Structural plasticity of peptidyl-prolyl isomerase sFkpA is a key to its chaperone function as revealed by solution NMR
Structural plasticity of peptidyl-prolyl isomerase sFkpA is a key to its chaperone function as revealed by solution NMR
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DOI：
10.1021/bi0607913
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发表时间：
2006-10-03
期刊：
影响因子：
2.9
通讯作者：
Pervushin, Konstantin
中科院分区：
文献类型：
--
作者：
Hu, Kaifeng;Galius, Veniamin;Pervushin, Konstantin
用核磁共振研究了周质分子伴侣FkpA-Delta CT（sFkpA）及其与部分结构化底物的复合物在溶液中的分子内动力学。sFkpA的骨架酰胺N-15弛豫揭示了在sFkpA的X射线结构中鉴定的二聚化结构域和两个并置的催化结构域之间的相对取向的灵活性。这种灵活性归因于由残基84和91组成的长α-螺旋臂（螺旋III）内的结构可塑性。残余偶极偶联（RDC）表明sFkpA结构域之间不存在固定取向。sFkpA的底物结合表面通过sFkpA与其相应的蛋白质底物（部分折叠的RNA酶A S-蛋白和还原的羧甲基化牛α-乳白蛋白（RCM-1a））复合引入的化学位移扰动的映射在X射线结构上定义。apo-sFkpA及其与RNase A S-蛋白复合物的15 N弛豫的比较表明长α-螺旋III内的刚性增加，复合物的结构域间迁移率降低。我们推测，这些动态特性可能发挥了关键作用的sFkpA分子伴侣活性，因为能够结合不同的基板可能需要分子伴侣蛋白的结构适应。我们表明，结合sFkpA的核糖核酸酶A的S-蛋白大大减少了人口的聚合寡聚物物种的核糖核酸酶A的S-蛋白。最后，提出了一个分子模型，即所谓的“母亲的手臂”模型，来说明FkpA的伴侣活性机制。
Intramolecular dynamics of periplasmic chaperone FkpA-Delta CT (sFkpA) and its complexes with partially structured substrates are studied by NMR in solution. The backbone amide N-15 relaxation of sFkpA reveals flexibility in the relative orientation between the dimerization domain and two juxtaposed catalytic domains identified in the X-ray structure of sFkpA. This flexibility is attributed to the structural plasticity within the long alpha-helical arm (helix III) consisting of residues 84 and 91. Residual dipolar couplings (RDCs) indicate an absence of fixed orientation between the sFkpA domains. The substrate binding surface of sFkpA is defined on the X-ray structure by mapping of chemical shift perturbations introduced by complexation of sFkpA with its corresponding protein substrates: partially folded RNase A S-protein and reduced carboxymethylated bovine alpha-lactalbumin (RCM-1a). A comparison of 15N relaxation of apo-sFkpA and its complex with RNase A S-protein indicates an increased rigidity within the long alpha-helix III and decreased interdomain mobility of the complex. We speculate that these dynamic properties may play a key role in the chaperone activity of sFkpA, since ability to bind different substrates potentially requires structural adaptations of the chaperone protein. We show that binding of sFkpA to RNase A S-protein greatly reduces the population of aggregated oligomeric species of RNase A S-protein. Finally, a molecular model, the so-called "mother's arms" model, is proposed to illustrate the mechanism of chaperone activity by FkpA.