A novel STIM1-Orai1 gating interface essential for CRAC channel activation
A novel STIM1-Orai1 gating interface essential for CRAC channel activation
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DOI：
10.1016/j.ceca.2019.02.009
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发表时间：
2019-05-01
期刊：
影响因子：
4
通讯作者：
Romanin, Christoph
中科院分区：
文献类型：
--
作者：
Butorac, Carmen;Muik, Martin;Romanin, Christoph
通过钙库操纵 (SOC) 进入的钙信号传导对于 T 细胞激活和适应性免疫反应至关重要。该进入是通过原型 Ca2+ 释放激活 Ca2+ (CRAC) 通道发生的。 STIM1 是该过程的关键分子成分，位于内质网 (ER) 膜中，最初在 Ca2+ 储备耗尽时被激活。该激活信号通过 STIM1 和高度 Ca2+ 选择性离子通道 Orai1 之间发生的直接物理相互作用传递到质膜。 STIM1 的激活会诱导胞质构象延伸。这反过来又暴露了 CAD/SOAR 结构域并导致 STIM1 寡聚物的形成。在本研究中，我们重点关注位于 CAD/SOAR 域内的一个小螺旋段（STIM1 α 3，aa 400-403）。我们确定了该片段在 STIM1 激活和 Orai1 门控方面的特定功能作用。 STIM1 α 3 结构域对于 STIM1 与 Orai1 相互作用似乎不是必需的。相反，它代表了将 STIM1 交互传递到 Orai1 通道门控的关键域。半胱氨酸交联实验的结果显示STIM1α3与Orai1内的一个区域非常接近，该区域位于跨膜螺旋3的胞质延伸处，形成STIM1-Orai1门控界面(SOGI)。我们认为 STIM1 α 3 和 Orai1 TM3 之间的相互作用允许 STIM1 耦合转化为生理 CRAC 通道激活。
Calcium signalling through store-operated calcium (SOC) entry is of crucial importance for T-cell activation and the adaptive immune response. This entry occurs via the prototypic Ca2+ release-activated Ca2+ (CRAC) channel. STIM1, a key molecular component of this process, is located in the membrane of the endoplasmic reticulum (ER) and is initially activated upon Ca2+ store depletion. This activation signal is transmitted to the plasma membrane via a direct physical interaction that takes place between STIM1 and the highly Ca2+-selective ion channel Orai1. The activation of STIM1 induces an extended cytosolic conformation. This, in turn, exposes the CAD/SOAR domain and leads to the formation of STIM1 oligomers. In this study, we focused on a small helical segment (STIM1 alpha 3, aa 400-403), which is located within the CAD/SOAR domain. We determined this segment's specific functional role in terms of STIM1 activation and Orai1 gating. The STIM1 alpha 3 domain appears not essential for STIM1 to interact with Orai1. Instead, it represents a key domain that conveys STIM1 interaction into Orai1 channel gating. The results of cysteine crosslinking experiments revealed the close proximity of STIM1 alpha 3 to a region within Orai1, which was located at the cytosolic extension of transmembrane helix 3, forming a STIM1-Orai1 gating interface (SOGI). We suggest that the interplay between STIM1 alpha 3 and Orai1 TM3 allows STIM1 coupling to be transmitted into physiological CRAC channel activation.