6VY0

SthK P300A cyclic nucleotide-gated potassium channel in a putative active state, in complex with cAMP

Summary for 6VY0

• Entry DOI: 10.2210/pdb6vy0/pdb
• Related: 6VXZ
• EMDB information: 21453 21454 7484
• Descriptor: SthK (1 entity in total)
• Functional Keywords: transport protein
• Biological source: Spirochaeta thermophila DSM 6578
• Total number of polymer chains: 4
• Total formula weight: 204370.16

Authors

Schmidpeter, P.A.M.,Rheinberger, J.,Nimigean, C.M. (deposition date: 2020-02-25, release date: 2020-11-11, Last modification date: 2024-03-06)

Primary citation

Schmidpeter, P.A.M.,Rheinberger, J.,Nimigean, C.M.
Prolyl isomerization controls activation kinetics of a cyclic nucleotide-gated ion channel.
Nat Commun, 11:6401-6401, 2020

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 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.

PubMed: 33328472
DOI: 10.1038/s41467-020-20104-4

Experimental method

ELECTRON MICROSCOPY (6.68 Å)