Functional interactions between Prp8, Prp18, Slu7, and U5 snRNA during the second step of pre-mRNA splicing
Functional interactions between Prp8, Prp18, Slu7, and U5 snRNA during the second step of pre-mRNA splicing
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DOI：
10.1261/rna.572807
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发表时间：
2007-09-01
期刊：
影响因子：
4.5
通讯作者：
Schwer, Beate
中科院分区：
文献类型：
--
作者：
Aronova, Anna;Bacikova, Dagmar;Schwer, Beate
在前体mRNA剪接的第二个酯交换步骤之后，Prp 22解旋酶通过破坏可能涉及Prp 8的剪接体中的接触来催化剪接mRNA的释放。Prp 8中Arg 1753的突变抑制解旋酶缺陷型prp 22突变体，引起温度敏感性生长表型，表明涉及Prp 8-R1753的剪接体中的相互作用可能在37 ℃下过早地被破坏。在这里，我们报告说，在环I的U 5 snRNA或Prp 18突变可以抑制温度敏感的prp 8-R1753突变体。相同的功能获得性PRP 18等位基因也可以减轻多种slu 7-ts突变体的生长表型，表明Prp 8与第二步剪接因子Prp 18和Slu 7之间存在功能联系。这些发现以及Prp 8中Arg 1753的变化损害了体外前体mRNA剪接的第2步的证明，与以下模型一致：（1）Arg 1753在外显子连接之前稳定U 5/外显子相互作用中起作用，（2）这些接触持续存在，直到它们被解旋酶Prp 22破坏。
After the second transesterification step of pre-mRNA splicing, the Prp22 helicase catalyzes release of spliced mRNA by disrupting contacts in the spliceosome that likely involve Prp8. Mutations at Arg1753 in Prp8, which suppress helicase-defective prp22 mutants, elicit temperature-sensitive growth phenotypes, indicating that interactions in the spliceosome involving Prp8-R1753 might be broken prematurely at 37 degrees C. Here we report that mutations in loop I of the U5 snRNA or in Prp18 can suppress the temperature-sensitive prp8-R1753 mutants. The same gain-of-function PRP18 alleles can also alleviate the growth phenotypes of multiple slu7-ts mutants, indicating a functional link between Prp8 and the second step splicing factors Prp18 and Slu7. These findings, together with the demonstration that changes at Arg1753 in Prp8 impair step 2 of pre-mRNA splicing in vitro, are consistent with a model in which (1) Arg1753 plays a role in stabilizing U5/exon interactions prior to exon joining and (2) these contacts persist until they are broken by the helicase Prp22.