NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584, CH Utrecht, The Netherlands.
Department of Biochemistry and Molecular Biology, The University of Chicago, 929 E57th Street, Chicago, IL, 60637, USA.
Nat Commun. 2019 Jan 10;10(1):123. doi: 10.1038/s41467-018-07973-6.
Spontaneous activity shifts at constant experimental conditions represent a widespread regulatory mechanism in ion channels. The molecular origins of these modal gating shifts are poorly understood. In the K channel KcsA, a multitude of fast activity shifts that emulate the native modal gating behaviour can be triggered by point-mutations in the hydrogen bonding network that controls the selectivity filter. Using solid-state NMR and molecular dynamics simulations in a variety of KcsA mutants, here we show that modal gating shifts in K channels are associated with important changes in the channel dynamics that strongly perturb the selectivity filter equilibrium conformation. Furthermore, our study reveals a drastically different motional and conformational selectivity filter landscape in a mutant that mimics voltage-gated K channels, which provides a foundation for an improved understanding of eukaryotic K channels. Altogether, our results provide a high-resolution perspective on some of the complex functional behaviour of K channels.
在恒定的实验条件下，自发活动的转变代表了离子通道中一种广泛存在的调节机制。这些模态门控转变的分子起源还不太清楚。在 K 通道 KcsA 中，通过控制选择性过滤器的氢键网络中的点突变，可以触发多种模拟天然模态门控行为的快速活性转变。在这里，我们使用固态 NMR 和各种 KcsA 突变体的分子动力学模拟表明，K 通道中的模态门控转变与通道动力学的重要变化有关，这些变化强烈干扰了选择性过滤器的平衡构象。此外，我们的研究揭示了一个模拟电压门控 K 通道的突变体中运动和构象选择性过滤器景观的巨大差异，为更好地理解真核 K 通道提供了基础。总的来说，我们的结果提供了 K 通道一些复杂功能行为的高分辨率视角。
