Proteasomes tether to two distinct sites at the nuclear pore complex.
Proteasomes tether to two distinct sites at the nuclear pore complex.
复制标题
DOI：
10.1073/pnas.1716305114
复制
发表时间：
2017-12-26
影响因子：
11.1
通讯作者：
Engel BD
中科院分区：
文献类型：
--
作者：
Albert S;Schaffer M;Beck F;Mosalaganti S;Asano S;Thomas HF;Plitzko JM;Beck M;Baumeister W;Engel BD
这项研究比较了细胞质和核蛋白酶体的天然结构，直接在细胞内可视化。每个隔室中蛋白酶体的组装状态和功能状态相似，表明每个蛋白酶体的蛋白水解活性水平相当。核蛋白酶体被拴系到核孔复合物（NPC）的两个不同位点：内核膜和NPC篮。结构分析揭示了两个拴系相互作用的机制细节。这些结果提供了蛋白酶体与NPC结合的直接证据，在细胞核和细胞质之间的通道处建立了蛋白质降解的细胞中心。这项工作展示了冷冻电子断层扫描如何通过直接观察天然细胞环境中分子复合物之间的相互作用来揭示生物学机制。细胞成分在细胞核和细胞质之间的分配是真核生物的定义特征。核孔复合物（NPC）选择性地门控这些隔室之间的大分子运输，但目前尚不清楚是否存在监督机制来加强这一功能。通过利用原位冷冻电子断层扫描成像的天然细胞环境的莱茵衣藻，我们观察到，核26 S蛋白酶体周围的NPC人群。通过亚断层图像平均和纳米精度定位的组合，我们确定了两类蛋白酶体通过其Rpn 9亚基拴系到两个特定的NPC位置：NPC篮上的结合位点，反映了其八重对称性和更丰富的结合位点在内核膜包围NPC。这些篮栓系和膜栓系的蛋白酶体，具有与细胞中其他地方的蛋白酶体相似的底物加工状态频率，理想地定位于调节转录并对转运NPC的可溶性和膜蛋白进行质量控制。
This study compares the native structures of cytosolic and nuclear proteasomes, visualized directly within cells. The assembly states and functional states of proteasomes in each compartment were similar, indicating comparable levels of proteolytic activity per proteasome. Nuclear proteasomes were tethered to two different sites at the nuclear pore complex (NPC): the inner nuclear membrane and the NPC basket. Structural analysis revealed mechanistic details of the two tethering interactions. These results present direct evidence that proteasomes bind at NPCs, establishing a cellular hub for protein degradation at the gateway between the nucleus and cytoplasm. This work demonstrates how cryo-electron tomography can reveal biological mechanisms by directly observing the interactions between molecular complexes within the native cellular environment. The partitioning of cellular components between the nucleus and cytoplasm is the defining feature of eukaryotic life. The nuclear pore complex (NPC) selectively gates the transport of macromolecules between these compartments, but it is unknown whether surveillance mechanisms exist to reinforce this function. By leveraging in situ cryo-electron tomography to image the native cellular environment of Chlamydomonas reinhardtii, we observed that nuclear 26S proteasomes crowd around NPCs. Through a combination of subtomogram averaging and nanometer-precision localization, we identified two classes of proteasomes tethered via their Rpn9 subunits to two specific NPC locations: binding sites on the NPC basket that reflect its eightfold symmetry and more abundant binding sites at the inner nuclear membrane that encircle the NPC. These basket-tethered and membrane-tethered proteasomes, which have similar substrate-processing state frequencies as proteasomes elsewhere in the cell, are ideally positioned to regulate transcription and perform quality control of both soluble and membrane proteins transiting the NPC.
登录
查看更多内容
影响因子：
7.7
作者：
Bykov YS;Schaffer M;Dodonova SO;Albert S;Plitzko JM;Baumeister W;Engel BD;Briggs JA
通讯作者：
Briggs JA
影响因子：
16.6
作者：
Eibauer, Matthias;Pellanda, Mauro;Turgay, Yagmur;Dubrovsky, Anna;Wild, Annik;Medalia, Ohad
通讯作者：
Medalia, Ohad
DOI：
10.1111/tpj.12795
发表时间：
2015-05
期刊：
The Plant journal : for cell and molecular biology
影响因子：
--
作者：
Cross FR;Umen JG
通讯作者：
Umen JG
DOI：
10.1083/jcb.200106046
发表时间：
2002-02-18
期刊：
The Journal of cell biology
影响因子：
--
作者：
Frosst P;Guan T;Subauste C;Hahn K;Gerace L
通讯作者：
Gerace L
影响因子：
8
作者：
Gallagher, Pamela S.;Oeser, Michelle L.;Abraham, Ayelet-chen;Kaganovich, Daniel;Gardner, Richard G.
通讯作者：
Gardner, Richard G.