Studies of alpha-helicity and intersegmental interactions in voltage-gated Na+ channels: S2D4.
Studies of alpha-helicity and intersegmental interactions in voltage-gated Na+ channels: S2D4.
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DOI：
10.1371/journal.pone.0007674
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发表时间：
2009-11-02
期刊：
影响因子：
3.7
通讯作者：
Kallen RG
中科院分区：
文献类型：
--
作者：
Ma Z;Kong J;Kallen RG
许多数据，包括晶体学，支持钠和钾通道的结构模型，包括S1-S4跨膜片段（“电压敏感域”）聚集在中央成孔区域（S5-S6片段和居间环）周围。电压门控钠通道具有四个不同的结构域，这将它们与形成当前结构模型基础的同源四聚体钾通道区分开来。由于钾和钠通道也表现出许多不同的功能特征，并且钠通道的第四结构域（D4）在功能上与其他结构域（D1-D3）不同，因此我们探索了其结构，以确定钠通道D4中的片段是否与钾通道中确定的片段显著不同。我们通过半胱氨酸扫描诱变（用色氨酸和谷氨酰胺取代天然半胱氨酸）探测了Nav1.4的二级和三级结构以及S2 D4）的单个氨基酸残基的作用。稳态失活门控自由能扰动的傅里叶变换功率谱（使用中点电位和Boltzmann方程的斜率拟合通道可用性，h∞-V图）表明S2 D4中存在大量的α-螺旋结构（峰值在106°，α-周期性指数（α-PI）为3.10），对于进入（β）和离开（α）的速率常数的扰动，α-PI值分别为3.28和2.84相对于WT通道，突变通道在0 mV下快速失活，假设从开放状态到失活状态的转变为简单的两态模型。S2 D4 α-螺旋两个最敏感位点（N1382和E1392 C）的半胱氨酸取代结果支持S2和Nav1.4D4内其他跨膜片段之间存在静电网络相互作用，与K+通道相似但不相同。
Much data, including crystallographic, support structural models of sodium and potassium channels consisting of S1–S4 transmembrane segments (the “voltage-sensing domain”) clustered around a central pore-forming region (S5–S6 segments and the intervening loop). Voltage gated sodium channels have four non-identical domains which differentiates them from the homotetrameric potassium channels that form the basis for current structural models. Since potassium and sodium channels also exhibit many different functional characteristics and the fourth domain (D4) of sodium channels differs in function from other domains (D1–D3), we have explored its structure in order to determine whether segments in D4 of sodium channels differ significantly from that determined for potassium channels. We have probed the secondary and tertiary structure and the role of the individual amino acid residues of the S2D4) of Nav1.4 by employing cysteine-scanning mutagenesis (with tryptophan and glutamine substituted for native cysteine). A Fourier transform power spectrum of perturbations in free energy of steady-state inactivation gating (using midpoint potentials and slopes of Boltzmann equation fits of channel availability, h∞-V plots) indicates a substantial amount of α-helical structure in S2D4 (peak at 106°, α-Periodicity Index (α-PI) of 3.10), This conclusion is supported by α-PI values of 3.28 and 2.84 for the perturbations in rate constants of entry into (β) and exit from (α) fast inactivation at 0 mV for mutant channels relative to WT channels assuming a simple two-state model for transition from the open to inactivated state. The results of cysteine substitution at the two most sensitive sites of the S2D4 α-helix (N1382 and E1392C) support the existence of electrostatic network interactions between S2 and other transmembrane segments within Nav1.4D4 similar to but not identical to those proposed for K+ channels.
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影响因子：
16.2
作者：
Aggarwal, SK;MacKinnon, R
通讯作者：
MacKinnon, R
影响因子：
56.9
作者：
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通讯作者：
MacKinnon, R
DOI：
10.1073/pnas.0806486105
发表时间：
2008-09-30
影响因子：
11.1
作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
2.5
作者：
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通讯作者：
BROWN, RH