Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH 45267.
Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, Cincinnati, OH 45267.
Proc Natl Acad Sci U S A. 2021 Jun 29;118(26). doi: 10.1073/pnas.2104809118.
Anti-Müllerian hormone (AMH), or Müllerian-inhibiting substance, is a protein hormone that promotes Müllerian duct regression during male fetal sexual differentiation and regulation of folliculogenesis in women. AMH is a member of the transforming growth factor beta (TGF-β) family, which has evolved to signal through its own dedicated type II receptor, AMH receptor type II (AMHR2). Structures of other TGF-β family members have revealed how ligands infer specificity for their cognate receptors; however, it is unknown how AMH binds AMHR2 at the molecular level. Therefore, in this study, we solved the X-ray crystal structure of AMH bound to the extracellular domain of AMHR2 to a resolution of 2.6Å. The structure reveals that while AMH binds AMHR2 in a similar location to Activin and BMP ligand binding to their type II receptors, differences in both AMH and AMHR2 account for a highly specific interaction. Furthermore, using an AMH responsive cell-based luciferase assay, we show that a conformation in finger 1 of AMHR2 and a salt bridge formed by K534 on AMH and D81/E84 of AMHR2 are key to the AMH/AMHR2 interaction. Overall, our study highlights how AMH engages AMHR2 using a modified paradigm of receptor binding facilitated by modifications to the three-finger toxin fold of AMHR2. Furthermore, understanding these elements contributing to the specificity of binding will help in the design of agonists or antagonists or the selection of antibody therapies.
抗缪勒管激素(AMH),又称缪勒管抑制物质,是一种蛋白激素,在雄性胎儿性分化过程中促进缪勒管退化,并调节女性的卵泡发生。AMH 是转化生长因子β(TGF-β)家族的成员,该家族进化出通过其自身专用的 II 型受体 AMH 受体 II(AMHR2)进行信号传递的能力。其他 TGF-β家族成员的结构揭示了配体如何推断其同源受体的特异性;然而,目前尚不清楚 AMH 如何在分子水平上与 AMHR2 结合。因此,在这项研究中,我们解析了 AMH 与 AMHR2 胞外结构域结合的 X 射线晶体结构,分辨率为 2.6Å。该结构表明,尽管 AMH 与 AMHR2 的结合位置与激活素和 BMP 配体与它们的 II 型受体结合的位置相似,但 AMH 和 AMHR2 的差异导致了高度特异性的相互作用。此外,我们使用 AMH 反应性细胞基础的荧光素酶测定法,证明 AMHR2 手指 1 中的构象以及 AMH 上的 K534 和 AMHR2 上的 D81/E84 形成的盐桥是 AMH/AMHR2 相互作用的关键。总体而言,我们的研究强调了 AMH 如何使用 AMHR2 的三指毒素折叠修饰的受体结合范例来结合 AMHR2,并进一步理解这些参与结合特异性的元素将有助于设计激动剂或拮抗剂,或选择抗体疗法。