The network of protein-protein interactions within the human U4/U6.U5 tri-snRNP
The network of protein-protein interactions within the human U4/U6.U5 tri-snRNP
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DOI：
10.1261/rna.55406
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发表时间：
2006-07-01
期刊：
影响因子：
4.5
通讯作者：
Luehrmann, Reinhard
中科院分区：
文献类型：
--
作者：
Liu, Sunbin;Rauhut, Reinhard;Luehrmann, Reinhard
人25 S U4/U6.U5三-snRNP是U2型剪接体的主要结构单元，除了U4、U6和U 5 snRNA外，还含有至少30种不同的蛋白质。为了了解更多关于三-snRNP的分子结构，我们已经研究了三-snRNP蛋白质之间的相互作用，使用酵母双杂交试验和体外结合试验，此外，已经确定了不同的蛋白质结构域，这是至关重要的连接，这种蛋白质网络在人类三-snRNP。这些研究揭示了U 5蛋白hPrp 8、hBrr 2（一种DExH/D-box解旋酶）和hSnu 114（一种推定的GTdR）的不同结构域之间的多种相互作用，这些结构域是剪接体催化活化的关键参与者，在此期间，U4/U6碱基配对相互作用被破坏，U4从剪接体释放。U 5特异性的、含有TPR/HAT重复序列的hPrp 6蛋白和tri-snRNP特异性的hSnu 66蛋白都与几种U 5和U4/U6相关蛋白相互作用，包括与U6 snRNA接触的hBrr 2和hPrp 3。因此，这两种蛋白质都位于三-snRNP复合物中U 5和U4/U6之间的界面，并且可能在剪接体激活期间将U 5 snRNP中的hBrr 2和hSnu 114的活性传递到U4/U6双链体中发挥重要作用。对这些蛋白质相互作用的更详细分析表明，不同的HAT重复序列介导与特定hPrp 6伴侣的相互作用。总之，本文提供的数据提供了人三-snRNP内蛋白质相互作用网络的详细图片。
The human 25S U4/U6.U5 tri-snRNP is a major building block of the U2-type spliceosome and contains, in addition to the U4, U6, and U5 snRNAs, at least 30 distinct proteins. To learn more about the molecular architecture of the tri-snRNP, we have investigated interactions between tri-snRNP proteins using the yeast two-hybrid assay and in vitro binding assays, and, in addition, have identified distinct protein domains that are critical for the connectivity of this protein network in the human tri-snRNP. These studies revealed multiple interactions between distinct domains of the U5 proteins hPrp8, hBrr2 (a DExH/D-box helicase), and hSnu114 ( a putative GTPase), which are key players in the catalytic activation of the spliceosome, during which the U4/U6 base-pairing interaction is disrupted and U4 is released from the spliceosome. Both the U5-specific, TPR/HAT-repeat-containing hPrp6 protein and the tri-snRNP-specific hSnu66 protein interact with several U5- and U4/U6-associated proteins, including hBrr2 and hPrp3, which contacts the U6 snRNA. Thus, both proteins are located at the interface between U5 and U4/U6 in the tri-snRNP complex, and likely play an important role in transmitting the activity of hBrr2 and hSnu114 in the U5 snRNP to the U4/U6 duplex during spliceosome activation. A more detailed analysis of these protein interactions revealed that different HAT repeats mediate interactions with specific hPrp6 partners. Taken together, data presented here provide a detailed picture of the network of protein interactions within the human tri-snRNP.