Cordero-Morales Julio F, Cuello Luis G, Zhao Yanxiang, Jogini Vishwanath, Cortes D Marien, Roux Benoît, Perozo Eduardo
Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22906, USA.
Nat Struct Mol Biol. 2006 Apr;13(4):311-8. doi: 10.1038/nsmb1069. Epub 2006 Mar 12.
We show that in the potassium channel KcsA, proton-dependent activation is followed by an inactivation process similar to C-type inactivation, and this process is suppressed by an E71A mutation in the pore helix. EPR spectroscopy demonstrates that the inner gate opens maximally at low pH regardless of the magnitude of the single-channel-open probability, implying that stationary gating originates mostly from rearrangements at the selectivity filter. Two E71A crystal structures obtained at 2.5 A reveal large structural excursions of the selectivity filter during ion conduction and provide a glimpse of the range of conformations available to this region of the channel during gating. These data establish a mechanistic basis for the role of the selectivity filter during channel activation and inactivation.
我们发现，在钾通道KcsA中，质子依赖性激活之后是一个类似于C型失活的失活过程，且该过程被孔螺旋中的E71A突变所抑制。电子顺磁共振波谱表明，无论单通道开放概率的大小如何，内门在低pH值时都会最大程度地打开，这意味着静态门控主要源于选择性过滤器的重排。在2.5埃分辨率下获得的两个E71A晶体结构揭示了离子传导过程中选择性过滤器的大幅度结构偏移，并让我们得以一窥通道该区域在门控过程中可采用的构象范围。这些数据为选择性过滤器在通道激活和失活过程中的作用奠定了机制基础。
