4KL1 image
Entry Detail
PDB ID:
4KL1
Title:
HCN4 CNBD in complex with cGMP
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2013-05-07
Release Date:
2014-04-30
Method Details:
Experimental Method:
Resolution:
2.70 Å
R-Value Free:
0.27
R-Value Work:
0.21
R-Value Observed:
0.21
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 4
Chain IDs:A, B, C, D
Chain Length:199
Number of Molecules:4
Biological Source:Homo sapiens
Modified Residue
Compound ID Chain ID Parent Comp ID Details 2D Image
CSO A CYS S-HYDROXYCYSTEINE
Primary Citation
Cyclic dinucleotides bind the C-linker of HCN4 to control channel cAMP responsiveness.
Nat.Chem.Biol. 10 457 462 (2014)
PMID: 24776929 DOI: 10.1038/nchembio.1521

Abstact

cAMP mediates autonomic regulation of heart rate by means of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which underlie the pacemaker current If. cAMP binding to the C-terminal cyclic nucleotide binding domain enhances HCN open probability through a conformational change that reaches the pore via the C-linker. Using structural and functional analysis, we identified a binding pocket in the C-linker of HCN4. Cyclic dinucleotides, an emerging class of second messengers in mammals, bind the C-linker pocket (CLP) and antagonize cAMP regulation of the channel. Accordingly, cyclic dinucleotides prevent cAMP regulation of If in sinoatrial node myocytes, reducing heart rate by 30%. Occupancy of the CLP hence constitutes an efficient mechanism to hinder β-adrenergic stimulation on If. Our results highlight the regulative role of the C-linker and identify a potential drug target in HCN4. Furthermore, these data extend the signaling scope of cyclic dinucleotides in mammals beyond their first reported role in innate immune system.

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