SUPPRESSORS OF A U4 SNRNA MUTATION DEFINE A NOVEL U6 SNRNP PROTEIN WITH RNA-BINDING MOTIFS
SUPPRESSORS OF A U4 SNRNA MUTATION DEFINE A NOVEL U6 SNRNP PROTEIN WITH RNA-BINDING MOTIFS
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DOI：
10.1101/gad.5.5.773
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发表时间：
1991-05-01
影响因子：
10.5
通讯作者：
GUTHRIE, C
中科院分区：
文献类型：
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作者：
SHANNON, KW;GUTHRIE, C
U4 和 U6 小核 RNA 通过广泛的碱基配对相互作用相关联，每一轮剪接都必须破坏和重组这种相互作用。 U4/U6 相互作用域内的 U4 突变会在体外破坏复合物的稳定性，并在体内引起冷敏感表型。 U6 中的显性（功能获得）补偿性突变使 U4/U6 螺旋重新稳定，导致野生型生长。冷不敏感生长也可以通过两类隐性（功能丧失）抑制因子来恢复：（1）PRP24 突变，我们证明它是 RNP 共有家族的 U6 特异性结合蛋白； (2) U6 中的突变，位于相互作用域之外并识别假定的 PRP24 结合位点。 U4/U6 螺旋的不稳定会导致 PRP24/U4/U6 复合物的积累，这在野生型细胞中是检测不到的。功能丧失抑制突变抑制 PRP24 与 U6 的结合，因此可能促进 PRP24 从 PRP24/U4/U6 复合物中释放以及碱基配对的 U4/U6 snRNP 的重组。我们认为 PRP24/U4/U6 复合物通常是剪接体循环中高度瞬时的中间体，并且 PRP24 促进 U6 与 U4 的重新退火。
U4 and U6 small nuclear RNAs are associated by an extensive base-pairing interaction that must be disrupted and reformed with each round of splicing. U4 mutations within the U4/U6 interaction domain destabilize the complex in vitro and cause a cold-sensitive phenotype in vivo. Restabilization of the U4/U6 helix by dominant (gain-of-function), compensatory mutations in U6 results in wild-type growth. Cold-insensitive growth can also be restored by two classes of recessive (loss-of-function) suppressors: (1) mutations in PRP24, which we show to be a U6-specific binding protein of the RNP-consensus family; and (2) mutations in U6, which lie outside the interaction domain and identify putative PRP24-binding sites. Destabilization of the U4/U6 helix causes the accumulation of a PRP24/U4/U6 complex, which is undetectable in wild-type cells. The loss-of-function suppressor mutations inhibit the binding of PRP24 to U6, and thus presumably promote the release of PRP24 from the PRP24/U4/U6 complex and the reformation of the base-paired U4/U6 snRNP. We propose that the PRP24/U4/U6 complex is normally a highly transient intermediate in the spliceosome cycle and that PRP24 promotes the reannealing of U6 with U4.