Synchronizing Nuclear Import of Ribosomal Proteins with Ribosome Assembly
Synchronizing Nuclear Import of Ribosomal Proteins with Ribosome Assembly
复制标题
DOI：
10.1126/science.1226960
复制
发表时间：
2012-11-02
期刊：
影响因子：
56.9
通讯作者：
Hurt, Ed
中科院分区：
文献类型：
--
作者：
Kressler, Dieter;Bange, Gert;Hurt, Ed
核糖体蛋白在细胞核输入和与核糖体RNA （rRNA）组装之前在细胞质中合成。关于核糖体组装与核胞质转运的协调，我们所知甚少。在这里，我们发现了一个转运适配器，Syo1，它促进了两个5S-rRNA结合蛋白Rpl5和Rpl11的同步共导入。体外研究表明Syo1可同时结合Rpl5-Rpl11，并进一步招募输入受体Kap104。Syo1-Rpl5-Rpl11导入复合物通过RanGTP从Kap104中释放出来，可以直接转移到5S rRNA上。Syo1可以通过与苯丙氨酸-甘氨酸核孔蛋白相互作用而穿梭回细胞质。x射线晶体学揭示了a-螺线管对称蛋白是如何将Rpl5氨基端（通常与5S rRNA结合）容纳在一个延伸的凹槽中。同体位蛋白介导的Rpl5-Rpl11的共导入可以确保这些蛋白在60s前核糖体中的协调和化学计量结合。
Ribosomal proteins are synthesized in the cytoplasm, before nuclear import and assembly with ribosomal RNA (rRNA). Little is known about coordination of nucleocytoplasmic transport with ribosome assembly. Here, we identify a transport adaptor, symportin 1 (Syo1), that facilitates synchronized coimport of the two 5S-rRNA binding proteins Rpl5 and Rpl11. In vitro studies revealed that Syo1 concomitantly binds Rpl5-Rpl11 and furthermore recruits the import receptor Kap104. The Syo1-Rpl5-Rpl11 import complex is released from Kap104 by RanGTP and can be directly transferred onto the 5S rRNA. Syo1 can shuttle back to the cytoplasm by interaction with phenylalanine-glycine nucleoporins. X-ray crystallography uncovered how the a-solenoid symportin accommodates the Rpl5 amino terminus, normally bound to 5S rRNA, in an extended groove. Symportin-mediated coimport of Rpl5-Rpl11 could ensure coordinated and stoichiometric incorporation of these proteins into pre-60S ribosomes.