Akulov Vasily, Jiménez Panizo Alba, Estébanez-Perpiñá Eva, van Noort John, Mashaghi Alireza
Medical Systems Biophysics and Bioengineering, Division of Systems Pharmacology and Pharmacy, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands.
Leiden Institute of Physics, Leiden University, 2300 RA Leiden, The Netherlands.
J Phys Chem B. 2025 Jul 31;129(30):7719-7730. doi: 10.1021/acs.jpcb.5c03257. Epub 2025 Jul 17.
Site-specific phosphorylation of disordered proteins is often considered a marker of protein activity, yet it remains unclear how phosphorylation alters the conformational dynamics of disordered protein chains, such as those in the nuclear receptor superfamily. In the case of the disordered human glucocorticoid receptor N-terminal domain (GR NTD), a negatively charged region known as core activation function 1 (AF1c) features three phosphorylation sites, regulating its function and intracellular localization. Deletion of this sequence dramatically reduces the GR transcriptional activation ability in cell experiments. By developing a circuit topology-based fold analysis approach, combined with atomistic simulations, we reveal that site-specific phosphorylation facilitates the formation of nonlocal contacts, leading to the emergence of disordered compact topologies with significant entanglement, which are distinct from solvent-exposed topologies. While we observe that the topological buildup of solvent-exposed states is similar across different phosphovariants, it depends on the exact phosphorylation site for the disordered topologically compact states. This study thus reveals the complex regulatory role of the GR phosphorylation and introduces a unique analysis framework that can be broadly applied to studying the topological dynamics of disordered proteins.
无序蛋白质的位点特异性磷酸化通常被视为蛋白质活性的标志物，但磷酸化如何改变无序蛋白质链（如核受体超家族中的那些）的构象动力学仍不清楚。就无序的人类糖皮质激素受体N端结构域（GR NTD）而言，一个被称为核心激活功能1（AF1c）的带负电荷区域有三个磷酸化位点，调节其功能和细胞内定位。在细胞实验中删除该序列会显著降低GR的转录激活能力。通过开发一种基于电路拓扑的折叠分析方法，并结合原子模拟，我们发现位点特异性磷酸化促进了非局部接触的形成，导致出现具有显著缠结的无序紧密拓扑结构，这与溶剂暴露拓扑结构不同。虽然我们观察到不同磷酸化变体的溶剂暴露状态的拓扑构建相似，但它取决于无序拓扑紧密状态的具体磷酸化位点。因此，这项研究揭示了GR磷酸化的复杂调节作用，并引入了一个独特的分析框架，可广泛应用于研究无序蛋白质的拓扑动力学。
