Full opening of helix bundle crossing does not lead to NaK channel activation.
Full opening of helix bundle crossing does not lead to NaK channel activation.
复制标题
螺旋束交叉的全部开放不会导致NAK通道激活。
DOI：
10.1085/jgp.202213196
复制
发表时间：
2022-12-05
影响因子：
3.8
通讯作者：
Henzler-Wildman, Katherine
中科院分区：
文献类型：
--
作者：
Kurauskas, Vilius;Tonelli, Marco;Henzler-Wildman, Katherine
解释钾通道门控的主要模型通常会引起螺旋束交叉的加宽和缩小。本文表明，一个密切相关的通道，钠钾，不门控这种机制的螺旋束交叉在非导电通道已经开放。离子通道功能的关键部分是响应刺激而打开和关闭的能力，从而以受调节的方式传导离子。虽然离子通道的X射线衍射研究表明，一般的空间门控机制位于螺旋束交叉（HBC），最近的功能研究几个通道表明，螺旋束交叉是完全开放的，即使在功能非导电通道。两个NaK通道变体以非常不同的开放和闭合构象结晶，这是HBC门控假说的重要模型。然而，这些NaK变体在脂质体中均不导电，除非苯丙氨酸92突变为丙氨酸（F92A）。在这里，我们使用NMR探测距离在近原子分辨率的两个钠钾变体在脂质bicelles。我们证明，在晶体结构的对比，这两个钠钾变体是在一个完全开放的构象，类似于Ca2+结合的MthK通道结构的HBC是广泛开放的。虽然我们无法确定导电NaK结构是什么样的，但我们对门控机制的进一步研究表明，选择性过滤器和孔螺旋与下面的M2螺旋偶联，并且当F92突变时，结构发生变化。总的来说，我们的数据表明，NaK表现出选择性过滤器和HBC之间的耦合，类似于K+通道，并且具有比以前认为的更复杂的门控机制，其中HBC的完全打开不会导致通道激活。
The dominant models explaining potassium channel gating often invoke widening and narrowing of the helix bundle crossing. This paper shows that a closely related channel, NaK, is not gated by this mechanism as the helix bundle crossing in the nonconducting channel is already open. A critical part of ion channel function is the ability to open and close in response to stimuli and thus conduct ions in a regulated fashion. While x-ray diffraction studies of ion channels suggested a general steric gating mechanism located at the helix bundle crossing (HBC), recent functional studies on several channels indicate that the helix bundle crossing is wide-open even in functionally nonconductive channels. Two NaK channel variants were crystallized in very different open and closed conformations, which served as important models of the HBC gating hypothesis. However, neither of these NaK variants is conductive in liposomes unless phenylalanine 92 is mutated to alanine (F92A). Here, we use NMR to probe distances at near-atomic resolution of the two NaK variants in lipid bicelles. We demonstrate that in contrast to the crystal structures, both NaK variants are in a fully open conformation, akin to Ca2+-bound MthK channel structure where the HBC is widely open. While we were not able to determine what a conductive NaK structure is like, our further inquiry into the gating mechanism suggests that the selectivity filter and pore helix are coupled to the M2 helix below and undergo changes in the structure when F92 is mutated. Overall, our data show that NaK exhibits coupling between the selectivity filter and HBC, similar to K+ channels, and has a more complex gating mechanism than previously thought, where the full opening of HBC does not lead to channel activation.
登录
查看更多内容
DOI：
10.1085/jgp.201711803
发表时间：
2017-12-04
期刊：
The Journal of general physiology
影响因子：
--
作者：
Gonzalez-Gutierrez G;Wang Y;Cymes GD;Tajkhorshid E;Grosman C
通讯作者：
Grosman C
影响因子：
56.9
作者：
Doyle, DA;Cabral, JM;MacKinnon, R
通讯作者：
MacKinnon, R
DOI：
10.1085/jgp.200609638
发表时间：
2006-11
期刊：
The Journal of general physiology
影响因子：
--
作者：
Blunck R;Cordero-Morales JF;Cuello LG;Perozo E;Bezanilla F
通讯作者：
Bezanilla F
影响因子：
16.8
作者：
通讯作者：
--
影响因子：
16.6
作者：
Ben Soussia, Ismail;El Mouridi, Sonia;Boulin, Thomas
通讯作者：
Boulin, Thomas