The role of solvation on the conformational landscape of α-synuclein
The role of solvation on the conformational landscape of α-synuclein
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DOI：
10.1039/d3an01680c
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发表时间：
2023-11-17
期刊：
影响因子：
4.2
通讯作者：
Webb，Ian K.
中科院分区：
文献类型：
--
作者：
Kit，Melanie Cheung See;Cropley，Tyler C.;Webb，Ian K.
原生离子迁移率质谱法已广泛用于表征内在无序蛋白质（IDP）构象的集合，但气体测量在多大程度上提供了这种柔性蛋白质的溶液构象的真实图像仍不清楚。因此，我们通过测量溶液中阴离子蛋白α-synuclein （αSN）正离子和阴离子形式的电喷雾电荷态和碰撞截面（CCS）分布，系统地研究了溶液与气体结构系综之间的关系，并通过气体α-synuclein阳离子与形成强静电键的二磺酸连接剂之间的离子/离子反应，直接探测气相残渣到残渣的距离。此外，我们还将天然串联质谱（MS/MS）鉴定的溶液中蛋白质交联结果与IDPConformerGenerator计算生成的初始αSN系综结合起来，生成了实验抑制的αSN系综。直接计算了由核磁共振确定的溶液系的CCS分布，并与预测的气体构象进行了比较。虽然电荷态和碰撞截面分布对于定性描述蛋白质的相对结构动力学和由溶液状态变化引起的主要构象变化是有用的，但预测和测量的气相构象包括的亚群与完全“冻结”溶液构象并将其保存在气相中所期望的亚群有显著不同。然而，我们对溶剂在稳定α-突触核蛋白等极动态蛋白的各种构象中的各种作用有了深入的了解。
Native ion mobility mass spectrometry has been used extensively to characterize ensembles of intrinsically disordered protein (IDP) conformers, but the extent to which the gaseous measurements provide realistic pictures of the solution conformations for such flexible proteins remains unclear. Therefore, we systematically studied the relationship between the solution and gaseous structural ensembles by measuring electrospray charge state and collision cross section (CCS) distributions for cationic and anionic forms of α-synuclein (αSN), an anionic protein in solution, as well as directly probed gas phase residue to residue distances via ion/ion reactions between gaseous α-synuclein cations and disulfonic acid linkers that form strong electrostatic bonds. We also combined results from in-solution protein crosslinking identified from native tandem mass spectrometry (MS/MS) with an initial αSN ensemble generated computationally by IDPConformerGenerator to generate an experimentally restrained solution ensemble of αSN. CCS distributions were directly calculated for the solution ensembles determined by NMR and compared to predicted gaseous conformers. While charge state and collision cross section distributions are useful for qualitatively describing the relative structural dynamics of proteins and major conformational changes induced by changes to solution states, the predicted and measured gas phase conformers include subpopulations that are significantly different than those expected from completely" freezing" solution conformations and preserving them in the gas phase. However, insights were gained on the various roles of solvent in stabilizing various conformers for extremely dynamic proteins like α-synuclein.