Amyloid-like interactions within nucleoporin FG hydrogels
Amyloid-like interactions within nucleoporin FG hydrogels
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DOI：
10.1073/pnas.0910163107
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发表时间：
2010-04-06
影响因子：
11.1
通讯作者：
Baldus, Marc
中科院分区：
文献类型：
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作者：
Ader, Christian;Frey, Steffen;Baldus, Marc
核孔蛋白Nsp1p的62 kDa FG重复结构域形成了一个基于水凝胶的筛状通透性屏障，它排除了惰性大分子，但允许核运输受体(NTR)快速进入。我们发现，该结构域的N-末端部分形成了一种坚韧的水凝胶，其特征是富含ASN的FG间隔物。C-末端部分由带电的FG间隔物组成，本身显示出低的胶凝倾向，但结合了N-末端部分并使FG水凝胶钝化，不受非选择性相互作用的影响。以前的研究表明，FG水凝胶的形成需要包含Phe残基的疏水塌陷。利用固体核磁共振波谱，我们现在发现了另外两种类型的凝胶内相互作用，即Phe和甲基侧链之间的瞬时疏水相互作用以及富含AsN的间隔区之间的分子间β-折叠。后者似乎是FG水凝胶中动力学上最稳定的结构。它们也是由富含天冬氨酸/谷氨酸氨基的淀粉样蛋白和蛋白形成的神经元包涵体的中心特征。FG重复序列和酵母Pron Sup35p中的Asn/Gln富含结构域的结合特性看起来确实非常相似，以至于这两个模块以反式方式相互作用。因此，我们的数据表明，这种链间β结构在维持核孔的通透性屏障方面具有完全意想不到的细胞功能。它们解释了FG重复序列之间的接触如何获得动力学稳定性，以抑制通过核孔的被动通量，同时又允许快速的NTR通过。
The 62 kDa FG repeat domain of the nucleoporin Nsp1p forms a hydrogel-based, sieve-like permeability barrier that excludes inert macromolecules but allows rapid entry of nuclear transport receptors (NTRs). We found that the N-terminal part of this domain, which is characterized by Asn-rich inter-FG spacers, forms a tough hydrogel. The C-terminal part comprises charged inter-FG spacers, shows low gelation propensity on its own, but binds the N-terminal part and passivates the FG hydrogel against nonselective interactions. It was previously shown that a hydrophobic collapse involving Phe residues is required for FG hydrogel formation. Using solid-state NMR spectroscopy, we now identified two additional types of intragel interactions, namely, transient hydrophobic interactions between Phe and methyl side chains as well as intermolecular beta-sheets between the Asn-rich spacer regions. The latter appear to be the kinetically most stable structures within the FG hydrogel. They are also a central feature of neuronal inclusions formed by Asn/Gln-rich amyloid and prion proteins. The cohesive properties of FG repeats and the Asn/Gln-rich domain from the yeast prion Sup35p appear indeed so similar to each other that these two modules interact in trans. Our data, therefore, suggest a fully unexpected cellular function of such interchain beta-structures in maintaining the permeability barrier of nuclear pores. They provide an explanation for how contacts between FG repeats might gain the kinetic stability to suppress passive fluxes through nuclear pores and yet allow rapid NTR passage.