摘要
Intrinsically disordered proteins(IDPs)and their regions(IDRs)play crucial roles in cellular func-tions despite their lack of stable three-dimensional structures.In this study,we investigate the interac-tions between the C-terminal do-main of protein 4.1G(4.1G CTD)and the nuclear mitotic apparatus protein(NuMA)under varying pH and salt ion conditions to under-stand the regulatory mechanisms affecting their binding.4.1G CTD and NuMA bind effec-tively under neutral and alkaline conditions,but their interaction is disrupted under acidic conditions(pH 3.6).The protonation of positively charged residues at the C-terminal of 4.1G CTD under acidic conditions leads to increased electrostatic repulsion,weakening the overall binding free energy.Secondary structure analysis shows that specific regions of 4.1G CTD re-main stable under both pH conditions,but the C-terminal region(aa 990−1000)and the N-terminal region of NuMA(aa 1800−1810)exhibit significant reductions in secondary struc-ture probability under acidic conditions.Contact map analysis and solvent-accessible surface area analysis further support these findings by showing a reduced contact probability be-tween these regions under pH 3.6.These results provide a comprehensive understanding of how pH and ionic strength regulate the binding dynamics of 4.1G CTD and NuMA,emphasiz-ing the regulatory role of electrostatic interactions.
固有无序蛋白及固有无序蛋白区域尽管缺乏稳定的三维结构,但在细胞功能中发挥着至关重要的作用。本文研究了蛋白4.1 G的C端结构域与核有丝分裂器蛋白在不同pH值和盐离子浓度下的相互作用,以了解影响其结合的调控机制.4.1 G的C端结构域和核有丝分裂器蛋白在中性和碱性条件下有效结合,但在酸性条件下(pH 3.6)它们的相互作用受到干扰。酸性条件下4.1 G的C端结构域C端负电荷残基的质子化会导致静电排斥增加,削弱整体结合自由能,二级结构分析显示,在两种pH条件下,4.1 G的C端结构域的特定区域保持稳定,但C末端区域(氨基酸990~1000)和核有丝分裂器蛋白的N末端区域(氨基酸1800~1810)在酸性条件下表现出显著的二级结构概率降低。接触图分析和溶剂可接触表面积分析进一步印证,在pH3.6时这些区域之间的接触概率减少.这些结果提供了关于pH和离子强度如何调节4.1 G的C端结构域与核有丝分裂器蛋白结合动态的全面理解,强调了静电相互作用的调控作用.
基金
supported by the National Natural Science Foundation of China(No.22073018,No.22377015).
