K_2P2.1 (TREK-1)-activator complexes reveal a cryptic selectivity filter binding site.

Area of Science:

• Neuroscience
• Structural Biology
• Pharmacology

Background:

• Two-pore domain potassium (K2P) channels, particularly the TREK subfamily, regulate neuronal excitability and sensory perception.
• These channels are implicated in pain, temperature sensation, and anesthetic responses.
• Current understanding of K2P channel mechanisms is limited by a lack of effective pharmacological tools.

Purpose of the Study:

• To identify and characterize small molecules that activate TREK subfamily channels.
• To elucidate the structural basis for small-molecule activation of K2P channels.
• To provide novel pharmacological probes for studying K2P channel function.

Main Methods:

• X-ray crystallography was used to determine the structures of K2P2.1 (TREK-1) alone and in complex with activators ML335 and ML402.
• Functional electrophysiology assays were performed to assess channel activity in response to small molecules.
• Structure-based drug design principles were applied to understand the binding interactions.

Main Results:

• A novel class of small-molecule activators (ML335 and ML402) for TREK channels was identified.
• Structural studies revealed a unique cryptic binding pocket distinct from other ion channel sites.
• These activators function as molecular wedges, stabilizing the C-type gate in a 'leak mode' via cation-π interactions.

Conclusions:

• A druggable binding site on K2P channels has been identified, enabling the stabilization of the C-type gate.
• These findings provide direct evidence for selectivity filter gating in K2P channels.
• The discovered activators offer valuable tools for future research into K2P channel physiology and pharmacology.