Laboratory of Physical Chemistry , ETH Zürich , Wolfgang-Pauli-Strasse 10 , 8093 Zürich , Switzerland.
Structural Biology Laboratory , Salk Institute , 10010 North Torrey Pines Road , La Jolla , California 92037 , United States.
Biochemistry. 2019 Oct 1;58(39):4017-4027. doi: 10.1021/acs.biochem.9b00471. Epub 2019 Sep 21.
The human voltage-gated proton channel [Hv1 or VSDO] plays an important role in the human innate immune system. Its structure differs considerably from those of other cation channels. It is built solely of a voltage-sensing domain and thus lacks the central pore domain, which is essential for other cation channels. Here, we determined the solution structure of an N- and C-terminally truncated human Hv1 (Δ-Hv1) in the resting state by nuclear magnetic resonance (NMR) spectroscopy. Δ-Hv1 comprises the typical voltage-sensing antiparallel four-helix bundle (S1-S4) preceded by an amphipathic helix (S0). The solution structure corresponds to an intermediate state between resting and activated forms of voltage-sensing domains. Furthermore, Zn-induced closing of proton channel Δ-Hv1 was studied with two-dimensional NMR spectroscopy, which showed that characteristic large scale dynamics of open Δ-Hv1 are absent in the closed state of the channel. Additionally, pH titration studies demonstrated that a higher H concentration is required for the protonation of side chains in the Zn-induced closed state than in the open state. These observations demonstrate both structural and dynamical changes involved in the process of voltage gating of the Hv1 channel and, in the future, may help to explain the unique properties of unidirectional conductance and the exceptional ion selectivity of the channel.
人类电压门控质子通道 [Hv1 或 VSDO] 在人体先天免疫系统中发挥着重要作用。它的结构与其他阳离子通道有很大的不同。它仅由一个电压感应结构域组成，因此缺乏对其他阳离子通道至关重要的中央孔结构域。在这里，我们通过核磁共振（NMR）光谱法确定了在静止状态下 N 端和 C 端截断的人类 Hv1（Δ-Hv1）的溶液结构。Δ-Hv1 包含典型的电压感应反平行四螺旋束（S1-S4），前面是一个两亲性螺旋（S0）。溶液结构对应于电压感应结构域的静止和激活状态之间的中间状态。此外，通过二维 NMR 光谱研究了 Zn 诱导的质子通道 Δ-Hv1 的关闭，结果表明，在通道的关闭状态下，开Δ-Hv1 的特征大尺度动力学不存在。此外，pH 滴定研究表明，Zn 诱导的关闭状态下侧链质子化所需的 H 浓度高于开放状态。这些观察结果表明，Hv1 通道电压门控过程涉及结构和动力学变化，未来可能有助于解释单向传导的独特性质和通道的异常离子选择性。
