A competing hydrophobic tug on L596 to the membrane core unlatches S4-S5 linker elbow from TRP helix and allows TRPV4 channel to open.
A competing hydrophobic tug on L596 to the membrane core unlatches S4-S5 linker elbow from TRP helix and allows TRPV4 channel to open.
复制标题
L596 上与膜核心的竞争疏水性拉力将 S4-S5 连接器肘部从 TRP 螺旋上解开，并允许 TRPV4 通道打开。
DOI：
10.1073/pnas.1613523113
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发表时间：
2016
影响因子：
11.1
通讯作者：
Kung,Ching
中科院分区：
文献类型：
--
作者：
Teng,Jinfeng;Loukin,StephenH;Anishkin,Andriy;Kung,Ching
我们对离子通道如何与周围脂质相互作用有一些普遍的物理理解，但对特定氨基酸与接触脂质的相互作用如何调节门控的详细描述很少。在这里，我们发现了一个氨基酸和内小叶脂质之间的结构特异性相互作用，支配TRPV 4（瞬时受体电位香草酸4型）的门控转换。许多阳离子通道使用S4-S5连接器将刺激传输到门。TRPV 4的接头螺旋的起始处是亮氨酸596。TRP螺旋的W733的吲哚与L596的主链氧之间的氢键确保螺旋/接头接触，其充当维持通道闭合的闩锁。在我们的模型中，L596的建模侧链与极性-非极性界面附近的内部脂质小叶相互作用-我们通过诱变探索的相互作用。我们检测了表达TRPV 4的异种卵母细胞在去极化时的外向电流以及表达TRPV 4的酵母细胞的表型。使该残基疏水性降低（L596 A/G/W/Q/K）降低了开放概率[Po;功能丧失（LOF）]，可能是由于极性-非极性界面的相互作用改变。L596 I提高了Po [功能获得（GOF）]，显然是通过将其甲基进一步向内放置并接受更强的水排斥。分子动力学模拟结果表明，L596和W733的α-碳原子水平之间的距离在LOF中缩短，在GOF中延长，分别加强或削弱了连接子/TRP螺旋锁。这些结果突出了L596脂质吸引力在拔河中抵消闩锁键以调节TRPV 4的Po。
We have some generalized physical understanding of how ion channels interact with surrounding lipids but few detailed descriptions on how interactions of particular amino acids with contacting lipids may regulate gating. Here we discovered a structure-specific interaction between an amino acid and inner-leaflet lipid that governs the gating transformations of TRPV4 (transient receptor potential vanilloid type 4). Many cation channels use a S4–S5 linker to transmit stimuli to the gate. At the start of TRPV4’s linker helix is leucine 596. A hydrogen bond between the indole of W733 of the TRP helix and the backbone oxygen of L596 secures the helix/linker contact, which acts as a latch maintaining channel closure. The modeled side chain of L596 interacts with the inner lipid leaflet near the polar–nonpolar interface in our model—an interaction that we explored by mutagenesis. We examined the outward currents of TRPV4-expressingXenopusoocyte upon depolarizations as well as phenotypes of expressing yeast cells. Making this residue less hydrophobic (L596A/G/W/Q/K) reduces open probability [Po; loss-of-function (LOF)], likely due to altered interactions at the polar–nonpolar interface. L596I raises Po [gain-of-function (GOF)], apparently by placing its methyl group further inward and receiving stronger water repulsion. Molecular dynamics simulations showed that the distance between the levels of α-carbons of H-bonded residues L596 and W733 is shortened in the LOFs and lengthened in the GOFs, strengthening or weakening the linker/TRP helix latch, respectively. These results highlight that L596 lipid attraction counteracts the latch bond in a tug-of-war to tune the Po of TRPV4.