Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, FL, 33458, USA.
Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, Jupiter, FL, 33458, USA.
Nat Commun. 2018 Nov 8;9(1):4687. doi: 10.1038/s41467-018-07133-w.
Small chemical modifications can have significant effects on ligand efficacy and receptor activity, but the underlying structural mechanisms can be difficult to predict from static crystal structures alone. Here we show how a simple phenyl-to-pyridyl substitution between two common covalent orthosteric ligands targeting peroxisome proliferator-activated receptor (PPAR) gamma converts a transcriptionally neutral antagonist (GW9662) into a repressive inverse agonist (T0070907) relative to basal cellular activity. X-ray crystallography, molecular dynamics simulations, and mutagenesis coupled to activity assays reveal a water-mediated hydrogen bond network linking the T0070907 pyridyl group to Arg288 that is essential for corepressor-selective inverse agonism. NMR spectroscopy reveals that PPARγ exchanges between two long-lived conformations when bound to T0070907 but not GW9662, including a conformation that prepopulates a corepressor-bound state, priming PPARγ for high affinity corepressor binding. Our findings demonstrate that ligand engagement of Arg288 may provide routes for developing corepressor-selective repressive PPARγ ligands.
小的化学修饰可以对配体的功效和受体活性产生重大影响，但仅从静态晶体结构很难预测潜在的结构机制。在这里，我们展示了如何通过在两种靶向过氧化物酶体增殖物激活受体 (PPAR)γ 的常见共价正位配体之间进行简单的苯基到吡啶基取代，将转录中性拮抗剂 (GW9662) 转化为相对于基础细胞活性的抑制性反向激动剂 (T0070907)。X 射线晶体学、分子动力学模拟以及与活性测定相结合的突变分析揭示了一个由水介导的氢键网络，将 T0070907 的吡啶基团与 Arg288 连接起来，对于核心抑制剂选择性的反向激动作用至关重要。NMR 光谱揭示了当与 T0070907 结合时，PPARγ 在两种长寿命构象之间交换，但与 GW9662 结合时则不会，包括一种预先存在的核心抑制剂结合状态的构象，使 PPARγ 能够与高亲和力的核心抑制剂结合。我们的研究结果表明，Arg288 的配体结合可能为开发核心抑制剂选择性抑制性 PPARγ 配体提供途径。
