Structural and Functional Analysis of the CAPS SNARE-Binding Domain Required for SNARE Complex Formation and Exocytosis
Structural and Functional Analysis of the CAPS SNARE-Binding Domain Required for SNARE Complex Formation and Exocytosis
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SNARE 复合物形成和胞吐作用所需的 CAPS SNARE 结合域的结构和功能分析
DOI：
10.1016/j.celrep.2019.02.064
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发表时间：
2019
期刊：
影响因子：
8.8
通讯作者：
Ma Cong
中科院分区：
文献类型：
--
作者：
Zhou Hao;Wei Ziqing;Wang Shen;Yao Deqiang;Zhang Rongguang;Ma Cong
突触囊泡和密核囊泡的胞外分泌需要Munc13和CAPS （Ca2+依赖性激活蛋白分泌）蛋白。CAPS含有可溶性乙基马来酰亚胺敏感因子附着蛋白受体（SNARE）结合区（称为DAMH结构域），已发现该区域对SNARE介导的胞外分泌至关重要。在这里，我们报告了2.9-Å分辨率的CAPS-1 DAMH结构域的晶体结构，并揭示了CAPS-1在SNARE复合物形成中的双重作用。CAPS-1的抑制作用依赖于DAMH结构域与Munc13-1的MUN结构域的结合，从而阻碍Munc13催化syntaxin-1打开的能力，抑制SNARE复合物的形成；而伴侣作用依赖于DAMH结构域与syntaxin-1/SNAP-25复合物的相互作用，从而稳定Syx1的打开构象，促进SNARE复合物的形成。我们的研究结果表明，CAPS-1通过DAMH结构域促进SNARE复合物的形成，这种方式依赖于与Munc13-1和SNARE蛋白的顺序和合作相互作用。
Exocytosis of synaptic vesicles and dense-core vesicles requires both the Munc13 and CAPS (Ca2+-dependent activator proteins for secretion) proteins. CAPS contains a solubleN-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-binding region (called the DAMH domain), which has been found to be essential for SNARE-mediated exocytosis. Here we report a crystal structure of the CAPS-1 DAMH domain at 2.9-Å resolution and reveal a dual role of CAPS-1 in SNARE complex formation. CAPS-1 plays an inhibitory role dependent on binding of the DAMH domain to the MUN domain of Munc13-1, which hinders the ability of Munc13 to catalyze opening of syntaxin-1, inhibiting SNARE complex formation, and a chaperone role dependent on interaction of the DAMH domain with the syntaxin-1/SNAP-25 complex, which stabilizes the open conformation of Syx1, facilitating SNARE complex formation. Our results suggest that CAPS-1 facilitates SNARE complex formation via the DAMH domain in a manner dependent on sequential and cooperative interaction with Munc13-1 and SNARE proteins.