Homology model and targeted mutagenesis identify critical residues for arachidonic acid inhibition of Kv4 channels.
Homology model and targeted mutagenesis identify critical residues for arachidonic acid inhibition of Kv4 channels.
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DOI：
10.4161/chan.23453
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发表时间：
2013-03
期刊：
影响因子：
--
通讯作者：
Boland LM
中科院分区：
文献类型：
--
作者：
Heler R;Bell JK;Boland LM
多不饱和脂肪酸如花生四烯酸（AA）表现出对Kv4钾通道的抑制性调节。使用Kv4.2同源性模型的分子对接方法预测了AA的膜嵌入结合口袋，其由一个亚基上的S4-S5接头和来自相邻亚基的S3、S5和S6内的几个疏水残基组成。该口袋在Kv4通道中是保守的。我们测试的假设，AA对Kv4.2/KChIP通道的调节作用需要访问该网站。S4-S5连接子中的极性残基（K318）和非极性残基（G314）以及S3中的非极性残基（V261）的靶向突变显著削弱了AA对爪蟾卵母细胞K+电流的影响。这些残基在稳定（K318）或调节对脂肪酸上带负电荷的羧酸酯部分的接近（V261，G314）中可能是重要的。结构特异性得到了缺乏AA效应破坏的支持，观察到在预测结合口袋附近但不在预测结合口袋内的残基处发生突变。此外，我们发现，相关的Kv1.2/2.1嵌合体的晶体结构缺乏目前在建议的AA对接位点的Kv4.2和Kv1.2/2.1 K+电流的结构特征不受AA。我们在我们的Kv4.2模型中模拟了诱变取代，以证明特定突变如何破坏推定的AA结合口袋。我们得出结论，AA抑制Kv4通道电流，并通过结合在通道中的疏水口袋内促进电流衰减，其中S4-S5接头内的K318是AA相互作用的关键残基。
Polyunsaturated fatty acids such as arachidonic acid (AA) exhibit inhibitory modulation of Kv4 potassium channels. Molecular docking approaches using a Kv4.2 homology model predicted a membrane-embedded binding pocket for AA comprised of the S4-S5 linker on one subunit and several hydrophobic residues within S3, S5 and S6 from an adjacent subunit. The pocket is conserved among Kv4 channels. We tested the hypothesis that modulatory effects of AA on Kv4.2/KChIP channels require access to this site. Targeted mutation of a polar residue (K318) and a nonpolar residue (G314) within the S4-S5 linker as well as a nonpolar residue in S3 (V261) significantly impaired the effects of AA on K+ currents in Xenopus oocytes. These residues may be important in stabilizing (K318) or regulating access to (V261, G314) the negatively charged carboxylate moiety on the fatty acid. Structural specificity was supported by the lack of disruption of AA effects observed with mutations at residues located near, but not within the predicted binding pocket. Furthermore, we found that the crystal structure of the related Kv1.2/2.1 chimera lacks the structural features present in the proposed AA docking site of Kv4.2 and the Kv1.2/2.1 K+ currents were unaffected by AA. We simulated the mutagenic substitutions in our Kv4.2 model to demonstrate how specific mutations may disrupt the putative AA binding pocket. We conclude that AA inhibits Kv4 channel currents and facilitates current decay by binding within a hydrophobic pocket in the channel in which K318 within the S4-S5 linker is a critical residue for AA interaction.
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影响因子：
16.6
作者：
通讯作者：
--
影响因子：
20.1
作者：
Guo, WN;Jung, WE;Nerbonne, JM
通讯作者：
Nerbonne, JM
影响因子：
4.8
作者：
Harris, T;Shahidullah, M;Covarrubias, M
通讯作者：
Covarrubias, M
DOI：
10.1085/jgp.200810048
发表时间：
2008-12
期刊：
The Journal of general physiology
影响因子：
--
作者：
Labro AJ;Raes AL;Grottesi A;Van Hoorick D;Sansom MS;Snyders DJ
通讯作者：
Snyders DJ
影响因子：
5.1
作者：
Bazan, NG
通讯作者：
Bazan, NG