Role of the KcsA Channel Cytoplasmic Domain in pH-Dependent Gating
Role of the KcsA Channel Cytoplasmic Domain in pH-Dependent Gating
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DOI：
10.1016/j.bpj.2011.09.024
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发表时间：
2011-11-02
影响因子：
3.4
通讯作者：
Ide, Toru
中科院分区：
文献类型：
--
作者：
Hirano, Minako;Onishi, Yukiko;Ide, Toru
KcsA通道是受pH变化激活的钾离子通道的代表。以往的研究表明，感知pH的区域完全在其跨膜段内。然而，我们最近发现细胞质结构域也有一个重要的作用，因为它的构象被观察到随着pH的变化而急剧变化。在这里，为了研究细胞质结构域对ph依赖性门控的影响，我们制作了一个由KcsA通道的细胞质结构域和MthK通道的跨膜区域组成的嵌合体突变通道。嵌合体表现出与KcsA类似的pH依赖性，表明细胞质结构域可以作为pH传感器。为了确定该区域如何检测pH值，我们用KcsA通道中的中性氨基酸取代了pH值为7时通常带负电荷的细胞质结构域氨基酸。这些突变体独立于pH打开，表明静电荷在细胞质域感知和响应pH的能力中起主要作用。
The KcsA channel is a representative potassium channel that is activated by changes in pH. Previous studies suggested that the region that senses pH is entirely within its transmembrane segments. However, we recently revealed that the cytoplasmic domain also has an important role, because its conformation was observed to change dramatically in response to pH changes. Here, to investigate the effects of the cytoplasmic domain on pH-dependent gating, we made a chimera mutant channel consisting of the cytoplasmic domain of the KcsA channel and the transmembrane region of the MthK channel. The chimera showed a pH dependency similar to that of KcsA, indicating that the cytoplasmic domain can act as a pH sensor. To identify how this region detects pH, we substituted certain cytoplasmic domain amino acids that are normally negatively charged at pH 7 for neutral ones in the KcsA channels. These mutants opened independently of pH, suggesting that electrostatic charges have a major role in the cytoplasmic domain's ability to sense and respond to pH.