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 ...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.展开更多
基金supported by the National Natural Science Foundation of China(No.22073018,No.22377015).
文摘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.
