Department of Pharmacology and Toxicology, University of Lausanne, 1011, Lausanne, Switzerland.
Molecular Modeling Group, Swiss Institute of Bioinformatics, 1015, Lausanne, Switzerland.
Sci Rep. 2019 Feb 22;9(1):2599. doi: 10.1038/s41598-018-37426-5.
Modulation by neuropeptides enhances several functions of acid-sensing ion channels (ASICs), such as pain sensation and acid-induced neuronal injury. The acid-induced opening of ASICs is transient, because of a rapid desensitization. Neuropeptides containing an Arg-Phe-amide motif affect ASIC desensitization and allow continuous activity of ASICs. In spite of the importance of the sustained ASIC activity during prolonged acidification, the molecular mechanisms of ASIC modulation by neuropeptides is only poorly understood. To identify the FRRFa (Phe-Arg-Arg-Phe-amide) binding site on ASIC1a, we carried out an in silico docking analysis and verified functionally the docking predictions. The docking experiments indicated three possible binding pockets, located (1) in the acidic pocket between the thumb, finger, β-ball and palm domains, (2) in a pocket at the bottom of the thumb domain, and (3) in the central vestibule along with the connected side cavities. Functional measurements of mutant ASIC1a confirmed the importance of residues of the lower palm, which encloses the central vestibule and its side cavities, for the FRRFa effects. The combined docking and functional experiments strongly suggest that FRRFa binds to the central vestibule and its side cavities to change ASIC desensitization.
神经肽对酸感应离子通道（ASICs）的多种功能具有调节作用，如痛觉和酸诱导的神经元损伤。由于快速脱敏，ASICs 的酸诱导开放是短暂的。含有精氨酸-苯丙氨酸酰胺基序的神经肽会影响 ASIC 的脱敏，使 ASIC 持续激活。尽管在长时间酸化过程中持续的 ASIC 活性非常重要，但神经肽对 ASIC 的调节的分子机制仍知之甚少。为了确定 ASIC1a 上 FRRFa（苯丙氨酸-精氨酸-精氨酸-苯丙氨酸酰胺）结合位点，我们进行了计算机对接分析，并验证了对接预测的功能。对接实验表明存在三个可能的结合口袋，分别位于（1）在拇指、手指、β-球和手掌结构域之间的酸性口袋中，（2）在拇指结构域底部的口袋中，以及（3）在中央前庭和连接的侧腔中。对突变 ASIC1a 的功能测量证实了围绕中央前庭及其侧腔的下部手掌对 FRRFa 效应的重要性。结合对接和功能实验强烈表明，FRRFa 结合到中央前庭及其侧腔以改变 ASIC 的脱敏。
