The voltage-dependent gate in MthK potassium channels is located at the selectivity filter
The voltage-dependent gate in MthK potassium channels is located at the selectivity filter
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DOI：
10.1038/nsmb.2473
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发表时间：
2013-02-01
影响因子：
16.8
通讯作者：
Nimigean, Crina M.
中科院分区：
文献类型：
--
作者：
Posson, David J.;McCoy, Jason G.;Nimigean, Crina M.
了解离子通道如何打开和关闭它们的毛孔对于理解它们的生理作用是至关重要的。我们使用细胞内季铵阻滞剂、电生理学和X射线结晶学来定位甲烷自养杆菌MthK钾通道上的电压依赖门。阻滞剂结合在两个假定的门之间的水腔中：细胞内门和选择性过滤器。因此，这些阻滞剂直接探测细胞内门关闭时的门位置将阻止结合，而选择性过滤器门总是允许结合。通过对四丁基铵阻断单通道MthK的动力学分析，结合对含四丁基锑的孔的X射线晶体分析，明确地确定电压依赖门与真核通道中的C型失活门一样，位于选择性过滤器处。依赖于状态的结合动力学表明，MthK失活会导致空腔内和细胞内孔入口的构象变化。
Understanding how ion channels open and close their pores is crucial for comprehending their physiological roles. We used intracellular quaternary ammonium blockers, electrophysiology and X-ray crystallography to locate the voltage-dependent gate in MthK potassium channels from Methanobacterium thermoautotrophicum. Blockers bind in an aqueous cavity between two putative gates: an intracellular gate and the selectivity filter. Thus, these blockers directly probe gate location an intracellular gate will prevent binding when closed, whereas a selectivity filter gate will always allow binding. Kinetic analysis of tetrabutylammonium block of single MthK channels combined with X-ray crystallographic analysis of the pore with tetrabutyl antimony unequivocally determined that the voltage-dependent gate, like the C-type inactivation gate in eukaryotic channels, is located at the selectivity filter. State-dependent binding kinetics suggest that MthK inactivation leads to conformational changes within the cavity and intracellular pore entrance.