Vullo Sabrina, Ambrosio Nicolas, Kucera Jan P, Bignucolo Olivier, Kellenberger Stephan
Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland.
Department of Physiology, University of Bern, Bern, Switzerland.
Elife. 2021 Mar 17;10:e66488. doi: 10.7554/eLife.66488.
Acid-sensing ion channels (ASICs) are neuronal Na channels that are activated by a drop in pH. Their established physiological and pathological roles, involving fear behaviors, learning, pain sensation, and neurodegeneration after stroke, make them promising targets for future drugs. Currently, the ASIC activation mechanism is not understood. Here, we used voltage-clamp fluorometry (VCF) combined with fluorophore-quencher pairing to determine the kinetics and direction of movements. We show that conformational changes with the speed of channel activation occur close to the gate and in more distant extracellular sites, where they may be driven by local protonation events. Further, we provide evidence for fast conformational changes in a pathway linking protonation sites to the channel pore, in which an extracellular interdomain loop interacts via aromatic residue interactions with the upper end of a transmembrane helix and would thereby open the gate.
酸敏感离子通道（ASICs）是一类神经元钠通道，可被pH值下降激活。它们已明确的生理和病理作用，包括恐惧行为、学习、痛觉以及中风后的神经退行性变，使其成为未来药物的有前景靶点。目前，ASIC的激活机制尚不清楚。在此，我们使用电压钳荧光测定法（VCF）结合荧光团-猝灭剂配对来确定运动的动力学和方向。我们表明，与通道激活速度一致的构象变化发生在靠近门控的位置以及更远的细胞外位点，在这些位点它们可能由局部质子化事件驱动。此外，我们提供了证据，表明在将质子化位点与通道孔连接起来的一条途径中存在快速构象变化，其中一个细胞外结构域间环通过芳香族残基相互作用与跨膜螺旋的上端相互作用，从而打开门控。
