来自德国海德堡大学的研究人员发现细胞转运适配体蛋白——同向转运体(Syo1)介导一对5S-rRNA结合蛋白——Rpl5和Rpl11按化学计量比共同转运到细胞核中。

-2012年11月2日《科学》

中文翻译


【题目】研究发现核糖体蛋白的核输入过程与核糖体组装同步进行

【译文】核糖体蛋白在细胞质中合成,随后与核糖体RNA(rRNA)结合,再进入细胞核内。细胞核与细胞质物质交换与核糖体组装如何协调运行,相关的机制还知之甚少。本研究鉴定到一个转运适配体蛋白——同向转运体1(Syo1),它能促进两个5S-rRNA结合蛋白Rpl5和Rpl11同步共转入到细胞核中。体外研究表明Syo1能够同时结合Rpl5-Rpl11,而且还能招募输入受体Kap104。RanGTP将Kap104从Syo1-Rpl5-Rpl11输入复合物上脱下,然后Syo1-Rpl5-Rpl11输入复合物直接转移到5S rRNA上。Syo1通过与苯丙氨酸-甘氨酸核孔蛋白互作,跨越核膜回到细胞质中。X射线晶体学研究揭示α螺旋的同向转运体如何容纳Rpl5的氨基末端,一般情况下,Rpl5的氨基末端是结合到5S rRNA上扩展的凹槽中。同向转运体介导的Rpl5-Rpl11共转运能够确保这些蛋白协调地且按化学计量比相结合,最终形成前60S核糖体。

英文原稿


[Title]: Synchronizing Nuclear Import of Ribosomal Proteins with Ribosome Assembly

[Authors]: Dieter Kressler, Gert Bange, Yutaka Ogawa, Goran Stjepanovic, Bettina Bradatsch, Dagmar Pratte, Stefan Amlacher, Daniela Strauß, Yoshihiro Yoneda, Jun Katahira, Irmgard Sinning, and Ed Hurt

[Abstract]: 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 α-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.

原文地址

http://www.sciencemag.org/content/338/6107/666.abstract

 

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