Calmodulin Regulates Human Ether à Go-Go 1 (hEAG1) Potassium Channels through Interactions of the Eag Domain with the Cyclic Nucleotide Binding Homology Domain.
Calmodulin Regulates Human Ether à Go-Go 1 (hEAG1) Potassium Channels through Interactions of the Eag Domain with the Cyclic Nucleotide Binding Homology Domain.
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钙调蛋白通过EAG结构域与环状核苷酸结合同源性结构域的相互作用来调节人类的go-go 1（Heag1）钾通道。
DOI：
10.1074/jbc.m116.733576
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发表时间：
2016-08-19
期刊：
影响因子：
--
通讯作者：
Mitcheson JS
中科院分区：
文献类型：
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作者：
Lörinczi E;Helliwell M;Finch A;Stansfeld PJ;Davies NW;Mahaut-Smith M;Muskett FW;Mitcheson JS
电压门控钾通道的醚<s:1> go-go家族在结构上是不同的。N端包含一个eag结构域（eagD），该结构域包含一个per - art - sim （PAS）结构域，其前面是一个由25-27个氨基酸组成的保守序列，称为PAS-cap。C端包含一个与环核苷酸结合域（cNBHD）同源的区域，该区域直接与通道孔相连。人类EAG1 （hEAG1）通道对细胞内钙（Ca2+i）的抑制非常敏感，通过Ca2+-钙调蛋白结合到邻近eagD和cNBHD的三个位点。在这里，我们展示了eagD和cNBHD相互作用来调节Ca2+钙调蛋白以及电压依赖性门控。Ca2+i的持续升高导致hEAG1电流的初始深度抑制，随后是电流振幅部分恢复的阶段，但激活门控减慢并转移到去极化电位。删除eagD或cNBHD均可消除Ca2+i的抑制作用。然而，仅PAS-cap的缺失导致了对Ca2+i升高的响应的bb10 - 15倍增强。eagD和cNBHD交界面残基的突变与人类癌症有关。当cNBHD上的Glu-600被体积更大的残基取代时，导致hEAG1电流被Ca2+i深度增强，其方式与ΔPAS-cap突变体相似。这些发现提供了eagD和cNBHD相互作用调节Ca2+依赖性门控的第一个证据，并表明PAS-cap与cNBHD的结合是CaM结合时通道关闭所必需的。
The ether à go-go family of voltage-gated potassium channels is structurally distinct. The N terminus contains an eag domain (eagD) that contains a Per-Arnt-Sim (PAS) domain that is preceded by a conserved sequence of 25–27 amino acids known as the PAS-cap. The C terminus contains a region with homology to cyclic nucleotide binding domains (cNBHD), which is directly linked to the channel pore. The human EAG1 (hEAG1) channel is remarkably sensitive to inhibition by intracellular calcium (Ca2+i) through binding of Ca2+-calmodulin to three sites adjacent to the eagD and cNBHD. Here, we show that the eagD and cNBHD interact to modulate Ca2+-calmodulin as well as voltage-dependent gating. Sustained elevation of Ca2+i resulted in an initial profound inhibition of hEAG1 currents, which was followed by a phase when current amplitudes partially recovered, but activation gating was slowed and shifted to depolarized potentials. Deletion of either the eagD or cNBHD abolished the inhibition by Ca2+i. However, deletion of just the PAS-cap resulted in a >15-fold potentiation in response to elevated Ca2+i. Mutations of residues at the interface between the eagD and cNBHD have been linked to human cancer. Glu-600 on the cNBHD, when substituted with residues with a larger volume, resulted in hEAG1 currents that were profoundly potentiated by Ca2+i in a manner similar to the ΔPAS-cap mutant. These findings provide the first evidence that eagD and cNBHD interactions are regulating Ca2+-dependent gating and indicate that the binding of the PAS-cap with the cNBHD is required for the closure of the channels upon CaM binding.