Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
Nat Commun. 2021 Feb 4;12(1):786. doi: 10.1038/s41467-020-20788-8.
The anion channel TMEM16A is activated by intracellular Ca in a highly cooperative process. By combining electrophysiology and autocorrelation analysis, we investigated the mechanism of channel activation and the concurrent rearrangement of the gate in the narrow part of the pore. Features in the fluctuation characteristics of steady-state current indicate the sampling of intermediate conformations that are successively occupied during gating. The initial step is related to conformational changes induced by Ca binding, which is ensued by rearrangements that open the pore. Mutations in the gate shift the equilibrium of transitions in a manner consistent with a progressive destabilization of this region during pore opening. We come up with a mechanism of channel activation where the binding of Ca induces conformational changes in the protein that, in a sequential manner, propagate from the binding site and couple to the gate in the narrow pore to allow ion permeation.
阴离子通道 TMEM16A 通过高度协同的过程被细胞内 Ca 激活。通过结合电生理学和自相关分析，我们研究了通道激活的机制以及孔道狭窄部位门控的伴随重排。稳态电流波动特征中的特征表明，在门控过程中，中间构象被连续采样。初始步骤与 Ca 结合诱导的构象变化有关，随后发生的构象变化打开了孔道。门控中突变会以一种渐进的方式破坏该区域的稳定性，从而改变构象变化的平衡。我们提出了一种通道激活的机制，其中 Ca 的结合诱导蛋白质的构象变化，这些构象变化以顺序的方式从结合位点传播，并与狭窄孔道中的门连接，从而允许离子渗透。
