Connexons Coupling to Gap Junction Channel: Potential Role for Extracellular Protein Stabilization Centers

Area of Science:

• Cellular Biology
• Biophysics
• Structural Biology

Background:

• Connexin (Cx) proteins form intercellular gap junction channels (Cx GJCs) via hemichannel coupling.
• The GJ interface involves extracellular loops with conserved cysteines, crucial for channel structure.
• Previous inhibitors lacked subtype specificity, highlighting the need to understand interface formation.

Purpose of the Study:

• To elucidate the structural basis of GJ interface formation.
• To identify connexin subtype-specific stabilization centers (SCs) involved in GJC assembly.
• To explore potential targets for developing selective Cx inhibitors.

Main Methods:

• Devised a Cx43 GJC homology model embedded in membrane bilayers.
• Applied molecular dynamics simulations to analyze SC fluctuation dynamics.
• Investigated the role of disulfide bonds and specific residue angles in interface stability.

Main Results:

• Discovered Cx GJC subtype-specific SCs at the GJ interface.
• Confirmed the critical role of conserved and non-conserved residues in EL1 loops for GJC stabilization.
• Identified specific disulfide bonds and proline residue angles influencing interface formation and stability.

Conclusions:

• Cx subtype-specific SCs are crucial for GJ interface architecture and stabilization.
• Understanding these SCs and their interactions enables the design of targeted Cx inhibitors.
• This research paves the way for developing selective modulators of connexon-connexon coupling.