Structure and Dynamics of Adrenomedullin Receptors AM1 and AM2 Reveal Key Mechanisms in the Control of Receptor Phenotype by Receptor Activity-Modifying Proteins
Structure and Dynamics of Adrenomedullin Receptors AM1 and AM2 Reveal Key Mechanisms in the Control of Receptor Phenotype by Receptor Activity-Modifying Proteins
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DOI：
10.1021/acsptsci.9b00080
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发表时间：
2020-04-10
影响因子：
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通讯作者：
Sexton, Patrick M.
中科院分区：
文献类型：
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作者：
Liang, Yi-Lynn;Belousoff, Matthew J.;Sexton, Patrick M.
肾上腺髓质素（AM）和降钙素基因相关肽（CGRP）受体对代谢、血管张力和炎症反应至关重要。AM受体也是正常淋巴管和血管发育和血管生成所需的。它们在胚胎植入和生育中起着关键作用，可以提供对缺氧和氧化应激的保护。CGRP和AM受体是降钙素受体样受体（CGRP）和受体活性修饰蛋白1（RAMP 1）（CGRP）以及RAMP 2或RAMP 3（分别为AM（1）R和AM（2）R）的异源二聚体。然而，RAMP调节RAMP表型的机制基础尚不清楚。在这项研究中，我们报告了AM（1）R与AM和Gs复合物的冷冻电镜结构，全球分辨率为3.0埃，AM（2）R与AM或中间蛋白/肾上腺髓质素2（AM 2）和Gs复合物的结构分别为2.4和2.3埃。这些结构揭示了细胞外结构域（ECD）相对于受体核心的主要方向的区别以及受体依赖性的细胞外环3（ECL 3）的不同定位。对冷冻EM显微照片中的动态数据进行分析，发现ECD的移动程度存在其他差异。连接TM螺旋和ECD的RAMP的接头区的嵌合交换支持该区段在控制受体表型中的作用。此外，一个子集的运动的ECD出现协调与运动的G蛋白相对于受体的核心，这表明受体ECD的动力学可能会影响G蛋白的相互作用。这项工作为我们了解GPCR功能以及辅助蛋白如何变构调节GPCR功能提供了根本性进展。
Adrenomedullin (AM) and calcitonin gene-related peptide (CGRP) receptors are critically important for metabolism, vascular tone, and inflammatory response. AM receptors are also required for normal lymphatic and blood vascular development and angiogenesis. They play a pivotal role in embryo implantation and fertility and can provide protection against hypoxic and oxidative stress. CGRP and AM receptors are heterodimers of the calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1) (CGRPR), as well as RAMP2 or RAMP3 (AM(1)R and AM(2)R, respectively). However, the mechanistic basis for RAMP modulation of CLR phenotype is unclear. In this study, we report the cryo-EM structure of the AM(1)R in complex with AM and Gs at a global resolution of 3.0 angstrom, and structures of the AM(2)R in complex with either AM or intermedin/adrenomedullin 2 (AM2) and Gs at 2.4 and 2.3 angstrom, respectively. The structures reveal distinctions in the primary orientation of the extracellular domains (ECDs) relative to the receptor core and distinct positioning of extracellular loop 3 (ECL3) that are receptor-dependent. Analysis of dynamic data present in the cryo-EM micrographs revealed additional distinctions in the extent of mobility of the ECDs. Chimeric exchange of the linker region of the RAMPs connecting the TM helix and the ECD supports a role for this segment in controlling receptor phenotype. Moreover, a subset of the motions of the ECD appeared coordinated with motions of the G protein relative to the receptor core, suggesting that receptor ECD dynamics could influence G protein interactions. This work provides fundamental advances in our understanding of GPCR function and how this can be allosterically modulated by accessory proteins.