How phosphorylation activates the protein phosphatase-1 • inhibitor-2 complex
How phosphorylation activates the protein phosphatase-1 • inhibitor-2 complex
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DOI：
10.1016/j.bbapap.2012.09.003
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发表时间：
2013-01-01
影响因子：
3.2
通讯作者：
Cannon, John F.
中科院分区：
文献类型：
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作者：
Cannon, John F.
磷酸化调节许多蛋白质的活性；然而，原子水平的细节很少为人所知。抑制物-2(12)通过阻断对含有金属的活性部位的访问来抑制普遍存在的蛋白磷酸酶-1(PP1)酶的活性。12Thr74磷酸化导致PP1激活，而不是12从PP1-I2复合体解离。含有Thr74的12个73个残基的动态无序结构阻碍了PP1-12的X射线结晶学的可视化。在这项工作中，我使用模拟退火法生成了这一片段的结构，并将其融合到结晶学PP1-12坐标中，并使用分子动力学研究了Thr74磷酸化对导致PP1激活的结构变化的影响。12Thr74磷酸化后，12Tyr149从PP1活性部位移位的频率显著增加，酚性Tyr149侧链旋转以防止其重新插入，以及重新定位12个抑制螺旋以将PP1活性部位暴露于溶剂和底物中。在这些步骤之后，另一种结合生成PP1-Mn-2-I2的金属将12的磷酸化形式与其活性部位保持得不那么紧密，而不是保持去磷酸化的I2。12Thr74位于残基的可变动态群落的边缘，在那里它形成各种变构通路，在20埃外的PP1活性部位诱导运动。这些分子动力学模拟表明，在PPI-12激活的早期步骤，12的非结构化区域如何利用磷酸化Thr74周围增强的快速运动，将12个残基从PPI-12激活的早期步骤中撬开。(C)2012爱思唯尔B.V.保留所有权利。
Phosphorylation regulates activity of many proteins; however, atomic level details are known for very few examples. Inhibitor-2 (12) squelches the ubiquitous protein phosphatase-1 (PP1) enzyme activity by blocking access to the metal-containing active site. 12 Thr74 phosphorylation results in PP1 activation without 12 dissociation from the PP1-I2 complex. The dynamic disordered structure of the 73-residue segment of 12 containing Thr74, prevented visualization by X-ray crystallography of PP1-12. In this work, I generated structures of this segment using simulated annealing to NMR restraints, fused them to the crystallographic PP1-12 coordinates, and used molecular dynamics to study the impact of Thr74 phosphorylation on structural alterations leading to PP1 activation. Frequencies of 12 Tyr149 displacement from the PP1 active site, rotation of the phenolic Tyr149 side chain to prevent its reinsertion, and repositioning the 12 inhibitory helix to expose the PP1 active site to solvent and substrates significantly increased upon 12 Thr74 phosphorylation. After these steps, a second metal bound to produce PP1-Mn-2-I2, which held the phosphoiylated form of 12 to its active site less tightly than it held dephosphorylated I2. 12 Thr74 lies on the edge of variable dynamic communities of residues where it forms various allosteric pathways that induce motions at the PP1 active site 20 angstrom away. These molecular dynamics simulations show how an unstructured region of 12 can harness enhanced rapid movements around phosphorylated Thr74 to pry 12 residues away from the PP1 active site in early steps of PPI-12 activation. (C) 2012 Elsevier B.V. All rights reserved.