Phosphorylation-induced structural changes in the amyloid precursor protein cytoplasmic tail detected by NMR
Phosphorylation-induced structural changes in the amyloid precursor protein cytoplasmic tail detected by NMR
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DOI：
10.1006/jmbi.2001.4535
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发表时间：
2001-03-30
影响因子：
5.6
通讯作者：
Nicholson, LK
中科院分区：
文献类型：
--
作者：
Ramelot, TA;Nicholson, LK
淀粉样前体蛋白（APPc）的胞质尾区与阿尔茨海默病患者老年斑中发现的淀粉样β肽的细胞内信号传导或蛋白水解产生中涉及的几种细胞因子相互作用。APPc含有两个苏氨酸残基（相对于APP 695为654和668，或相对于APPc为6和20）和一个丝氨酸残基（分别为655或7），已知这些残基在体内被磷酸化，并可能在这些事件中起调节作用。我们通过溶液NMR光谱的49个残基的胞质尾肽（APP-C），在所有三种情况下，磷酸化诱导骨架二面角的变化，可以归因于磷酸基团和附近的酰胺质子之间形成的局部氢键。57的磷酸化还诱导疏水簇（残基I8-V13）中的化学位移变化，表明另外的中程效应。最显著的变化发生在T20磷酸化后，T20是一个神经元特异性磷酸化位点，其中先前表征该区域的N-末端螺旋帽盒被改变。扭转角和瞬时氢键的表征表明，脯氨酰异构化的pThr-Pro的肽键的结果从两个不稳定的N-末端螺旋帽盒和稳定的顺式异构体通过瞬时氢键。T20磷酸化后存在的顺式异构体的显著群体（9%）表明顺式异构体与反式异构体的选择性识别在响应APP磷酸化中的潜在作用。总之，这些结构变化表明磷酸化可能在APP的胞质尾部中作为构象开关，以改变与胞质伴侣结合的特异性和亲和力，特别是对与阿尔茨海默病相关的异常磷酸化事件的反应。(C)北京：科学出版社.
The cytoplasmic tail of the amyloid precursor protein (APPc) interacts with several cellular factors implicated in intracellular signaling or proteolytic production of amyloid beta peptide found in senile plaques of Alzheimer's disease patients. APPc contains two threonine residues (654 and 668 relative to APP695, or 6 and 20 relative to APPc) and a serine residue (655 or 7, respectively) that are known to be phosphorylated in vivo and may play regulatory roles in these events. We show by solution NMR spectroscopy of a 49 residue cytoplasmic tail peptide (APP-C) that in all three cases, phosphorylation induces changes in backbone dihedral angles that can be attributed to formation of local hydrogen bonds between the phosphate group and nearby amide protons. Phosphorylation of 57 also induces chemical shift changes in the hydrophobic cluster (residues I8-V13), indicating additional medium-range effects. The most pronounced changes occur upon phosphorylation of T20, a neuron-specific phosphorylation site, where the N-terminal helix capping box previously characterized for this region is altered. Characterization of torsion angles and transient hydrogen bonds indicates that prolyl isomerization of the pThr-Pro peptide bond results from both destabilization of the N-terminal helix capping box and stabilization of the cis isomer by transient hydrogen bonds. The significant population of the cis isomer (9%) present after phosphorylation of T20 suggests a potential role of selective recognition of cis versus trans isomers in response to phosphorylation of APP. Together, these structural changes indicate that phosphorylation may act as a conformational switch in the cytoplasmic tail of APP to alter specificity and affinity of binding to cytosolic partners, particularly in response to the abnormal phosyhorylation events associated with Alzheimer's disease. (C) 2001 Academic Press.