Download MendeleyProlyl isomerization controls activation kinetics of a cyclic nucleotide-gated ion channel.
Schmidpeter, P.A.M., Rheinberger, J., Nimigean, C.M.(2020) Nat Commun 11: 6401-6401
- PubMed: 33328472
- DOI: https://doi.org/10.1038/s41467-020-20104-4
- Primary Citation of Related Structures:
6VXZ, 6VY0 - 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.
Organizational Affiliation:
Weill Cornell Medicine, Department of Anesthesiology, 1300 York Avenue, New York, NY, 10065, USA.
