Banerjee Priya R, Mitrea Diana M, Kriwacki Richard W, Deniz Ashok A
Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92307, USA.
Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.
Angew Chem Int Ed Engl. 2016 Jan 26;55(5):1675-9. doi: 10.1002/anie.201507728. Epub 2015 Dec 17.
As for many intrinsically disordered proteins, order-disorder transitions in the N-terminal oligomerization domain of the multifunctional nucleolar protein nucleophosmin (Npm-N) are central to its function, with phosphorylation and partner binding acting as regulatory switches. However, the mechanism of this transition and its regulation remain poorly understood. In this study, single-molecule and ensemble experiments revealed pathways with alternative sequences of folding and assembly steps for Npm-N. Pathways could be switched by altering the ionic strength. Phosphorylation resulted in pathway-specific effects, and decoupled folding and assembly steps to facilitate disorder. Conversely, binding to a physiological partner locked Npm-N in ordered pentamers and counteracted the effects of phosphorylation. The mechanistic plasticity found in the Npm-N order-disorder transition enabled a complex interplay of phosphorylation and partner-binding steps to modulate its folding landscape.
对于许多内在无序蛋白质而言，多功能核仁蛋白核磷蛋白（Npm-N）的N端寡聚化结构域中的有序-无序转变是其功能的核心，磷酸化和与伴侣结合起着调节开关的作用。然而，这种转变及其调节机制仍知之甚少。在本研究中，单分子和整体实验揭示了Npm-N折叠和组装步骤具有替代序列的途径。通过改变离子强度可以切换途径。磷酸化产生途径特异性效应，并使折叠和组装步骤解偶联以促进无序状态。相反，与生理伴侣结合将Npm-N锁定在有序的五聚体中，并抵消了磷酸化的影响。在Npm-N有序-无序转变中发现的机制可塑性使得磷酸化和伴侣结合步骤之间能够进行复杂的相互作用，从而调节其折叠状态。
