Allosteric coupling between proximal C-terminus and selectivity filter is facilitated by the movement of transmembrane segment 4 in TREK-2 channel.
Allosteric coupling between proximal C-terminus and selectivity filter is facilitated by the movement of transmembrane segment 4 in TREK-2 channel.
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DOI：
10.1038/srep21248
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发表时间：
2016-02-16
影响因子：
4.6
通讯作者：
Ma XY
中科院分区：
文献类型：
--
作者：
Zhuo RG;Peng P;Liu XY;Yan HT;Xu JP;Zheng JQ;Wei XL;Ma XY
TREK-2是双孔结构域钾通道家族的成员，调节细胞对多种刺激的兴奋性。然而，这些刺激如何控制通道功能仍不清楚。在此，通过表征胞质近端C末端缺失体（ΔpCt）和跨膜片段4（M4）-甘氨酸铰链突变体（G312 A）对TREK-2激活剂2-氨基乙氧基二苯基硼酸酯（2-APB）的反应，我们表明从pCt结构域开始的转导通过M4的运动与选择性过滤器（SF）的构象变构偶联，而不依赖于SF的原始状态。此外，ΔpCt和G312 A也表现出对细胞外碱化的钝化反应，这是诱导SF构象转变的模型。这些结果表明，pCt结构域和SF之间的耦合是双向的，M4运动参与了这两个过程。进一步的机制探索表明，Phe 316（靠近M4 C-末端的残基）的功能与这种通信有关。然而，与TREK-2不同，TREK-1的M4铰链仅控制从pCt到SF的传递，而不是由pHo变化触发的SF构象变化。总之，我们的研究结果揭示了TREK-2独特的门控特性，并阐明了细胞外和细胞内刺激如何利用孔门控变构的机制。
TREK-2, a member of two-pore-domain potassium channel family, regulates cellular excitability in response to diverse stimuli. However, how such stimuli control channel function remains unclear. Here, by characterizing the responses of cytosolic proximal C-terminus deletant (ΔpCt) and transmembrane segment 4 (M4)-glycine hinge mutant (G312A) to 2-Aminoethoxydiphenyl borate (2-APB), an activator of TREK-2, we show that the transduction initiated from pCt domain is allosterically coupled with the conformation of selectivity filter (SF) via the movements of M4, without depending on the original status of SF. Moreover, ΔpCt and G312A also exhibited blunted responses to extracellular alkalization, a model to induce SF conformational transition. These results suggest that the coupling between pCt domain and SF is bidirectional, and M4 movements are involved in both processes. Further mechanistic exploration reveals that the function of Phe316, a residue close to the C-terminus of M4, is associated with such communications. However, unlike TREK-2, M4-hinge of TREK-1 only controls the transmission from pCt to SF, rather than SF conformational changes triggered by pHo changes. Together, our findings uncover the unique gating properties of TREK-2, and elucidate the mechanisms for how the extracellular and intracellular stimuli harness the pore gating allosterically.