page 6401, Year 2020 |
Publish date | Dec 16, 2020 |
Authors | Philipp A M Schmidpeter / Jan Rheinberger / Crina M Nimigean / |
PubMed Abstract | SthK, a cyclic nucleotide-modulated ion channel from Spirochaeta thermophila, activates slowly upon cAMP increase. This is reminiscent of the slow, cAMP-induced activation reported for the ...SthK, a cyclic nucleotide-modulated ion channel from Spirochaeta thermophila, activates slowly upon cAMP increase. This is reminiscent of the slow, cAMP-induced activation reported for the hyperpolarization-activated and cyclic nucleotide-gated channel HCN2 in the family of so-called pacemaker channels. Here, we investigate slow cAMP-induced activation in purified SthK channels using stopped-flow assays, mutagenesis, enzymatic catalysis and inhibition assays revealing that the cis/trans conformation of a conserved proline in the cyclic nucleotide-binding domain determines the activation kinetics of SthK. We propose that SthK exists in two forms: trans Pro300 SthK with high ligand binding affinity and fast activation, and cis Pro300 SthK with low affinity and slow activation. Following channel activation, the cis/trans equilibrium, catalyzed by prolyl isomerases, is shifted towards trans, while steady-state channel activity is unaffected. Our results reveal prolyl isomerization as a regulatory mechanism for SthK, and potentially eukaryotic HCN channels. This mechanism could contribute to electrical rhythmicity in cells. |
External links | Nat Commun / PubMed:33328472 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.42 - 6.68 Å |
Structure data | EMDB-21453, PDB-6vxz: EMDB-21454, PDB-6vy0: |
Chemicals | ChemComp-CMP: ChemComp-PGW: |
Source |
|
Keywords | TRANSPORT PROTEIN |