The Ribosome Cooperates with the Assembly Chaperone pICln to Initiate Formation of snRNPs.
The Ribosome Cooperates with the Assembly Chaperone pICln to Initiate Formation of snRNPs.
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DOI：
10.1016/j.celrep.2016.08.047
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发表时间：
2016-09
期刊：
影响因子：
8.8
通讯作者：
E. Paknia;A. Chari;H. Stark;U. Fischer
中科院分区：
文献类型：
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作者：
E. Paknia;A. Chari;H. Stark;U. Fischer
在拥挤的细胞环境中，大分子复合物的形成通常需要装配伴侣的帮助。PRMT5和SMN复合物介导了前mrna加工小核核糖核蛋白颗粒（snRNPs）共同核心的组装任务。核心形成是由prmt5复合物亚基pICln启动的，它将核心蛋白预先排列到组装的snRNP所占据的空间位置。然后SMN复合体接受这些picn结合蛋白并将它们与小核RNA （snRNA）结合。在这里，我们分析了新合成的snRNP蛋白是如何进入组装途径以逃避错误组装的。我们发现它们最初与多肽出口通道附近的核糖体结合，并在与pICln结合时解离。与其释放活性相一致的是，pICln确保同源异聚物的形成并伴随其进入组装途径。我们的研究确定了核糖体质量控制中心是一个可以启动伴侣介导的大分子复合物组装的位点。
The formation of macromolecular complexes within the crowded environment of cells often requires aid from assembly chaperones. PRMT5 and SMN complexes mediate this task for the assembly of the common core of pre-mRNA processing small nuclear ribonucleoprotein particles (snRNPs). Core formation is initiated by the PRMT5-complex subunit pICln, which pre-arranges the core proteins into spatial positions occupied in the assembled snRNP. The SMN complex then accepts these pICln-bound proteins and unites them with small nuclear RNA (snRNA). Here, we have analyzed how newly synthesized snRNP proteins are channeled into the assembly pathway to evade mis-assembly. We show that they initially remain bound to the ribosome near the polypeptide exit tunnel and dissociate upon association with pICln. Coincident with its release activity, pICln ensures the formation of cognate heterooligomers and their chaperoned guidance into the assembly pathway. Our study identifies the ribosomal quality control hub as a site where chaperone-mediated assembly of macromolecular complexes can be initiated.