Evidence for an evolutionary relationship between the large adaptor nucleoporin Nup192 and karyopherins.
Evidence for an evolutionary relationship between the large adaptor nucleoporin Nup192 and karyopherins.
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大接头核孔蛋白 Nup192 和核传递蛋白之间进化关系的证据。
DOI：
10.1073/pnas.1311081111
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发表时间：
2014
影响因子：
11.1
通讯作者：
Hoelz,André
中科院分区：
文献类型：
--
作者：
Stuwe,Tobias;Lin,DanielH;Collins,LeslieN;Hurt,Ed;Hoelz,André
核孔复合物（NPC）促进核细胞质运输，核孔复合物是嵌入核膜中的大量蛋白质运输通道。 Nup192 是接头核孔蛋白亚复合物的主要组成部分，拟将 NPC 外壳与中央运输通道连接起来。在这里，我们以 2.7-Å 分辨率展示了 Nup192 ∼110-kDa N 端结构域 (NTD) 的结构。该结构揭示了由亨廷顿蛋白、EF3、PP2A、TOR1 (HEAT) 和犰狳 (ARM) 重复序列组成的开放环形结构。不同构象的比较表明 NTD 由通过柔性铰链连接的两个刚性半部分组成。出乎意料的是，环的两半在结构上与核传递蛋白-α（Kap-α）和β-核传递蛋白家族成员相关。在生化方面，我们鉴定了一个保守的补丁，该补丁结合了 Nup53 中的非结构化片段，并表明 C 端尾部区域结合了 Nic96 中的推定螺旋片段。结合 Nup192 的 Nup53 片段是经典的核定位样序列，它以相互排斥且机制不同的方式与 Kap-α 相互作用。体内 Nup53 和 Nic96 结合位点的破坏会产生生长和 mRNA 输出缺陷，揭示了它们在 NPC 正常功能中的关键作用。令人惊讶的是，这两种相互作用对于 NPC 定位都是可有可无的，这表明 Nup192 拥有另一个核孔蛋白相互作用伙伴。这些数据表明，衔接子核孔蛋白复合物中的结构域通过肽相互作用结合在一起，类似于在核传递蛋白·货物复合物中发现的肽相互作用，并且支持衔接子核孔蛋白源自祖先核传递蛋白的提议。
Nucleocytoplasmic transport is facilitated by nuclear pore complexes (NPCs), which are massive proteinaceous transport channels embedded in the nuclear envelope. Nup192 is a major component of an adaptor nucleoporin subcomplex proposed to link the NPC coat with the central transport channel. Here, we present the structure of the ∼110-kDa N-terminal domain (NTD) of Nup192 at 2.7-Å resolution. The structure reveals an open ring-shaped architecture composed of Huntingtin, EF3, PP2A, and TOR1 (HEAT) and Armadillo (ARM) repeats. A comparison of different conformations indicates that the NTD consists of two rigid halves connected by a flexible hinge. Unexpectedly, the two halves of the ring are structurally related to karyopherin-α (Kap-α) and β-karyopherin family members. Biochemically, we identify a conserved patch that binds an unstructured segment in Nup53 and show that a C-terminal tail region binds to a putative helical fragment in Nic96. The Nup53 segment that binds Nup192 is a classical nuclear localization-like sequence that interacts with Kap-α in a mutually exclusive and mechanistically distinct manner. The disruption of the Nup53 and Nic96 binding sites in vivo yields growth and mRNA export defects, revealing their critical role in proper NPC function. Surprisingly, both interactions are dispensable for NPC localization, suggesting that Nup192 possesses another nucleoporin interaction partner. These data indicate that the structured domains in the adaptor nucleoporin complex are held together by peptide interactions that resemble those found in karyopherin•cargo complexes and support the proposal that the adaptor nucleoporins arose from ancestral karyopherins.