Journal Article

Gating the pore of the calcium-activated chloride channel TMEM16A

Dutzler, Raimund, Rheinberger, Jan, Paulino, Cristina, Lam, Andy K. M.

2021

Overview

The binding of cytoplasmic Ca 2+ to the anion-selective channel TMEM16A triggers a conformational change around its binding site that is coupled to the release of a gate at the constricted neck of an hourglass-shaped pore. By combining mutagenesis, electrophysiology, and cryo-electron microscopy, we identified three hydrophobic residues at the intracellular entrance of the neck as constituents of this gate. Mutation of each of these residues increases the potency of Ca 2+ and results in pronounced basal activity. The structure of an activating mutant shows a conformational change of an α-helix that contributes to Ca 2+ binding as a likely cause for the basal activity. Although not in physical contact, the three residues are functionally coupled to collectively contribute to the stabilization of the gate in the closed conformation of the pore, thus explaining the low open probability of the channel in the absence of Ca 2+ . The binding of cytoplasmic Ca 2+ to the anion-selective channel TMEM16A triggers a conformational change around its binding site that is coupled to the release of a gate at the constricted neck. Here authors use cryo-EM and electrophysiology to identify three hydrophobic residues at the intracellular entrance of the neck as constituents of this gate.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 101/28 / 631/45/269/1147 / 631/535/1258/1259 / 631/57/2270/1140 / 631/57/2283 / 82/80 / 82/83 / 9/74 / Anions / Anoctamin-1 - genetics / Anoctamin-1 - metabolism / Anoctamin-1 - ultrastructure / Binding sites / Binding Sites - genetics / Calcium - metabolism / Calcium chloride / Calcium ions / Cations, Divalent - metabolism / Channel gating / Chloride channels (calcium-gated) / Chloride ions / Chlorides - metabolism / Conformation / Constituents / Cryoelectron Microscopy / Electron microscopy / Electrophysiology / HEK293 Cells / Humanities and Social Sciences / Humans / Hydrophobic and Hydrophilic Interactions / Hydrophobicity / Intracellular / Ion Channel Gating / Ion channels / Models, Molecular / multidisciplinary / Mutagenesis / Mutation / Neck / Neoplasm Proteins - genetics / Neoplasm Proteins - metabolism / Neoplasm Proteins - ultrastructure / Protein Binding / Protein Conformation, alpha-Helical / Residues / Science / Science (multidisciplinary)