Molecular recognition of parathyroid hormone by its G protein-coupled receptor
Molecular recognition of parathyroid hormone by its G protein-coupled receptor
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DOI：
10.1073/pnas.0801027105
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发表时间：
2008-04-01
影响因子：
11.1
通讯作者：
Xu, H. Eric
中科院分区：
文献类型：
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作者：
Pioszak, Augen A.;Xu, H. Eric
甲状旁腺激素(PTH)是脊椎动物钙稳态和骨骼维持的中心，因此它已被用于治疗骨质疏松症。它主要通过与其受体PTH1R结合发挥作用，PTH1R是B类G蛋白偶联受体(GPCR)家族的成员，该家族还包括胰高血糖素、降钙素和其他具有重要治疗意义的多肽激素的受体。尽管有相当大的兴趣和大量的研究，但由于难以纯化受体并获得衍射质量的晶体，确定受体-激素复合体的结构一直受到阻碍。在这里，我们提出了一种表达和纯化人PTH1R胞外区(ECD)的方法，该融合蛋白是一种易于结晶的麦芽糖结合蛋白(MBP)。PTH与MBP-PTH1R-ECD融合的1.95埃结构表明，PTH作为两亲性螺旋对接到由PTH1R ECD的三层α-β-βα折叠形成的中心疏水凹槽中，类似于面包里的热狗。ECD支架和多肽激素螺旋结构的保守性强调了这种热狗模型是B类GPCRs共同的激素识别的一般机制。我们的发现揭示了对甲状旁腺素作用的关键见解，并为针对这一激素信号通路的药物设计提供了一个合理的模板。
Parathyroid hormone (PTH) is central to calcium homeostasis and bone maintenance in vertebrates, and as such it has been used for treating osteoporosis. It acts primarily by binding to its receptor, PTH1R, a member of the class B G protein-coupled receptor (GPCR) family that also includes receptors for glucagon, calcitonin, and other therapeutically important peptide hormones. Despite considerable interest and much research, determining the structure of the receptor-hormone complex has been hindered by difficulties in purifying the receptor and obtaining diffraction-quality crystals. Here, we present a method for expression and purification of the extracellular domain (ECD) of human PTH1R engineered as a maltose-binding protein (MBP) fusion that readily crystallizes. The 1.95-angstrom structure of PTH bound to the MBP-PTH1R-ECD fusion reveals that PTH docks as an amphipathic helix into a central hydrophobic groove formed by a three-layer alpha-beta-beta alpha fold of the PTH1R ECD, resembling a hot dog in a bun. Conservation in the ECD scaffold and the helical structure of peptide hormones emphasizes this hot dog model as a general mechanism of hormone recognition common to class B GPCRs. Our findings reveal critical insights into PTH actions and provide a rational template for drug design that targets this hormone signaling pathway.