Intersubunit conformational changes mediate epithelial sodium channel gating.
Intersubunit conformational changes mediate epithelial sodium channel gating.
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DOI：
10.1085/jgp.201411208
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发表时间：
2014-10
期刊：
影响因子：
--
通讯作者：
Snyder PM
中科院分区：
文献类型：
--
作者：
Collier DM;Tomkovicz VR;Peterson ZJ;Benson CJ;Snyder PM
在三个ENaC亚基之间形成界面的残基参与了在开放状态和封闭状态之间过渡所需的构象变化。上皮Na+通道（ENaC）是肾和肺吸收Na+的途径，对Na+稳态和血压调节至关重要。然而，控制ENaC门控的基本机制尚不清楚。在这里，我们定义了在三个ENaC亚基的胞外结构域之间形成界面的残基的门控作用。利用半胱氨酸取代结合化学交联，我们确定了位于三个亚基（αK477、βE446和γE455）中等效位置的残基与相邻亚基（分别为βV85、γV87和αL120）中的残基形成界面。这些残基的交联以长度依赖的方式改变ENaC活性；长交联剂通过增加ENaC的开断概率来增加ENaC电流，而短交联剂则降低ENaC的开断概率。交联还破坏了ENaC对细胞外pH和Na+的门控反应，这些信号在体积状态变化期间调节ENaC的活性。在界面残基上引入带电侧链以电荷依赖的方式改变ENaC活性。当相似电荷存在于两个界面残基时，电流增加，而相反电荷则降低电流。总之，这些数据表明，亚基间界面的构象变化参与了ENaC在开放和封闭状态之间的转变；增加亚基间距离的运动有利于开放状态，而当距离减少时有利于封闭状态。这提供了一种调节ENaC门控的机制，以应对威胁Na+稳态的细胞外条件的变化。
Residues forming interfaces between the three ENaC subunits participate in conformational changes required for transition between open and closed states. The epithelial Na+ channel (ENaC) functions as a pathway for Na+ absorption in the kidney and lung, where it is crucial for Na+ homeostasis and blood pressure regulation. However, the basic mechanisms that control ENaC gating are poorly understood. Here we define a role in gating for residues forming interfaces between the extracellular domains of the three ENaC subunits. Using cysteine substitution combined with chemical cross-linking, we determined that residues located at equivalent positions in the three subunits (αK477, βE446, and γE455) form interfaces with residues in adjacent subunits (βV85, γV87, and αL120, respectively). Cross-linking of these residues altered ENaC activity in a length-dependent manner; long cross-linkers increased ENaC current by increasing its open probability, whereas short cross-linkers reduced ENaC open probability. Cross-linking also disrupted ENaC gating responses to extracellular pH and Na+, signals which modulate ENaC activity during shifts in volume status. Introduction of charged side chains at the interfacing residues altered ENaC activity in a charge-dependent manner. Current increased when like charges were present at both interfacing residues, whereas opposing charges reduced current. Together, these data indicate that conformational changes at intersubunit interfaces participate in ENaC transitions between the open and closed states; movements that increase intersubunit distance favor the open state, whereas the closed state is favored when the distance is reduced. This provides a mechanism to modulate ENaC gating in response to changing extracellular conditions that threaten Na+ homeostasis.
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影响因子：
64.8
作者：
Gonzales, Eric B.;Kawate, Toshimitsu;Gouaux, Eric
通讯作者：
Gouaux, Eric
影响因子：
56.9
作者：
Lifton, RP
通讯作者：
Lifton, RP
影响因子：
15.9
作者：
BOUCHER, RC;STUTTS, MJ;GATZY, JT
通讯作者：
GATZY, JT
影响因子：
4.8
作者：
CZAJKOWSKI, C;KARLIN, A
通讯作者：
KARLIN, A
DOI：
10.1073/pnas.90.13.6285
发表时间：
1993-07-01
影响因子：
11.1
作者：
CZAJKOWSKI, C;KAUFMANN, C;KARLIN, A
通讯作者：
KARLIN, A