A pentameric TRPV3 channel with a dilated pore.

Area of Science:

• Structural biology
• Ion channel biophysics
• Molecular physiology

Background:

• Transient receptor potential (TRP) channels are crucial eukaryotic ion channel superfamilies with diverse physiological roles, making them significant drug targets.
• While numerous TRP channel structures exist, the mechanism of TRPV channel pore dilation, characterized by increased conductance and permeability, remains poorly understood.
• Canonical TRP channel structures are known to be tetrameric.

Purpose of the Study:

• To investigate the structural basis of TRPV3 channel pore dilation at the single-molecule level.
• To explore potential non-canonical structural assemblies of TRP channels beyond the established tetrameric form.

Main Methods:

• High-speed atomic force microscopy (HS-AFM) for dynamic, single-molecule imaging of membrane-embedded TRPV3.
• Cryo-electron microscopy (cryo-EM) to determine the high-resolution structure of the identified TRPV3 assembly.
• Utilized a specialized protein production and data analysis pipeline.

Main Results:

• Discovery of a transient and reversible pentameric state of TRPV3 channels in dynamic equilibrium with the canonical tetramer.
• Increased pentamer formation upon addition of diphenylboronic anhydride (DPBA), an agonist known to induce pore dilation.
• Cryo-EM structure revealed an enlarged pore in the pentameric state compared to the tetramer, correlating with pore dilation.

Conclusions:

• The pentameric TRPV3 assembly represents the structural correlate of the pore dilation phenomenon.
• Membrane diffusive protomer exchange is identified as a mechanism for structural changes and conformational variability in TRP channels.
• Provides the first structural evidence for a non-canonical pentameric TRP channel assembly, opening new avenues for TRP channel research.