Intrapore lipids hydrophobically gate pannexin-1 channels

Area of Science:

• Molecular Biology
• Cell Physiology
• Biophysics

Background:

• Large-pore ion channels, including pannexin-1 (PANX1), lack defined constriction sites, making their gating mechanisms poorly understood.
• The functional closure of PANX1 channels has remained speculative due to the absence of clear pore-blocking elements.

Purpose of the Study:

• To elucidate the molecular mechanism by which pannexin-1 (PANX1) channels are gated or functionally closed.
• To investigate the role of the PANX1 amino-terminal helix in channel activity regulation.

Main Methods:

• Analysis of structural rearrangements within the PANX1 amino-terminal helix.
• Investigation of lipid interactions with the PANX1 channel pore.
• Functional assays to assess ion conduction and channel gating.

Main Results:

• Identified rearrangements in the PANX1 amino-terminal helix as key mediators of channel gating.
• Demonstrated a novel mechanism where lipids physically block the ion conduction pathway.
• Characterized this lipid-mediated blockage as a 'hydrophobic gate' controlling PANX1 channel function.

Conclusions:

• The study reveals a surprising lipid-based gating mechanism for large-pore PANX1 channels.
• Structural changes in the amino-terminal helix facilitate lipid binding and channel closure.
• This finding provides a new understanding of ion channel regulation in cellular physiology.