The desensitization gating of the MthK K+ channel is governed by its cytoplasmic amino terminus.
The desensitization gating of the MthK K+ channel is governed by its cytoplasmic amino terminus.
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MTHK K+通道的脱敏门控受其细胞质氨基末端的控制。
DOI：
10.1371/journal.pbio.0060223
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发表时间：
2008-10-28
期刊：
影响因子：
9.8
通讯作者：
Choe, Senyon
中科院分区：
文献类型：
--
作者：
Kuo, Mario Meng-Chiang;Maslennikov, Innokentiy;Molden, Brent;Choe, Senyon
含RCK的MthK通道经历两个失活过程：激活偶联脱敏和酸诱导失活。酸失活由C-末端RCK结构域组装介导。在这里，我们报告说，脱敏门控是由细胞质N-末端17个残基的脱敏域（DD）。DD的缺失完全消除了脱敏，该过程可以完全恢复由合成的DD肽添加在trans. Mutagenesis分析揭示了一个序列特异性决定因素的初始疏水段内的DD脱敏。用合成肽和分离的RCK进行的质子核磁共振（1H NMR）光谱分析显示两个末端结构域之间的相互作用。此外，我们表明，DD的缺失不影响酸诱导的失活，表明这两个失活过程是相互独立的。我们的研究结果表明，短的N-末端DD的MthK功能作为一个完整的可移动模块负责脱敏。其与C-末端RCK结构域的相互作用可能在门控过程中发挥作用。神经细胞使用离子通道，细胞膜上的孔，以电信号的形式在细胞之间发送信息。大多数离子通道都进化出了几种复杂的机制，使通道在打开后能迅速关闭，以防止电化学势神经元通讯的流通穿过细胞膜的浪费性泄漏。这个过程被称为失活或脱敏。先前对放大的大肠杆菌膜中含有模型RCK的MthK K+通道的研究表明，该古细菌通道也经历了脱敏。使用相同的方法，我们证明，脱敏确实是一个内在的MthK蛋白的分子特性。我们发现，MthK的一个特定区域，短的N末端的蛋白质，功能作为一个结构上独立的域，是完全负责的脱敏门控过程。此外，我们表明，这个N-末端结构域与C-末端RCK结构域相互作用的脱敏机制的一部分。这种独特的脱敏机制，通过两个细胞质末端之间的相互作用，是不同于那些传统的机制，被称为N-和C-型失活中发现的许多电压门控Na+和K+通道或作为脱敏中观察到的谷氨酸受体。由于KTN/RCK结构域存在于大量的原核K+通道和转运蛋白中，因此这种独特的机制可能是这些转运系统共同的，用于调节通过细胞膜的K+通量。离子通道MthK的N末端作为结构上独立的结构域起作用，并且完全负责神经元到神经元通信所需的脱敏门控过程。
The RCK-containing MthK channel undergoes two inactivation processes: activation-coupled desensitization and acid-induced inactivation. The acid inactivation is mediated by the C-terminal RCK domain assembly. Here, we report that the desensitization gating is governed by a desensitization domain (DD) of the cytoplasmic N-terminal 17 residues. Deletion of DD completely removes the desensitization, and the process can be fully restored by a synthetic DD peptide added in trans. Mutagenesis analyses reveal a sequence-specific determinant for desensitization within the initial hydrophobic segment of DD. Proton nuclear magnetic resonance (1H NMR) spectroscopy analyses with synthetic peptides and isolated RCK show interactions between the two terminal domains. Additionally, we show that deletion of DD does not affect the acid-induced inactivation, indicating that the two inactivation processes are mutually independent. Our results demonstrate that the short N-terminal DD of MthK functions as a complete moveable module responsible for the desensitization. Its interaction with the C-terminal RCK domain may play a role in the gating process. Nerve cells use ion channels, pores in the cell membrane, to send messages in the form of electrical signals between cells. Most ion channels have evolved several elaborate mechanisms that allow the channels to close quickly after opening to prevent wasteful leakage of the electrochemical potential—the currency of neuron communication—across the cell membrane. The process is known as inactivation or desensitization. Previous study on the model RCK-containing MthK K+ channel in the enlarged Escherichia coli membrane has shown that this archaeon channel also undergoes desensitization. Using the same method, we demonstrate that the desensitization is indeed an intrinsic molecular property of the MthK protein. We show that a specific region of MthK, the short N terminus of the protein, functions as a structurally independent domain and is entirely responsible for the desensitization gating process. Moreover, we show that this N-terminal domain interacts with the C-terminal RCK domain as part of the desensitization mechanism. This unique desensitization mechanism, by interaction between the two cytoplasmic termini, is distinct from those traditional mechanisms known as N- and C-type inactivation found in many voltage-gated Na+ and K+ channels or as the desensitization observed in the glutamate receptors. Since the KTN/RCK domain is found in a large number of prokaryotic K+ channels and transporters, this unique mechanism may be common to these transport systems for regulating the K+ flux through the cell membrane. The N terminus of the ion channel MthK functions as a structurally independent domain and is entirely responsible for the desensitization gating process required for neuron-to-neuron communication.
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DOI：
10.1085/jgp.200609655
发表时间：
2007-02
期刊：
The Journal of general physiology
影响因子：
--
作者：
Li Y;Berke I;Chen L;Jiang Y
通讯作者：
Jiang Y
DOI：
10.1007/s10969-007-9033-4
发表时间：
2007-12-01
期刊：
Journal of Structural and Functional Genomics
影响因子：
--
作者：
Kefala, Georgia;Kwiatkowski, Witek;Choe, Senyon
通讯作者：
Choe, Senyon
影响因子：
4.8
作者：
Parfenova, Lyubov V.;Crane, Brittany M.;Rothberg, Brad S.
通讯作者：
Rothberg, Brad S.
影响因子：
25
作者：
Pegan, S;Arrabit, C;Choe, S
通讯作者：
Choe, S
影响因子：
16.2
作者：
Jiang, YX;Pico, A;MacKinnon, R
通讯作者：
MacKinnon, R