National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
R01GM124451
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
R01GM088352
米国
American Heart Association
18POST33960309
米国
引用
ジャーナル: Nat Commun / 年: 2020 タイトル: Prolyl isomerization controls activation kinetics of a cyclic nucleotide-gated ion channel. 著者: Philipp A M Schmidpeter / Jan Rheinberger / Crina M Nimigean / 要旨: 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.
名称: SthK P300A bound to cAMP / タイプ: complex / ID: 1 / 親要素: 0 / 含まれる分子: all 詳細: Low-populated state of SthK P300A reconstituted into nanodiscs. Due to the low resolution, side chains could not be assigned and all amino acids are modeled as alanine. The register is ...詳細: Low-populated state of SthK P300A reconstituted into nanodiscs. Due to the low resolution, side chains could not be assigned and all amino acids are modeled as alanine. The register is maintained from the high-resolution structure of the closed state.