Luc7p, a novel yeast U1 snRNP protein with role in 5′ splice site recognition
Luc7p, a novel yeast U1 snRNP protein with role in 5′ splice site recognition
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DOI：
10.1101/gad.13.18.2425
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发表时间：
1999-09-15
影响因子：
10.5
通讯作者：
Mattaj, IW
中科院分区：
文献类型：
--
作者：
Fortes, P;Bilbao-Cortés, D;Mattaj, IW
介绍了一种新型酵母剪接因子Luc 7 p的特性。LUC 7基因是通过在缺乏核帽结合复合物（CBC）的酵母菌株中导致致死性的突变来鉴定的。Luc 7 p在序列上类似于具有剪接因子家族特征的丝氨酸-丝氨酸和丝氨酸-谷氨酸重复序列的后生动物蛋白。我们表明，Luc 7 p是酵母U1 snRNP的组成部分，是营养生长所必需的。酵母U1 snRNP的组成在luc 7突变株中改变。这些菌株的提取物不能支持任何定义的剪接步骤，除非添加重组Luc 7 p。尽管在luc 7突变株中剪接野生型报告基因内含子的体内缺陷相对较轻，但具有非共有5'剪接位点或分支点序列的内含子的剪接在突变株中比野生型菌株中更有缺陷。通过使用具有两个竞争性5'剪接位点的报告基因，在luc 7细胞中观察到与帽近端剪接位点的有效剪接的损失，类似于在缺乏CBC的菌株中观察到的缺陷。CBC可以与来自野生型的U1 snRNP共沉淀，但不能与来自luc 7酵母菌株的U1 snRNP共沉淀。这些数据表明Luc 7 p的缺失破坏了U1 snRNP-CBC相互作用，并且这种相互作用有助于正常的5'剪接位点识别。
The characterization of a novel yeast-splicing factor, Luc7p, is presented. The LUC7 gene was identified by a mutation that causes lethality in a yeast strain lacking the nuclear cap-binding complex (CBC). Luc7p is similar in sequence to metazoan proteins that have arginine-serine and arginine-glutamic acid repeat sequences characteristic of a family of splicing factors. We show that Luc7p is a component of yeast U1 snRNP and is essential for vegetative growth. The composition of yeast U1 snRNP is altered in luc7 mutant strains. Extracts of these strains are unable to support any of the defined steps of splicing unless recombinant Luc7p is added. Although the in vivo defect in splicing wild-type reporter introns in a luc7 mutant strain is comparatively mild, splicing of introns with nonconsensus 5' splice site or branchpoint sequences is more defective in the mutant strain than in wild-type strains. By use of reporters that have two competing 5' splice sites, a loss of efficient splicing to the cap proximal splice site is observed in luc7 cells, analogous to the defect seen in strains lacking CBC. CBC can be coprecipitated with U1 snRNP from wild-type, but not from luc7, yeast strains. These data suggest that the loss of Luc7p disrupts U1 snRNP-CBC interaction, and that this interaction contributes to normal 5' splice site recognition.