C 端激活结构域可促进 pannexin 1 通道开放。

IF 9.4 1区 综合性期刊 Q1 MULTIDISCIPLINARY SCIENCES
Erik Henze, Jacqueline J Ehrlich, Janice L Robertson, Eric Gelsleichter, Toshimitsu Kawate
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引用次数: 0

摘要

Pannexin 1(Panx1)是一个大孔通道,负责从凋亡细胞中释放三磷酸腺苷(ATP)。有确凿证据表明,C-端由 Caspase 介导的裂解可通过拔出孔来促进 Panx1 通道的开放。然而,仅靠这种简单的孔插机制无法解释在 Caspase 裂解位点之前结束的 Panx1 构建物仍处于关闭状态这一观察结果。在这里,我们展示了位于紧靠caspase裂解位点之前的一个螺旋区域(称为 "C-末端激活结构域(CAD)")在促进Panx1活化方面起着关键作用。电生理学和诱变研究发现,CAD 中的两个保守亮氨酸残基起着关键作用。冷冻电子显微镜(Cryo-EM)分析表明,在到达 CAD 之前结束的构建体的 N 端延伸到细胞内的口袋中。相比之下,包含 CAD 的构建物显示,该结构域占据了细胞内袋,导致 N 端在孔内向上翻转。对封闭构象的静电自由能分析表明,离子渗透孔的细胞内侧可能被 ATP 等阴离子占据,从而对试图渗透孔的阴离子形成静电障碍。当 N 端向上翻转时,就会减少带正电的表面,从而减少阴离子在孔内聚集的动力。静电景观的这种动态变化可能有助于选择渗透离子。总之,这些实验提出了一种机制,即 C 端裂解释放出 CAD,导致 N 端重新定位,从而促进 Panx1 通道开放。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
The C-terminal activating domain promotes pannexin 1 channel opening.

Pannexin 1 (Panx1) constitutes a large pore channel responsible for the release of adenosine triphosphate (ATP) from apoptotic cells. Strong evidence indicates that caspase-mediated cleavage of the C-terminus promotes the opening of the Panx1 channel by unplugging the pore. However, this simple pore-plugging mechanism alone cannot account for the observation that a Panx1 construct ending before the caspase cleavage site remains closed. Here, we show that a helical region located immediately before the caspase cleavage site, referred to as the "C-terminal activating domain (CAD)", plays a pivotal role in facilitating Panx1 activation. Electrophysiology and mutagenesis studies uncovered that two conserved leucine residues within the CAD play a pivotal role. Cryoelectron microscopy (Cryo-EM) analysis of the construct ending before reaching the CAD demonstrated that the N terminus extends into an intracellular pocket. In contrast, the construct including the CAD revealed that this domain occupies the intracellular pocket, causing the N terminus to flip upward within the pore. Analysis of electrostatic free energy landscape in the closed conformation indicated that the intracellular side of the ion permeation pore may be occupied by anions like ATP, creating an electrostatic barrier for anions attempting to permeate the pore. When the N terminus flips up, it diminishes the positively charged surface, thereby reducing the drive to accumulate anions inside the pore. This dynamic change in the electrostatic landscape likely contributes to the selection of permeant ions. Collectively, these experiments put forth a mechanism in which C-terminal cleavage liberates the CAD, causing the repositioning of the N terminus to promote Panx1 channel opening.

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来源期刊
CiteScore
19.00
自引率
0.90%
发文量
3575
审稿时长
2.5 months
期刊介绍: The Proceedings of the National Academy of Sciences (PNAS), a peer-reviewed journal of the National Academy of Sciences (NAS), serves as an authoritative source for high-impact, original research across the biological, physical, and social sciences. With a global scope, the journal welcomes submissions from researchers worldwide, making it an inclusive platform for advancing scientific knowledge.
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