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Structure of a eukaryotic cyclic-nucleotide-gated channel
Minghui Li1, Xiaoyuan Zhou2, Shu Wang3,4,5,6
1Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Nature
|January 19, 2017
Summary
Cyclic-nucleotide-gated channels, crucial for senses, were structurally analyzed in their open state. This reveals how cyclic nucleotides control ion flow, offering insights into channel function and disease.
Area of Science:
- Molecular Biology
- Structural Biology
- Neuroscience
Background:
- Cyclic-nucleotide-gated (CNG) channels are vital for sensory transduction in vision and olfaction.
- These channels, part of the voltage-gated ion channel superfamily, are modulated by intracellular cyclic nucleotides, not voltage.
- Understanding CNG channel structure is key to deciphering their unique gating mechanisms.
Purpose of the Study:
- To determine the high-resolution structure of a CNG channel.
- To elucidate the gating mechanism coupling cyclic nucleotide binding to channel opening.
- To provide a structural basis for ion permeation and channelopathies.
Main Methods:
- Single-particle electron cryo-microscopy (cryo-EM) at 3.5-Å resolution.
- Analysis of a specific CNG channel from *Caenorhabditis elegans*.
- Structural determination in the cyclic guanosine monophosphate (cGMP)-bound open state.
Main Results:
- A detailed 3D structure of the CNG channel in its open conformation was obtained.
- An unusual voltage-sensor-like domain was identified, explaining reduced voltage dependence.
- A gating ring, formed by a linker and pore/binding domains, was observed to couple cGMP binding to channel gate control.
Conclusions:
- The structure provides a mechanistic framework for CNG channel gating and ion permeation.
- Insights into the role of the voltage-sensor-like domain and gating ring in channel function.
- This structural information aids in understanding channelopathies and developing related therapeutics.
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