Infrared and fluorescence assessment of the hydration status of the tryptophan gate in the influenza A M2 proton channel.
Infrared and fluorescence assessment of the hydration status of the tryptophan gate in the influenza A M2 proton channel.
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DOI：
10.1039/c6cp03426h
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发表时间：
2016-10-19
期刊：
影响因子：
--
通讯作者：
Gai F
中科院分区：
文献类型：
--
作者：
Markiewicz BN;Lemmin T;Zhang W;Ahmed IA;Jo H;Fiorin G;Troxler T;DeGrado WF;Gai F
甲型流感病毒的 M2 质子通道因其在病毒复制中的关键作用而成为广泛研究的主题。因此，我们现在对其作用机制了解很多，特别是它如何以不对称方式选择和传导质子。该通道的电导被调整为以相对较低的生物学有用速率传导质子，这允许内体中包埋的病毒的病毒内部酸化，但不会大到在病毒包装之前对受感染的宿主细胞造成毒性。引起这种调节的动力学、结构和化学特征尚未完全了解。在此，我们使用色氨酸 (Trp) 类似物、5-氰基色氨酸以及各种方法，包括线性和非线性红外光谱、静态和时间分辨荧光技术以及分子动力学模拟，来定点询问 M2 质子通道跨膜域中 Trp41 门的结构和水合动力学。我们的结果表明，Trp41 侧链采用 t90 旋转异构体，当 pH 从 7.4 变为 5.0 时，其 χ2 二面角增加约 35°。此外，我们发现 Trp41 位于缺乏大量水的环境中，令人惊讶的是，水密度和动态在高 pH 状态 (7.4) 和低 pH 状态 (5.0) 之间没有显示出可测量的差异。由于之前的研究表明，通道打开时水会流入组氨酸四联体 (His37) 上方的空腔，因此本发现提供的证据表明，Trp41 附近缺乏建立连续氢键网络所需的足够水分子，这对质子传导造成了额外的能量瓶颈。
The M2 proton channel of the Influenza A virus has been the subject of extensive studies because of its critical role in viral replication. As such, we now know a great deal about its mechanism of action, especially how it selects and conducts protons in an asymmetric fashion. The conductance of this channel is tuned to conduct protons at a relatively low biologically useful rate, which allows acidification of the viral interior of a virus entrapped within an endosome, but not so great as to cause toxicity to the infected host cell prior to packaging of the virus. The dynamic, structural and chemical features that give rise to this tuning are not fully understood. Herein, we use a tryptophan (Trp) analog, 5-cyanotryptophan, and various methods, including linear and nonlinear infrared spectroscopies, static and time-resolved fluorescence techniques, and molecular dynamics simulations, to site-specifically interrogate the structure and hydration dynamics of the Trp41 gate in the transmembrane domain of the M2 proton channel. Our results suggest that the Trp41 sidechain adopts the t90 rotamer whose χ2 dihedral angle undergoes an increase of approximately 35° upon changing the pH from 7.4 to 5.0. Furthermore, we find that Trp41 is situated in an environment lacking bulk-like water, and somewhat surprisingly, the water density and dynamics do not show a measurable difference between the high (7.4) and low (5.0) pH states. Since previous studies have shown that upon channel opening water flows into the cavity above the histidine tetrad (His37), the present finding thus provides evidence indicating that the lack of sufficient water molecules near Trp41 needed to establish a continuous hydrogen bonding network poses an additional energetic bottleneck for proton conduction.
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影响因子：
3.4
作者：
Chen, Hanning;Wu, Yujie;Voth, Gregory A.
通讯作者：
Voth, Gregory A.
DOI：
10.1073/pnas.0811720106
发表时间：
2009-01-27
影响因子：
11.1
作者：
Khurana, Ekta;Dal Peraro, Matteo;Klein, Michael L.
通讯作者：
Klein, Michael L.
来自固态NMR的流感M2质子通道中质子传导和门控的机制。
DOI：
10.1126/science.1191714
发表时间：
2010-10-22
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Hu F;Luo W;Hong M
通讯作者：
Hong M
影响因子：
2.9
作者：
Balannik V;Carnevale V;Fiorin G;Levine BG;Lamb RA;Klein ML;Degrado WF;Pinto LH
通讯作者：
Pinto LH
DOI：
10.1021/acs.jpcb.6b03199
发表时间：
2016-06-16
期刊：
The journal of physical chemistry. B
影响因子：
--
作者：
Ding B;Hilaire MR;Gai F
通讯作者：
Gai F