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Conformational changes and CO2-induced channel gating in connexin26
Deborah H Brotherton1, Christos G Savva2, Timothy J Ragan2
1School of Life Sciences, University of Warwick, Gibbet Hill Road, CV4 7AL Coventry, UK.
Structure (London, England : 1993)
|March 11, 2022
Summary
Increasing carbon dioxide levels close connexin26 (Cx26) channels by altering pore size. Cryo-EM reveals CO2 directly causes conformational changes in Cx26 gap junctions, impacting cellular communication.
Area of Science:
- Structural biology
- Cellular biophysics
- Membrane protein structure
Background:
- Connexins form cell membrane channels (gap junctions/hemichannels) regulating molecule/ion transport.
- Channel dysregulation is linked to various diseases.
- Elevated carbon dioxide (PCO2) closes connexin26 (Cx26) channels.
Purpose of the Study:
- Determine the structure of human Cx26 gap junctions under varying PCO2 levels.
- Elucidate the mechanism by which PCO2 affects Cx26 channel conformation and function.
Main Methods:
- Cryo-electron microscopy (cryo-EM) to visualize human Cx26 gap junctions.
- Structural analysis of Cx26 at different partial pressures of carbon dioxide (PCO2).
Main Results:
- A direct correlation exists between PCO2 levels and Cx26 pore aperture size.
- CO2 alone induces conformational changes in Cx26 proteins.
- N-terminal helix movements are coupled to subunit rotation and transmembrane helix flexing.
Conclusions:
- CO2 directly regulates Cx26 channel gating through conformational changes.
- Understanding Cx26 structural dynamics under varying PCO2 is crucial for disease research.
- N-terminal helix movements play a key role in CO2-mediated channel modulation.
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