Peregrination of the selectivity filter delineates the pore of the human voltage-gated proton channel hHV1.
Peregrination of the selectivity filter delineates the pore of the human voltage-gated proton channel hHV1.
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DOI：
10.1085/jgp.201311045
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发表时间：
2013-12
期刊：
影响因子：
--
通讯作者：
DeCoursey TE
中科院分区：
文献类型：
--
作者：
Morgan D;Musset B;Kulleperuma K;Smith SM;Rajan S;Cherny VV;Pomès R;DeCoursey TE
对所有质子传导分子，包括人类电压门控质子通道(Hhv1)来说，非凡的选择性是至关重要的，因为质子浓度比其他阳离子低106倍。在这里，我们使用“选择性过滤扫描”来阐明hHV1中质子特定传导的分子要求。Asp112位于S1跨膜螺旋的中间，是野生型(WT)通道选择性过滤器的重要组成部分。在通过将Asp112突变为Ala(D112A)来中和Asp112之后，我们在S1从108到118的每个位置都引入了Asp，寻找“第二位点抑制物”的活性。令人惊讶的是，大多数突变体甚至缺乏D112A所表现出的阴离子传导。质子特异性传导仅在第116位用天冬氨酸或谷氨酸恢复。D112V/V116D通道在选择性、动力学和ΔpH依赖门控方面与WT非常相似。该突变体的S4片段与开放通道中的WT相似，因为R211H/D112V/V116D被内部施加的锌离子抑制。第109位的天冬氨酸氨基转移酶允许阴离子与D112A结合，但不能挽救非传导D112V突变体的功能，表明选择性是在F150处的收缩外部建立的。在我们的同源模型中，允许传导的三个位置都排列在孔内，清楚地描绘了传导途径。显然，羧基必须直接面对孔洞才能传导。分子动力学模拟表明，D112V/V116D的外前庭氢键网络发生了重组。在产生质子选择性的两个位置，天冬氨酸经常与来自S4的一个或多个Arg残基进行盐键连接。令人惊讶的是，在质子选择性、阴离子渗透性和非导电结构中，平均水化曲线是相似的。选择性过滤器在新位置的作用有助于确定产生质子选择性传导所需的当地环境特征。
Extraordinary selectivity is crucial to all proton-conducting molecules, including the human voltage-gated proton channel (hHV1), because the proton concentration is >106 times lower than that of other cations. Here we use “selectivity filter scanning” to elucidate the molecular requirements for proton-specific conduction in hHV1. Asp112, in the middle of the S1 transmembrane helix, is an essential part of the selectivity filter in wild-type (WT) channels. After neutralizing Asp112 by mutating it to Ala (D112A), we introduced Asp at each position along S1 from 108 to 118, searching for “second site suppressor” activity. Surprisingly, most mutants lacked even the anion conduction exhibited by D112A. Proton-specific conduction was restored only with Asp or Glu at position 116. The D112V/V116D channel strikingly resembled WT in selectivity, kinetics, and ΔpH-dependent gating. The S4 segment of this mutant has similar accessibility to WT in open channels, because R211H/D112V/V116D was inhibited by internally applied Zn2+. Asp at position 109 allowed anion permeation in combination with D112A but did not rescue function in the nonconducting D112V mutant, indicating that selectivity is established externally to the constriction at F150. The three positions that permitted conduction all line the pore in our homology model, clearly delineating the conduction pathway. Evidently, a carboxyl group must face the pore directly to enable conduction. Molecular dynamics simulations indicate reorganization of hydrogen bond networks in the external vestibule in D112V/V116D. At both positions where it produces proton selectivity, Asp frequently engages in salt linkage with one or more Arg residues from S4. Surprisingly, mean hydration profiles were similar in proton-selective, anion-permeable, and nonconducting constructs. That the selectivity filter functions in a new location helps to define local environmental features required to produce proton-selective conduction.
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影响因子：
33.6
作者：
DeCoursey TE
通讯作者：
DeCoursey TE
影响因子：
30.5
作者：
通讯作者：
--
DOI：
10.1073/pnas.0507225103
发表时间：
2006-01-10
影响因子：
11.1
作者：
Beitz, E;Wu, BH;Zeuthen, T
通讯作者：
Zeuthen, T
DOI：
10.1073/pnas.92.5.1604
发表时间：
1995-02-28
影响因子：
11.1
作者：
FETTER, JR;QIAN, J;FERGUSONMILLER, S
通讯作者：
FERGUSONMILLER, S
影响因子：
2.9
作者：
GARCIAHORSMAN, JA;PUUSTINEN, A;WIKSTROM, M
通讯作者：
WIKSTROM, M