Elevated levels of a U4/U6.U5 snRNP-associated protein, Spp381p, rescue a mutant defective in spliceosome maturation.
Elevated levels of a U4/U6.U5 snRNP-associated protein, Spp381p, rescue a mutant defective in spliceosome maturation.
复制标题
U4/U6.U5 snRNP 相关蛋白 Spp381p 水平升高可挽救剪接体成熟缺陷的突变体。
DOI：
10.1128/mcb.19.1.577
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发表时间：
1999
影响因子：
5.3
通讯作者：
Rymond,BC
中科院分区：
文献类型：
--
作者：
Lybarger,S;Beickman,K;Brown,V;Dembla-Rajpal,N;Morey,K;Seipelt,R;Rymond,BC
U4 snRNA从剪接体释放是通过一个重要的但不明确的依赖prp38p的步骤发生的。在这里，我们报告了剂量抑制筛选的结果，以确定有助于toprp38功能的基因。SPP381基因的表达升高可以有效地抑制温度敏感（Ts）突变体prp38-1的生长和剪接缺陷。这种抑制是特异性的，因为spp381表达的增强不会改变无内含子RNA转录物的丰度或抑制其他突变体的Ts表型。由于spp381不抑制aprp38::LEU2null等位基因，很明显Spp381p帮助Prp38p剪接，但不替代它。酵母spp381干扰物严重生长受损并积累未剪接的前mrna。免疫沉淀研究表明，与Prp38p一样，Spp381p存在于U4/U6中。U5三snrnp粒子。双杂交分析支持Spp381p的羧基一半直接与Prp38p蛋白相互作用的观点。Spp381p中一个假定的PEST蛋白水解结构域对于Spp381p - prp38p相互作用和抑制prp38-1是必不可少的，但它有助于Spp381p在剪接中的功能。奇怪的是，在体外，Spp381p可能不需要pre-mRNA剪接的化学反应。基于本研究的体内和体外实验结果，我们提出两个没有明显RNA结合结构域的酸性小蛋白Spp381p和Prp38p协同促进U4/U5。U6三snrnp在剪接体周期中的作用。
U4 snRNA release from the spliceosome occurs through an essential but ill-defined Prp38p-dependent step. Here we report the results of a dosage suppressor screen to identify genes that contribute toPRP38function. Elevated expression of a previously uncharacterized gene,SPP381, efficiently suppresses the growth and splicing defects of a temperature-sensitive (Ts) mutantprp38-1. This suppression is specific in that enhancedSPP381expression does not alter the abundance of intronless RNA transcripts or suppress the Ts phenotypes of otherprpmutants. SinceSPP381does not suppress aprp38::LEU2null allele, it is clear that Spp381p assists Prp38p in splicing but does not substitute for it. YeastSPP381disruptants are severely growth impaired and accumulate unspliced pre-mRNA. Immune precipitation studies show that, like Prp38p, Spp381p is present in the U4/U6.U5 tri-snRNP particle. Two-hybrid analyses support the view that the carboxyl half of Spp381p directly interacts with the Prp38p protein. A putative PEST proteolysis domain within Spp381p is dispensable for the Spp381p–Prp38p interaction and forprp38-1suppression but contributes to Spp381p function in splicing. Curiously, in vitro, Spp381p may not be needed for the chemistry of pre-mRNA splicing. Based on the in vivo and in vitro results presented here, we propose that two small acidic proteins without obvious RNA binding domains, Spp381p and Prp38p, act in concert to promote U4/U5.U6 tri-snRNP function in the spliceosome cycle.