Protein-protein and protein-RNA contacts both contribute to the 15.5K-mediated assembly of the U4/U6 snRNP and the box C/D snoRNPs
Protein-protein and protein-RNA contacts both contribute to the 15.5K-mediated assembly of the U4/U6 snRNP and the box C/D snoRNPs
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DOI：
10.1128/mcb.02374-05
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发表时间：
2006-07-01
影响因子：
5.3
通讯作者：
Luehrmann, Reinhard
中科院分区：
文献类型：
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作者：
Schultz, Annemarie;Nottrott, Stephanie;Luehrmann, Reinhard
k-转角结合蛋白15.5 K是独特的，因为它对于组成和功能都不同的三种RNP复合物的分级组装是必需的，即，U4/U6 snRNP、盒C/D snoRNP和组装在U3盒B/C基序上的RNP复合物。15.5K通过诱导配合机制与同源RNA相互作用，这导致周围RNA的折叠，以产生RNP特异性蛋白的结合位点。然而，15.5K也可能通过与复合物特异性蛋白质的蛋白质-蛋白质相互作用介导RNP形成。为了研究这种可能性，我们创建了一系列15.5K突变，其中蛋白质的表面性质已经改变。我们评估了它们支持三种不同RNP复合物形成的能力，发现每个RNP的形成需要15.5K表面上的一组不同区域。这意味着蛋白质-蛋白质接触对于每个复合物中的RNP形成是必不可少的。进一步支持这一观点，可以在hU 3 - 55 K和15.5K之间观察到直接的蛋白质-蛋白质相互作用。总之，我们的数据表明，每个RNP的形成涉及15.5K蛋白和特定RNA中的特定元件的直接识别。
The k-turn-binding protein 15.5K is unique in that it is essential for the hierarchical assembly of three RNP complexes distinct in both composition and function, namely, the U4/U6 snRNP, the box C/D snoRNP, and the RNP complex assembled on the U3 box B/C motif. 15.5K interacts with the cognate RNAs via an induced fit mechanism, which results in the folding of the surrounding RNA to create a binding site(s) for the RNP-specific proteins. However, it is possible that 15.5K also mediates RNP formation via protein-protein interactions with the complex-specific proteins. To investigate this possibility, we created a series of 15.5K mutations in which the surface properties of the protein had been changed. We assessed their ability to support the formation of the three distinct RNP complexes and found that the formation of each RNP requires a distinct set of regions on the surface of 15.5K. This implies that protein-protein contacts are essential for RNP formation in each complex. Further supporting this idea, direct protein-protein interaction could be observed between hU3-55K and 15.5K. In conclusion, our data suggest that the formation of each RNP involves the direct recognition of specific elements in both 15.5K protein and the specific RNA.