AI 中文总结
该研究通过粗粒度模型模拟，探究近电荷中性ProTα-组蛋白H1凝聚物的结构、扩散与弛豫特性，明确其链构象对压力不敏感、扩散系数随压力降低等规律，揭示瞬时静电接触的调控机制。
AI 中文摘要
由带相反电荷的固有无序蛋白形成的凝聚物，是研究瞬时静电相互作用如何调控生物分子组装体结构与动力学的模型体系。本研究采用单残基单珠粗粒度模型，结合无序区的HPS亲水性模型与组蛋白H1球状结构域的Go模型，在2至12 bar的NPT条件下，对由50个原胸腺素α（ProTα）和40个组蛋白H1分子组成的近电荷中性凝聚物展开研究。结果表明，链尺寸（包括回转半径Rg、端到端距离Ree及其比值R）对压力不敏感，在研究的压力范围内链构象基本保持不变；组蛋白H1因“球状核心+无序尾部”的结构，其R值系统性大于ProTα。平动扩散系数随压力单调降低，从约0.22 nm²/ns降至0.06 nm²/ns，且存在与平均扩散系数相当的显著链间异质性。链弛豫遵循 stretched exponential 规律，其指数β小于1且随压力降低；ProTα的弛豫时间约为12至40 ns，服从Rouse标度，而组蛋白H1因球状结构域的内部约束偏离该标度。ProTα-组蛋白H1的接触寿命约为0.43至0.56 ns，远短于Rouse弛豫时间，使系统处于快速交换 regime，其中瞬时静电接触会重新标度链摩擦，而非作为永久交联，这与所有压力下观测到的约0.55至0.70的中等拉伸指数β一致。
英文摘要
Condensates formed by oppositely charged intrinsically disordered proteins provide model systems for understanding how transient electrostatic interactions govern structure and dynamics in biomolecular assemblies. Here we investigate a nearly charge-neutral condensate composed of 50 Prothymosin alpha (ProTalpha) and 40 Histone H1 molecules using a single-bead-per-residue coarse-grained model combining the HPS hydropathy model for disordered regions with a Go model for the globular domain of Histone H1 under NPT conditions at pressures from 2 to 12 bar. We find that chain dimensions, including the radius of gyration (Rg), end-to-end distance (Ree), and their ratio R, are insensitive to pressure, indicating that chain conformations remain largely unchanged over the pressure range studied. Histone H1 exhibits systematically larger values of R than ProTalpha because of its globular-core plus disordered-tail architecture. Translational diffusion coefficients decrease monotonically with pressure, from approximately 0.22 to 0.06 nm^2/ns, with substantial chain-to-chain heterogeneity comparable to the mean diffusion coefficient. Chain relaxation follows a stretched exponential with beta less than 1 that decreases with pressure. ProTalpha relaxation times of approximately 12 to 40 ns obey Rouse scaling, whereas Histone H1 deviates because of the internal constraint imposed by its globular domain. ProTalpha-Histone H1 contact lifetimes of approximately 0.43 to 0.56 ns are much shorter than the Rouse relaxation time, placing the system firmly in the fast-exchange regime where transient electrostatic contacts renormalize chain friction rather than acting as permanent cross-links, consistent with the moderate stretching exponent beta of approximately 0.55 to 0.70 observed across all pressures.
