Structural dynamics and permeability of the TRPV3 pentamer

Area of Science:

• Structural biology
• Ion channel biophysics
• Molecular dynamics simulations

Background:

• Transient Receptor Potential Vanilloid 3 (TRPV3) channels are tetrameric proteins.
• Previous studies identified a transient pentameric state of TRPV3 using high-speed atomic force microscopy (HS-AFM) and cryo-electron microscopy (cryo-EM).

Purpose of the Study:

• To determine a higher resolution structure of the TRPV3 pentamer.
• To elucidate the molecular mechanism of the tetramer-to-pentamer transition.
• To characterize the functional properties of the TRPV3 pentamer.

Main Methods:

• High-resolution cryo-electron microscopy (cryo-EM)
• High-speed atomic force microscopy (HS-AFM)
• Molecular dynamics (MD) simulations
• Potential of Mean Force (PMF) calculations
• Thermal denaturation experiments

Main Results:

• A higher resolution and more complete structure of the TRPV3 pentamer was determined, revealing a domain-swapped architecture, a collapsed vanilloid binding site, and a large pore.
• MD simulations and PMF calculations demonstrated high protein dynamics and permeability to large cations.
• Subunit interface analysis and thermal denaturation experiments supported a proposed molecular mechanism for the tetramer-to-pentamer transition, consistent with HS-AFM observations.

Conclusions:

• The TRPV3 pentamer represents a hyper-activated state of the channel.
• The TRPV3 pentamer possesses unique and highly permissive permeation properties.
• A molecular mechanism for the tetramer-to-pentamer transition in TRPV3 was proposed and experimentally supported.