Callaway David J E, Matsui Tsutomu, Weiss Thomas, Stingaciu Laura R, Stanley Christopher B, Heller William T, Bu Zimei
Department of Chemistry and Biochemistry, City College of New York, CUNY, New York, NY 10031, USA.
Stanford Synchrotron Radiation Light Source, Menlo Park, CA 94025, USA.
J Mol Biol. 2017 Apr 7;429(7):987-998. doi: 10.1016/j.jmb.2017.03.003. Epub 2017 Mar 8.
The phosphorylation of specific residues in a flexible disordered activation loop yields precise control of signal transduction. One paradigm is the phosphorylation of S339/S340 in the intrinsically disordered tail of the multi-domain scaffolding protein NHERF1, which affects the intracellular localization and trafficking of NHERF1 assembled signaling complexes. Using neutron spin echo spectroscopy (NSE), we show salt-concentration-dependent excitation of nanoscale motion at the tip of the C-terminal tail in the phosphomimic S339D/S340D mutant. The "tip of the whip" that is unleashed is near the S339/S340 phosphorylation site and flanks the hydrophobic Ezrin-binding motif. The kinetic association rate constant of the binding of the S339D/S340D mutant to the FERM domain of Ezrin is sensitive to buffer salt concentration, correlating with the excited nanoscale dynamics. The results suggest that electrostatics modulates the activation of nanoscale dynamics of an intrinsically disordered protein, controlling the binding kinetics of signaling partners. NSE can pinpoint the nanoscale dynamics changes in a highly specific manner.
在一个灵活的无序激活环中特定残基的磷酸化产生对信号转导的精确控制。一个范例是多结构域支架蛋白NHERF1内在无序尾部的S339/S340磷酸化，这会影响NHERF1组装的信号复合物的细胞内定位和运输。使用中子自旋回波光谱法（NSE），我们展示了在磷酸模拟物S339D/S340D突变体中C末端尾部尖端纳米级运动的盐浓度依赖性激发。被释放的“鞭梢”靠近S339/S340磷酸化位点，并位于疏水埃兹蛋白结合基序的两侧。S339D/S340D突变体与埃兹蛋白的FERM结构域结合的动力学缔合速率常数对缓冲盐浓度敏感，与激发的纳米级动力学相关。结果表明，静电作用调节内在无序蛋白的纳米级动力学激活，控制信号伴侣的结合动力学。NSE可以以高度特异性的方式精确指出纳米级动力学变化。
