TREK1, a two-pore-domain (2P) mammalian potassium (K+) channel, regulates the resting potential across cell membranes, presenting a promising therapeutic target for neuropathy treatment. The gating of this channel converges in the conformation of the narrowest part of the pore: the selectivity filter (SF). Various hypotheses explain TREK1 gating modulation, including the dynamics of loops connecting the SF with transmembrane helices and the stability of hydrogen bond (HB) networks adjacent to the SF. Recently, two small molecules (Q6F and Q5F) were reported as activators to affect TREK1 by increasing its open probability in single-channel current measurements. Here, using molecular dynamics (MD) simulations, we investigate the effect of these ligands on the previously proposed modulation mechanisms of TREK1 gating compared to the apo channel. Our findings reveal that loop dynamics at the upper region of the SF exhibit only a weak correlation with permeation/ non-permeation events, whereas the HB network behind the SF appears more correlated. These non-permeation events arise from both distinct mechanisms: A C-type inactivation (resulting from dilation at the top of the SF), which has been described previously; and a carbonyl flipping in a SF binding site. We find that, besides the prevention of C-type inactivation in the channel, the ligands increase the probability of permeation by modulating the dynamics of the carbonyl flipping, influenced by a threonine residue at the bottom of the SF. These results offer insights for rational ligand design to optimize the gating modulation of TREK1 and related K+ channels.

中文翻译：

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两种激活器对 K2P 通道门控的影响

TREK1 是一种双孔结构域 (2P) 哺乳动物钾 (K+) 通道，可调节跨细胞膜的静息电位，为神经病治疗提供了一个有前景的治疗靶点。该通道的门控会聚在孔最窄部分的构象中：选择性过滤器（SF）。各种假设解释了 TREK1 门控调制，包括连接 SF 与跨膜螺旋的环的动力学以及与 SF 相邻的氢键 (HB) 网络的稳定性。最近，两种小分子（Q6F 和 Q5F）被报道作为激活剂，通过增加单通道电流测量中的开放概率来影响 TREK1。在这里，我们使用分子动力学 (MD) 模拟，研究了这些配体对先前提出的 TREK1 门控调制机制（与 apo 通道相比）的影响。我们的研究结果表明，SF 上部区域的环路动力学与渗透/非渗透事件仅表现出较弱的相关性，而 SF 后面的 HB 网络似乎相关性更强。这些非渗透事件由两种不同的机制引起：C 型失活（由 SF 顶部扩张引起），之前已描述过；以及 SF 结合位点中的羰基翻转。我们发现，除了防止通道中的 C 型失活之外，配体还通过调节羰基翻转的动力学（受 SF 底部苏氨酸残基的影响）来增加渗透的可能性。这些结果为合理的配体设计提供了见解，以优化 TREK1 和相关 K+ 通道的门控调节。