Structural and Biophysical Analysis of the CLCA1 VWA Domain Suggests Mode of TMEM16A Engagement
Structural and Biophysical Analysis of the CLCA1 VWA Domain Suggests Mode of TMEM16A Engagement
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DOI：
10.1016/j.celrep.2019.12.059
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发表时间：
2020-01-28
期刊：
影响因子：
8.8
通讯作者：
Brett, Tom J.
中科院分区：
文献类型：
--
作者：
Berry, Kayla N.;Brett, Tom J.
分泌蛋白钙激活氯离子通道调节因子1（CLCA 1）利用血管性血友病因子A型（VWA）结构域结合并增强钙激活氯离子通道TMEM 16 A。为了深入了解这种独特的增强机制，我们确定了与Ca2+结合的人CLCA1 VWA的2.0埃晶体结构。该结构揭示了高亲和力“开放”构象中的金属离子依赖性粘附位点（MIDAS），参与可能模拟CLCA 1如何与TMEM 16 A接合的晶体接触。CLCA1 VWA在α 3和α 4之间含有一个二硫键，非常接近MIDAS，该二硫键在CLCA家族中是不变的，在VWA结构中是独特的。进一步的生物物理学研究表明，CLCA 1 VWA优选地通过Mg 2+而不是Ca 2+稳定，并且α 6从VWA核心延伸。最后，TMEM16A结构的分析表明残基可能介导与CLCA1 VWA的相互作用。
The secreted protein calcium-activated chloride channel regulator 1 (CLCA1) utilizes a von Willebrand factor type A (VWA) domain to bind to and potentiate the calcium-activated chloride channel TMEM16A. To gain insight into this unique potentiation mechanism, we determined the 2.0-angstrom crystal structure of human CLCA1 VWA bound to Ca2+. The structure reveals the metal-ion-dependent adhesion site (MIDAS) in a high-affinity "open" conformation, engaging in crystal contacts that likely mimic how CLCA1 engages TMEM16A. The CLCA1 VWA contains a disulfide bond between alpha 3 and alpha 4 in close proximity to the MIDAS that is invariant in the CLCA family and unique in VWA structures. Further biophysical studies indicate that CLCA1 VWA is preferably stabilized by Mg2+ over Ca2+ and that alpha 6 atypically extends from the VWA core. Finally, an analysis of TMEM16A structures suggests residues likely to mediate interaction with CLCA1 VWA.