Structural basis of human Slo2.2 channel gating and modulation

Area of Science:

• Neuroscience
• Structural Biology
• Ion Channel Physiology

Background:

• The sodium-activated Slo2.2 channel is crucial for neuronal excitability in the brain.
• The precise mechanisms of sodium ion (Na+) binding and activation are not fully understood.

Purpose of the Study:

• To elucidate the structural basis of Slo2.2 channel gating and regulation by cations and inhibitors.
• To provide a detailed molecular understanding of Na+-dependent activation.

Main Methods:

• Cryoelectron microscopy (cryo-EM) was used to determine high-resolution structures of human Slo2.2.
• Structures were obtained for the closed, open, and inhibitor-bound states of the channel.

Main Results:

• Cryo-EM structures revealed cation binding sites (K+, Zn2+) stabilizing the closed state.
• Na+ binding sites were identified in the open state, inducing gating ring conformational changes to open the inner gate.
• A potent inhibitor was observed to bind within a pocket formed by pore and S6 helices, blocking channel activity.

Conclusions:

• The study provides a comprehensive structural framework for Slo2.2 channel gating and Na+ sensing.
• These findings advance the understanding of neuronal excitability regulation and potential therapeutic targeting of Slo2.2 channels.