Voltage-Dependent Protonation of the Calcium Pocket Enable Activation of the Calcium-Activated Chloride Channel Anoctamin-1 (TMEM16A)
| Autor: | José J. De Jesús-Pérez, Guadalupe Segura-Covarrubias, Patricia Pérez-Cornejo, Alfredo Sánchez-Solano, Iván A. Aréchiga-Figueroa, Jorge Arreola |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Patch-Clamp Techniques
Cations Divalent Physiology Recombinant Fusion Proteins Green Fluorescent Proteins Biophysics chemistry.chemical_element Action Potentials lcsh:Medicine Protonation Gating Calcium Transfection Article Divalent ANO1 Mice Structure-Activity Relationship Chlorides Genes Reporter Animals Humans Patch clamp lcsh:Science Anoctamin-1 chemistry.chemical_classification Anthracenes Multidisciplinary Ion Transport biology lcsh:R HEK293 Cells chemistry Mutation Chloride channel biology.protein lcsh:Q Protons Ion Channel Gating Tannins Intracellular Plasmids |
| Zdroj: | Scientific Reports, Vol 10, Iss 1, Pp 1-12 (2020) Scientific Reports |
| ISSN: | 2045-2322 |
| Popis: | Anoctamin-1 (ANO1 or TMEM16A) is a homo-dimeric Ca2+-activated Cl− channel responsible for essential physiological processes. Each monomer harbours a pore and a Ca2+-binding pocket; the voltage-dependent binding of two intracellular Ca2+ ions to the pocket gates the pore. However, in the absence of intracellular Ca2+ voltage activates TMEM16A by an unknown mechanism. Here we show voltage-activated anion currents that are outwardly rectifying, time-independent with fast or absent tail currents that are inhibited by tannic and anthracene-9-carboxylic acids. Since intracellular protons compete with Ca2+ for binding sites in the pocket, we hypothesized that voltage-dependent titration of these sites would induce gating. Indeed intracellular acidification enabled activation of TMEM16A by voltage-dependent protonation, which enhanced the open probability of the channel. Mutating Glu/Asp residues in the Ca2+-binding pocket to glutamine (to resemble a permanent protonated Glu) yielded channels that were easier to activate at physiological pH. Notably, the response of these mutants to intracellular acidification was diminished and became voltage-independent. Thus, voltage-dependent protonation of glutamate/aspartate residues (Glu/Asp) located in the Ca2+-binding pocket underlines TMEM16A activation in the absence of intracellular Ca2+. |
| Databáze: | OpenAIRE |
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