Coonen Laura, Martinez-Morales Evelyn, Van De Sande Dieter V, Snyders Dirk J, Cortes D Marien, Cuello Luis G, Labro Alain J
Department of Biomedical Sciences, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, 2610 Antwerp, Belgium.
Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
Sci Adv. 2022 Sep 16;8(37):eabn1731. doi: 10.1126/sciadv.abn1731.
Voltage-gated K (Kv) channels mediate the flow of K across the cell membrane by regulating the conductive state of their activation gate (AG). Several Kv channels display slow C-type inactivation, a process whereby their selectivity filter (SF) becomes less or nonconductive. It has been proposed that, in the fast inactivation-removed Shaker-IR channel, the W434F mutation epitomizes the C-type inactivated state because it functionally accelerates this process. By introducing another pore mutation that prevents AG closure, P475D, we found a way to record ionic currents of the Shaker-IR-W434F-P475D mutant at hyperpolarized membrane potentials as the W434F-mutant SF recovers from its inactivated state. This W434F conductive state lost its high K over Na selectivity, and even NMDG can permeate, features not observed in a wild-type SF. This indicates that, at least during recovery from inactivation, the W434F-mutant SF transitions to a widened and noncationic specific conformation.
电压门控钾（Kv）通道通过调节其激活门（AG）的导电状态来介导钾离子跨细胞膜的流动。几种Kv通道表现出缓慢的C型失活，在这个过程中它们的选择性过滤器（SF）导电性降低或变为非导电状态。有人提出，在去除快速失活的Shaker-IR通道中，W434F突变体现了C型失活状态，因为它在功能上加速了这个过程。通过引入另一个阻止AG关闭的孔道突变P475D，我们找到了一种方法来记录Shaker-IR-W434F-P475D突变体在超极化膜电位下的离子电流，因为W434F突变体的SF从其失活状态恢复。这种W434F导电状态失去了其对钾离子高于钠离子的选择性，甚至NMDG也能通透，这是野生型SF中未观察到的特征。这表明，至少在从失活状态恢复期间，W434F突变体的SF转变为一种变宽的、非阳离子特异性的构象。
