Section of Neurobiology and Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712, USA.
J Gen Physiol. 2011 Aug;138(2):137-54. doi: 10.1085/jgp.201110632. Epub 2011 Jul 11.
The pore-lining amino acids of ion channel proteins reside on the interface between a polar (the pore) and a nonpolar environment (the rest of the protein). The structural dynamics of this region, which physically controls ionic flow, are essential components of channel gating. Using large-conductance, Ca(2+)-dependent K(+) (BK) channels, we devised a systematic charge-substitution method to probe conformational changes in the pore region during channel gating. We identified a deep-pore residue (314 in hSlo1) as a marker of structural dynamics. We manipulated the charge states of this residue by substituting amino acids with different valence and pKa, and by adjusting intracellular pH. We found that the charged states of the 314 residues stabilized an open state of the BK channel. With models based on known structures of related channels, we postulate a dynamic rearrangement of the deep-pore region during BK channel opening/closing, which involves a change of the degree of pore exposure for 314.
离子通道蛋白的孔衬氨基酸位于极性环境（孔）和非极性环境（蛋白质的其余部分）之间的界面上。该区域的结构动力学是控制离子流的物理过程，是通道门控的重要组成部分。使用大电导、钙依赖性钾 (BK) 通道，我们设计了一种系统的电荷取代方法来探测通道门控过程中孔区域的构象变化。我们确定了一个深孔残基（hSlo1 中的 314 位）作为结构动力学的标志物。我们通过用具有不同价态和 pKa 的氨基酸取代以及调节细胞内 pH 值来操纵该残基的电荷状态。我们发现，314 位残基的电荷状态稳定了 BK 通道的开放状态。基于相关通道的已知结构模型，我们推测在 BK 通道打开/关闭过程中，深孔区域会发生动态重排，其中涉及 314 位的孔暴露程度的变化。
